- markus@cvs.openbsd.org 2003/02/06 09:29:18

     [sftp-server.c]
     fix races in rename/symlink; from Tony Finch; ok djm@

1 files changed, 14 insertions, 14 deletions

diff --git a/sftp-server.c b/sftp-server.c
index 84264693d..4eb31d94e 100644
--- a/sftp-server.c
+++ b/sftp-server.c
@@ -22,7 +22,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include "includes.h"
-RCSID("$OpenBSD: sftp-server.c,v 1.38 2002/09/11 22:41:50 djm Exp $");
+RCSID("$OpenBSD: sftp-server.c,v 1.39 2003/02/06 09:29:18 markus Exp $");
 
 #include "buffer.h"
 #include "bufaux.h"
@@ -832,19 +832,22 @@ static void
 process_rename(void)
 {
         u_int32_t id;
-        struct stat st;
         char *oldpath, *newpath;
-        int ret, status = SSH2_FX_FAILURE;
+        int status;
 
         id = get_int();
         oldpath = get_string(NULL);
         newpath = get_string(NULL);
         TRACE("rename id %u old %s new %s", id, oldpath, newpath);
         /* fail if 'newpath' exists */
-        if (stat(newpath, &st) == -1) {
-                ret = rename(oldpath, newpath);
-                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
-        }
+        if (link(oldpath, newpath) == -1)
+                status = errno_to_portable(errno);
+        else if (unlink(oldpath) == -1) {
+                status = errno_to_portable(errno);
+                /* clean spare link */
+                unlink(newpath);
+        } else
+                status = SSH2_FX_OK;
         send_status(id, status);
         xfree(oldpath);
         xfree(newpath);
@@ -878,19 +881,16 @@ static void
 process_symlink(void)
 {
         u_int32_t id;
-        struct stat st;
         char *oldpath, *newpath;
-        int ret, status = SSH2_FX_FAILURE;
+        int ret, status;
 
         id = get_int();
         oldpath = get_string(NULL);
         newpath = get_string(NULL);
         TRACE("symlink id %u old %s new %s", id, oldpath, newpath);
-        /* fail if 'newpath' exists */
-        if (stat(newpath, &st) == -1) {
-                ret = symlink(oldpath, newpath);
-                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
-        }
+        /* this will fail if 'newpath' exists */
+        ret = symlink(oldpath, newpath);
+        status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
         send_status(id, status);
         xfree(oldpath);
         xfree(newpath);