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