#include <elf.h> #include <link.h> #include <limits.h> #include <stdint.h> #include <string.h> #include "libc.h" #include "syscall.h" #ifdef VDSO_USEFUL #if ULONG_MAX == 0xffffffff typedef Elf32_Ehdr Ehdr; typedef Elf32_Phdr Phdr; typedef Elf32_Sym Sym; typedef Elf32_Verdef Verdef; typedef Elf32_Verdaux Verdaux; #else typedef Elf64_Ehdr Ehdr; typedef Elf64_Phdr Phdr; typedef Elf64_Sym Sym; typedef Elf64_Verdef Verdef; typedef Elf64_Verdaux Verdaux; #endif static int checkver(Verdef *def, int vsym, const char *vername, char *strings) { vsym &= 0x7fff; for (;;) { if (!(def->vd_flags & VER_FLG_BASE) && (def->vd_ndx & 0x7fff) == vsym) break; if (def->vd_next == 0) return 0; def = (Verdef *)((char *)def + def->vd_next); } Verdaux *aux = (Verdaux *)((char *)def + def->vd_aux); return !strcmp(vername, strings + aux->vda_name); } #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON) #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE) void *__vdsosym(const char *vername, const char *name) { size_t i; for (i=0; libc.auxv[i] != AT_SYSINFO_EHDR; i+=2) if (!libc.auxv[i]) return 0; if (!libc.auxv[i+1]) return 0; Ehdr *eh = (void *)libc.auxv[i+1]; Phdr *ph = (void *)((char *)eh + eh->e_phoff); size_t *dynv=0, base=-1; for (i=0; i<eh->e_phnum; i++, ph=(void *)((char *)ph+eh->e_phentsize)) { if (ph->p_type == PT_LOAD) base = (size_t)eh + ph->p_offset - ph->p_vaddr; else if (ph->p_type == PT_DYNAMIC) dynv = (void *)((char *)eh + ph->p_offset); } if (!dynv || base==(size_t)-1) return 0; char *strings = 0; Sym *syms = 0; Elf_Symndx *hashtab = 0; uint16_t *versym = 0; Verdef *verdef = 0; for (i=0; dynv[i]; i+=2) { void *p = (void *)(base + dynv[i+1]); switch(dynv[i]) { case DT_STRTAB: strings = p; break; case DT_SYMTAB: syms = p; break; case DT_HASH: hashtab = p; break; case DT_VERSYM: versym = p; break; case DT_VERDEF: verdef = p; break; } } if (!strings || !syms || !hashtab) return 0; if (!verdef) versym = 0; for (i=0; i<hashtab[1]; i++) { if (!(1<<(syms[i].st_info&0xf) & OK_TYPES)) continue; if (!(1<<(syms[i].st_info>>4) & OK_BINDS)) continue; if (!syms[i].st_shndx) continue; if (strcmp(name, strings+syms[i].st_name)) continue; if (versym && !checkver(verdef, versym[i], vername, strings)) continue; return (void *)(base + syms[i].st_value); } return 0; } #endif