f45b0e9ede
dlclose used to unmap the part of the reserved region for ANDROID_DLEXT_RESERVED_ADDRESS that was neccessary to map PT_LOAD segments. With this change dlclose replaces mapped PT_LOAD segments with a PROT_NONE, MAP_ANONYMOUS | MAP_NORESERVE. Previously caller was unmapping the reserved region after the failed dlclose which led to race condition when someone else reused the region freed by dlclose but before the unmap by the chromium code. Bug: http://code.google.com/p/chromium/issues/detail?id=568880 Change-Id: I0f5eaa2bf6641f83dde469b631c518482acc59a2
138 lines
5 KiB
C++
138 lines
5 KiB
C++
/*
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* Copyright (C) 2012 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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#ifndef LINKER_PHDR_H
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#define LINKER_PHDR_H
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/* Declarations related to the ELF program header table and segments.
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*
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* The design goal is to provide an API that is as close as possible
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* to the ELF spec, and does not depend on linker-specific data
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* structures (e.g. the exact layout of struct soinfo).
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*/
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#include "linker.h"
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#include "linker_mapped_file_fragment.h"
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class ElfReader {
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public:
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ElfReader();
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bool Read(const char* name, int fd, off64_t file_offset, off64_t file_size);
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bool Load(const android_dlextinfo* extinfo);
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const char* name() const { return name_.c_str(); }
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size_t phdr_count() const { return phdr_num_; }
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ElfW(Addr) load_start() const { return reinterpret_cast<ElfW(Addr)>(load_start_); }
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size_t load_size() const { return load_size_; }
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ElfW(Addr) load_bias() const { return load_bias_; }
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const ElfW(Phdr)* loaded_phdr() const { return loaded_phdr_; }
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const ElfW(Dyn)* dynamic() const { return dynamic_; }
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const char* get_string(ElfW(Word) index) const;
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bool is_mapped_by_caller() const { return mapped_by_caller_; }
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private:
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bool ReadElfHeader();
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bool VerifyElfHeader();
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bool ReadProgramHeaders();
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bool ReadSectionHeaders();
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bool ReadDynamicSection();
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bool ReserveAddressSpace(const android_dlextinfo* extinfo);
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bool LoadSegments();
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bool FindPhdr();
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bool CheckPhdr(ElfW(Addr));
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bool CheckFileRange(ElfW(Addr) offset, size_t size);
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bool did_read_;
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bool did_load_;
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std::string name_;
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int fd_;
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off64_t file_offset_;
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off64_t file_size_;
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ElfW(Ehdr) header_;
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size_t phdr_num_;
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MappedFileFragment phdr_fragment_;
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const ElfW(Phdr)* phdr_table_;
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MappedFileFragment shdr_fragment_;
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const ElfW(Shdr)* shdr_table_;
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size_t shdr_num_;
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MappedFileFragment dynamic_fragment_;
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const ElfW(Dyn)* dynamic_;
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MappedFileFragment strtab_fragment_;
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const char* strtab_;
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size_t strtab_size_;
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// First page of reserved address space.
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void* load_start_;
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// Size in bytes of reserved address space.
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size_t load_size_;
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// Load bias.
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ElfW(Addr) load_bias_;
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// Loaded phdr.
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const ElfW(Phdr)* loaded_phdr_;
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// Is map owned by the caller
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bool mapped_by_caller_;
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};
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size_t phdr_table_get_load_size(const ElfW(Phdr)* phdr_table, size_t phdr_count,
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ElfW(Addr)* min_vaddr = nullptr, ElfW(Addr)* max_vaddr = nullptr);
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int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table,
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size_t phdr_count, ElfW(Addr) load_bias);
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int phdr_table_unprotect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count,
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ElfW(Addr) load_bias);
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int phdr_table_protect_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count,
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ElfW(Addr) load_bias);
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int phdr_table_serialize_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count,
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ElfW(Addr) load_bias, int fd);
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int phdr_table_map_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count,
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ElfW(Addr) load_bias, int fd);
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#if defined(__arm__)
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int phdr_table_get_arm_exidx(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias,
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ElfW(Addr)** arm_exidx, size_t* arm_exidix_count);
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#endif
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void phdr_table_get_dynamic_section(const ElfW(Phdr)* phdr_table, size_t phdr_count,
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ElfW(Addr) load_bias, ElfW(Dyn)** dynamic,
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ElfW(Word)* dynamic_flags);
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const char* phdr_table_get_interpreter_name(const ElfW(Phdr) * phdr_table, size_t phdr_count,
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ElfW(Addr) load_bias);
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#endif /* LINKER_PHDR_H */
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