Commit Graph

11 Commits

Author SHA1 Message Date
David Woodhouse
bfd4bda097 Merge with master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6.git 2005-05-05 13:59:37 +01:00
Herbert Xu
2a0a6ebee1 [NETLINK]: Synchronous message processing.
Let's recap the problem.  The current asynchronous netlink kernel
message processing is vulnerable to these attacks:

1) Hit and run: Attacker sends one or more messages and then exits
before they're processed.  This may confuse/disable the next netlink
user that gets the netlink address of the attacker since it may
receive the responses to the attacker's messages.

Proposed solutions:

a) Synchronous processing.
b) Stream mode socket.
c) Restrict/prohibit binding.

2) Starvation: Because various netlink rcv functions were written
to not return until all messages have been processed on a socket,
it is possible for these functions to execute for an arbitrarily
long period of time.  If this is successfully exploited it could
also be used to hold rtnl forever.

Proposed solutions:

a) Synchronous processing.
b) Stream mode socket.

Firstly let's cross off solution c).  It only solves the first
problem and it has user-visible impacts.  In particular, it'll
break user space applications that expect to bind or communicate
with specific netlink addresses (pid's).

So we're left with a choice of synchronous processing versus
SOCK_STREAM for netlink.

For the moment I'm sticking with the synchronous approach as
suggested by Alexey since it's simpler and I'd rather spend
my time working on other things.

However, it does have a number of deficiencies compared to the
stream mode solution:

1) User-space to user-space netlink communication is still vulnerable.

2) Inefficient use of resources.  This is especially true for rtnetlink
since the lock is shared with other users such as networking drivers.
The latter could hold the rtnl while communicating with hardware which
causes the rtnetlink user to wait when it could be doing other things.

3) It is still possible to DoS all netlink users by flooding the kernel
netlink receive queue.  The attacker simply fills the receive socket
with a single netlink message that fills up the entire queue.  The
attacker then continues to call sendmsg with the same message in a loop.

Point 3) can be countered by retransmissions in user-space code, however
it is pretty messy.

In light of these problems (in particular, point 3), we should implement
stream mode netlink at some point.  In the mean time, here is a patch
that implements synchronous processing.  

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-03 14:55:09 -07:00
Chris Wright
0dd8e06bda [PATCH] add new audit data to last skb
When adding more formatted audit data to an skb for delivery to userspace,
the kernel will attempt to reuse an skb that has spare room.  However, if
the audit message has already been fragmented to multiple skb's, the search
for spare room in the skb uses the head of the list.  This will corrupt the
audit message with trailing bytes being placed midway through the stream.
Fix is to look at the end of the list.

Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-05-03 14:01:15 +01:00
Chris Wright
37509e749d [AUDIT] Requeue messages at head of queue, up to audit_backlog
If netlink_unicast() fails, requeue the skb back at the head of the queue
it just came from, instead of the tail. And do so unless we've exceeded
the audit_backlog limit; not according to some other arbitrary limit.

From: Chris Wright <chrisw@osdl.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-29 17:19:14 +01:00
Serge Hallyn
c94c257c88 Add audit uid to netlink credentials
Most audit control messages are sent over netlink.In order to properly
log the identity of the sender of audit control messages, we would like
to add the loginuid to the netlink_creds structure, as per the attached
patch.

Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-29 16:27:17 +01:00
85c8721ff3 audit: update pointer to userspace tools, remove emacs mode tags 2005-04-29 16:23:29 +01:00
Peter Martuccelli
c7fcb0ee74 [AUDIT] Avoid using %*.*s format strings.
They don't seem to work correctly (investigation ongoing), but we don't
actually need to do it anyway.

Patch from Peter Martuccelli <peterm@redhat.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-29 16:10:24 +01:00
Steve Grubb
d812ddbb89 [AUDIT] Fix signedness of 'serial' in various routines.
Attached is a patch that corrects a signed/unsigned warning. I also noticed
that we needlessly init serial to 0. That only needs to occur if the kernel
was compiled without the audit system.

-Steve Grubb

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-29 16:09:52 +01:00
Andrew Morton
81b7854d52 audit_log_untrustedstring() warning fix
kernel/audit.c: In function `audit_log_untrustedstring':
kernel/audit.c:736: warning: comparison is always false due to limited range of data type

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-29 15:59:11 +01:00
83c7d09173 AUDIT: Avoid log pollution by untrusted strings.
We log strings from userspace, such as arguments to open(). These could
be formatted to contain \n followed by fake audit log entries. Provide
a function for logging such strings, which gives a hex dump when the
string contains anything but basic printable ASCII characters. Use it
for logging filenames.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-29 15:54:44 +01:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00