2078 lines
64 KiB
C++
Executable file
2078 lines
64 KiB
C++
Executable file
/*
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* Copyright (C) 2008, 2009 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <dlfcn.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/auxvec.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/atomics.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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// Private C library headers.
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#include <private/bionic_tls.h>
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#include <private/logd.h>
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#include <private/ScopedPthreadMutexLocker.h>
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#include "linker.h"
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#include "linker_debug.h"
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#include "linker_environ.h"
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#include "linker_format.h"
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#include "linker_phdr.h"
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/* Assume average path length of 64 and max 8 paths */
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#define LDPATH_BUFSIZE 512
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#define LDPATH_MAX 8
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#define LDPRELOAD_BUFSIZE 512
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#define LDPRELOAD_MAX 8
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/* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<<
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*
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* Do NOT use malloc() and friends or pthread_*() code here.
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* Don't use printf() either; it's caused mysterious memory
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* corruption in the past.
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* The linker runs before we bring up libc and it's easiest
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* to make sure it does not depend on any complex libc features
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*
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* open issues / todo:
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*
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* - are we doing everything we should for ARM_COPY relocations?
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* - cleaner error reporting
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* - after linking, set as much stuff as possible to READONLY
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* and NOEXEC
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*/
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static bool soinfo_link_image(soinfo* si);
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// We can't use malloc(3) in the dynamic linker. We use a linked list of anonymous
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// maps, each a single page in size. The pages are broken up into as many struct soinfo
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// objects as will fit, and they're all threaded together on a free list.
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#define SOINFO_PER_POOL ((PAGE_SIZE - sizeof(soinfo_pool_t*)) / sizeof(soinfo))
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struct soinfo_pool_t {
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soinfo_pool_t* next;
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soinfo info[SOINFO_PER_POOL];
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};
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static struct soinfo_pool_t* gSoInfoPools = NULL;
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static soinfo* gSoInfoFreeList = NULL;
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static soinfo *solist = &libdl_info;
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static soinfo *sonext = &libdl_info;
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static soinfo *somain; /* main process, always the one after libdl_info */
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static const char* const gSoPaths[] = {
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"/vendor/lib",
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"/system/lib",
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NULL
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};
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static char gLdPathsBuffer[LDPATH_BUFSIZE];
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static const char* gLdPaths[LDPATH_MAX + 1];
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static char gLdPreloadsBuffer[LDPRELOAD_BUFSIZE];
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static const char* gLdPreloadNames[LDPRELOAD_MAX + 1];
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static soinfo *preloads[LDPRELOAD_MAX + 1];
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static int debug_verbosity;
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enum RelocationKind {
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kRelocAbsolute = 0,
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kRelocRelative,
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kRelocCopy,
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kRelocSymbol,
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kRelocMax
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};
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#if STATS
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struct linker_stats_t {
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int count[kRelocMax];
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};
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static linker_stats_t linker_stats;
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static void count_relocation(RelocationKind kind) {
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++linker_stats.count[kind];
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}
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#else
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static void count_relocation(RelocationKind) {
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}
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#endif
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#if COUNT_PAGES
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static unsigned bitmask[4096];
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#define MARK(offset) \
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do { \
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bitmask[((offset) >> 12) >> 3] |= (1 << (((offset) >> 12) & 7)); \
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} while(0)
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#else
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#define MARK(x) do {} while (0)
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#endif
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// You shouldn't try to call memory-allocating functions in the dynamic linker.
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// Guard against the most obvious ones.
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#define DISALLOW_ALLOCATION(return_type, name, ...) \
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return_type name __VA_ARGS__ \
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{ \
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const char* msg = "ERROR: " #name " called from the dynamic linker!\n"; \
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__libc_android_log_write(ANDROID_LOG_FATAL, "linker", msg); \
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write(2, msg, strlen(msg)); \
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abort(); \
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}
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#define UNUSED __attribute__((unused))
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DISALLOW_ALLOCATION(void*, malloc, (size_t u UNUSED));
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DISALLOW_ALLOCATION(void, free, (void* u UNUSED));
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DISALLOW_ALLOCATION(void*, realloc, (void* u1 UNUSED, size_t u2 UNUSED));
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DISALLOW_ALLOCATION(void*, calloc, (size_t u1 UNUSED, size_t u2 UNUSED));
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static char tmp_err_buf[768];
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static char __linker_dl_err_buf[768];
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#define DL_ERR(fmt, x...) \
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do { \
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format_buffer(__linker_dl_err_buf, sizeof(__linker_dl_err_buf), fmt, ##x); \
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/* If LD_DEBUG is set high enough, send every dlerror(3) message to the log. */ \
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DEBUG(fmt "\n", ##x); \
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} while(0)
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const char* linker_get_error() {
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return &__linker_dl_err_buf[0];
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}
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/*
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* This function is an empty stub where GDB locates a breakpoint to get notified
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* about linker activity.
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*/
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extern "C" void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity();
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static r_debug _r_debug = {1, NULL, &rtld_db_dlactivity,
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RT_CONSISTENT, 0};
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static link_map* r_debug_tail = 0;
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static pthread_mutex_t gDebugMutex = PTHREAD_MUTEX_INITIALIZER;
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static void insert_soinfo_into_debug_map(soinfo * info) {
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// Copy the necessary fields into the debug structure.
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link_map* map = &(info->linkmap);
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map->l_addr = info->base;
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map->l_name = (char*) info->name;
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map->l_ld = (uintptr_t)info->dynamic;
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/* Stick the new library at the end of the list.
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* gdb tends to care more about libc than it does
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* about leaf libraries, and ordering it this way
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* reduces the back-and-forth over the wire.
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*/
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if (r_debug_tail) {
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r_debug_tail->l_next = map;
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map->l_prev = r_debug_tail;
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map->l_next = 0;
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} else {
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_r_debug.r_map = map;
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map->l_prev = 0;
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map->l_next = 0;
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}
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r_debug_tail = map;
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}
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static void remove_soinfo_from_debug_map(soinfo* info) {
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link_map* map = &(info->linkmap);
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if (r_debug_tail == map) {
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r_debug_tail = map->l_prev;
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}
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if (map->l_prev) {
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map->l_prev->l_next = map->l_next;
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}
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if (map->l_next) {
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map->l_next->l_prev = map->l_prev;
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}
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}
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static void notify_gdb_of_load(soinfo* info) {
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if (info->flags & FLAG_EXE) {
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// GDB already knows about the main executable
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return;
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}
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ScopedPthreadMutexLocker locker(&gDebugMutex);
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_r_debug.r_state = RT_ADD;
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rtld_db_dlactivity();
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insert_soinfo_into_debug_map(info);
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_r_debug.r_state = RT_CONSISTENT;
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rtld_db_dlactivity();
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}
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static void notify_gdb_of_unload(soinfo* info) {
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if (info->flags & FLAG_EXE) {
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// GDB already knows about the main executable
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return;
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}
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ScopedPthreadMutexLocker locker(&gDebugMutex);
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_r_debug.r_state = RT_DELETE;
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rtld_db_dlactivity();
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remove_soinfo_from_debug_map(info);
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_r_debug.r_state = RT_CONSISTENT;
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rtld_db_dlactivity();
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}
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void notify_gdb_of_libraries() {
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_r_debug.r_state = RT_ADD;
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rtld_db_dlactivity();
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_r_debug.r_state = RT_CONSISTENT;
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rtld_db_dlactivity();
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}
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static bool ensure_free_list_non_empty() {
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if (gSoInfoFreeList != NULL) {
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return true;
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}
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// Allocate a new pool.
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soinfo_pool_t* pool = reinterpret_cast<soinfo_pool_t*>(mmap(NULL, sizeof(*pool),
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PROT_READ|PROT_WRITE,
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MAP_PRIVATE|MAP_ANONYMOUS, 0, 0));
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if (pool == MAP_FAILED) {
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return false;
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}
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// Add the pool to our list of pools.
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pool->next = gSoInfoPools;
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gSoInfoPools = pool;
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// Chain the entries in the new pool onto the free list.
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gSoInfoFreeList = &pool->info[0];
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soinfo* next = NULL;
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for (int i = SOINFO_PER_POOL - 1; i >= 0; --i) {
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pool->info[i].next = next;
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next = &pool->info[i];
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}
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return true;
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}
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static void set_soinfo_pool_protection(int protection) {
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for (soinfo_pool_t* p = gSoInfoPools; p != NULL; p = p->next) {
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if (mprotect(p, sizeof(*p), protection) == -1) {
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abort(); // Can't happen.
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}
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}
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}
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static soinfo* soinfo_alloc(const char* name) {
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if (strlen(name) >= SOINFO_NAME_LEN) {
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DL_ERR("library name \"%s\" too long", name);
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return NULL;
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}
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|
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if (!ensure_free_list_non_empty()) {
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DL_ERR("out of memory when loading \"%s\"", name);
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return NULL;
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}
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// Take the head element off the free list.
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soinfo* si = gSoInfoFreeList;
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gSoInfoFreeList = gSoInfoFreeList->next;
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// Initialize the new element.
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memset(si, 0, sizeof(soinfo));
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strlcpy(si->name, name, sizeof(si->name));
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sonext->next = si;
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sonext = si;
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TRACE("name %s: allocated soinfo @ %p\n", name, si);
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return si;
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}
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static void soinfo_free(soinfo* si)
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{
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if (si == NULL) {
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return;
|
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}
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soinfo *prev = NULL, *trav;
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TRACE("name %s: freeing soinfo @ %p\n", si->name, si);
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for(trav = solist; trav != NULL; trav = trav->next){
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if (trav == si)
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break;
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prev = trav;
|
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}
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if (trav == NULL) {
|
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/* si was not ni solist */
|
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DL_ERR("name \"%s\" is not in solist!", si->name);
|
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return;
|
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}
|
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|
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/* prev will never be NULL, because the first entry in solist is
|
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always the static libdl_info.
|
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*/
|
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prev->next = si->next;
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if (si == sonext) sonext = prev;
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si->next = gSoInfoFreeList;
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gSoInfoFreeList = si;
|
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}
|
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|
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#ifdef ANDROID_ARM_LINKER
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|
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/* For a given PC, find the .so that it belongs to.
|
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* Returns the base address of the .ARM.exidx section
|
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* for that .so, and the number of 8-byte entries
|
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* in that section (via *pcount).
|
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*
|
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* Intended to be called by libc's __gnu_Unwind_Find_exidx().
|
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*
|
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* This function is exposed via dlfcn.cpp and libdl.so.
|
|
*/
|
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_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int *pcount)
|
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{
|
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soinfo *si;
|
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unsigned addr = (unsigned)pc;
|
|
|
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for (si = solist; si != 0; si = si->next){
|
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if ((addr >= si->base) && (addr < (si->base + si->size))) {
|
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*pcount = si->ARM_exidx_count;
|
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return (_Unwind_Ptr)si->ARM_exidx;
|
|
}
|
|
}
|
|
*pcount = 0;
|
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return NULL;
|
|
}
|
|
|
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#elif defined(ANDROID_X86_LINKER) || defined(ANDROID_MIPS_LINKER)
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|
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/* Here, we only have to provide a callback to iterate across all the
|
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* loaded libraries. gcc_eh does the rest. */
|
|
int
|
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dl_iterate_phdr(int (*cb)(dl_phdr_info *info, size_t size, void *data),
|
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void *data)
|
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{
|
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int rv = 0;
|
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for (soinfo* si = solist; si != NULL; si = si->next) {
|
|
dl_phdr_info dl_info;
|
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dl_info.dlpi_addr = si->linkmap.l_addr;
|
|
dl_info.dlpi_name = si->linkmap.l_name;
|
|
dl_info.dlpi_phdr = si->phdr;
|
|
dl_info.dlpi_phnum = si->phnum;
|
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rv = cb(&dl_info, sizeof(dl_phdr_info), data);
|
|
if (rv != 0) {
|
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break;
|
|
}
|
|
}
|
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return rv;
|
|
}
|
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|
|
#endif
|
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|
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static Elf32_Sym *soinfo_elf_lookup(soinfo *si, unsigned hash, const char *name)
|
|
{
|
|
Elf32_Sym *s;
|
|
Elf32_Sym *symtab = si->symtab;
|
|
const char *strtab = si->strtab;
|
|
unsigned n;
|
|
|
|
TRACE_TYPE(LOOKUP, "SEARCH %s in %s@0x%08x %08x %d\n",
|
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name, si->name, si->base, hash, hash % si->nbucket);
|
|
n = hash % si->nbucket;
|
|
|
|
for(n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]){
|
|
s = symtab + n;
|
|
if(strcmp(strtab + s->st_name, name)) continue;
|
|
|
|
/* only concern ourselves with global and weak symbol definitions */
|
|
switch(ELF32_ST_BIND(s->st_info)){
|
|
case STB_GLOBAL:
|
|
case STB_WEAK:
|
|
if(s->st_shndx == SHN_UNDEF)
|
|
continue;
|
|
|
|
TRACE_TYPE(LOOKUP, "FOUND %s in %s (%08x) %d\n",
|
|
name, si->name, s->st_value, s->st_size);
|
|
return s;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static unsigned elfhash(const char *_name)
|
|
{
|
|
const unsigned char *name = (const unsigned char *) _name;
|
|
unsigned h = 0, g;
|
|
|
|
while(*name) {
|
|
h = (h << 4) + *name++;
|
|
g = h & 0xf0000000;
|
|
h ^= g;
|
|
h ^= g >> 24;
|
|
}
|
|
return h;
|
|
}
|
|
|
|
static Elf32_Sym *
|
|
soinfo_do_lookup(soinfo *si, const char *name, soinfo **lsi,
|
|
soinfo *needed[])
|
|
{
|
|
unsigned elf_hash = elfhash(name);
|
|
Elf32_Sym *s = NULL;
|
|
int i;
|
|
|
|
if (si != NULL && somain != NULL) {
|
|
|
|
/*
|
|
* Local scope is executable scope. Just start looking into it right away
|
|
* for the shortcut.
|
|
*/
|
|
|
|
if (si == somain) {
|
|
s = soinfo_elf_lookup(si, elf_hash, name);
|
|
if (s != NULL) {
|
|
*lsi = si;
|
|
goto done;
|
|
}
|
|
} else {
|
|
/* Order of symbol lookup is controlled by DT_SYMBOLIC flag */
|
|
|
|
/*
|
|
* If this object was built with symbolic relocations disabled, the
|
|
* first place to look to resolve external references is the main
|
|
* executable.
|
|
*/
|
|
|
|
if (!si->has_DT_SYMBOLIC) {
|
|
DEBUG("%s: looking up %s in executable %s\n",
|
|
si->name, name, somain->name);
|
|
s = soinfo_elf_lookup(somain, elf_hash, name);
|
|
if (s != NULL) {
|
|
*lsi = somain;
|
|
goto done;
|
|
}
|
|
}
|
|
|
|
/* Look for symbols in the local scope (the object who is
|
|
* searching). This happens with C++ templates on i386 for some
|
|
* reason.
|
|
*
|
|
* Notes on weak symbols:
|
|
* The ELF specs are ambiguous about treatment of weak definitions in
|
|
* dynamic linking. Some systems return the first definition found
|
|
* and some the first non-weak definition. This is system dependent.
|
|
* Here we return the first definition found for simplicity. */
|
|
|
|
s = soinfo_elf_lookup(si, elf_hash, name);
|
|
if (s != NULL) {
|
|
*lsi = si;
|
|
goto done;
|
|
}
|
|
|
|
/*
|
|
* If this object was built with -Bsymbolic and symbol is not found
|
|
* in the local scope, try to find the symbol in the main executable.
|
|
*/
|
|
|
|
if (si->has_DT_SYMBOLIC) {
|
|
DEBUG("%s: looking up %s in executable %s after local scope\n",
|
|
si->name, name, somain->name);
|
|
s = soinfo_elf_lookup(somain, elf_hash, name);
|
|
if (s != NULL) {
|
|
*lsi = somain;
|
|
goto done;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Next, look for it in the preloads list */
|
|
for(i = 0; preloads[i] != NULL; i++) {
|
|
s = soinfo_elf_lookup(preloads[i], elf_hash, name);
|
|
if(s != NULL) {
|
|
*lsi = preloads[i];
|
|
goto done;
|
|
}
|
|
}
|
|
|
|
for(i = 0; needed[i] != NULL; i++) {
|
|
DEBUG("%s: looking up %s in %s\n",
|
|
si->name, name, needed[i]->name);
|
|
s = soinfo_elf_lookup(needed[i], elf_hash, name);
|
|
if (s != NULL) {
|
|
*lsi = needed[i];
|
|
goto done;
|
|
}
|
|
}
|
|
|
|
done:
|
|
if(s != NULL) {
|
|
TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = 0x%08x, "
|
|
"found in %s, base = 0x%08x, load bias = 0x%08x\n",
|
|
si->name, name, s->st_value,
|
|
(*lsi)->name, (*lsi)->base, (*lsi)->load_bias);
|
|
return s;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/* This is used by dl_sym(). It performs symbol lookup only within the
|
|
specified soinfo object and not in any of its dependencies.
|
|
*/
|
|
Elf32_Sym *soinfo_lookup(soinfo *si, const char *name)
|
|
{
|
|
return soinfo_elf_lookup(si, elfhash(name), name);
|
|
}
|
|
|
|
/* This is used by dl_sym(). It performs a global symbol lookup.
|
|
*/
|
|
Elf32_Sym *lookup(const char *name, soinfo **found, soinfo *start)
|
|
{
|
|
unsigned elf_hash = elfhash(name);
|
|
Elf32_Sym *s = NULL;
|
|
soinfo *si;
|
|
|
|
if(start == NULL) {
|
|
start = solist;
|
|
}
|
|
|
|
for(si = start; (s == NULL) && (si != NULL); si = si->next)
|
|
{
|
|
if(si->flags & FLAG_ERROR)
|
|
continue;
|
|
s = soinfo_elf_lookup(si, elf_hash, name);
|
|
if (s != NULL) {
|
|
*found = si;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if(s != NULL) {
|
|
TRACE_TYPE(LOOKUP, "%s s->st_value = 0x%08x, si->base = 0x%08x\n",
|
|
name, s->st_value, si->base);
|
|
return s;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
soinfo *find_containing_library(const void *addr)
|
|
{
|
|
soinfo *si;
|
|
|
|
for(si = solist; si != NULL; si = si->next)
|
|
{
|
|
if((unsigned)addr >= si->base && (unsigned)addr - si->base < si->size) {
|
|
return si;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
Elf32_Sym *soinfo_find_symbol(soinfo* si, const void *addr)
|
|
{
|
|
unsigned int i;
|
|
unsigned soaddr = (unsigned)addr - si->base;
|
|
|
|
/* Search the library's symbol table for any defined symbol which
|
|
* contains this address */
|
|
for(i=0; i<si->nchain; i++) {
|
|
Elf32_Sym *sym = &si->symtab[i];
|
|
|
|
if(sym->st_shndx != SHN_UNDEF &&
|
|
soaddr >= sym->st_value &&
|
|
soaddr < sym->st_value + sym->st_size) {
|
|
return sym;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
#if 0
|
|
static void dump(soinfo *si)
|
|
{
|
|
Elf32_Sym *s = si->symtab;
|
|
unsigned n;
|
|
|
|
for(n = 0; n < si->nchain; n++) {
|
|
TRACE("%04d> %08x: %02x %04x %08x %08x %s\n", n, s,
|
|
s->st_info, s->st_shndx, s->st_value, s->st_size,
|
|
si->strtab + s->st_name);
|
|
s++;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
static int open_library_on_path(const char* name, const char* const paths[]) {
|
|
char buf[512];
|
|
for (size_t i = 0; paths[i] != NULL; ++i) {
|
|
int n = format_buffer(buf, sizeof(buf), "%s/%s", paths[i], name);
|
|
if (n < 0 || n >= static_cast<int>(sizeof(buf))) {
|
|
PRINT("Warning: ignoring very long library path: %s/%s\n", paths[i], name);
|
|
continue;
|
|
}
|
|
int fd = TEMP_FAILURE_RETRY(open(buf, O_RDONLY | O_CLOEXEC));
|
|
if (fd != -1) {
|
|
return fd;
|
|
}
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
static int open_library(const char* name) {
|
|
TRACE("[ opening %s ]\n", name);
|
|
|
|
// If the name contains a slash, we should attempt to open it directly and not search the paths.
|
|
if (strchr(name, '/') != NULL) {
|
|
int fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC));
|
|
if (fd != -1) {
|
|
return fd;
|
|
}
|
|
// ...but nvidia binary blobs (at least) rely on this behavior, so fall through for now.
|
|
}
|
|
|
|
// Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths.
|
|
int fd = open_library_on_path(name, gLdPaths);
|
|
if (fd == -1) {
|
|
fd = open_library_on_path(name, gSoPaths);
|
|
}
|
|
return fd;
|
|
}
|
|
|
|
// Returns 'true' if the library is prelinked or on failure so we error out
|
|
// either way. We no longer support prelinking.
|
|
static bool is_prelinked(int fd, const char* name)
|
|
{
|
|
struct prelink_info_t {
|
|
long mmap_addr;
|
|
char tag[4]; // "PRE ".
|
|
};
|
|
|
|
off_t sz = lseek(fd, -sizeof(prelink_info_t), SEEK_END);
|
|
if (sz < 0) {
|
|
DL_ERR("lseek failed: %s", strerror(errno));
|
|
return true;
|
|
}
|
|
|
|
prelink_info_t info;
|
|
int rc = TEMP_FAILURE_RETRY(read(fd, &info, sizeof(info)));
|
|
if (rc != sizeof(info)) {
|
|
DL_ERR("could not read prelink_info_t structure for \"%s\": %s", name, strerror(errno));
|
|
return true;
|
|
}
|
|
|
|
if (memcmp(info.tag, "PRE ", 4) == 0) {
|
|
DL_ERR("prelinked libraries no longer supported: %s", name);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/* verify_elf_header
|
|
* Verifies the content of an ELF header.
|
|
*
|
|
* Args:
|
|
*
|
|
* Returns:
|
|
* 0 on success
|
|
* -1 if no valid ELF object is found @ base.
|
|
*/
|
|
static int
|
|
verify_elf_header(const Elf32_Ehdr* hdr)
|
|
{
|
|
if (hdr->e_ident[EI_MAG0] != ELFMAG0) return -1;
|
|
if (hdr->e_ident[EI_MAG1] != ELFMAG1) return -1;
|
|
if (hdr->e_ident[EI_MAG2] != ELFMAG2) return -1;
|
|
if (hdr->e_ident[EI_MAG3] != ELFMAG3) return -1;
|
|
if (hdr->e_type != ET_DYN) return -1;
|
|
|
|
/* TODO: Should we verify anything else in the header? */
|
|
#ifdef ANDROID_ARM_LINKER
|
|
if (hdr->e_machine != EM_ARM) return -1;
|
|
#elif defined(ANDROID_X86_LINKER)
|
|
if (hdr->e_machine != EM_386) return -1;
|
|
#elif defined(ANDROID_MIPS_LINKER)
|
|
if (hdr->e_machine != EM_MIPS) return -1;
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
struct scoped_fd {
|
|
~scoped_fd() {
|
|
if (fd != -1) {
|
|
close(fd);
|
|
}
|
|
}
|
|
int fd;
|
|
};
|
|
|
|
struct soinfo_ptr {
|
|
soinfo_ptr(const char* name) {
|
|
const char* bname = strrchr(name, '/');
|
|
ptr = soinfo_alloc(bname ? bname + 1 : name);
|
|
}
|
|
~soinfo_ptr() {
|
|
soinfo_free(ptr);
|
|
}
|
|
soinfo* release() {
|
|
soinfo* result = ptr;
|
|
ptr = NULL;
|
|
return result;
|
|
}
|
|
soinfo* ptr;
|
|
};
|
|
|
|
// TODO: rewrite linker_phdr.h to use a class, then lose this.
|
|
struct phdr_ptr {
|
|
phdr_ptr() : phdr_mmap(NULL) {}
|
|
~phdr_ptr() {
|
|
if (phdr_mmap != NULL) {
|
|
phdr_table_unload(phdr_mmap, phdr_size);
|
|
}
|
|
}
|
|
void* phdr_mmap;
|
|
Elf32_Addr phdr_size;
|
|
};
|
|
|
|
static soinfo* load_library(const char* name) {
|
|
// Open the file.
|
|
scoped_fd fd;
|
|
fd.fd = open_library(name);
|
|
if (fd.fd == -1) {
|
|
DL_ERR("library \"%s\" not found", name);
|
|
return NULL;
|
|
}
|
|
|
|
// Read the ELF header.
|
|
Elf32_Ehdr header[1];
|
|
int ret = TEMP_FAILURE_RETRY(read(fd.fd, (void*)header, sizeof(header)));
|
|
if (ret < 0) {
|
|
DL_ERR("can't read file \"%s\": %s", name, strerror(errno));
|
|
return NULL;
|
|
}
|
|
if (ret != (int)sizeof(header)) {
|
|
DL_ERR("too small to be an ELF executable: %s", name);
|
|
return NULL;
|
|
}
|
|
if (verify_elf_header(header) < 0) {
|
|
DL_ERR("not a valid ELF executable: %s", name);
|
|
return NULL;
|
|
}
|
|
|
|
// Read the program header table.
|
|
const Elf32_Phdr* phdr_table;
|
|
phdr_ptr phdr_holder;
|
|
ret = phdr_table_load(fd.fd, header->e_phoff, header->e_phnum,
|
|
&phdr_holder.phdr_mmap, &phdr_holder.phdr_size, &phdr_table);
|
|
if (ret < 0) {
|
|
DL_ERR("can't load program header table: %s: %s", name, strerror(errno));
|
|
return NULL;
|
|
}
|
|
size_t phdr_count = header->e_phnum;
|
|
|
|
// Get the load extents.
|
|
Elf32_Addr ext_sz = phdr_table_get_load_size(phdr_table, phdr_count);
|
|
TRACE("[ '%s' wants sz=0x%08x ]\n", name, ext_sz);
|
|
if (ext_sz == 0) {
|
|
DL_ERR("no loadable segments in file: %s", name);
|
|
return NULL;
|
|
}
|
|
|
|
// We no longer support pre-linked libraries.
|
|
if (is_prelinked(fd.fd, name)) {
|
|
return NULL;
|
|
}
|
|
|
|
// Reserve address space for all loadable segments.
|
|
void* load_start = NULL;
|
|
Elf32_Addr load_size = 0;
|
|
Elf32_Addr load_bias = 0;
|
|
ret = phdr_table_reserve_memory(phdr_table,
|
|
phdr_count,
|
|
&load_start,
|
|
&load_size,
|
|
&load_bias);
|
|
if (ret < 0) {
|
|
DL_ERR("can't reserve %d bytes in address space for \"%s\": %s",
|
|
ext_sz, name, strerror(errno));
|
|
return NULL;
|
|
}
|
|
|
|
TRACE("[ allocated memory for %s @ %p (0x%08x) ]\n", name, load_start, load_size);
|
|
|
|
/* Map all the segments in our address space with default protections */
|
|
ret = phdr_table_load_segments(phdr_table,
|
|
phdr_count,
|
|
load_bias,
|
|
fd.fd);
|
|
if (ret < 0) {
|
|
DL_ERR("can't map loadable segments for \"%s\": %s",
|
|
name, strerror(errno));
|
|
return NULL;
|
|
}
|
|
|
|
soinfo_ptr si(name);
|
|
if (si.ptr == NULL) {
|
|
return NULL;
|
|
}
|
|
|
|
si.ptr->base = (Elf32_Addr) load_start;
|
|
si.ptr->size = load_size;
|
|
si.ptr->load_bias = load_bias;
|
|
si.ptr->flags = 0;
|
|
si.ptr->entry = 0;
|
|
si.ptr->dynamic = (unsigned *)-1;
|
|
si.ptr->phnum = phdr_count;
|
|
si.ptr->phdr = phdr_table_get_loaded_phdr(phdr_table, phdr_count, load_bias);
|
|
if (si.ptr->phdr == NULL) {
|
|
DL_ERR("can't find loaded PHDR for \"%s\"", name);
|
|
return NULL;
|
|
}
|
|
|
|
return si.release();
|
|
}
|
|
|
|
static soinfo* init_library(soinfo* si) {
|
|
// At this point we know that whatever is loaded @ base is a valid ELF
|
|
// shared library whose segments are properly mapped in.
|
|
TRACE("[ init_library base=0x%08x sz=0x%08x name='%s') ]\n",
|
|
si->base, si->size, si->name);
|
|
|
|
if (!soinfo_link_image(si)) {
|
|
munmap((void *)si->base, si->size);
|
|
return NULL;
|
|
}
|
|
|
|
return si;
|
|
}
|
|
|
|
static soinfo *find_loaded_library(const char *name)
|
|
{
|
|
soinfo *si;
|
|
const char *bname;
|
|
|
|
// TODO: don't use basename only for determining libraries
|
|
// http://code.google.com/p/android/issues/detail?id=6670
|
|
|
|
bname = strrchr(name, '/');
|
|
bname = bname ? bname + 1 : name;
|
|
|
|
for(si = solist; si != NULL; si = si->next){
|
|
if(!strcmp(bname, si->name)) {
|
|
return si;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static soinfo* find_library_internal(const char* name) {
|
|
if (name == NULL) {
|
|
return somain;
|
|
}
|
|
|
|
soinfo* si = find_loaded_library(name);
|
|
if (si != NULL) {
|
|
if (si->flags & FLAG_ERROR) {
|
|
DL_ERR("\"%s\" failed to load previously", name);
|
|
return NULL;
|
|
}
|
|
if (si->flags & FLAG_LINKED) {
|
|
return si;
|
|
}
|
|
DL_ERR("OOPS: recursive link to \"%s\"", si->name);
|
|
return NULL;
|
|
}
|
|
|
|
TRACE("[ '%s' has not been loaded yet. Locating...]\n", name);
|
|
si = load_library(name);
|
|
if (si != NULL) {
|
|
si = init_library(si);
|
|
}
|
|
|
|
return si;
|
|
}
|
|
|
|
static soinfo* find_library(const char* name) {
|
|
soinfo* si = find_library_internal(name);
|
|
if (si != NULL) {
|
|
si->refcount++;
|
|
}
|
|
return si;
|
|
}
|
|
|
|
static int soinfo_unload(soinfo* si) {
|
|
if (si->refcount == 1) {
|
|
TRACE("unloading '%s'\n", si->name);
|
|
si->CallDestructors();
|
|
|
|
for (unsigned* d = si->dynamic; *d; d += 2) {
|
|
if (d[0] == DT_NEEDED) {
|
|
soinfo* lsi = find_loaded_library(si->strtab + d[1]);
|
|
if (lsi != NULL) {
|
|
TRACE("%s needs to unload %s\n", si->name, lsi->name);
|
|
soinfo_unload(lsi);
|
|
} else {
|
|
// TODO: should we return -1 in this case?
|
|
DL_ERR("\"%s\": could not unload dependent library", si->name);
|
|
}
|
|
}
|
|
}
|
|
|
|
munmap(reinterpret_cast<void*>(si->base), si->size);
|
|
notify_gdb_of_unload(si);
|
|
soinfo_free(si);
|
|
si->refcount = 0;
|
|
} else {
|
|
si->refcount--;
|
|
TRACE("not unloading '%s', decrementing refcount to %d\n", si->name, si->refcount);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
soinfo* do_dlopen(const char* name, int flags) {
|
|
if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL)) != 0) {
|
|
DL_ERR("invalid flags to dlopen: %x", flags);
|
|
return NULL;
|
|
}
|
|
set_soinfo_pool_protection(PROT_READ | PROT_WRITE);
|
|
soinfo* si = find_library(name);
|
|
if (si != NULL) {
|
|
si->CallConstructors();
|
|
}
|
|
set_soinfo_pool_protection(PROT_READ);
|
|
return si;
|
|
}
|
|
|
|
int do_dlclose(soinfo* si) {
|
|
set_soinfo_pool_protection(PROT_READ | PROT_WRITE);
|
|
int result = soinfo_unload(si);
|
|
set_soinfo_pool_protection(PROT_READ);
|
|
return result;
|
|
}
|
|
|
|
/* TODO: don't use unsigned for addrs below. It works, but is not
|
|
* ideal. They should probably be either uint32_t, Elf32_Addr, or unsigned
|
|
* long.
|
|
*/
|
|
static int soinfo_relocate(soinfo *si, Elf32_Rel *rel, unsigned count,
|
|
soinfo *needed[])
|
|
{
|
|
Elf32_Sym *symtab = si->symtab;
|
|
const char *strtab = si->strtab;
|
|
Elf32_Sym *s;
|
|
Elf32_Rel *start = rel;
|
|
soinfo *lsi;
|
|
|
|
for (size_t idx = 0; idx < count; ++idx, ++rel) {
|
|
unsigned type = ELF32_R_TYPE(rel->r_info);
|
|
unsigned sym = ELF32_R_SYM(rel->r_info);
|
|
unsigned reloc = (unsigned)(rel->r_offset + si->load_bias);
|
|
unsigned sym_addr = 0;
|
|
char *sym_name = NULL;
|
|
|
|
DEBUG("Processing '%s' relocation at index %d\n", si->name, idx);
|
|
if (type == 0) { // R_*_NONE
|
|
continue;
|
|
}
|
|
if(sym != 0) {
|
|
sym_name = (char *)(strtab + symtab[sym].st_name);
|
|
s = soinfo_do_lookup(si, sym_name, &lsi, needed);
|
|
if(s == NULL) {
|
|
/* We only allow an undefined symbol if this is a weak
|
|
reference.. */
|
|
s = &symtab[sym];
|
|
if (ELF32_ST_BIND(s->st_info) != STB_WEAK) {
|
|
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name);
|
|
return -1;
|
|
}
|
|
|
|
/* IHI0044C AAELF 4.5.1.1:
|
|
|
|
Libraries are not searched to resolve weak references.
|
|
It is not an error for a weak reference to remain
|
|
unsatisfied.
|
|
|
|
During linking, the value of an undefined weak reference is:
|
|
- Zero if the relocation type is absolute
|
|
- The address of the place if the relocation is pc-relative
|
|
- The address of nominal base address if the relocation
|
|
type is base-relative.
|
|
*/
|
|
|
|
switch (type) {
|
|
#if defined(ANDROID_ARM_LINKER)
|
|
case R_ARM_JUMP_SLOT:
|
|
case R_ARM_GLOB_DAT:
|
|
case R_ARM_ABS32:
|
|
case R_ARM_RELATIVE: /* Don't care. */
|
|
#elif defined(ANDROID_X86_LINKER)
|
|
case R_386_JMP_SLOT:
|
|
case R_386_GLOB_DAT:
|
|
case R_386_32:
|
|
case R_386_RELATIVE: /* Dont' care. */
|
|
#endif /* ANDROID_*_LINKER */
|
|
/* sym_addr was initialized to be zero above or relocation
|
|
code below does not care about value of sym_addr.
|
|
No need to do anything. */
|
|
break;
|
|
|
|
#if defined(ANDROID_X86_LINKER)
|
|
case R_386_PC32:
|
|
sym_addr = reloc;
|
|
break;
|
|
#endif /* ANDROID_X86_LINKER */
|
|
|
|
#if defined(ANDROID_ARM_LINKER)
|
|
case R_ARM_COPY:
|
|
/* Fall through. Can't really copy if weak symbol is
|
|
not found in run-time. */
|
|
#endif /* ANDROID_ARM_LINKER */
|
|
default:
|
|
DL_ERR("unknown weak reloc type %d @ %p (%d)",
|
|
type, rel, (int) (rel - start));
|
|
return -1;
|
|
}
|
|
} else {
|
|
/* We got a definition. */
|
|
#if 0
|
|
if((base == 0) && (si->base != 0)){
|
|
/* linking from libraries to main image is bad */
|
|
DL_ERR("cannot locate \"%s\"...",
|
|
strtab + symtab[sym].st_name);
|
|
return -1;
|
|
}
|
|
#endif
|
|
sym_addr = (unsigned)(s->st_value + lsi->load_bias);
|
|
}
|
|
count_relocation(kRelocSymbol);
|
|
} else {
|
|
s = NULL;
|
|
}
|
|
|
|
/* TODO: This is ugly. Split up the relocations by arch into
|
|
* different files.
|
|
*/
|
|
switch(type){
|
|
#if defined(ANDROID_ARM_LINKER)
|
|
case R_ARM_JUMP_SLOT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned*)reloc) = sym_addr;
|
|
break;
|
|
case R_ARM_GLOB_DAT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO GLOB_DAT %08x <- %08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned*)reloc) = sym_addr;
|
|
break;
|
|
case R_ARM_ABS32:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO ABS %08x <- %08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned*)reloc) += sym_addr;
|
|
break;
|
|
case R_ARM_REL32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO REL32 %08x <- %08x - %08x %s\n",
|
|
reloc, sym_addr, rel->r_offset, sym_name);
|
|
*((unsigned*)reloc) += sym_addr - rel->r_offset;
|
|
break;
|
|
#elif defined(ANDROID_X86_LINKER)
|
|
case R_386_JMP_SLOT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned*)reloc) = sym_addr;
|
|
break;
|
|
case R_386_GLOB_DAT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO GLOB_DAT %08x <- %08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned*)reloc) = sym_addr;
|
|
break;
|
|
#elif defined(ANDROID_MIPS_LINKER)
|
|
case R_MIPS_JUMP_SLOT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned*)reloc) = sym_addr;
|
|
break;
|
|
case R_MIPS_REL32:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO REL32 %08x <- %08x %s\n",
|
|
reloc, sym_addr, (sym_name) ? sym_name : "*SECTIONHDR*");
|
|
if (s) {
|
|
*((unsigned*)reloc) += sym_addr;
|
|
} else {
|
|
*((unsigned*)reloc) += si->base;
|
|
}
|
|
break;
|
|
#endif /* ANDROID_*_LINKER */
|
|
|
|
#if defined(ANDROID_ARM_LINKER)
|
|
case R_ARM_RELATIVE:
|
|
#elif defined(ANDROID_X86_LINKER)
|
|
case R_386_RELATIVE:
|
|
#endif /* ANDROID_*_LINKER */
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
if (sym) {
|
|
DL_ERR("odd RELATIVE form...");
|
|
return -1;
|
|
}
|
|
TRACE_TYPE(RELO, "RELO RELATIVE %08x <- +%08x\n", reloc, si->base);
|
|
*((unsigned*)reloc) += si->base;
|
|
break;
|
|
|
|
#if defined(ANDROID_X86_LINKER)
|
|
case R_386_32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
|
|
TRACE_TYPE(RELO, "RELO R_386_32 %08x <- +%08x %s\n", reloc, sym_addr, sym_name);
|
|
*((unsigned *)reloc) += (unsigned)sym_addr;
|
|
break;
|
|
|
|
case R_386_PC32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO R_386_PC32 %08x <- +%08x (%08x - %08x) %s\n",
|
|
reloc, (sym_addr - reloc), sym_addr, reloc, sym_name);
|
|
*((unsigned *)reloc) += (unsigned)(sym_addr - reloc);
|
|
break;
|
|
#endif /* ANDROID_X86_LINKER */
|
|
|
|
#ifdef ANDROID_ARM_LINKER
|
|
case R_ARM_COPY:
|
|
if ((si->flags & FLAG_EXE) == 0) {
|
|
/*
|
|
* http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf
|
|
*
|
|
* Section 4.7.1.10 "Dynamic relocations"
|
|
* R_ARM_COPY may only appear in executable objects where e_type is
|
|
* set to ET_EXEC.
|
|
*
|
|
* TODO: FLAG_EXE is set for both ET_DYN and ET_EXEC executables.
|
|
* We should explicitly disallow ET_DYN executables from having
|
|
* R_ARM_COPY relocations.
|
|
*/
|
|
DL_ERR("%s R_ARM_COPY relocations only supported for ET_EXEC", si->name);
|
|
return -1;
|
|
}
|
|
count_relocation(kRelocCopy);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO %08x <- %d @ %08x %s\n", reloc, s->st_size, sym_addr, sym_name);
|
|
if (reloc == sym_addr) {
|
|
Elf32_Sym *src = soinfo_do_lookup(NULL, sym_name, &lsi, needed);
|
|
|
|
if (src == NULL) {
|
|
DL_ERR("%s R_ARM_COPY relocation source cannot be resolved", si->name);
|
|
return -1;
|
|
}
|
|
if (lsi->has_DT_SYMBOLIC) {
|
|
DL_ERR("%s invalid R_ARM_COPY relocation against DT_SYMBOLIC shared "
|
|
"library %s (built with -Bsymbolic?)", si->name, lsi->name);
|
|
return -1;
|
|
}
|
|
if (s->st_size < src->st_size) {
|
|
DL_ERR("%s R_ARM_COPY relocation size mismatch (%d < %d)",
|
|
si->name, s->st_size, src->st_size);
|
|
return -1;
|
|
}
|
|
memcpy((void*)reloc, (void*)(src->st_value + lsi->load_bias), src->st_size);
|
|
} else {
|
|
DL_ERR("%s R_ARM_COPY relocation target cannot be resolved", si->name);
|
|
return -1;
|
|
}
|
|
break;
|
|
#endif /* ANDROID_ARM_LINKER */
|
|
|
|
default:
|
|
DL_ERR("unknown reloc type %d @ %p (%d)",
|
|
type, rel, (int) (rel - start));
|
|
return -1;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
#ifdef ANDROID_MIPS_LINKER
|
|
static int mips_relocate_got(soinfo* si, soinfo* needed[]) {
|
|
unsigned *got;
|
|
unsigned local_gotno, gotsym, symtabno;
|
|
Elf32_Sym *symtab, *sym;
|
|
unsigned g;
|
|
|
|
got = si->plt_got;
|
|
local_gotno = si->mips_local_gotno;
|
|
gotsym = si->mips_gotsym;
|
|
symtabno = si->mips_symtabno;
|
|
symtab = si->symtab;
|
|
|
|
/*
|
|
* got[0] is address of lazy resolver function
|
|
* got[1] may be used for a GNU extension
|
|
* set it to a recognizable address in case someone calls it
|
|
* (should be _rtld_bind_start)
|
|
* FIXME: maybe this should be in a separate routine
|
|
*/
|
|
|
|
if ((si->flags & FLAG_LINKER) == 0) {
|
|
g = 0;
|
|
got[g++] = 0xdeadbeef;
|
|
if (got[g] & 0x80000000) {
|
|
got[g++] = 0xdeadfeed;
|
|
}
|
|
/*
|
|
* Relocate the local GOT entries need to be relocated
|
|
*/
|
|
for (; g < local_gotno; g++) {
|
|
got[g] += si->load_bias;
|
|
}
|
|
}
|
|
|
|
/* Now for the global GOT entries */
|
|
sym = symtab + gotsym;
|
|
got = si->plt_got + local_gotno;
|
|
for (g = gotsym; g < symtabno; g++, sym++, got++) {
|
|
const char *sym_name;
|
|
Elf32_Sym *s;
|
|
soinfo *lsi;
|
|
|
|
/* This is an undefined reference... try to locate it */
|
|
sym_name = si->strtab + sym->st_name;
|
|
s = soinfo_do_lookup(si, sym_name, &lsi, needed);
|
|
if (s == NULL) {
|
|
/* We only allow an undefined symbol if this is a weak
|
|
reference.. */
|
|
s = &symtab[g];
|
|
if (ELF32_ST_BIND(s->st_info) != STB_WEAK) {
|
|
DL_ERR("cannot locate \"%s\"...", sym_name);
|
|
return -1;
|
|
}
|
|
*got = 0;
|
|
}
|
|
else {
|
|
/* FIXME: is this sufficient?
|
|
* For reference see NetBSD link loader
|
|
* http://cvsweb.netbsd.org/bsdweb.cgi/src/libexec/ld.elf_so/arch/mips/mips_reloc.c?rev=1.53&content-type=text/x-cvsweb-markup
|
|
*/
|
|
*got = lsi->load_bias + s->st_value;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
/* Please read the "Initialization and Termination functions" functions.
|
|
* of the linker design note in bionic/linker/README.TXT to understand
|
|
* what the following code is doing.
|
|
*
|
|
* The important things to remember are:
|
|
*
|
|
* DT_PREINIT_ARRAY must be called first for executables, and should
|
|
* not appear in shared libraries.
|
|
*
|
|
* DT_INIT should be called before DT_INIT_ARRAY if both are present
|
|
*
|
|
* DT_FINI should be called after DT_FINI_ARRAY if both are present
|
|
*
|
|
* DT_FINI_ARRAY must be parsed in reverse order.
|
|
*/
|
|
void soinfo::CallArray(const char* array_name UNUSED, unsigned* array, int count, bool reverse) {
|
|
if (array == NULL) {
|
|
return;
|
|
}
|
|
|
|
int step = 1;
|
|
if (reverse) {
|
|
array += (count-1);
|
|
step = -1;
|
|
}
|
|
|
|
TRACE("[ Calling %s @ %p [%d] for '%s' ]\n", array_name, array, count, name);
|
|
|
|
for (int n = count; n > 0; n--) {
|
|
TRACE("[ Looking at %s[%d] *%p == 0x%08x ]\n", array_name, n, array, *array);
|
|
void (*func)() = (void (*)()) *array;
|
|
array += step;
|
|
if (((int) func == 0) || ((int) func == -1)) {
|
|
continue;
|
|
}
|
|
TRACE("[ Calling func @ %p ]\n", func);
|
|
func();
|
|
}
|
|
|
|
TRACE("[ Done calling %s for '%s' ]\n", array_name, name);
|
|
}
|
|
|
|
void soinfo::CallFunction(const char* function_name UNUSED, void (*function)()) {
|
|
if (function == NULL) {
|
|
return;
|
|
}
|
|
|
|
TRACE("[ Calling %s @ %p for '%s' ]\n", function_name, function, name);
|
|
function();
|
|
TRACE("[ Done calling %s for '%s' ]\n", function_name, name);
|
|
}
|
|
|
|
void soinfo::CallPreInitConstructors() {
|
|
CallArray("DT_PREINIT_ARRAY", preinit_array, preinit_array_count, false);
|
|
}
|
|
|
|
void soinfo::CallConstructors() {
|
|
if (constructors_called) {
|
|
return;
|
|
}
|
|
|
|
// We set constructors_called before actually calling the constructors, otherwise it doesn't
|
|
// protect against recursive constructor calls. One simple example of constructor recursion
|
|
// is the libc debug malloc, which is implemented in libc_malloc_debug_leak.so:
|
|
// 1. The program depends on libc, so libc's constructor is called here.
|
|
// 2. The libc constructor calls dlopen() to load libc_malloc_debug_leak.so.
|
|
// 3. dlopen() calls the constructors on the newly created
|
|
// soinfo for libc_malloc_debug_leak.so.
|
|
// 4. The debug .so depends on libc, so CallConstructors is
|
|
// called again with the libc soinfo. If it doesn't trigger the early-
|
|
// out above, the libc constructor will be called again (recursively!).
|
|
constructors_called = true;
|
|
|
|
if (!(flags & FLAG_EXE) && preinit_array) {
|
|
DL_ERR("shared library \"%s\" has a preinit_array table @ %p", name, preinit_array);
|
|
return;
|
|
}
|
|
|
|
if (dynamic) {
|
|
for (unsigned* d = dynamic; *d; d += 2) {
|
|
if (d[0] == DT_NEEDED) {
|
|
soinfo* lsi = find_loaded_library(strtab + d[1]);
|
|
if (lsi == NULL) {
|
|
DL_ERR("\"%s\": could not initialize dependent library", name);
|
|
} else {
|
|
lsi->CallConstructors();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
CallFunction("DT_INIT", init_func);
|
|
CallArray("DT_INIT_ARRAY", init_array, init_array_count, false);
|
|
}
|
|
|
|
void soinfo::CallDestructors() {
|
|
CallArray("DT_FINI_ARRAY", fini_array, fini_array_count, true);
|
|
CallFunction("DT_FINI", fini_func);
|
|
}
|
|
|
|
/* Force any of the closed stdin, stdout and stderr to be associated with
|
|
/dev/null. */
|
|
static int nullify_closed_stdio() {
|
|
int dev_null, i, status;
|
|
int return_value = 0;
|
|
|
|
dev_null = TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR));
|
|
if (dev_null < 0) {
|
|
DL_ERR("cannot open /dev/null: %s", strerror(errno));
|
|
return -1;
|
|
}
|
|
TRACE("[ Opened /dev/null file-descriptor=%d]\n", dev_null);
|
|
|
|
/* If any of the stdio file descriptors is valid and not associated
|
|
with /dev/null, dup /dev/null to it. */
|
|
for (i = 0; i < 3; i++) {
|
|
/* If it is /dev/null already, we are done. */
|
|
if (i == dev_null) {
|
|
continue;
|
|
}
|
|
|
|
TRACE("[ Nullifying stdio file descriptor %d]\n", i);
|
|
status = TEMP_FAILURE_RETRY(fcntl(i, F_GETFL));
|
|
|
|
/* If file is opened, we are good. */
|
|
if (status != -1) {
|
|
continue;
|
|
}
|
|
|
|
/* The only error we allow is that the file descriptor does not
|
|
exist, in which case we dup /dev/null to it. */
|
|
if (errno != EBADF) {
|
|
DL_ERR("fcntl failed: %s", strerror(errno));
|
|
return_value = -1;
|
|
continue;
|
|
}
|
|
|
|
/* Try dupping /dev/null to this stdio file descriptor and
|
|
repeat if there is a signal. Note that any errors in closing
|
|
the stdio descriptor are lost. */
|
|
status = TEMP_FAILURE_RETRY(dup2(dev_null, i));
|
|
if (status < 0) {
|
|
DL_ERR("dup2 failed: %s", strerror(errno));
|
|
return_value = -1;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* If /dev/null is not one of the stdio file descriptors, close it. */
|
|
if (dev_null > 2) {
|
|
TRACE("[ Closing /dev/null file-descriptor=%d]\n", dev_null);
|
|
status = TEMP_FAILURE_RETRY(close(dev_null));
|
|
if (status == -1) {
|
|
DL_ERR("close failed: %s", strerror(errno));
|
|
return_value = -1;
|
|
}
|
|
}
|
|
|
|
return return_value;
|
|
}
|
|
|
|
static bool soinfo_link_image(soinfo* si) {
|
|
si->flags |= FLAG_ERROR;
|
|
|
|
/* "base" might wrap around UINT32_MAX. */
|
|
Elf32_Addr base = si->load_bias;
|
|
const Elf32_Phdr *phdr = si->phdr;
|
|
int phnum = si->phnum;
|
|
int relocating_linker = (si->flags & FLAG_LINKER) != 0;
|
|
soinfo **needed, **pneeded;
|
|
|
|
/* We can't debug anything until the linker is relocated */
|
|
if (!relocating_linker) {
|
|
INFO("[ linking %s ]\n", si->name);
|
|
DEBUG("si->base = 0x%08x si->flags = 0x%08x\n", si->base, si->flags);
|
|
}
|
|
|
|
/* Extract dynamic section */
|
|
size_t dynamic_count;
|
|
phdr_table_get_dynamic_section(phdr, phnum, base, &si->dynamic,
|
|
&dynamic_count);
|
|
if (si->dynamic == NULL) {
|
|
if (!relocating_linker) {
|
|
DL_ERR("missing PT_DYNAMIC in \"%s\"", si->name);
|
|
}
|
|
return false;
|
|
} else {
|
|
if (!relocating_linker) {
|
|
DEBUG("dynamic = %p\n", si->dynamic);
|
|
}
|
|
}
|
|
|
|
#ifdef ANDROID_ARM_LINKER
|
|
(void) phdr_table_get_arm_exidx(phdr, phnum, base,
|
|
&si->ARM_exidx, &si->ARM_exidx_count);
|
|
#endif
|
|
|
|
/* extract useful information from dynamic section */
|
|
for (unsigned* d = si->dynamic; *d; ++d) {
|
|
DEBUG("d = %p, d[0] = 0x%08x d[1] = 0x%08x\n", d, d[0], d[1]);
|
|
switch(*d++){
|
|
case DT_HASH:
|
|
si->nbucket = ((unsigned *) (base + *d))[0];
|
|
si->nchain = ((unsigned *) (base + *d))[1];
|
|
si->bucket = (unsigned *) (base + *d + 8);
|
|
si->chain = (unsigned *) (base + *d + 8 + si->nbucket * 4);
|
|
break;
|
|
case DT_STRTAB:
|
|
si->strtab = (const char *) (base + *d);
|
|
break;
|
|
case DT_SYMTAB:
|
|
si->symtab = (Elf32_Sym *) (base + *d);
|
|
break;
|
|
case DT_PLTREL:
|
|
if(*d != DT_REL) {
|
|
DL_ERR("unsupported DT_RELA in \"%s\"", si->name);
|
|
return false;
|
|
}
|
|
break;
|
|
case DT_JMPREL:
|
|
si->plt_rel = (Elf32_Rel*) (base + *d);
|
|
break;
|
|
case DT_PLTRELSZ:
|
|
si->plt_rel_count = *d / 8;
|
|
break;
|
|
case DT_REL:
|
|
si->rel = (Elf32_Rel*) (base + *d);
|
|
break;
|
|
case DT_RELSZ:
|
|
si->rel_count = *d / 8;
|
|
break;
|
|
case DT_PLTGOT:
|
|
/* Save this in case we decide to do lazy binding. We don't yet. */
|
|
si->plt_got = (unsigned *)(base + *d);
|
|
break;
|
|
case DT_DEBUG:
|
|
#if !defined(ANDROID_MIPS_LINKER)
|
|
// Set the DT_DEBUG entry to the address of _r_debug for GDB
|
|
*d = (int) &_r_debug;
|
|
#endif
|
|
break;
|
|
case DT_RELA:
|
|
DL_ERR("unsupported DT_RELA in \"%s\"", si->name);
|
|
return false;
|
|
case DT_INIT:
|
|
si->init_func = (void (*)(void))(base + *d);
|
|
DEBUG("%s constructors (init func) found at %p\n", si->name, si->init_func);
|
|
break;
|
|
case DT_FINI:
|
|
si->fini_func = (void (*)(void))(base + *d);
|
|
DEBUG("%s destructors (fini func) found at %p\n", si->name, si->fini_func);
|
|
break;
|
|
case DT_INIT_ARRAY:
|
|
si->init_array = (unsigned *)(base + *d);
|
|
DEBUG("%s constructors (init_array) found at %p\n", si->name, si->init_array);
|
|
break;
|
|
case DT_INIT_ARRAYSZ:
|
|
si->init_array_count = ((unsigned)*d) / sizeof(Elf32_Addr);
|
|
break;
|
|
case DT_FINI_ARRAY:
|
|
si->fini_array = (unsigned *)(base + *d);
|
|
DEBUG("%s destructors (fini_array) found at %p\n", si->name, si->fini_array);
|
|
break;
|
|
case DT_FINI_ARRAYSZ:
|
|
si->fini_array_count = ((unsigned)*d) / sizeof(Elf32_Addr);
|
|
break;
|
|
case DT_PREINIT_ARRAY:
|
|
si->preinit_array = (unsigned *)(base + *d);
|
|
DEBUG("%s constructors (preinit_array) found at %p\n", si->name, si->preinit_array);
|
|
break;
|
|
case DT_PREINIT_ARRAYSZ:
|
|
si->preinit_array_count = ((unsigned)*d) / sizeof(Elf32_Addr);
|
|
break;
|
|
case DT_TEXTREL:
|
|
si->has_text_relocations = true;
|
|
break;
|
|
case DT_SYMBOLIC:
|
|
si->has_DT_SYMBOLIC = true;
|
|
break;
|
|
#if defined(DT_FLAGS)
|
|
case DT_FLAGS:
|
|
if (*d & DF_TEXTREL) {
|
|
si->has_text_relocations = true;
|
|
}
|
|
if (*d & DF_SYMBOLIC) {
|
|
si->has_DT_SYMBOLIC = true;
|
|
}
|
|
break;
|
|
#endif
|
|
#if defined(ANDROID_MIPS_LINKER)
|
|
case DT_NEEDED:
|
|
case DT_STRSZ:
|
|
case DT_SYMENT:
|
|
case DT_RELENT:
|
|
break;
|
|
case DT_MIPS_RLD_MAP:
|
|
// Set the DT_MIPS_RLD_MAP entry to the address of _r_debug for GDB.
|
|
{
|
|
r_debug** dp = (r_debug**) *d;
|
|
*dp = &_r_debug;
|
|
}
|
|
break;
|
|
case DT_MIPS_RLD_VERSION:
|
|
case DT_MIPS_FLAGS:
|
|
case DT_MIPS_BASE_ADDRESS:
|
|
case DT_MIPS_UNREFEXTNO:
|
|
case DT_MIPS_RWPLT:
|
|
break;
|
|
|
|
case DT_MIPS_PLTGOT:
|
|
#if 0
|
|
/* not yet... */
|
|
si->mips_pltgot = (unsigned *)(si->base + *d);
|
|
#endif
|
|
break;
|
|
|
|
case DT_MIPS_SYMTABNO:
|
|
si->mips_symtabno = *d;
|
|
break;
|
|
|
|
case DT_MIPS_LOCAL_GOTNO:
|
|
si->mips_local_gotno = *d;
|
|
break;
|
|
|
|
case DT_MIPS_GOTSYM:
|
|
si->mips_gotsym = *d;
|
|
break;
|
|
|
|
default:
|
|
DEBUG("Unused DT entry: type 0x%08x arg 0x%08x\n", d[-1], d[0]);
|
|
break;
|
|
#endif
|
|
}
|
|
}
|
|
|
|
DEBUG("si->base = 0x%08x, si->strtab = %p, si->symtab = %p\n",
|
|
si->base, si->strtab, si->symtab);
|
|
|
|
// Sanity checks.
|
|
if (si->nbucket == 0) {
|
|
DL_ERR("empty/missing DT_HASH in \"%s\" (built with --hash-style=gnu?)", si->name);
|
|
return false;
|
|
}
|
|
if (si->strtab == 0) {
|
|
DL_ERR("empty/missing DT_STRTAB in \"%s\"", si->name);
|
|
return false;
|
|
}
|
|
if (si->symtab == 0) {
|
|
DL_ERR("empty/missing DT_SYMTAB in \"%s\"", si->name);
|
|
return false;
|
|
}
|
|
|
|
/* if this is the main executable, then load all of the preloads now */
|
|
if (si->flags & FLAG_EXE) {
|
|
memset(preloads, 0, sizeof(preloads));
|
|
for (size_t i = 0; gLdPreloadNames[i] != NULL; i++) {
|
|
soinfo* lsi = find_library(gLdPreloadNames[i]);
|
|
if (lsi == NULL) {
|
|
strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf));
|
|
DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",
|
|
gLdPreloadNames[i], si->name, tmp_err_buf);
|
|
return false;
|
|
}
|
|
preloads[i] = lsi;
|
|
}
|
|
}
|
|
|
|
/* dynamic_count is an upper bound for the number of needed libs */
|
|
pneeded = needed = (soinfo**) alloca((1 + dynamic_count) * sizeof(soinfo*));
|
|
|
|
for (unsigned* d = si->dynamic; *d; d += 2) {
|
|
if (d[0] == DT_NEEDED) {
|
|
DEBUG("%s needs %s\n", si->name, si->strtab + d[1]);
|
|
soinfo* lsi = find_library(si->strtab + d[1]);
|
|
if (lsi == NULL) {
|
|
strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf));
|
|
DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",
|
|
si->strtab + d[1], si->name, tmp_err_buf);
|
|
return false;
|
|
}
|
|
*pneeded++ = lsi;
|
|
}
|
|
}
|
|
*pneeded = NULL;
|
|
|
|
if (si->has_text_relocations) {
|
|
/* Unprotect the segments, i.e. make them writable, to allow
|
|
* text relocations to work properly. We will later call
|
|
* phdr_table_protect_segments() after all of them are applied
|
|
* and all constructors are run.
|
|
*/
|
|
if (phdr_table_unprotect_segments(si->phdr, si->phnum, si->load_bias) < 0) {
|
|
DL_ERR("can't unprotect loadable segments for \"%s\": %s",
|
|
si->name, strerror(errno));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
if (si->plt_rel) {
|
|
DEBUG("[ relocating %s plt ]\n", si->name );
|
|
if(soinfo_relocate(si, si->plt_rel, si->plt_rel_count, needed)) {
|
|
return false;
|
|
}
|
|
}
|
|
if (si->rel) {
|
|
DEBUG("[ relocating %s ]\n", si->name );
|
|
if(soinfo_relocate(si, si->rel, si->rel_count, needed)) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
#ifdef ANDROID_MIPS_LINKER
|
|
if (mips_relocate_got(si, needed)) {
|
|
return false;
|
|
}
|
|
#endif
|
|
|
|
si->flags |= FLAG_LINKED;
|
|
DEBUG("[ finished linking %s ]\n", si->name);
|
|
|
|
if (si->has_text_relocations) {
|
|
/* All relocations are done, we can protect our segments back to
|
|
* read-only. */
|
|
if (phdr_table_protect_segments(si->phdr, si->phnum, si->load_bias) < 0) {
|
|
DL_ERR("can't protect segments for \"%s\": %s",
|
|
si->name, strerror(errno));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* We can also turn on GNU RELRO protection */
|
|
if (phdr_table_protect_gnu_relro(si->phdr, si->phnum, si->load_bias) < 0) {
|
|
DL_ERR("can't enable GNU RELRO protection for \"%s\": %s",
|
|
si->name, strerror(errno));
|
|
return false;
|
|
}
|
|
|
|
// If this is a setuid/setgid program, close the security hole described in
|
|
// ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc
|
|
if (get_AT_SECURE()) {
|
|
nullify_closed_stdio();
|
|
}
|
|
notify_gdb_of_load(si);
|
|
si->flags &= ~FLAG_ERROR;
|
|
return true;
|
|
}
|
|
|
|
static void parse_path(const char* path, const char* delimiters,
|
|
const char** array, char* buf, size_t buf_size, size_t max_count)
|
|
{
|
|
if (path == NULL) {
|
|
return;
|
|
}
|
|
|
|
size_t len = strlcpy(buf, path, buf_size);
|
|
|
|
size_t i = 0;
|
|
char* buf_p = buf;
|
|
while (i < max_count && (array[i] = strsep(&buf_p, delimiters))) {
|
|
if (*array[i] != '\0') {
|
|
++i;
|
|
}
|
|
}
|
|
|
|
// Forget the last path if we had to truncate; this occurs if the 2nd to
|
|
// last char isn't '\0' (i.e. wasn't originally a delimiter).
|
|
if (i > 0 && len >= buf_size && buf[buf_size - 2] != '\0') {
|
|
array[i - 1] = NULL;
|
|
} else {
|
|
array[i] = NULL;
|
|
}
|
|
}
|
|
|
|
static void parse_LD_LIBRARY_PATH(const char* path) {
|
|
parse_path(path, ":", gLdPaths,
|
|
gLdPathsBuffer, sizeof(gLdPathsBuffer), LDPATH_MAX);
|
|
}
|
|
|
|
static void parse_LD_PRELOAD(const char* path) {
|
|
// We have historically supported ':' as well as ' ' in LD_PRELOAD.
|
|
parse_path(path, " :", gLdPreloadNames,
|
|
gLdPreloadsBuffer, sizeof(gLdPreloadsBuffer), LDPRELOAD_MAX);
|
|
}
|
|
|
|
/*
|
|
* This code is called after the linker has linked itself and
|
|
* fixed it's own GOT. It is safe to make references to externs
|
|
* and other non-local data at this point.
|
|
*/
|
|
static unsigned __linker_init_post_relocation(unsigned **elfdata, unsigned linker_base)
|
|
{
|
|
static soinfo linker_soinfo;
|
|
|
|
int argc = (int) *elfdata;
|
|
char **argv = (char**) (elfdata + 1);
|
|
unsigned *vecs = (unsigned*) (argv + argc + 1);
|
|
|
|
/* NOTE: we store the elfdata pointer on a special location
|
|
* of the temporary TLS area in order to pass it to
|
|
* the C Library's runtime initializer.
|
|
*
|
|
* The initializer must clear the slot and reset the TLS
|
|
* to point to a different location to ensure that no other
|
|
* shared library constructor can access it.
|
|
*/
|
|
__libc_init_tls(elfdata);
|
|
|
|
#if TIMING
|
|
struct timeval t0, t1;
|
|
gettimeofday(&t0, 0);
|
|
#endif
|
|
|
|
// Initialize environment functions, and get to the ELF aux vectors table.
|
|
vecs = linker_env_init(vecs);
|
|
|
|
debugger_init();
|
|
|
|
// Get a few environment variables.
|
|
const char* LD_DEBUG = linker_env_get("LD_DEBUG");
|
|
if (LD_DEBUG != NULL) {
|
|
debug_verbosity = atoi(LD_DEBUG);
|
|
}
|
|
|
|
// Normally, these are cleaned by linker_env_init, but the test
|
|
// doesn't cost us anything.
|
|
const char* ldpath_env = NULL;
|
|
const char* ldpreload_env = NULL;
|
|
if (!get_AT_SECURE()) {
|
|
ldpath_env = linker_env_get("LD_LIBRARY_PATH");
|
|
ldpreload_env = linker_env_get("LD_PRELOAD");
|
|
}
|
|
|
|
INFO("[ android linker & debugger ]\n");
|
|
DEBUG("elfdata @ 0x%08x\n", (unsigned)elfdata);
|
|
|
|
soinfo* si = soinfo_alloc(argv[0]);
|
|
if (si == NULL) {
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
/* bootstrap the link map, the main exe always needs to be first */
|
|
si->flags |= FLAG_EXE;
|
|
link_map* map = &(si->linkmap);
|
|
|
|
map->l_addr = 0;
|
|
map->l_name = argv[0];
|
|
map->l_prev = NULL;
|
|
map->l_next = NULL;
|
|
|
|
_r_debug.r_map = map;
|
|
r_debug_tail = map;
|
|
|
|
/* gdb expects the linker to be in the debug shared object list.
|
|
* Without this, gdb has trouble locating the linker's ".text"
|
|
* and ".plt" sections. Gdb could also potentially use this to
|
|
* relocate the offset of our exported 'rtld_db_dlactivity' symbol.
|
|
* Don't use soinfo_alloc(), because the linker shouldn't
|
|
* be on the soinfo list.
|
|
*/
|
|
strlcpy((char*) linker_soinfo.name, "/system/bin/linker", sizeof linker_soinfo.name);
|
|
linker_soinfo.flags = 0;
|
|
linker_soinfo.base = linker_base;
|
|
/*
|
|
* Set the dynamic field in the link map otherwise gdb will complain with
|
|
* the following:
|
|
* warning: .dynamic section for "/system/bin/linker" is not at the
|
|
* expected address (wrong library or version mismatch?)
|
|
*/
|
|
Elf32_Ehdr *elf_hdr = (Elf32_Ehdr *) linker_base;
|
|
Elf32_Phdr *phdr =
|
|
(Elf32_Phdr *)((unsigned char *) linker_base + elf_hdr->e_phoff);
|
|
phdr_table_get_dynamic_section(phdr, elf_hdr->e_phnum, linker_base,
|
|
&linker_soinfo.dynamic, NULL);
|
|
insert_soinfo_into_debug_map(&linker_soinfo);
|
|
|
|
/* extract information passed from the kernel */
|
|
while (vecs[0] != 0){
|
|
switch(vecs[0]){
|
|
case AT_PHDR:
|
|
si->phdr = (Elf32_Phdr*) vecs[1];
|
|
break;
|
|
case AT_PHNUM:
|
|
si->phnum = (int) vecs[1];
|
|
break;
|
|
case AT_ENTRY:
|
|
si->entry = vecs[1];
|
|
break;
|
|
}
|
|
vecs += 2;
|
|
}
|
|
|
|
/* Compute the value of si->base. We can't rely on the fact that
|
|
* the first entry is the PHDR because this will not be true
|
|
* for certain executables (e.g. some in the NDK unit test suite)
|
|
*/
|
|
int nn;
|
|
si->base = 0;
|
|
si->size = phdr_table_get_load_size(si->phdr, si->phnum);
|
|
si->load_bias = 0;
|
|
for ( nn = 0; nn < si->phnum; nn++ ) {
|
|
if (si->phdr[nn].p_type == PT_PHDR) {
|
|
si->load_bias = (Elf32_Addr)si->phdr - si->phdr[nn].p_vaddr;
|
|
si->base = (Elf32_Addr) si->phdr - si->phdr[nn].p_offset;
|
|
break;
|
|
}
|
|
}
|
|
si->dynamic = (unsigned *)-1;
|
|
si->refcount = 1;
|
|
|
|
// Use LD_LIBRARY_PATH and LD_PRELOAD (but only if we aren't setuid/setgid).
|
|
parse_LD_LIBRARY_PATH(ldpath_env);
|
|
parse_LD_PRELOAD(ldpreload_env);
|
|
|
|
somain = si;
|
|
|
|
if (!soinfo_link_image(si)) {
|
|
const char* msg = "CANNOT LINK EXECUTABLE\n";
|
|
write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf));
|
|
write(2, msg, strlen(msg));
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
si->CallPreInitConstructors();
|
|
|
|
for (size_t i = 0; preloads[i] != NULL; ++i) {
|
|
preloads[i]->CallConstructors();
|
|
}
|
|
|
|
/*After the link_image, the si->load_bias is initialized.
|
|
*For so lib, the map->l_addr will be updated in notify_gdb_of_load.
|
|
*We need to update this value for so exe here. So Unwind_Backtrace
|
|
*for some arch like x86 could work correctly within so exe.
|
|
*/
|
|
map->l_addr = si->load_bias;
|
|
si->CallConstructors();
|
|
|
|
#if TIMING
|
|
gettimeofday(&t1,NULL);
|
|
PRINT("LINKER TIME: %s: %d microseconds\n", argv[0], (int) (
|
|
(((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) -
|
|
(((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec)
|
|
));
|
|
#endif
|
|
#if STATS
|
|
PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol\n", argv[0],
|
|
linker_stats.count[kRelocAbsolute],
|
|
linker_stats.count[kRelocRelative],
|
|
linker_stats.count[kRelocCopy],
|
|
linker_stats.count[kRelocSymbol]);
|
|
#endif
|
|
#if COUNT_PAGES
|
|
{
|
|
unsigned n;
|
|
unsigned i;
|
|
unsigned count = 0;
|
|
for(n = 0; n < 4096; n++){
|
|
if(bitmask[n]){
|
|
unsigned x = bitmask[n];
|
|
for(i = 0; i < 8; i++){
|
|
if(x & 1) count++;
|
|
x >>= 1;
|
|
}
|
|
}
|
|
}
|
|
PRINT("PAGES MODIFIED: %s: %d (%dKB)\n", argv[0], count, count * 4);
|
|
}
|
|
#endif
|
|
|
|
#if TIMING || STATS || COUNT_PAGES
|
|
fflush(stdout);
|
|
#endif
|
|
|
|
TRACE("[ Ready to execute '%s' @ 0x%08x ]\n", si->name, si->entry);
|
|
return si->entry;
|
|
}
|
|
|
|
/*
|
|
* Find the value of AT_BASE passed to us by the kernel. This is the load
|
|
* location of the linker.
|
|
*/
|
|
static unsigned find_linker_base(unsigned **elfdata) {
|
|
int argc = (int) *elfdata;
|
|
char **argv = (char**) (elfdata + 1);
|
|
unsigned *vecs = (unsigned*) (argv + argc + 1);
|
|
while (vecs[0] != 0) {
|
|
vecs++;
|
|
}
|
|
|
|
/* The end of the environment block is marked by two NULL pointers */
|
|
vecs++;
|
|
|
|
while(vecs[0]) {
|
|
if (vecs[0] == AT_BASE) {
|
|
return vecs[1];
|
|
}
|
|
vecs += 2;
|
|
}
|
|
|
|
return 0; // should never happen
|
|
}
|
|
|
|
/* Compute the load-bias of an existing executable. This shall only
|
|
* be used to compute the load bias of an executable or shared library
|
|
* that was loaded by the kernel itself.
|
|
*
|
|
* Input:
|
|
* elf -> address of ELF header, assumed to be at the start of the file.
|
|
* Return:
|
|
* load bias, i.e. add the value of any p_vaddr in the file to get
|
|
* the corresponding address in memory.
|
|
*/
|
|
static Elf32_Addr
|
|
get_elf_exec_load_bias(const Elf32_Ehdr* elf)
|
|
{
|
|
Elf32_Addr offset = elf->e_phoff;
|
|
const Elf32_Phdr* phdr_table = (const Elf32_Phdr*)((char*)elf + offset);
|
|
const Elf32_Phdr* phdr_end = phdr_table + elf->e_phnum;
|
|
const Elf32_Phdr* phdr;
|
|
|
|
for (phdr = phdr_table; phdr < phdr_end; phdr++) {
|
|
if (phdr->p_type == PT_LOAD) {
|
|
return (Elf32_Addr)elf + phdr->p_offset - phdr->p_vaddr;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This is the entry point for the linker, called from begin.S. This
|
|
* method is responsible for fixing the linker's own relocations, and
|
|
* then calling __linker_init_post_relocation().
|
|
*
|
|
* Because this method is called before the linker has fixed it's own
|
|
* relocations, any attempt to reference an extern variable, extern
|
|
* function, or other GOT reference will generate a segfault.
|
|
*/
|
|
extern "C" unsigned __linker_init(unsigned **elfdata) {
|
|
unsigned linker_addr = find_linker_base(elfdata);
|
|
Elf32_Ehdr *elf_hdr = (Elf32_Ehdr *) linker_addr;
|
|
Elf32_Phdr *phdr =
|
|
(Elf32_Phdr *)((unsigned char *) linker_addr + elf_hdr->e_phoff);
|
|
|
|
soinfo linker_so;
|
|
memset(&linker_so, 0, sizeof(soinfo));
|
|
|
|
linker_so.base = linker_addr;
|
|
linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum);
|
|
linker_so.load_bias = get_elf_exec_load_bias(elf_hdr);
|
|
linker_so.dynamic = (unsigned *) -1;
|
|
linker_so.phdr = phdr;
|
|
linker_so.phnum = elf_hdr->e_phnum;
|
|
linker_so.flags |= FLAG_LINKER;
|
|
|
|
if (!soinfo_link_image(&linker_so)) {
|
|
// It would be nice to print an error message, but if the linker
|
|
// can't link itself, there's no guarantee that we'll be able to
|
|
// call write() (because it involves a GOT reference).
|
|
//
|
|
// This situation should never occur unless the linker itself
|
|
// is corrupt.
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
// We have successfully fixed our own relocations. It's safe to run
|
|
// the main part of the linker now.
|
|
unsigned start_address = __linker_init_post_relocation(elfdata, linker_addr);
|
|
|
|
set_soinfo_pool_protection(PROT_READ);
|
|
|
|
// Return the address that the calling assembly stub should jump to.
|
|
return start_address;
|
|
}
|