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authorRich Felker <dalias@aerifal.cx>2015-04-03 16:35:43 -0400
committerRich Felker <dalias@aerifal.cx>2015-04-03 16:35:43 -0400
commit2963a9f79406c829d5fd710a2e8fe510ee83c006 (patch)
tree3857b91c4dcc6ccf2f6d02da5829f76890387f31 /src
parent5e25d87b09d1dafc527833d9b4e9a6de99b79aab (diff)
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halt dynamic linker library search on errors resolving $ORIGIN in rpath
this change hardens the dynamic linker against the possibility of loading the wrong library due to inability to expand $ORIGIN in rpath. hard failures such as excessively long paths or absence of /proc (when resolving /proc/self/exe for the main executable's origin) do not stop the path search, but memory allocation failures and any other potentially transient failures do. to implement this change, the meaning of the return value of fixup_rpath function is changed. returning zero no longer indicates that the dso's rpath string pointer is non-null; instead, the caller needs to check. a return value of -1 indicates a failure that should stop further path search.
Diffstat (limited to 'src')
-rw-r--r--src/ldso/dynlink.c26
1 files changed, 18 insertions, 8 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 0eb763e7..4a371839 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -599,8 +599,7 @@ static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
size_t n, l;
const char *s, *t, *origin;
char *d;
- if (p->rpath) return 0;
- if (!p->rpath_orig) return -1;
+ if (p->rpath || !p->rpath_orig) return 0;
if (!strchr(p->rpath_orig, '$')) {
p->rpath = p->rpath_orig;
return 0;
@@ -609,11 +608,11 @@ static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
s = p->rpath_orig;
while ((t=strchr(s, '$'))) {
if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
- return -1;
+ return 0;
s = t+1;
n++;
}
- if (n > SSIZE_MAX/PATH_MAX) return -1;
+ if (n > SSIZE_MAX/PATH_MAX) return 0;
if (p->kernel_mapped) {
/* $ORIGIN searches cannot be performed for the main program
@@ -623,10 +622,18 @@ static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
* since the library's pathname came from a trusted source
* (either system paths or a call to dlopen). */
if (libc.secure)
- return -1;
+ return 0;
l = readlink("/proc/self/exe", buf, buf_size);
- if (l >= buf_size)
+ if (l == -1) switch (errno) {
+ case ENOENT:
+ case ENOTDIR:
+ case EACCES:
+ break;
+ default:
return -1;
+ }
+ if (l >= buf_size)
+ return 0;
buf[l] = 0;
origin = buf;
} else {
@@ -735,9 +742,12 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
if (strlen(name) > NAME_MAX) return 0;
fd = -1;
if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
- for (p=needed_by; fd == -1 && p; p=p->needed_by)
- if (!fixup_rpath(p, buf, sizeof buf))
+ for (p=needed_by; fd == -1 && p; p=p->needed_by) {
+ if (fixup_rpath(p, buf, sizeof buf) < 0)
+ fd = -2; /* Inhibit further search. */
+ if (p->rpath)
fd = path_open(name, p->rpath, buf, sizeof buf);
+ }
if (fd == -1) {
if (!sys_path) {
char *prefix = 0;