075ad800c5
Implement a new method of sideloading over ADB that does not require the entire package to be held in RAM (useful for low-RAM devices and devices using block OTA where we'd rather have more RAM available for binary patching). We communicate with the host using a new adb service called "sideload-host", which makes the host act as a server, sending us different parts of the package file on request. We create a FUSE filesystem that creates a virtual file "/sideload/package.zip" that is backed by the ADB connection -- users see a normal file, but when they read from the file we're actually fetching the data from the adb host. This file is then passed to the verification and installation systems like any other. To prevent a malicious adb host implementation from serving different data to the verification and installation phases of sideloading, the FUSE filesystem verifies that the contents of the file don't change between reads -- every time we fetch a block from the host we compare its hash to the previous hash for that block (if it was read before) and cause the read to fail if it changes. One necessary change is that the minadbd started by recovery in sideload mode no longer drops its root privileges (they're needed to mount the FUSE filesystem). We rely on SELinux enforcement to restrict the set of things that can be accessed. Change-Id: Ida7dbd3b04c1d4e27a2779d88c1da0c7c81fb114
147 lines
3.4 KiB
C
147 lines
3.4 KiB
C
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include "sysdeps.h"
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#include "fdevent.h"
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#include "fuse_sideload.h"
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#define TRACE_TAG TRACE_SERVICES
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#include "adb.h"
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typedef struct stinfo stinfo;
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struct stinfo {
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void (*func)(int fd, void *cookie);
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int fd;
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void *cookie;
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};
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void *service_bootstrap_func(void *x)
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{
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stinfo *sti = x;
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sti->func(sti->fd, sti->cookie);
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free(sti);
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return 0;
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}
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static void sideload_host_service(int sfd, void* cookie)
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{
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char* saveptr;
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const char* s = strtok_r(cookie, ":", &saveptr);
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uint64_t file_size = strtoull(s, NULL, 10);
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s = strtok_r(NULL, ":", &saveptr);
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uint32_t block_size = strtoul(s, NULL, 10);
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printf("sideload-host file size %llu block size %lu\n", file_size, block_size);
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int result = run_fuse(sfd, file_size, block_size);
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printf("sideload_host finished\n");
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sleep(1);
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exit(result == 0 ? 0 : 1);
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}
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#if 0
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static void echo_service(int fd, void *cookie)
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{
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char buf[4096];
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int r;
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char *p;
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int c;
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for(;;) {
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r = read(fd, buf, 4096);
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if(r == 0) goto done;
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if(r < 0) {
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if(errno == EINTR) continue;
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else goto done;
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}
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c = r;
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p = buf;
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while(c > 0) {
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r = write(fd, p, c);
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if(r > 0) {
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c -= r;
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p += r;
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continue;
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}
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if((r < 0) && (errno == EINTR)) continue;
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goto done;
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}
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}
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done:
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close(fd);
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}
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#endif
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static int create_service_thread(void (*func)(int, void *), void *cookie)
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{
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stinfo *sti;
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adb_thread_t t;
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int s[2];
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if(adb_socketpair(s)) {
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printf("cannot create service socket pair\n");
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return -1;
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}
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sti = malloc(sizeof(stinfo));
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if(sti == 0) fatal("cannot allocate stinfo");
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sti->func = func;
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sti->cookie = cookie;
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sti->fd = s[1];
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if(adb_thread_create( &t, service_bootstrap_func, sti)){
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free(sti);
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adb_close(s[0]);
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adb_close(s[1]);
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printf("cannot create service thread\n");
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return -1;
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}
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D("service thread started, %d:%d\n",s[0], s[1]);
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return s[0];
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}
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int service_to_fd(const char *name)
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{
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int ret = -1;
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if (!strncmp(name, "sideload:", 9)) {
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// this exit status causes recovery to print a special error
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// message saying to use a newer adb (that supports
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// sideload-host).
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exit(3);
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} else if (!strncmp(name, "sideload-host:", 14)) {
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ret = create_service_thread(sideload_host_service, (void*)(name + 14));
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#if 0
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} else if(!strncmp(name, "echo:", 5)){
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ret = create_service_thread(echo_service, 0);
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#endif
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}
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if (ret >= 0) {
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close_on_exec(ret);
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}
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return ret;
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}
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