diff options
Diffstat (limited to 'Documentation/vDSO/parse_vdso.c')
| -rw-r--r-- | Documentation/vDSO/parse_vdso.c | 67 |
1 files changed, 40 insertions, 27 deletions
diff --git a/Documentation/vDSO/parse_vdso.c b/Documentation/vDSO/parse_vdso.c index 8587020..1dbb4b8 100644 --- a/Documentation/vDSO/parse_vdso.c +++ b/Documentation/vDSO/parse_vdso.c @@ -1,6 +1,6 @@ /* * parse_vdso.c: Linux reference vDSO parser - * Written by Andrew Lutomirski, 2011. + * Written by Andrew Lutomirski, 2011-2014. * * This code is meant to be linked in to various programs that run on Linux. * As such, it is available with as few restrictions as possible. This file @@ -11,13 +11,14 @@ * it starts a program. It works equally well in statically and dynamically * linked binaries. * - * This code is tested on x86_64. In principle it should work on any 64-bit + * This code is tested on x86. In principle it should work on any * architecture that has a vDSO. */ #include <stdbool.h> #include <stdint.h> #include <string.h> +#include <limits.h> #include <elf.h> /* @@ -45,11 +46,18 @@ extern void *vdso_sym(const char *version, const char *name); /* And here's the code. */ - -#ifndef __x86_64__ -# error Not yet ported to non-x86_64 architectures +#ifndef ELF_BITS +# if ULONG_MAX > 0xffffffffUL +# define ELF_BITS 64 +# else +# define ELF_BITS 32 +# endif #endif +#define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x +#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x) +#define ELF(x) ELF_BITS_XFORM(ELF_BITS, x) + static struct vdso_info { bool valid; @@ -59,14 +67,14 @@ static struct vdso_info uintptr_t load_offset; /* load_addr - recorded vaddr */ /* Symbol table */ - Elf64_Sym *symtab; + ELF(Sym) *symtab; const char *symstrings; - Elf64_Word *bucket, *chain; - Elf64_Word nbucket, nchain; + ELF(Word) *bucket, *chain; + ELF(Word) nbucket, nchain; /* Version table */ - Elf64_Versym *versym; - Elf64_Verdef *verdef; + ELF(Versym) *versym; + ELF(Verdef) *verdef; } vdso_info; /* Straight from the ELF specification. */ @@ -92,9 +100,14 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) vdso_info.load_addr = base; - Elf64_Ehdr *hdr = (Elf64_Ehdr*)base; - Elf64_Phdr *pt = (Elf64_Phdr*)(vdso_info.load_addr + hdr->e_phoff); - Elf64_Dyn *dyn = 0; + ELF(Ehdr) *hdr = (ELF(Ehdr)*)base; + if (hdr->e_ident[EI_CLASS] != + (ELF_BITS == 32 ? ELFCLASS32 : ELFCLASS64)) { + return; /* Wrong ELF class -- check ELF_BITS */ + } + + ELF(Phdr) *pt = (ELF(Phdr)*)(vdso_info.load_addr + hdr->e_phoff); + ELF(Dyn) *dyn = 0; /* * We need two things from the segment table: the load offset @@ -108,7 +121,7 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) + (uintptr_t)pt[i].p_offset - (uintptr_t)pt[i].p_vaddr; } else if (pt[i].p_type == PT_DYNAMIC) { - dyn = (Elf64_Dyn*)(base + pt[i].p_offset); + dyn = (ELF(Dyn)*)(base + pt[i].p_offset); } } @@ -118,7 +131,7 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) /* * Fish out the useful bits of the dynamic table. */ - Elf64_Word *hash = 0; + ELF(Word) *hash = 0; vdso_info.symstrings = 0; vdso_info.symtab = 0; vdso_info.versym = 0; @@ -131,22 +144,22 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) + vdso_info.load_offset); break; case DT_SYMTAB: - vdso_info.symtab = (Elf64_Sym *) + vdso_info.symtab = (ELF(Sym) *) ((uintptr_t)dyn[i].d_un.d_ptr + vdso_info.load_offset); break; case DT_HASH: - hash = (Elf64_Word *) + hash = (ELF(Word) *) ((uintptr_t)dyn[i].d_un.d_ptr + vdso_info.load_offset); break; case DT_VERSYM: - vdso_info.versym = (Elf64_Versym *) + vdso_info.versym = (ELF(Versym) *) ((uintptr_t)dyn[i].d_un.d_ptr + vdso_info.load_offset); break; case DT_VERDEF: - vdso_info.verdef = (Elf64_Verdef *) + vdso_info.verdef = (ELF(Verdef) *) ((uintptr_t)dyn[i].d_un.d_ptr + vdso_info.load_offset); break; @@ -168,8 +181,8 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) vdso_info.valid = true; } -static bool vdso_match_version(Elf64_Versym ver, - const char *name, Elf64_Word hash) +static bool vdso_match_version(ELF(Versym) ver, + const char *name, ELF(Word) hash) { /* * This is a helper function to check if the version indexed by @@ -188,7 +201,7 @@ static bool vdso_match_version(Elf64_Versym ver, /* First step: find the version definition */ ver &= 0x7fff; /* Apparently bit 15 means "hidden" */ - Elf64_Verdef *def = vdso_info.verdef; + ELF(Verdef) *def = vdso_info.verdef; while(true) { if ((def->vd_flags & VER_FLG_BASE) == 0 && (def->vd_ndx & 0x7fff) == ver) @@ -197,11 +210,11 @@ static bool vdso_match_version(Elf64_Versym ver, if (def->vd_next == 0) return false; /* No definition. */ - def = (Elf64_Verdef *)((char *)def + def->vd_next); + def = (ELF(Verdef) *)((char *)def + def->vd_next); } /* Now figure out whether it matches. */ - Elf64_Verdaux *aux = (Elf64_Verdaux*)((char *)def + def->vd_aux); + ELF(Verdaux) *aux = (ELF(Verdaux)*)((char *)def + def->vd_aux); return def->vd_hash == hash && !strcmp(name, vdso_info.symstrings + aux->vda_name); } @@ -213,10 +226,10 @@ void *vdso_sym(const char *version, const char *name) return 0; ver_hash = elf_hash(version); - Elf64_Word chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket]; + ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket]; for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) { - Elf64_Sym *sym = &vdso_info.symtab[chain]; + ELF(Sym) *sym = &vdso_info.symtab[chain]; /* Check for a defined global or weak function w/ right name. */ if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC) @@ -243,7 +256,7 @@ void *vdso_sym(const char *version, const char *name) void vdso_init_from_auxv(void *auxv) { - Elf64_auxv_t *elf_auxv = auxv; + ELF(auxv_t) *elf_auxv = auxv; for (int i = 0; elf_auxv[i].a_type != AT_NULL; i++) { if (elf_auxv[i].a_type == AT_SYSINFO_EHDR) { |