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authorRich Felker <dalias@aerifal.cx>2012-04-24 18:07:59 -0400
committerRich Felker <dalias@aerifal.cx>2012-04-24 18:07:59 -0400
commit60872cf9c93687e771c1b8bc41bb006bdcdc2e45 (patch)
tree5a90330df6f08de109d0f4f58347dbec642cbff6
parent848d30a1e5f75988be4b291a431713e78ae09f79 (diff)
downloadmusl-60872cf9c93687e771c1b8bc41bb006bdcdc2e45.tar.gz
first attempt at enabling stack protector support
the code is written to pre-init the thread pointer in static linked programs that pull in __stack_chk_fail or dynamic-linked programs that lookup the symbol. no explicit canary is set; the canary will be whatever happens to be in the thread structure at the offset gcc hard-coded. this can be improved later.
-rw-r--r--src/env/__init_security.c7
-rw-r--r--src/env/__stack_chk_fail.c14
-rw-r--r--src/ldso/dynlink.c7
3 files changed, 28 insertions, 0 deletions
diff --git a/src/env/__init_security.c b/src/env/__init_security.c
index 5fd12ecb..6893a252 100644
--- a/src/env/__init_security.c
+++ b/src/env/__init_security.c
@@ -8,11 +8,18 @@
#define AUX_CNT 24
+void dummy(void)
+{
+}
+weak_alias(dummy, __init_ssp);
+
void __init_security(size_t *auxv)
{
size_t i, aux[AUX_CNT] = { 0 };
struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} };
+ __init_ssp();
+
for (; auxv[0]; auxv+=2) if (auxv[0]<AUX_CNT) aux[auxv[0]] = auxv[1];
if (aux[AT_UID]==aux[AT_EUID] && aux[AT_GID]==aux[AT_EGID]
&& !aux[AT_SECURE]) return;
diff --git a/src/env/__stack_chk_fail.c b/src/env/__stack_chk_fail.c
new file mode 100644
index 00000000..bbba3511
--- /dev/null
+++ b/src/env/__stack_chk_fail.c
@@ -0,0 +1,14 @@
+#include "pthread_impl.h"
+#include "atomic.h"
+
+void __init_ssp(void)
+{
+#ifndef __PIC__
+ __pthread_self_init();
+#endif
+}
+
+void __stack_chk_fail(void)
+{
+ a_crash();
+}
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 0533bbb2..d04bef62 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -59,9 +59,13 @@ struct dso
char buf[];
};
+struct __pthread;
+struct __pthread *__pthread_self_init(void);
+
static struct dso *head, *tail, *libc;
static char *env_path, *sys_path, *r_path;
static int rtld_used;
+static int ssp_used;
static int runtime;
static jmp_buf rtld_fail;
static pthread_rwlock_t lock;
@@ -108,6 +112,7 @@ static void *find_sym(struct dso *dso, const char *s, int need_def)
void *def = 0;
if (h==0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
if (h==0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
+ if (h==0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
for (; dso; dso=dso->next) {
Sym *sym;
if (!dso->global) continue;
@@ -611,6 +616,8 @@ void *__dynlink(int argc, char **argv)
reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos);
}
+ if (ssp_used) __pthread_self_init();
+
errno = 0;
return (void *)aux[AT_ENTRY];
}