1#include <elf.h> 2#include <link.h> 3#include <limits.h> 4#include <stdint.h> 5#include <string.h> 6#include "libc.h" 7#include "syscall.h" 8 9#ifdef VDSO_USEFUL 10 11#if ULONG_MAX == 0xffffffff 12typedef Elf32_Ehdr Ehdr; 13typedef Elf32_Phdr Phdr; 14typedef Elf32_Sym Sym; 15typedef Elf32_Verdef Verdef; 16typedef Elf32_Verdaux Verdaux; 17#else 18typedef Elf64_Ehdr Ehdr; 19typedef Elf64_Phdr Phdr; 20typedef Elf64_Sym Sym; 21typedef Elf64_Verdef Verdef; 22typedef Elf64_Verdaux Verdaux; 23#endif 24 25static int checkver(Verdef *def, int vsym, const char *vername, char *strings) 26{ 27 vsym &= 0x7fff; 28 for (;;) { 29 if (!(def->vd_flags & VER_FLG_BASE) 30 && (def->vd_ndx & 0x7fff) == vsym) 31 break; 32 if (def->vd_next == 0) 33 return 0; 34 def = (Verdef *)((char *)def + def->vd_next); 35 } 36 Verdaux *aux = (Verdaux *)((char *)def + def->vd_aux); 37 return !strcmp(vername, strings + aux->vda_name); 38} 39 40#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON) 41#define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE) 42 43void *__vdsosym(const char *vername, const char *name) 44{ 45 size_t i; 46 for (i=0; libc.auxv[i] != AT_SYSINFO_EHDR; i+=2) 47 if (!libc.auxv[i]) return 0; 48 if (!libc.auxv[i+1]) return 0; 49 Ehdr *eh = (void *)libc.auxv[i+1]; 50 Phdr *ph = (void *)((char *)eh + eh->e_phoff); 51 size_t *dynv=0, base=-1; 52 for (i=0; i<eh->e_phnum; i++, ph=(void *)((char *)ph+eh->e_phentsize)) { 53 if (ph->p_type == PT_LOAD) 54 base = (size_t)eh + ph->p_offset - ph->p_vaddr; 55 else if (ph->p_type == PT_DYNAMIC) 56 dynv = (void *)((char *)eh + ph->p_offset); 57 } 58 if (!dynv || base==(size_t)-1) return 0; 59 60 char *strings = 0; 61 Sym *syms = 0; 62 Elf_Symndx *hashtab = 0; 63 uint16_t *versym = 0; 64 Verdef *verdef = 0; 65 66 for (i=0; dynv[i]; i+=2) { 67 void *p = (void *)(base + dynv[i+1]); 68 switch(dynv[i]) { 69 case DT_STRTAB: strings = p; break; 70 case DT_SYMTAB: syms = p; break; 71 case DT_HASH: hashtab = p; break; 72 case DT_VERSYM: versym = p; break; 73 case DT_VERDEF: verdef = p; break; 74 } 75 } 76 77 if (!strings || !syms || !hashtab) return 0; 78 if (!verdef) versym = 0; 79 80 for (i=0; i<hashtab[1]; i++) { 81 if (!(1<<(syms[i].st_info&0xf) & OK_TYPES)) continue; 82 if (!(1<<(syms[i].st_info>>4) & OK_BINDS)) continue; 83 if (!syms[i].st_shndx) continue; 84 if (strcmp(name, strings+syms[i].st_name)) continue; 85 if (versym && !checkver(verdef, versym[i], vername, strings)) 86 continue; 87 return (void *)(base + syms[i].st_value); 88 } 89 90 return 0; 91} 92 93#endif 94