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.

2 files changed, 21 insertions, 0 deletions

diff --git a/src/env/__init_security.c b/src/env/__init_security.c
index 5fd12ec..6893a25 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 0000000..bbba351
--- /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();
+}