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-rw-r--r--src/common/linux/file_id.cc160
1 files changed, 122 insertions, 38 deletions
diff --git a/src/common/linux/file_id.cc b/src/common/linux/file_id.cc
index 2227c83b..acd448a9 100644
--- a/src/common/linux/file_id.cc
+++ b/src/common/linux/file_id.cc
@@ -56,39 +56,46 @@
namespace google_breakpad {
+#ifndef NT_GNU_BUILD_ID
+#define NT_GNU_BUILD_ID 3
+#endif
+
FileID::FileID(const char* path) {
strncpy(path_, path, sizeof(path_));
}
struct ElfClass32 {
typedef Elf32_Ehdr Ehdr;
+ typedef Elf32_Nhdr Nhdr;
typedef Elf32_Shdr Shdr;
static const int kClass = ELFCLASS32;
};
struct ElfClass64 {
typedef Elf64_Ehdr Ehdr;
+ typedef Elf64_Nhdr Nhdr;
typedef Elf64_Shdr Shdr;
static const int kClass = ELFCLASS64;
};
-// These three functions are also used inside the crashed process, so be safe
+// These six functions are also used inside the crashed process, so be safe
// and use the syscall/libc wrappers instead of direct syscalls or libc.
template<typename ElfClass>
-static void FindElfClassTextSection(const char *elf_base,
- const void **text_start,
- int *text_size) {
+static void FindElfClassSection(const char *elf_base,
+ const char *section_name,
+ uint32_t section_type,
+ const void **section_start,
+ int *section_size) {
typedef typename ElfClass::Ehdr Ehdr;
typedef typename ElfClass::Shdr Shdr;
assert(elf_base);
- assert(text_start);
- assert(text_size);
+ assert(section_start);
+ assert(section_size);
assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
- const char* text_section_name = ".text";
- int name_len = my_strlen(text_section_name);
+ int name_len = my_strlen(section_name);
const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
@@ -97,30 +104,41 @@ static void FindElfClassTextSection(const char *elf_base,
reinterpret_cast<const Shdr*>(elf_base + elf_header->e_shoff);
const Shdr* string_section = sections + elf_header->e_shstrndx;
- const Shdr* text_section = NULL;
+ const Shdr* section = NULL;
for (int i = 0; i < elf_header->e_shnum; ++i) {
- if (sections[i].sh_type == SHT_PROGBITS) {
+ if (sections[i].sh_type == section_type) {
const char* section_name = (char*)(elf_base +
string_section->sh_offset +
sections[i].sh_name);
- if (!my_strncmp(section_name, text_section_name, name_len)) {
- text_section = &sections[i];
+ if (!my_strncmp(section_name, section_name, name_len)) {
+ section = &sections[i];
break;
}
}
}
- if (text_section != NULL && text_section->sh_size > 0) {
- *text_start = elf_base + text_section->sh_offset;
- *text_size = text_section->sh_size;
+ if (section != NULL && section->sh_size > 0) {
+ *section_start = elf_base + section->sh_offset;
+ *section_size = section->sh_size;
}
}
-static bool FindElfTextSection(const void *elf_mapped_base,
- const void **text_start,
- int *text_size) {
+// Attempt to find a section named |section_name| of type |section_type|
+// in the ELF binary data at |elf_mapped_base|. On success, returns true
+// and sets |*section_start| to point to the start of the section data,
+// and |*section_size| to the size of the section's data. If |elfclass|
+// is not NULL, set |*elfclass| to the ELF file class.
+static bool FindElfSection(const void *elf_mapped_base,
+ const char *section_name,
+ uint32_t section_type,
+ const void **section_start,
+ int *section_size,
+ int *elfclass) {
assert(elf_mapped_base);
- assert(text_start);
- assert(text_size);
+ assert(section_start);
+ assert(section_size);
+
+ *section_start = NULL;
+ *section_size = 0;
const char* elf_base =
static_cast<const char*>(elf_mapped_base);
@@ -129,14 +147,89 @@ static bool FindElfTextSection(const void *elf_mapped_base,
if (my_strncmp(elf_base, ELFMAG, SELFMAG) != 0)
return false;
+ if (elfclass) {
+ *elfclass = elf_header->e_ident[EI_CLASS];
+ }
+
if (elf_header->e_ident[EI_CLASS] == ELFCLASS32) {
- FindElfClassTextSection<ElfClass32>(elf_base, text_start, text_size);
+ FindElfClassSection<ElfClass32>(elf_base, section_name, section_type,
+ section_start, section_size);
+ return *section_start != NULL;
} else if (elf_header->e_ident[EI_CLASS] == ELFCLASS64) {
- FindElfClassTextSection<ElfClass64>(elf_base, text_start, text_size);
- } else {
+ FindElfClassSection<ElfClass64>(elf_base, section_name, section_type,
+ section_start, section_size);
+ return *section_start != NULL;
+ }
+
+ return false;
+}
+
+template<typename ElfClass>
+static bool ElfClassBuildIDNoteIdentifier(const void *section,
+ uint8_t identifier[kMDGUIDSize])
+{
+ typedef typename ElfClass::Nhdr Nhdr;
+
+ const Nhdr* note_header = reinterpret_cast<const Nhdr*>(section);
+ if (note_header->n_type != NT_GNU_BUILD_ID ||
+ note_header->n_descsz == 0) {
return false;
}
+ const char* build_id = reinterpret_cast<const char*>(section) +
+ sizeof(Nhdr) + note_header->n_namesz;
+ // Copy as many bits of the build ID as will fit
+ // into the GUID space.
+ my_memset(identifier, 0, kMDGUIDSize);
+ memcpy(identifier, build_id,
+ std::min(kMDGUIDSize, (size_t)note_header->n_descsz));
+
+ return true;
+}
+
+// Attempt to locate a .note.gnu.build-id section in an ELF binary
+// and copy as many bytes of it as will fit into |identifier|.
+static bool FindElfBuildIDNote(const void *elf_mapped_base,
+ uint8_t identifier[kMDGUIDSize])
+{
+ void* note_section;
+ int note_size, elfclass;
+ if (!FindElfSection(elf_mapped_base, ".note.gnu.build-id", SHT_NOTE,
+ (const void**)&note_section, &note_size, &elfclass) ||
+ note_size == 0) {
+ return false;
+ }
+
+ if (elfclass == ELFCLASS32) {
+ return ElfClassBuildIDNoteIdentifier<ElfClass32>(note_section, identifier);
+ } else if (elfclass == ELFCLASS64) {
+ return ElfClassBuildIDNoteIdentifier<ElfClass64>(note_section, identifier);
+ }
+
+ return false;
+}
+
+// Attempt to locate the .text section of an ELF binary and generate
+// a simple hash by XORing the first page worth of bytes into |identifier|.
+static bool HashElfTextSection(const void *elf_mapped_base,
+ uint8_t identifier[kMDGUIDSize]) {
+
+ void* text_section;
+ int text_size;
+ if (!FindElfSection(elf_mapped_base, ".text", SHT_PROGBITS,
+ (const void**)&text_section, &text_size, NULL) ||
+ text_size == 0) {
+ return false;
+ }
+
+ my_memset(identifier, 0, kMDGUIDSize);
+ const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section);
+ const uint8_t* ptr_end = ptr + std::min(text_size, 4096);
+ while (ptr < ptr_end) {
+ for (unsigned i = 0; i < kMDGUIDSize; i++)
+ identifier[i] ^= ptr[i];
+ ptr += kMDGUIDSize;
+ }
return true;
}
@@ -144,21 +237,12 @@ static bool FindElfTextSection(const void *elf_mapped_base,
bool FileID::ElfFileIdentifierFromMappedFile(void* base,
uint8_t identifier[kMDGUIDSize])
{
- const void* text_section = NULL;
- int text_size = 0;
- bool success = false;
- if (FindElfTextSection(base, &text_section, &text_size) && (text_size > 0)) {
- my_memset(identifier, 0, kMDGUIDSize);
- const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section);
- const uint8_t* ptr_end = ptr + std::min(text_size, 4096);
- while (ptr < ptr_end) {
- for (unsigned i = 0; i < kMDGUIDSize; i++)
- identifier[i] ^= ptr[i];
- ptr += kMDGUIDSize;
- }
- success = true;
- }
- return success;
+ // Look for a build id note first.
+ if (FindElfBuildIDNote(base, identifier))
+ return true;
+
+ // Fall back on hashing the first page of the text section.
+ return HashElfTextSection(base, identifier);
}
bool FileID::ElfFileIdentifier(uint8_t identifier[kMDGUIDSize]) {
generated by cgit v1.2.1 (git 2.18.0) at 2024-06-02 02:58:15 +0000