blob: 802190699806b489c26fc0d60f9fb56781d630d2 [file] [log] [blame]
From 40da794f65a4a656dbaf83a3f5af72147c85cb8f Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Sun, 26 Jan 2020 01:02:53 +0000
Subject: [PATCH] afs: Fix characters allowed into cell names
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: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index fd5133e26a38..78ba5f932287 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -134,8 +134,17 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net,
_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);
--
2.7.4