libsandbox: push down constructor init

Since every consumer of sb_open gets a copy of the sbio_open data, push
the init of this into the .data section of the respective consumers to
avoid the runtime overhead.

This just leaves sandbox_lib setup in the constructor function, but that
is only needed by the execve wrapper, so push down init of that to the
existing sb_init logic which happens before our execve wrapper gets used.

URL: http://bugs.gentoo.org/404013
Reported-by: Mike Gilbert <floppym@gentoo.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

4 files changed, 8 insertions, 49 deletions

diff --git a/libsandbox/libsandbox.c b/libsandbox/libsandbox.c
index 0fcbb65..a36e190 100644
--- a/libsandbox/libsandbox.c
+++ b/libsandbox/libsandbox.c
@@ -61,6 +61,7 @@ typedef struct {
 static char *cached_env_vars[MAX_DYN_PREFIXES];
 bool sandbox_on = true;
 static bool sb_init = false;
+int (*sbio_open)(const char *, int, mode_t) = sb_unwrapped_open;
 
 static char *resolve_path(const char *, int);
 static int check_prefixes(char **, int, const char *);
@@ -68,50 +69,15 @@ static void clean_env_entries(char ***, int *);
 static void init_context(sbcontext_t *);
 static void init_env_entries(char ***, int *, const char *, const char *, int);
 
-
-/*
- * Initialize the shabang
- */
-#if 0
-__attribute__((destructor))
-void libsb_fini(void)
-{
-	/* let the kernel reap our resources -- it's faster anyways */
-	int x;
-
-	sb_init = false;
-
-	for (x = 0; x < MAX_DYN_PREFIXES; ++x) {
-		if (NULL != cached_env_vars[x]) {
-			free(cached_env_vars[x]);
-			cached_env_vars[x] = NULL;
-		}
-	}
-
-	for (x = 0; x < MAX_DYN_PREFIXES; ++x)
-		clean_env_entries(&(sbcontext.prefixes[x]),
-				&(sbcontext.num_prefixes[x]));
-}
-#endif
-
+#ifdef SB_MEM_DEBUG
 __attribute__((constructor))
 void libsb_init(void)
 {
 	save_errno();
-
-#ifdef SB_MEM_DEBUG
 	mtrace();
-#endif
-
-	sb_set_open(sb_unwrapped_open);
-
-	/* Get the path and name to this library */
-	get_sandbox_lib(sandbox_lib);
-
-//	sb_init = true;
-
 	restore_errno();
 }
+#endif
 
 static const char *sb_get_fd_dir(void)
 {
@@ -1084,6 +1050,9 @@ bool before_syscall(int dirfd, int sb_nr, const char *func, const char *file, in
 	sb_lock();
 
 	if (!sb_init) {
+		/* Get the path and name to this library */
+		get_sandbox_lib(sandbox_lib);
+
 		init_context(&sbcontext);
 		sb_init = true;
 	}
diff --git a/libsbutil/sb_open.c b/libsbutil/sb_open.c
index 2e405c6..27dda9c 100644
--- a/libsbutil/sb_open.c
+++ b/libsbutil/sb_open.c
@@ -10,17 +10,6 @@
 #include "headers.h"
 #include "sbutil.h"
 
-static int (*sbio_open)(const char *, int, mode_t) = (void *)open;
-
-
-void sb_set_open(void *new_open)
-{
-	if (!check_ptr(new_open))
-		return;
-
-	sbio_open = new_open;
-}
-
 /* General purpose function to _reliably_ open a file
  *
  * Returns the file descriptor or -1 on error (and errno set)
diff --git a/libsbutil/sbutil.h b/libsbutil/sbutil.h
index e232b31..bdff33f 100644
--- a/libsbutil/sbutil.h
+++ b/libsbutil/sbutil.h
@@ -91,7 +91,7 @@ bool is_env_on (const char *);
 bool is_env_off (const char *);
 
 /* libsandbox need to use a wrapper for open */
-void sb_set_open(void *new_open);
+attribute_hidden extern int (*sbio_open)(const char *, int, mode_t);
 /* Convenience functions to reliably open, read and write to a file */
 int sb_open(const char *path, int flags, mode_t mode);
 size_t sb_read(int fd, void *buf, size_t count);
diff --git a/src/sandbox.c b/src/sandbox.c
index d36126e..a8e28fe 100644
--- a/src/sandbox.c
+++ b/src/sandbox.c
@@ -18,6 +18,7 @@
 static int print_debug = 0;
 #define dprintf(fmt, args...) do { if (print_debug) printf(fmt, ## args); } while (0)
 #define dputs(str) do { if (print_debug) puts(str); } while (0)
+int (*sbio_open)(const char *, int, mode_t) = (void *)open;
 
 volatile static int stop_called = 0;
 volatile static pid_t child_pid = 0;