Unverified Commit 3e914feb authored by David Howells's avatar David Howells Committed by Christian Brauner
Browse files

afs: Add rootcell checks 



Add some checks for the validity of the cell name.  It's may get put into a
symlink, so preclude it containing any slashes or "..".  Also disallow
starting/ending with a dot.  This makes /afs/@cell/ as a symlink less of a
security risk.

Also disallow multiple setting of /proc/net/afs/rootcell for any given
network namespace.  Once set, the value may not be changed.  This makes it
easier to only create /afs/@cell and /afs/.@cell if there's a rootcell.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20250107183454.608451-3-dhowells@redhat.com


cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 92f08e9d

fs/afs/cell.c

+8 −0
Original line number Diff line number Diff line
@@ -367,6 +367,14 @@ int afs_cell_init(struct afs_net *net, const char *rootcell) 
		len = cp - rootcell;

	}



	if (len == 0 || !rootcell[0] || rootcell[0] == '.' || rootcell[len - 1] == '.')

		return -EINVAL;

	if (memchr(rootcell, '/', len))

		return -EINVAL;

	cp = strstr(rootcell, "..");

	if (cp && cp < rootcell + len)

		return -EINVAL;



	/* allocate a cell record for the root cell */

	new_root = afs_lookup_cell(net, rootcell, len, vllist, false);

	if (IS_ERR(new_root)) {

fs/afs/proc.c

+7 −1
Original line number Diff line number Diff line
@@ -240,7 +240,13 @@ static int afs_proc_rootcell_write(struct file *file, char *buf, size_t size) 
	/* determine command to perform */

	_debug("rootcell=%s", buf);



	ret = -EEXIST;

	inode_lock(file_inode(file));

	if (!net->ws_cell)

		ret = afs_cell_init(net, buf);

	else

		printk("busy\n");

	inode_unlock(file_inode(file));



out:

	_leave(" = %d", ret);