From 864619bb2e68e4ec8fa5bcfc87b00bf6667601e3 Mon Sep 17 00:00:00 2001 From: Keith Seitz Date: Wed, 30 Oct 2019 12:23:16 +0000 Subject: [PATCH] Add the ability to the BFD library to read build-ids from core flies. * elf-bfd.h (elf_backend_data) : New field. (_bfd_elf32_core_find_build_id, _bfd_elf64_core_find_build_id): New functions. (elf_read_notes): Add declaration. * elf.c (elf_read_notes): Move elf-bfd.h. (_bfd_elf_core_find_build_id): New function. (bfd_section_from_phdr): Scan core file PT_LOAD segments for build-id if none is known. (elf_parse_notes): For core files, scan for notes. * elfcore.h (elf_core_file_matches_executable_p): If both BFDs have identical build-ids, then they match. (_bfd_elf_core_find_build_id): New function. * elfxx-target.h (elf_backend_core_find_build_id): Define. (elfNN_bed): Add elf_backend_core_find_build_id. --- bfd/ChangeLog | 18 ++++++++ bfd/elf-bfd.h | 7 +++ bfd/elf.c | 23 +++++++--- bfd/elfcore.h | 106 +++++++++++++++++++++++++++++++++++++++++++++ bfd/elfxx-target.h | 4 ++ 5 files changed, 153 insertions(+), 5 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 20d7d5a41a2..78cbd51f92a 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,21 @@ +2019-10-30 Keith Seitz + + * elf-bfd.h (elf_backend_data) : + New field. + (_bfd_elf32_core_find_build_id, _bfd_elf64_core_find_build_id): + New functions. + (elf_read_notes): Add declaration. + * elf.c (elf_read_notes): Move elf-bfd.h. + (_bfd_elf_core_find_build_id): New function. + (bfd_section_from_phdr): Scan core file PT_LOAD segments for + build-id if none is known. + (elf_parse_notes): For core files, scan for notes. + * elfcore.h (elf_core_file_matches_executable_p): If both + BFDs have identical build-ids, then they match. + (_bfd_elf_core_find_build_id): New function. + * elfxx-target.h (elf_backend_core_find_build_id): Define. + (elfNN_bed): Add elf_backend_core_find_build_id. + 2019-10-29 Andrew Eikum * libcoff-in.h (struct pe_tdata): Add dos_message field. diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h index ccd2c35f871..7309499119f 100644 --- a/bfd/elf-bfd.h +++ b/bfd/elf-bfd.h @@ -1377,6 +1377,8 @@ struct elf_backend_data int (*target_read_memory) (bfd_vma vma, bfd_byte *myaddr, bfd_size_type len)); + bfd_boolean (*elf_backend_core_find_build_id) (bfd *, bfd_vma); + /* This function is used by `_bfd_elf_get_synthetic_symtab'; see elf.c. */ bfd_vma (*plt_sym_val) (bfd_vma, const asection *, const arelent *); @@ -2403,6 +2405,8 @@ extern bfd_boolean bfd_elf32_core_file_matches_executable_p (bfd *, bfd *); extern int bfd_elf32_core_file_pid (bfd *); +extern bfd_boolean _bfd_elf32_core_find_build_id + (bfd *, bfd_vma); extern bfd_boolean bfd_elf32_swap_symbol_in (bfd *, const void *, const void *, Elf_Internal_Sym *); @@ -2449,6 +2453,8 @@ extern bfd_boolean bfd_elf64_core_file_matches_executable_p (bfd *, bfd *); extern int bfd_elf64_core_file_pid (bfd *); +extern bfd_boolean _bfd_elf64_core_find_build_id + (bfd *, bfd_vma); extern bfd_boolean bfd_elf64_swap_symbol_in (bfd *, const void *, const void *, Elf_Internal_Sym *); @@ -2773,6 +2779,7 @@ extern bfd_boolean _bfd_elf_merge_object_attributes extern bfd_boolean _bfd_elf_merge_unknown_attribute_low (bfd *, bfd *, int); extern bfd_boolean _bfd_elf_merge_unknown_attribute_list (bfd *, bfd *); extern Elf_Internal_Shdr *_bfd_elf_single_rel_hdr (asection *sec); +extern bfd_boolean elf_read_notes (bfd *, file_ptr, bfd_size_type, size_t); extern bfd_boolean _bfd_elf_parse_gnu_properties (bfd *, Elf_Internal_Note *); diff --git a/bfd/elf.c b/bfd/elf.c index 38872d7757e..be060d579cc 100644 --- a/bfd/elf.c +++ b/bfd/elf.c @@ -53,8 +53,6 @@ static int elf_sort_sections (const void *, const void *); static bfd_boolean assign_file_positions_except_relocs (bfd *, struct bfd_link_info *); static bfd_boolean prep_headers (bfd *); static bfd_boolean swap_out_syms (bfd *, struct elf_strtab_hash **, int) ; -static bfd_boolean elf_read_notes (bfd *, file_ptr, bfd_size_type, - size_t align) ; static bfd_boolean elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset, size_t align); @@ -3061,6 +3059,16 @@ _bfd_elf_make_section_from_phdr (bfd *abfd, return TRUE; } +static bfd_boolean +_bfd_elf_core_find_build_id (bfd *templ, bfd_vma offset) +{ + /* The return value is ignored. Build-ids are considered optional. */ + if (templ->xvec->flavour == bfd_target_elf_flavour) + return (*get_elf_backend_data (templ)->elf_backend_core_find_build_id) + (templ, offset); + return FALSE; +} + bfd_boolean bfd_section_from_phdr (bfd *abfd, Elf_Internal_Phdr *hdr, int hdr_index) { @@ -3072,7 +3080,11 @@ bfd_section_from_phdr (bfd *abfd, Elf_Internal_Phdr *hdr, int hdr_index) return _bfd_elf_make_section_from_phdr (abfd, hdr, hdr_index, "null"); case PT_LOAD: - return _bfd_elf_make_section_from_phdr (abfd, hdr, hdr_index, "load"); + if (! _bfd_elf_make_section_from_phdr (abfd, hdr, hdr_index, "load")) + return FALSE; + if (bfd_get_format (abfd) == bfd_core && abfd->build_id == NULL) + _bfd_elf_core_find_build_id (abfd, hdr->p_offset); + return TRUE; case PT_DYNAMIC: return _bfd_elf_make_section_from_phdr (abfd, hdr, hdr_index, "dynamic"); @@ -11838,7 +11850,8 @@ elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset, GROKER_ELEMENT ("NetBSD-CORE", elfcore_grok_netbsd_note), GROKER_ELEMENT ( "OpenBSD", elfcore_grok_openbsd_note), GROKER_ELEMENT ("QNX", elfcore_grok_nto_note), - GROKER_ELEMENT ("SPU/", elfcore_grok_spu_note) + GROKER_ELEMENT ("SPU/", elfcore_grok_spu_note), + GROKER_ELEMENT ("GNU", elfobj_grok_gnu_note) }; #undef GROKER_ELEMENT int i; @@ -11878,7 +11891,7 @@ elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset, return TRUE; } -static bfd_boolean +bfd_boolean elf_read_notes (bfd *abfd, file_ptr offset, bfd_size_type size, size_t align) { diff --git a/bfd/elfcore.h b/bfd/elfcore.h index 3550eaac272..1279327bf0d 100644 --- a/bfd/elfcore.h +++ b/bfd/elfcore.h @@ -49,6 +49,14 @@ elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd) return FALSE; } + /* If both BFDs have identical build-ids, then they match. */ + if (core_bfd->build_id != NULL + && exec_bfd->build_id != NULL + && core_bfd->build_id->size == exec_bfd->build_id->size + && memcmp (core_bfd->build_id->data, exec_bfd->build_id->data, + core_bfd->build_id->size) == 0) + return TRUE; + /* See if the name in the corefile matches the executable name. */ corename = elf_tdata (core_bfd)->core->program; if (corename != NULL) @@ -313,3 +321,101 @@ wrong: fail: return NULL; } + +/* Attempt to find a build-id in a core file from the core file BFD. + OFFSET is the file offset to a PT_LOAD segment that may contain + the build-id note. Returns TRUE upon success, FALSE otherwise. */ + +bfd_boolean +NAME(_bfd_elf, core_find_build_id) + (bfd *abfd, + bfd_vma offset) +{ + Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */ + Elf_Internal_Ehdr i_ehdr; /* Elf file header, internal form. */ + Elf_Internal_Phdr *i_phdr; + unsigned int i; + + /* Seek to the position of the segment at OFFSET. */ + if (bfd_seek (abfd, offset, SEEK_SET) != 0) + goto fail; + + /* Read in the ELF header in external format. */ + if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr)) + { + if (bfd_get_error () != bfd_error_system_call) + goto wrong; + else + goto fail; + } + + /* Now check to see if we have a valid ELF file, and one that BFD can + make use of. The magic number must match, the address size ('class') + and byte-swapping must match our XVEC entry, and it must have a + section header table (FIXME: See comments re sections at top of this + file). */ + if (! elf_file_p (&x_ehdr) + || x_ehdr.e_ident[EI_VERSION] != EV_CURRENT + || x_ehdr.e_ident[EI_CLASS] != ELFCLASS) + goto wrong; + + /* Check that file's byte order matches xvec's. */ + switch (x_ehdr.e_ident[EI_DATA]) + { + case ELFDATA2MSB: /* Big-endian. */ + if (! bfd_header_big_endian (abfd)) + goto wrong; + break; + case ELFDATA2LSB: /* Little-endian. */ + if (! bfd_header_little_endian (abfd)) + goto wrong; + break; + case ELFDATANONE: /* No data encoding specified. */ + default: /* Unknown data encoding specified . */ + goto wrong; + } + + elf_swap_ehdr_in (abfd, &x_ehdr, &i_ehdr); +#if DEBUG + elf_debug_file (&i_ehdr); +#endif + + if (i_ehdr.e_phentsize != sizeof (Elf_External_Phdr) || i_ehdr.e_phnum == 0) + goto fail; + + /* Read in program headers. */ + i_phdr = (Elf_Internal_Phdr *) bfd_alloc2 (abfd, i_ehdr.e_phnum, + sizeof (*i_phdr)); + if (i_phdr == NULL) + goto fail; + + if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff), SEEK_SET) != 0) + goto fail; + + /* Read in program headers and parse notes. */ + for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr) + { + Elf_External_Phdr x_phdr; + + if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr)) + goto fail; + elf_swap_phdr_in (abfd, &x_phdr, i_phdr); + + if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0) + { + elf_read_notes (abfd, offset + i_phdr->p_offset, + i_phdr->p_filesz, i_phdr->p_align); + if (abfd->build_id != NULL) + return TRUE; + } + } + + /* Having gotten this far, we have a valid ELF section, but no + build-id was found. */ + goto fail; + +wrong: + bfd_set_error (bfd_error_wrong_format); +fail: + return FALSE; +} diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h index 78a1f6314d0..29ad2e84818 100644 --- a/bfd/elfxx-target.h +++ b/bfd/elfxx-target.h @@ -521,6 +521,9 @@ #ifndef elf_backend_bfd_from_remote_memory #define elf_backend_bfd_from_remote_memory _bfd_elfNN_bfd_from_remote_memory #endif +#ifndef elf_backend_core_find_build_id +#define elf_backend_core_find_build_id _bfd_elfNN_core_find_build_id +#endif #ifndef elf_backend_got_header_size #define elf_backend_got_header_size 0 #endif @@ -860,6 +863,7 @@ static struct elf_backend_data elfNN_bed = elf_backend_mips_rtype_to_howto, elf_backend_ecoff_debug_swap, elf_backend_bfd_from_remote_memory, + elf_backend_core_find_build_id, elf_backend_plt_sym_val, elf_backend_common_definition, elf_backend_common_section_index, -- 2.30.2