summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--arch/i386/atomic.h5
-rw-r--r--arch/x86_64/atomic.h5
-rw-r--r--src/env/__environ.c7
-rw-r--r--src/env/__init_security.c26
-rw-r--r--src/env/__libc_start_main.c18
-rw-r--r--src/internal/libc.h6
6 files changed, 52 insertions, 15 deletions
diff --git a/arch/i386/atomic.h b/arch/i386/atomic.h
index 66059af9..77b0b3b7 100644
--- a/arch/i386/atomic.h
+++ b/arch/i386/atomic.h
@@ -119,5 +119,10 @@ static inline void a_spin()
__asm__ __volatile__( "pause" : : : "memory" );
}
+static inline void a_crash()
+{
+ __asm__ __volatile__( "hlt" : : : "memory" );
+}
+
#endif
diff --git a/arch/x86_64/atomic.h b/arch/x86_64/atomic.h
index 3235db16..0d3da6f8 100644
--- a/arch/x86_64/atomic.h
+++ b/arch/x86_64/atomic.h
@@ -118,5 +118,10 @@ static inline void a_spin()
__asm__ __volatile__( "pause" : : : "memory" );
}
+static inline void a_crash()
+{
+ __asm__ __volatile__( "hlt" : : : "memory" );
+}
+
#endif
diff --git a/src/env/__environ.c b/src/env/__environ.c
index d7bd5e50..0a2786fd 100644
--- a/src/env/__environ.c
+++ b/src/env/__environ.c
@@ -1,7 +1,6 @@
#include "libc.h"
#undef environ
-char **___environ = 0;
-weak_alias(___environ, __environ);
-weak_alias(___environ, _environ);
-weak_alias(___environ, environ);
+char **__environ = 0;
+weak_alias(__environ, _environ);
+weak_alias(__environ, environ);
diff --git a/src/env/__init_security.c b/src/env/__init_security.c
new file mode 100644
index 00000000..5fd12ecb
--- /dev/null
+++ b/src/env/__init_security.c
@@ -0,0 +1,26 @@
+#include <stddef.h>
+#include <elf.h>
+#include <poll.h>
+#include <fcntl.h>
+#include "syscall.h"
+#include "libc.h"
+#include "atomic.h"
+
+#define AUX_CNT 24
+
+void __init_security(size_t *auxv)
+{
+ size_t i, aux[AUX_CNT] = { 0 };
+ struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} };
+
+ 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;
+
+ __syscall(SYS_poll, pfd, 3, 0);
+ for (i=0; i<3; i++)
+ if (pfd[i].revents&POLLNVAL)
+ if (__syscall(SYS_open, "/dev/null", O_RDWR)<0)
+ a_crash();
+ libc.secure = 1;
+}
diff --git a/src/env/__libc_start_main.c b/src/env/__libc_start_main.c
index 70af77b5..f31222b2 100644
--- a/src/env/__libc_start_main.c
+++ b/src/env/__libc_start_main.c
@@ -1,21 +1,21 @@
#include "libc.h"
-/* Any use of __environ/environ will override this symbol. */
-char **__dummy_environ = (void *)-1;
-weak_alias(__dummy_environ, ___environ);
+void __init_security(size_t *);
int __libc_start_main(
int (*main)(int, char **, char **), int argc, char **argv,
int (*init)(int, char **, char **), void (*fini)(void),
void (*ldso_fini)(void))
{
- /* Save the environment if it may be used by libc/application */
- char **envp = argv+argc+1;
- if (___environ != (void *)-1) ___environ = envp;
+ char **envp = argv+argc+1, **auxv = envp;
- /* Avoid writing 0 and triggering unnecessary COW */
- if (ldso_fini) libc.ldso_fini = ldso_fini;
- if (fini) libc.fini = fini;
+ __environ = envp;
+ do auxv++; while (*auxv);
+ libc.auxv = (void *)++auxv;
+ libc.ldso_fini = ldso_fini;
+ libc.fini = fini;
+
+ __init_security((void *)auxv);
/* Execute constructors (static) linked into the application */
if (init) init(argc, argv, envp);
diff --git a/src/internal/libc.h b/src/internal/libc.h
index 115cd865..d985902c 100644
--- a/src/internal/libc.h
+++ b/src/internal/libc.h
@@ -7,13 +7,15 @@
struct __libc {
void *main_thread;
int threaded;
- int canceldisable;
+ int secure;
+ size_t *auxv;
int (*atexit)(void (*)(void));
void (*fini)(void);
void (*ldso_fini)(void);
volatile int threads_minus_1;
- int ofl_lock;
+ int canceldisable;
FILE *ofl_head;
+ int ofl_lock;
};