svn commit: r247617 - head/sys/kern

[Pawel Jakub Dawidek]

Author: pjd
Date: Sat Mar  2 09:58:47 2013
New Revision: 247617
URL: http://svnweb.freebsd.org/changeset/base/247617

Log:
  If the target file already exists, check for the CAP_UNLINKAT capabiity right
  on the target directory descriptor, but only if this is renameat(2) and real
  target directory descriptor is given (not AT_FDCWD). Without this fix regular
  rename(2) fails if the target file already exists.
  
  Reported by:	Michael Butler <imb at protected-networks.net>
  Reported by:	Larry Rosenman <ler at lerctr.org>
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/kern/vfs_syscalls.c

Modified: head/sys/kern/vfs_syscalls.c
==============================================================================
--- head/sys/kern/vfs_syscalls.c	Sat Mar  2 09:26:59 2013	(r247616)
+++ head/sys/kern/vfs_syscalls.c	Sat Mar  2 09:58:47 2013	(r247617)
@@ -3556,13 +3556,16 @@ kern_renameat(struct thread *td, int old
 			goto out;
 		}
 #ifdef CAPABILITIES
-		/*
-		 * If the target already exists we require CAP_UNLINKAT
-		 * from 'newfd'.
-		 */
-		error = cap_check(tond.ni_filecaps.fc_rights, CAP_UNLINKAT);
-		if (error != 0)
-			goto out;
+		if (newfd != AT_FDCWD) {
+			/*
+			 * If the target already exists we require CAP_UNLINKAT
+			 * from 'newfd'.
+			 */
+			error = cap_check(tond.ni_filecaps.fc_rights,
+			    CAP_UNLINKAT);
+			if (error != 0)
+				goto out;
+		}
 #endif
 	}
 	if (fvp == tdvp) {