linux-toradex.git/net/netlink/af_netlink.c, branch v3.12.27

netlink: Fix handling of error from netlink_dump().

2014-07-29T15:01:37+00:00

[ Upstream commit ac30ef832e6af0505b6f0251a6659adcfa74975e ]

netlink_dump() returns a negative errno value on error.  Until now,
netlink_recvmsg() directly recorded that negative value in sk->sk_err, but
that's wrong since sk_err takes positive errno values.  (This manifests as
userspace receiving a positive return value from the recv() system call,
falsely indicating success.) This bug was introduced in the commit that
started checking the netlink_dump() return value, commit b44d211 (netlink:
handle errors from netlink_dump()).

Multithreaded Netlink dumps are one way to trigger this behavior in
practice, as described in the commit message for the userspace workaround
posted here:
    http://openvswitch.org/pipermail/dev/2014-June/042339.html

This commit also fixes the same bug in netlink_poll(), introduced in commit
cd1df525d (netlink: add flow control for memory mapped I/O).

Signed-off-by: Ben Pfaff 
Signed-off-by: David S. Miller 
Signed-off-by: Jiri Slaby

netlink: Only check file credentials for implicit destinations

2014-06-23T08:27:57+00:00

[ Upstream commit 2d7a85f4b06e9c27ff629f07a524c48074f07f81 ]

It was possible to get a setuid root or setcap executable to write to
it's stdout or stderr (which has been set made a netlink socket) and
inadvertently reconfigure the networking stack.

To prevent this we check that both the creator of the socket and
the currentl applications has permission to reconfigure the network
stack.

Unfortunately this breaks Zebra which always uses sendto/sendmsg
and creates it's socket without any privileges.

To keep Zebra working don't bother checking if the creator of the
socket has privilege when a destination address is specified.  Instead
rely exclusively on the privileges of the sender of the socket.

Note from Andy: This is exactly Eric's code except for some comment
clarifications and formatting fixes.  Neither I nor, I think, anyone
else is thrilled with this approach, but I'm hesitant to wait on a
better fix since 3.15 is almost here.

Note to stable maintainers: This is a mess.  An earlier series of
patches in 3.15 fix a rather serious security issue (CVE-2014-0181),
but they did so in a way that breaks Zebra.  The offending series
includes:

    commit aa4cf9452f469f16cea8c96283b641b4576d4a7b
    Author: Eric W. Biederman 
    Date:   Wed Apr 23 14:28:03 2014 -0700

        net: Add variants of capable for use on netlink messages

If a given kernel version is missing that series of fixes, it's
probably worth backporting it and this patch.  if that series is
present, then this fix is critical if you care about Zebra.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Andy Lutomirski 
Signed-off-by: David S. Miller 
Signed-off-by: Jiri Slaby

net: Add variants of capable for use on netlink messages

2014-06-23T08:27:56+00:00

[ Upstream commit aa4cf9452f469f16cea8c96283b641b4576d4a7b ]

netlink_net_capable - The common case use, for operations that are safe on a network namespace
netlink_capable - For operations that are only known to be safe for the global root
netlink_ns_capable - The general case of capable used to handle special cases

__netlink_ns_capable - Same as netlink_ns_capable except taking a netlink_skb_parms instead of
		       the skbuff of a netlink message.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller 
Signed-off-by: Jiri Slaby

netlink: Rename netlink_capable netlink_allowed

2014-06-23T08:27:55+00:00

[ Upstream commit 5187cd055b6e81fc6526109456f8b20623148d5f ]

netlink_capable is a static internal function in af_netlink.c and we
have better uses for the name netlink_capable.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller 
Signed-off-by: Jiri Slaby

net: rework recvmsg handler msg_name and msg_namelen logic

2013-12-08T15:29:13+00:00

[ Upstream commit f3d3342602f8bcbf37d7c46641cb9bca7618eb1c ]

This patch now always passes msg->msg_namelen as 0. recvmsg handlers must
set msg_namelen to the proper size <= sizeof(struct sockaddr_storage)
to return msg_name to the user.

This prevents numerous uninitialized memory leaks we had in the
recvmsg handlers and makes it harder for new code to accidentally leak
uninitialized memory.

Optimize for the case recvfrom is called with NULL as address. We don't
need to copy the address at all, so set it to NULL before invoking the
recvmsg handler. We can do so, because all the recvmsg handlers must
cope with the case a plain read() is called on them. read() also sets
msg_name to NULL.

Also document these changes in include/linux/net.h as suggested by David
Miller.

Changes since RFC:

Set msg->msg_name = NULL if user specified a NULL in msg_name but had a
non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't
affect sendto as it would bail out earlier while trying to copy-in the
address. It also more naturally reflects the logic by the callers of
verify_iovec.

With this change in place I could remove "
if (!uaddr || msg_sys->msg_namelen == 0)
	msg->msg_name = NULL
".

This change does not alter the user visible error logic as we ignore
msg_namelen as long as msg_name is NULL.

Also remove two unnecessary curly brackets in ___sys_recvmsg and change
comments to netdev style.

Cc: David Miller 
Suggested-by: Eric Dumazet 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: netlink: filter particular protocols from analyzers

2013-09-06T18:43:48+00:00

Fix finer-grained control and let only a whitelist of allowed netlink
protocols pass, in our case related to networking. If later on, other
subsystems decide they want to add their protocol as well to the list
of allowed protocols they shall simply add it. While at it, we also
need to tell what protocol is in use otherwise BPF_S_ANC_PROTOCOL can
not pick it up (as it's not filled out).

Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller

netlink: Eliminate kmalloc in netlink dump operation.

2013-08-15T22:51:20+00:00

Following patch stores struct netlink_callback in netlink_sock
to avoid allocating and freeing it on every netlink dump msg.
Only one dump operation is allowed for a given socket at a time
therefore we can safely convert cb pointer to cb struct inside
netlink_sock.

Signed-off-by: Pravin B Shelar 
Signed-off-by: David S. Miller

net: netlink: minor: remove unused pointer in alloc_pg_vec

2013-08-02T22:26:12+00:00

Variable ptr is being assigned, but never used, so just remove it.

Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller

netlink: fix splat in skb_clone with large messages

2013-06-28T05:44:16+00:00

Since (c05cdb1 netlink: allow large data transfers from user-space),
netlink splats if it invokes skb_clone on large netlink skbs since:

* skb_shared_info was not correctly initialized.
* skb->destructor is not set in the cloned skb.

This was spotted by trinity:

[  894.990671] BUG: unable to handle kernel paging request at ffffc9000047b001
[  894.991034] IP: [] skb_clone+0x24/0xc0
[...]
[  894.991034] Call Trace:
[  894.991034]  [] nl_fib_input+0x6a/0x240
[  894.991034]  [] ? _raw_read_unlock+0x26/0x40
[  894.991034]  [] netlink_unicast+0x169/0x1e0
[  894.991034]  [] netlink_sendmsg+0x251/0x3d0

Fix it by:

1) introducing a new netlink_skb_clone function that is used in nl_fib_input,
   that sets our special skb->destructor in the cloned skb. Moreover, handle
   the release of the large cloned skb head area in the destructor path.

2) not allowing large skbuffs in the netlink broadcast path. I cannot find
   any reasonable use of the large data transfer using netlink in that path,
   moreover this helps to skip extra skb_clone handling.

I found two more netlink clients that are cloning the skbs, but they are
not in the sendmsg path. Therefore, the sole client cloning that I found
seems to be the fib frontend.

Thanks to Eric Dumazet for helping to address this issue.

Reported-by: Fengguang Wu 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: David S. Miller

net: netlink: virtual tap device management

2013-06-24T23:39:05+00:00

Similarly to the networking receive path with ptype_all taps, we add
the possibility to register netdevices that are for ARPHRD_NETLINK to
the netlink subsystem, so that those can be used for netlink analyzers
resp. debuggers. We do not offer a direct callback function as out-of-tree
modules could do crap with it. Instead, a netdevice must be registered
properly and only receives a clone, managed by the netlink layer. Symbols
are exported as GPL-only.

Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller