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authorDavid Howells <dhowells@redhat.com>2020-01-26 01:02:53 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-26 08:54:04 -0800
commita45ea48e2bcd92c1f678b794f488ca0bda9835b8 (patch)
treea2431d7794f409ed383c3813b4105494c32d58cd
parent2821e26f3a0a3872184581caac8115bb02641941 (diff)
downloadlinux-stericsson-a45ea48e2bcd92c1f678b794f488ca0bda9835b8.tar.gz
afs: Fix characters allowed into cell names
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>
-rw-r--r--fs/afs/cell.c11
1 files changed, 10 insertions, 1 deletions
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);