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implement PT_GNU_RELRO support

This commit is contained in:
Timo Teräs 2014-03-25 14:13:27 +02:00 committed by Rich Felker
parent 689e0e6bf7
commit e13a2b8953
1 changed files with 37 additions and 15 deletions
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52
src/ldso/dynlink.c
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@ -74,6 +74,7 @@ struct dso {
char *rpath_orig, *rpath;
void *tls_image;
size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
size_t relro_start, relro_end;
void **new_dtv;
unsigned char *new_tls;
int new_dtv_idx, new_tls_idx;
@ -281,27 +282,29 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
* and "donate" them to the heap by setting up minimal malloc
* structures and then freeing them. */
static void reclaim(unsigned char *base, size_t start, size_t end)
static void reclaim(struct dso *dso, size_t start, size_t end)
{
size_t *a, *z;
if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
if (start>end || end-start < 4*sizeof(size_t)) return;
a = (size_t *)(base + start);
z = (size_t *)(base + end);
a = (size_t *)(dso->base + start);
z = (size_t *)(dso->base + end);
a[-2] = 1;
a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
z[1] = 1;
free(a);
}
static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt)
static void reclaim_gaps(struct dso *dso, Phdr *ph, size_t phent, size_t phcnt)
{
for (; phcnt--; ph=(void *)((char *)ph+phent)) {
if (ph->p_type!=PT_LOAD) continue;
if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
reclaim(base, ph->p_vaddr+ph->p_memsz,
reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
reclaim(dso, ph->p_vaddr+ph->p_memsz,
ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
}
}
@ -346,11 +349,14 @@ static void *map_library(int fd, struct dso *dso)
for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
if (ph->p_type == PT_DYNAMIC)
dyn = ph->p_vaddr;
if (ph->p_type == PT_TLS) {
else if (ph->p_type == PT_TLS) {
tls_image = ph->p_vaddr;
dso->tls_align = ph->p_align;
dso->tls_len = ph->p_filesz;
dso->tls_size = ph->p_memsz;
} else if (ph->p_type == PT_GNU_RELRO) {
dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
}
if (ph->p_type != PT_LOAD) continue;
if (ph->p_vaddr < addr_min) {
@ -419,12 +425,12 @@ static void *map_library(int fd, struct dso *dso)
goto error;
break;
}
if (!runtime) reclaim_gaps(base, ph0, eh->e_phentsize, eh->e_phnum);
dso->map = map;
dso->map_len = map_len;
dso->base = base;
dso->dynv = (void *)(base+dyn);
if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
if (!runtime) reclaim_gaps(dso, ph0, eh->e_phentsize, eh->e_phnum);
free(allocated_buf);
return map;
noexec:
@ -766,6 +772,17 @@ static void reloc_all(struct dso *p)
2+(dyn[DT_PLTREL]==DT_RELA));
do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
if (p->relro_start != p->relro_end &&
mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
snprintf(errbuf, sizeof errbuf,
"Error relocating %s: RELRO protection failed",
p->name);
if (runtime) longjmp(*rtld_fail, 1);
dprintf(2, "%s\n", errbuf);
ldso_fail = 1;
}
p->relocated = 1;
}
}
@ -782,6 +799,10 @@ static void find_map_range(Phdr *ph, size_t cnt, size_t stride, struct dso *p)
{
size_t min_addr = -1, max_addr = 0;
for (; cnt--; ph = (void *)((char *)ph + stride)) {
if (ph->p_type == PT_GNU_RELRO) {
p->relro_start = ph->p_vaddr & -PAGE_SIZE;
p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
}
if (ph->p_type != PT_LOAD) continue;
if (ph->p_vaddr < min_addr)
min_addr = ph->p_vaddr;
@ -1133,9 +1154,9 @@ void *__dynlink(int argc, char **argv)
/* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
/* Donate unused parts of app and library mapping to malloc */
reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
reclaim_gaps(app, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
ehdr = (void *)lib->base;
reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
reclaim_gaps(lib, (void *)(lib->base+ehdr->e_phoff),
ehdr->e_phentsize, ehdr->e_phnum);
/* Load preload/needed libraries, add their symbols to the global
@ -1146,6 +1167,12 @@ void *__dynlink(int argc, char **argv)
load_deps(app);
make_global(app);
#ifndef DYNAMIC_IS_RO
for (i=0; app->dynv[i]; i+=2)
if (app->dynv[i]==DT_DEBUG)
app->dynv[i+1] = (size_t)&debug;
#endif
reloc_all(app->next);
reloc_all(app);
@ -1174,11 +1201,6 @@ void *__dynlink(int argc, char **argv)
* all memory used by the dynamic linker. */
runtime = 1;
#ifndef DYNAMIC_IS_RO
for (i=0; app->dynv[i]; i+=2)
if (app->dynv[i]==DT_DEBUG)
app->dynv[i+1] = (size_t)&debug;
#endif
debug.ver = 1;
debug.bp = _dl_debug_state;
debug.head = head;