We force a rate-limit on auditable events by making them wait for space 
on the backlog queue. However, if auditd really is AWOL then this could 
potentially bring the entire system to a halt, depending on the audit 
rules in effect.

Firstly, make sure the wait time is honoured correctly -- it's the 
maximum time the process should wait, rather than the time to wait 
_each_ time round the loop. We were getting re-woken _each_ time a 
packet was dequeued, and the timeout was being restarted each time.

Secondly, reset the wait time after audit_panic() is called. In general 
this will be reset to zero, to allow progress to be made. If the system
is configured to _actually_ panic on audit_panic() then that will 
already have happened; otherwise we know that audit records are being 
lost anyway. 

These two tunables can't be exposed via AUDIT_GET and AUDIT_SET because 
those aren't particularly well-designed. It probably should have been 
done by sysctls or sysfs anyway -- one for a later patch.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

They aren't errors.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Don't look up the task by its pid and then use the syscall filtering
helper. Just implement our own filter helper which operates solely on
the information in the netlink_skb_parms. 
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

It's not used any more.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Add a gfp_mask to audit_log_start() and audit_log(), to reduce the
amount of GFP_ATOMIC allocation -- most of it doesn't need to be 
GFP_ATOMIC. Also if the mask includes __GFP_WAIT, then wait up to
60 seconds for the auditd backlog to clear instead of immediately 
abandoning the message. 

The timeout should probably be made configurable, but for now it'll 
suffice that it only happens if auditd is actually running.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Also exempt USER_AVC message from being discarded to preserve 
existing behaviour for SE Linux.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

If we have enough rules to fill the netlink buffer space, it'll 
deadlock because auditctl isn't ever actually going to read from the 
socket until we return, and we aren't going to return until it 
reads... so we spawn a kernel thread to spew out the list and then
exit.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Turn the field from a bitmask to an enumeration and add a list to allow 
filtering of messages generated by userspace. We also define a list for 
file system watches in anticipation of that feature.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

These changes make processing of audit logs easier. Based on a patch
from Steve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Move audit_serial() into audit.c and use it to generate serial numbers 
on messages even when there is no audit context from syscall auditing.  
This allows us to disambiguate audit records when more than one is 
generated in the same millisecond.

Based on a patch by Steve Grubb after he observed the problem.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

The attached patch changes all occurrences of loginuid to auid. It also 
changes everything to %u that is an unsigned type.
Signed-off-by: NSteve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

The original AVC_USER message wasn't consolidated with the new range of
user messages. The attached patch fixes the kernel so the old messages 
work again.
Signed-off-by: NSteve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

The limit on the number of outstanding audit messages was inadvertently
removed with the switch to queuing skbs directly for sending by a kernel
thread. Put it back again.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

netlink_unicast() will attempt to reallocate and will free messages if
the socket's rcvbuf limit is reached unless we give it an infinite 
timeout. So do that, from a kernel thread which is dedicated to spewing
stuff up the netlink socket.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

* If vsnprintf returns -1, it will mess up the sk buffer space accounting. 
This is fixed by not calling skb_put with bogus len values.

* audit_log_hex was a loop that called audit_log_vformat with %02X for each 
character. This is very inefficient since conversion from unsigned character 
to Ascii representation is essentially masking, shifting, and byte lookups. 
Also, the length of the converted string is well known - it's twice the 
original. Fixed by rewriting the function.

* audit_log_untrustedstring had no comments. This makes it hard for 
someone to understand what the string format will be.

* audit_log_d_path was never fixed to use untrustedstring. This could mess
up user space parsers. This was fixed to make a temp buffer, call d_path, 
and log temp buffer using untrustedstring. 

From: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

It's silly to have to add explicit entries for new userspace messages
as we invent them. Just treat all messages in the user range the same.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Der... if you use max_t it helps if you give it a type. 

Note to self: Always just apply the tested patches, don't try to port 
them by hand. You're not clever enough.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

I'm going through the kernel code and have a patch that corrects 
several spelling errors in comments.

From: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

This patch adds more messages types to the audit subsystem so that audit 
analysis is quicker, intuitive, and more useful.
Signed-off-by: NSteve Grubb <sgrubb@redhat.com>
---
I forgot one type in the big patch. I need to add one for user space 
originating SE Linux avc messages. This is used by dbus and nscd.

-Steve
---
Updated to 2.6.12-rc4-mm1.
-dwmw2
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Otherwise, we will be repeatedly reallocating, even if we're only
adding a few bytes at a time. Pointed out by Steve Grubb.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Add audit_log_type to allow callers to specify type and pid when logging.
Convert audit_log to wrapper around audit_log_type.  Could have
converted all audit_log callers directly, but common case is default
of type AUDIT_KERNEL and pid 0.  Update audit_log_start to take type
and pid values when creating a new audit_buffer.  Move sequences that
did audit_log_start, audit_log_format, audit_set_type, audit_log_end,
to simply call audit_log_type directly.  This obsoletes audit_set_type
and audit_set_pid, so remove them.
Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Remove code conditionally dependent on CONFIG_AUDITSYSCALL from audit.c.
Move these dependencies to audit.h with the rest.
Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Audit now actually requires netlink.  So make it depend on CONFIG_NET, 
and remove the inline dependencies on CONFIG_NET.
Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

We're not allowed to use args twice; we need to use va_copy.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Let audit_expand() know how much it's expected to grow the buffer, in 
the case that we have that information to hand.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

We were setting nlmsg_len to skb->len, but we should be subtracting
the size of the header.

From: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Drop the use of a tmp buffer in the audit_buffer, and just buffer
directly to the skb.  All header data that was temporarily stored in
the audit_buffer can now be stored directly in the netlink header in
the skb.  Resize skb as needed.  This eliminates the extra copy (and
the audit_log_move function which was responsible for copying).
Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Introduce audit_expand and make the audit_buffer use a dynamic buffer
which can be resized.  When audit buffer is moved to skb it will not
be fragmented across skb's, so we can eliminate the sklist in the
audit_buffer.  During audit_log_move, we simply copy the full buffer
into a single skb, and then audit_log_drain sends it on.
Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

shutdown credential information. It creates a new message type 
AUDIT_TERM_INFO, which is used by the audit daemon to query who issued the 
shutdown. 

It requires the placement of a hook function that gathers the information. The 
hook is after the DAC & MAC checks and before the function returns. Racing 
threads could overwrite the uid & pid - but they would have to be root and 
have policy that allows signalling the audit daemon. That should be a 
manageable risk.

The userspace component will be released later in audit 0.7.2. When it 
receives the TERM signal, it queries the kernel for shutdown information. 
When it receives it, it writes the message and exits. The message looks 
like this:

type=DAEMON msg=auditd(1114551182.000) auditd normal halt, sending pid=2650 
uid=525, auditd pid=1685
Signed-off-by: NSteve Grubb <sgrubb@redhat.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

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: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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: NChris Wright <chrisw@osdl.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

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: NDavid Woodhouse <dwmw2@infradead.org>

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: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

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: NDavid Woodhouse <dwmw2@infradead.org>

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: NDavid Woodhouse <dwmw2@infradead.org>