Commit 5132861a authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

disable most mode changes on non-unix/non-cifsacl mounts 



CIFS currently allows you to change the mode of an inode on a share that
doesn't have unix extensions enabled, and isn't using cifsacl. The inode
in this case *only* has its mode changed in memory on the client. This
is problematic since it can change any time the inode is purged from the
cache.

This patch makes cifs_setattr silently ignore most mode changes when
unix extensions and cifsacl support are not enabled, and when the share
is not mounted with the "dynperm" option. The exceptions are:

When a mode change would remove all write access to an inode we turn on
the ATTR_READONLY bit on the server and remove all write bits from the
inode's mode in memory.

When a mode change would add a write bit to an inode that previously had
them all turned off, it turns off the ATTR_READONLY bit on the server,
and resets the mode back to what it would normally be (generally, the
file_mode or dir_mode of the share).

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent b7206153

fs/cifs/inode.c

+26 −12
Original line number Diff line number Diff line
@@ -1575,7 +1575,7 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs) 
		attrs->ia_valid &= ~ATTR_MODE;



	if (attrs->ia_valid & ATTR_MODE) {

		cFYI(1, ("Mode changed to 0x%x", attrs->ia_mode));

		cFYI(1, ("Mode changed to 0%o", attrs->ia_mode));

		mode = attrs->ia_mode;

	}
@@ -1590,18 +1590,18 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs) 
#ifdef CONFIG_CIFS_EXPERIMENTAL

		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL)

			rc = mode_to_acl(inode, full_path, mode);

		else if ((mode & S_IWUGO) == 0) {

#else

		if ((mode & S_IWUGO) == 0) {

		else

#endif

			/* not writeable */

			if ((cifsInode->cifsAttrs & ATTR_READONLY) == 0) {

		if (((mode & S_IWUGO) == 0) &&

		    (cifsInode->cifsAttrs & ATTR_READONLY) == 0) {

			set_dosattr = true;

				time_buf.Attributes =

					cpu_to_le32(cifsInode->cifsAttrs |

			time_buf.Attributes = cpu_to_le32(cifsInode->cifsAttrs |

							  ATTR_READONLY);

			}

		} else if (cifsInode->cifsAttrs & ATTR_READONLY) {

			/* fix up mode if we're not using dynperm */

			if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM) == 0)

				attrs->ia_mode = inode->i_mode & ~S_IWUGO;

		} else if ((mode & S_IWUGO) &&

			   (cifsInode->cifsAttrs & ATTR_READONLY)) {

			/* If file is readonly on server, we would

			not be able to write to it - so if any write

			bit is enabled for user or group or other we
@@ -1612,6 +1612,20 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs) 
			/* Windows ignores set to zero */

			if (time_buf.Attributes == 0)

				time_buf.Attributes |= cpu_to_le32(ATTR_NORMAL);



			/* reset local inode permissions to normal */

			if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM)) {

				attrs->ia_mode &= ~(S_IALLUGO);

				if (S_ISDIR(inode->i_mode))

					attrs->ia_mode |=

						cifs_sb->mnt_dir_mode;

				else

					attrs->ia_mode |=

						cifs_sb->mnt_file_mode;

			}

		} else if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM)) {

			/* ignore mode change - ATTR_READONLY hasn't changed */

			attrs->ia_valid &= ~ATTR_MODE;

		}

	}

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