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add rpath $ORIGIN processing to dynamic linker

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This commit is contained in:
Rich Felker 2013-08-23 13:56:30 -04:00
parent 709355e1f6
commit a897a20a57
1 changed files with 59 additions and 3 deletions
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62
src/ldso/dynlink.c
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@ -72,8 +72,9 @@ struct dso {
signed char global;
char relocated;
char constructed;
char kernel_mapped;
struct dso **deps, *needed_by;
char *rpath;
char *rpath_orig, *rpath;
void *tls_image;
size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
void **new_dtv;
@ -448,6 +449,58 @@ static int path_open(const char *name, const char *s, char *buf, size_t buf_size
}
}
static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
{
size_t n, l;
const char *s, *t, *origin;
char *d;
if (p->rpath) return 0;
if (!p->rpath_orig) return -1;
if (!strchr(p->rpath_orig, '$')) {
p->rpath = p->rpath_orig;
return 0;
}
n = 0;
s = p->rpath_orig;
while ((t=strstr(s, "$ORIGIN")) || (t=strstr(s, "${ORIGIN}"))) {
s = t+1;
n++;
}
if (n > SSIZE_MAX/PATH_MAX) return -1;
if (p->kernel_mapped) {
/* $ORIGIN searches cannot be performed for the main program
* when it is suid/sgid/AT_SECURE. This is because the
* pathname is under the control of the caller of execve.
* For libraries, however, $ORIGIN can be processed safely
* since the library's pathname came from a trusted source
* (either system paths or a call to dlopen). */
if (libc.secure)
return -1;
if (readlink("/proc/self/exe", buf, buf_size) >= buf_size)
return -1;
origin = buf;
} else {
origin = p->name;
}
t = strrchr(origin, '/');
l = t ? t-origin : 0;
p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
if (!p->rpath) return -1;
d = p->rpath;
s = p->rpath_orig;
while ((t=strstr(s, "$ORIGIN")) || (t=strstr(s, "${ORIGIN}"))) {
memcpy(d, s, t-s);
d += t-s;
memcpy(d, origin, l);
d += l;
s = t + 7 + 2*(t[1]=='{');
}
strcpy(d, s);
return 0;
}
static void decode_dyn(struct dso *p)
{
size_t dyn[DYN_CNT] = {0};
@ -457,7 +510,7 @@ static void decode_dyn(struct dso *p)
if (dyn[0]&(1<<DT_HASH))
p->hashtab = (void *)(p->base + dyn[DT_HASH]);
if (dyn[0]&(1<<DT_RPATH))
p->rpath = (void *)(p->strings + dyn[DT_RPATH]);
p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
if (search_vec(p->dynv, dyn, DT_GNU_HASH))
p->ghashtab = (void *)(p->base + *dyn);
if (search_vec(p->dynv, dyn, DT_VERSYM))
@ -525,7 +578,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
fd = -1;
if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
for (p=needed_by; fd < 0 && p; p=p->needed_by)
if (p->rpath)
if (!fixup_rpath(p, buf, sizeof buf))
fd = path_open(name, p->rpath, buf, sizeof buf);
if (fd < 0) {
if (!sys_path) {
@ -917,6 +970,7 @@ void *__dynlink(int argc, char **argv)
|| aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
env_path = 0;
env_preload = 0;
libc.secure = 1;
}
/* If the dynamic linker was invoked as a program itself, AT_BASE
@ -933,6 +987,7 @@ void *__dynlink(int argc, char **argv)
lib->base = (void *)aux[AT_BASE];
lib->name = lib->shortname = "libc.so";
lib->global = 1;
lib->kernel_mapped = 1;
ehdr = (void *)lib->base;
lib->phnum = ehdr->e_phnum;
lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
@ -962,6 +1017,7 @@ void *__dynlink(int argc, char **argv)
if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
if (interp_off) lib->name = (char *)app->base + interp_off;
app->name = argv[0];
app->kernel_mapped = 1;
app->dynv = (void *)(app->base + find_dyn(
(void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
find_map_range((void *)aux[AT_PHDR],