Commit 31d1726d authored by Al Viro's avatar Al Viro
Browse files

make build_open_flags() treat O_CREAT | O_EXCL as implying O_NOFOLLOW 



O_CREAT | O_EXCL means "-EEXIST if we run into a trailing symlink".
As it is, we might or might not have LOOKUP_FOLLOW in op->intent
in that case - that depends upon having O_NOFOLLOW in open flags.
It doesn't matter, since we won't be checking it in that case -
do_last() bails out earlier.

However, making sure it's not set (i.e. acting as if we had an explicit
O_NOFOLLOW) makes the behaviour more explicit and allows to reorder the
check for O_CREAT | O_EXCL in do_last() with the call of step_into()
immediately following it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1c9f5e06

fs/namei.c

+5 −10
Original line number Diff line number Diff line
@@ -3396,22 +3396,17 @@ static int do_last(struct nameidata *nd, 
	if (unlikely(error < 0))

		return error;



	/*

	 * create/update audit record if it already exists.

	 */

	audit_inode(nd->name, path.dentry, 0);



	if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) {

		path_to_nameidata(&path, nd);

		return -EEXIST;

	}



	seq = 0;	/* out of RCU mode, so the value doesn't matter */

	inode = d_backing_inode(path.dentry);

finish_lookup:

	error = step_into(nd, &path, 0, inode, seq);

	if (unlikely(error))

		return error;



	if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) {

		audit_inode(nd->name, nd->path.dentry, 0);

		return -EEXIST;

	}

finish_open:

	/* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */

	error = complete_walk(nd);

fs/open.c

+3 −1
Original line number Diff line number Diff line
@@ -1049,8 +1049,10 @@ inline int build_open_flags(const struct open_how *how, struct open_flags *op) 


	if (flags & O_CREAT) {

		op->intent |= LOOKUP_CREATE;

		if (flags & O_EXCL)

		if (flags & O_EXCL) {

			op->intent |= LOOKUP_EXCL;

			flags |= O_NOFOLLOW;

		}

	}



	if (flags & O_DIRECTORY)