path: root/fs/cifs/smb2pdu.c
diff options
authorAurelien Aptel <aaptel@suse.com>2020-02-21 11:19:06 +0100
committerSteve French <stfrench@microsoft.com>2020-02-24 14:20:38 -0600
commit86f740f2aed5ea7fe1aa86dc2df0fb4ab0f71088 (patch)
tree03b24267315eb060fb3ca1861904a836923c1221 /fs/cifs/smb2pdu.c
parentcifs: add missing mount option to /proc/mounts (diff)
cifs: fix rename() by ensuring source handle opened with DELETE bit
To rename a file in SMB2 we open it with the DELETE access and do a special SetInfo on it. If the handle is missing the DELETE bit the server will fail the SetInfo with STATUS_ACCESS_DENIED. We currently try to reuse any existing opened handle we have with cifs_get_writable_path(). That function looks for handles with WRITE access but doesn't check for DELETE, making rename() fail if it finds a handle to reuse. Simple reproducer below. To select handles with the DELETE bit, this patch adds a flag argument to cifs_get_writable_path() and find_writable_file() and the existing 'bool fsuid_only' argument is converted to a flag. The cifsFileInfo struct only stores the UNIX open mode but not the original SMB access flags. Since the DELETE bit is not mapped in that mode, this patch stores the access mask in cifs_fid on file open, which is accessible from cifsFileInfo. Simple reproducer: #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #define E(s) perror(s), exit(1) int main(int argc, char *argv[]) { int fd, ret; if (argc != 3) { fprintf(stderr, "Usage: %s A B\n" "create&open A in write mode, " "rename A to B, close A\n", argv[0]); return 0; } fd = openat(AT_FDCWD, argv[1], O_WRONLY|O_CREAT|O_SYNC, 0666); if (fd == -1) E("openat()"); ret = rename(argv[1], argv[2]); if (ret) E("rename()"); ret = close(fd); if (ret) E("close()"); return ret; } $ gcc -o bugrename bugrename.c $ ./bugrename /mnt/a /mnt/b rename(): Permission denied Fixes: 8de9e86c67ba ("cifs: create a helper to find a writeable handle by path name") CC: Stable <stable@vger.kernel.org> Signed-off-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Diffstat (limited to '')
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 1234f9ccab03..28c0be5e69b7 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2771,6 +2771,7 @@ SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
oparms->fid->persistent_fid = rsp->PersistentFileId;
oparms->fid->volatile_fid = rsp->VolatileFileId;
+ oparms->fid->access = oparms->desired_access;
oparms->fid->mid = le64_to_cpu(rsp->sync_hdr.MessageId);
#endif /* CIFS_DEBUG2 */