lkml.org 
[lkml]   [2020]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.4 034/104] afs: Fix characters allowed into cell names
Date
From: David Howells <dhowells@redhat.com>

commit a45ea48e2bcd92c1f678b794f488ca0bda9835b8 upstream.

The afs filesystem needs to prohibit certain characters from cell names,
such as '/', as these are used to form filenames in procfs, leading to
the following warning being generated:

WARNING: CPU: 0 PID: 3489 at fs/proc/generic.c:178

Fix afs_alloc_cell() to disallow nonprintable characters, '/', '@' and
names that begin with a dot.

Remove the check for "@cell" as that is then redundant.

This can be tested by running:

echo add foo/.bar 1.2.3.4 >/proc/fs/afs/cells

Note that we will also need to deal with:

- Names ending in ".invalid" shouldn't be passed to the DNS.

- Names that contain non-valid domainname chars shouldn't be passed to
the DNS.

- DNS replies that say "your-dns-needs-immediate-attention.<gTLD>" and
replies containing A records that say 127.0.53.53 should be
considered invalid.
[https://www.icann.org/en/system/files/files/name-collision-mitigation-01aug14-en.pdf]

but these need to be dealt with by the kafs-client DNS program rather
than the kernel.

Reported-by: syzbot+b904ba7c947a37b4b291@syzkaller.appspotmail.com
Cc: stable@kernel.org
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/afs/cell.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -134,8 +134,17 @@ static struct afs_cell *afs_alloc_cell(s
_leave(" = -ENAMETOOLONG");
return ERR_PTR(-ENAMETOOLONG);
}
- if (namelen == 5 && memcmp(name, "@cell", 5) == 0)
+
+ /* Prohibit cell names that contain unprintable chars, '/' and '@' or
+ * that begin with a dot. This also precludes "@cell".
+ */
+ if (name[0] == '.')
return ERR_PTR(-EINVAL);
+ for (i = 0; i < namelen; i++) {
+ char ch = name[i];
+ if (!isprint(ch) || ch == '/' || ch == '@')
+ return ERR_PTR(-EINVAL);
+ }

_enter("%*.*s,%s", namelen, namelen, name, addresses);


\
 
 \ /
  Last update: 2020-01-28 15:49    [W:0.238 / U:2.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site