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load vdso, if present, into the dso list

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This commit is contained in:
Rich Felker 2011-07-24 00:54:55 -04:00
parent f7adc39e37
commit 6ab444d97a
1 changed files with 31 additions and 2 deletions
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33
src/ldso/dynlink.c
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@ -298,7 +298,7 @@ static struct dso *load_library(const char *name)
if (!libc->prev) {
tail->next = libc;
libc->prev = tail;
tail = libc;
tail = libc->next ? libc->next : libc;
}
return libc;
}
@ -440,12 +440,15 @@ void *__dynlink(int argc, char **argv, size_t *got)
size_t *auxv, aux[AUX_CNT] = {0};
size_t app_dyn[DYN_CNT] = {0};
size_t lib_dyn[DYN_CNT] = {0};
size_t vdso_dyn[DYN_CNT] = {0};
size_t i;
Phdr *phdr;
Ehdr *ehdr;
static struct dso builtin_dsos[2];
static struct dso builtin_dsos[3];
struct dso *const app = builtin_dsos+0;
struct dso *const lib = builtin_dsos+1;
struct dso *const vdso = builtin_dsos+2;
size_t vdso_base=0;
/* Find aux vector just past environ[] */
for (i=argc+1; argv[i]; i++)
@ -455,6 +458,13 @@ void *__dynlink(int argc, char **argv, size_t *got)
decode_vec(auxv, aux, AUX_CNT);
for (i=0; auxv[i]; i+=2) {
if (auxv[i]==AT_SYSINFO_EHDR) {
vdso_base = auxv[i+1];
break;
}
}
/* Only trust user/env if kernel says we're not suid/sgid */
if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
|| aux[AT_GID]!=aux[AT_EGID]) {
@ -495,6 +505,25 @@ void *__dynlink(int argc, char **argv, size_t *got)
.relocated = 1
};
if (vdso_base) {
ehdr = (void *)vdso_base;
phdr = (void *)(vdso_base + ehdr->e_phoff);
for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
if (phdr->p_type == PT_DYNAMIC)
vdso->dynv = (void *)(vdso_base + phdr->p_offset);
if (phdr->p_type == PT_LOAD)
vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
}
decode_vec(vdso->dynv, vdso_dyn, DYN_CNT);
vdso->syms = (void *)(vdso->base + vdso_dyn[DT_SYMTAB]);
vdso->hashtab = (void *)(vdso->base + vdso_dyn[DT_HASH]);
vdso->strings = (void *)(vdso->base + vdso_dyn[DT_STRTAB]);
vdso->name = "linux-gate.so.1";
vdso->prev = lib;
lib->next = vdso;
}
/* Relocate the dynamic linker/libc */
do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]),
lib_dyn[DT_RELSZ], 2, lib->syms, lib->strings, app);