Commit Graph

23 Commits

Author SHA1 Message Date
Trent Jaeger
df71837d50 [LSM-IPSec]: Security association restriction.
This patch series implements per packet access control via the
extension of the Linux Security Modules (LSM) interface by hooks in
the XFRM and pfkey subsystems that leverage IPSec security
associations to label packets.  Extensions to the SELinux LSM are
included that leverage the patch for this purpose.

This patch implements the changes necessary to the XFRM subsystem,
pfkey interface, ipv4/ipv6, and xfrm_user interface to restrict a
socket to use only authorized security associations (or no security
association) to send/receive network packets.

Patch purpose:

The patch is designed to enable access control per packets based on
the strongly authenticated IPSec security association.  Such access
controls augment the existing ones based on network interface and IP
address.  The former are very coarse-grained, and the latter can be
spoofed.  By using IPSec, the system can control access to remote
hosts based on cryptographic keys generated using the IPSec mechanism.
This enables access control on a per-machine basis or per-application
if the remote machine is running the same mechanism and trusted to
enforce the access control policy.

Patch design approach:

The overall approach is that policy (xfrm_policy) entries set by
user-level programs (e.g., setkey for ipsec-tools) are extended with a
security context that is used at policy selection time in the XFRM
subsystem to restrict the sockets that can send/receive packets via
security associations (xfrm_states) that are built from those
policies.

A presentation available at
www.selinux-symposium.org/2005/presentations/session2/2-3-jaeger.pdf
from the SELinux symposium describes the overall approach.

Patch implementation details:

On output, the policy retrieved (via xfrm_policy_lookup or
xfrm_sk_policy_lookup) must be authorized for the security context of
the socket and the same security context is required for resultant
security association (retrieved or negotiated via racoon in
ipsec-tools).  This is enforced in xfrm_state_find.

On input, the policy retrieved must also be authorized for the socket
(at __xfrm_policy_check), and the security context of the policy must
also match the security association being used.

The patch has virtually no impact on packets that do not use IPSec.
The existing Netfilter (outgoing) and LSM rcv_skb hooks are used as
before.

Also, if IPSec is used without security contexts, the impact is
minimal.  The LSM must allow such policies to be selected for the
combination of socket and remote machine, but subsequent IPSec
processing proceeds as in the original case.

Testing:

The pfkey interface is tested using the ipsec-tools.  ipsec-tools have
been modified (a separate ipsec-tools patch is available for version
0.5) that supports assignment of xfrm_policy entries and security
associations with security contexts via setkey and the negotiation
using the security contexts via racoon.

The xfrm_user interface is tested via ad hoc programs that set
security contexts.  These programs are also available from me, and
contain programs for setting, getting, and deleting policy for testing
this interface.  Testing of sa functions was done by tracing kernel
behavior.

Signed-off-by: Trent Jaeger <tjaeger@cse.psu.edu>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-03 13:10:24 -08:00
Thomas Graf
88fc2c8431 [XFRM]: Use generic netlink receive queue processor
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-10 02:26:40 +01:00
Thomas Graf
a8f74b2288 [NETLINK]: Make netlink_callback->done() optional
Most netlink families make no use of the done() callback, making
it optional gets rid of all unnecessary dummy implementations.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-10 02:26:40 +01:00
Patrick McHardy
066286071d [NETLINK]: Add "groups" argument to netlink_kernel_create
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 16:01:11 -07:00
Patrick McHardy
ac6d439d20 [NETLINK]: Convert netlink users to use group numbers instead of bitmasks
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 16:00:54 -07:00
Patrick McHardy
43e943c32b [NETLINK]: Fix missing dst_groups initializations in netlink_broadcast users
netlink_broadcast users must initialize NETLINK_CB(skb).dst_groups to the
destination group mask for netlink_recvmsg.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 16:00:34 -07:00
Harald Welte
4fdb3bb723 [NETLINK]: Add properly module refcounting for kernel netlink sockets.
- Remove bogus code for compiling netlink as module
- Add module refcounting support for modules implementing a netlink
  protocol
- Add support for autoloading modules that implement a netlink protocol
  as soon as someone opens a socket for that protocol

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 15:35:08 -07:00
Herbert Xu
a4f1bac625 [XFRM]: Fix possible overflow of sock->sk_policy
Spotted by, and original patch by, Balazs Scheidler.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-26 15:43:17 -07:00
Herbert Xu
72cb6962a9 [IPSEC]: Add xfrm_init_state
This patch adds xfrm_init_state which is simply a wrapper that calls
xfrm_get_type and subsequently x->type->init_state.  It also gets rid
of the unused args argument.

Abstracting it out allows us to add common initialisation code, e.g.,
to set family-specific flags.

The add_time setting in xfrm_user.c was deleted because it's already
set by xfrm_state_alloc.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: James Morris <jmorris@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-20 13:18:08 -07:00
Herbert Xu
0603eac0d6 [IPSEC]: Add XFRMA_SA/XFRMA_POLICY for delete notification
This patch changes the format of the XFRM_MSG_DELSA and
XFRM_MSG_DELPOLICY notification so that the main message
sent is of the same format as that received by the kernel
if the original message was via netlink.  This also means
that we won't lose the byid information carried in km_event.

Since this user interface is introduced by Jamal's patch
we can still afford to change it.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-18 22:54:36 -07:00
Jamal Hadi Salim
ee57eef99b [IPSEC] Use NLMSG_LENGTH in xfrm_exp_state_notify
Small fixup to use netlink macros instead of hardcoding.

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-18 22:45:56 -07:00
Patrick McHardy
7d6dfe1f5b [IPSEC] Fix xfrm_state leaks in error path
Herbert Xu wrote:
> @@ -1254,6 +1326,7 @@ static int pfkey_add(struct sock *sk, st
>       if (IS_ERR(x))
>               return PTR_ERR(x);
>
> +     xfrm_state_hold(x);

This introduces a leak when xfrm_state_add()/xfrm_state_update()
fail. We hold two references (one from xfrm_state_alloc(), one
from xfrm_state_hold()), but only drop one. We need to take the
reference because the reference from xfrm_state_alloc() can
be dropped by __xfrm_state_delete(), so the fix is to drop both
references on error. Same problem in xfrm_user.c.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-18 22:45:31 -07:00
Herbert Xu
f60f6b8f70 [IPSEC] Use XFRM_MSG_* instead of XFRM_SAP_*
This patch removes XFRM_SAP_* and converts them over to XFRM_MSG_*.
The netlink interface is meant to map directly onto the underlying
xfrm subsystem.  Therefore rather than using a new independent
representation for the events we can simply use the existing ones
from xfrm_user.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2005-06-18 22:44:37 -07:00
Herbert Xu
e7443892f6 [IPSEC] Set byid for km_event in xfrm_get_policy
This patch fixes policy deletion in xfrm_user so that it sets
km_event.data.byid.  This puts xfrm_user on par with what af_key
does in this case.
   
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2005-06-18 22:44:18 -07:00
Herbert Xu
bf08867f91 [IPSEC] Turn km_event.data into a union
This patch turns km_event.data into a union.  This makes code that
uses it clearer.
  
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2005-06-18 22:44:00 -07:00
Jamal Hadi Salim
26b15dad9f [IPSEC] Add complete xfrm event notification
Heres the final patch.
What this patch provides

- netlink xfrm events
- ability to have events generated by netlink propagated to pfkey
  and vice versa.
- fixes the acquire lets-be-happy-with-one-success issue

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2005-06-18 22:42:13 -07:00
Herbert Xu
31c26852cb [IPSEC]: Verify key payload in verify_one_algo
We need to verify that the payload contains enough data so that
attach_one_algo can copy alg_key_len bits from the payload.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-19 12:39:49 -07:00
Herbert Xu
b9e9dead05 [IPSEC]: Fixed alg_key_len usage in attach_one_algo
The variable alg_key_len is in bits and not bytes.  The function
attach_one_algo is currently using it as if it were in bytes.
This causes it to read memory which may not be there.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-19 12:39:04 -07:00
David S. Miller
0f4821e7b9 [XFRM/RTNETLINK]: Decrement qlen properly in {xfrm_,rt}netlink_rcv().
If we free up a partially processed packet because it's
skb->len dropped to zero, we need to decrement qlen because
we are dropping out of the top-level loop so it will do
the decrement for us.

Spotted by Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-03 16:15:59 -07:00
David S. Miller
09e1430598 [NETLINK]: Fix infinite loops in synchronous netlink changes.
The qlen should continue to decrement, even if we
pop partially processed SKBs back onto the receive queue.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-03 15:30:05 -07:00
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
Thomas Graf
492b558b31 [XFRM]: Cleanup xfrm_msg_min and xfrm_dispatch
Converts xfrm_msg_min and xfrm_dispatch to use c99 designated
initializers to make greping a little bit easier. Also replaces
two hardcoded message type with meaningful names.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-03 14:26:40 -07:00
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