[352] | 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
|
---|
| 12 | typedef Elf32_Ehdr Ehdr;
|
---|
| 13 | typedef Elf32_Phdr Phdr;
|
---|
| 14 | typedef Elf32_Sym Sym;
|
---|
| 15 | typedef Elf32_Verdef Verdef;
|
---|
| 16 | typedef Elf32_Verdaux Verdaux;
|
---|
| 17 | #else
|
---|
| 18 | typedef Elf64_Ehdr Ehdr;
|
---|
| 19 | typedef Elf64_Phdr Phdr;
|
---|
| 20 | typedef Elf64_Sym Sym;
|
---|
| 21 | typedef Elf64_Verdef Verdef;
|
---|
| 22 | typedef Elf64_Verdaux Verdaux;
|
---|
| 23 | #endif
|
---|
| 24 |
|
---|
| 25 | static 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 |
|
---|
| 43 | void *__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
|
---|