linux-stable.git/net/core, branch v6.3.7

rtnetlink: add the missing IFLA_GRO_ tb check in validate_linkmsg

2023-06-09T08:47:57+00:00

[ Upstream commit 65d6914e253f3d83b724a9bbfc889ae95711e512 ]

This fixes the issue that dev gro_max_size and gso_ipv4_max_size
can be set to a huge value:

  # ip link add dummy1 type dummy
  # ip link set dummy1 gro_max_size 4294967295
  # ip -d link show dummy1
    dummy addrgenmode eui64 ... gro_max_size 4294967295

Fixes: 0fe79f28bfaf ("net: allow gro_max_size to exceed 65536")
Fixes: 9eefedd58ae1 ("net: add gso_ipv4_max_size and gro_ipv4_max_size per device")
Reported-by: Xiumei Mu 
Signed-off-by: Xin Long 
Reviewed-by: Simon Horman 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

rtnetlink: move IFLA_GSO_ tb check to validate_linkmsg

2023-06-09T08:47:57+00:00

[ Upstream commit fef5b228dd38378148bc850f7e69a7783f3b95a4 ]

These IFLA_GSO_* tb check should also be done for the new created link,
otherwise, they can be set to a huge value when creating links:

  # ip link add dummy1 gso_max_size 4294967295 type dummy
  # ip -d link show dummy1
    dummy addrgenmode eui64 ... gso_max_size 4294967295

Fixes: 46e6b992c250 ("rtnetlink: allow GSO maximums to be set on device creation")
Fixes: 9eefedd58ae1 ("net: add gso_ipv4_max_size and gro_ipv4_max_size per device")
Signed-off-by: Xin Long 
Reviewed-by: Simon Horman 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

rtnetlink: call validate_linkmsg in rtnl_create_link

2023-06-09T08:47:56+00:00

[ Upstream commit b0ad3c179059089d809b477a1d445c1183a7b8fe ]

validate_linkmsg() was introduced by commit 1840bb13c22f5b ("[RTNL]:
Validate hardware and broadcast address attribute for RTM_NEWLINK")
to validate tb[IFLA_ADDRESS/BROADCAST] for existing links. The same
check should also be done for newly created links.

This patch adds validate_linkmsg() call in rtnl_create_link(), to
avoid the invalid address set when creating some devices like:

  # ip link add dummy0 type dummy
  # ip link add link dummy0 name mac0 address 01:02 type macsec

Fixes: 0e06877c6fdb ("[RTNETLINK]: rtnl_link: allow specifying initial device address")
Signed-off-by: Xin Long 
Reviewed-by: Simon Horman 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

udp6: Fix race condition in udp6_sendmsg & connect

2023-06-09T08:47:54+00:00

[ Upstream commit 448a5ce1120c5bdbce1f1ccdabcd31c7d029f328 ]

Syzkaller got the following report:
BUG: KASAN: use-after-free in sk_setup_caps+0x621/0x690 net/core/sock.c:2018
Read of size 8 at addr ffff888027f82780 by task syz-executor276/3255

The function sk_setup_caps (called by ip6_sk_dst_store_flow->
ip6_dst_store) referenced already freed memory as this memory was
freed by parallel task in udpv6_sendmsg->ip6_sk_dst_lookup_flow->
sk_dst_check.

          task1 (connect)              task2 (udp6_sendmsg)
        sk_setup_caps->sk_dst_set |
                                  |  sk_dst_check->
                                  |      sk_dst_set
                                  |      dst_release
        sk_setup_caps references  |
        to already freed dst_entry|

The reason for this race condition is: sk_setup_caps() keeps using
the dst after transferring the ownership to the dst cache.

Found by Linux Verification Center (linuxtesting.org) with syzkaller.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Vladislav Efanov 
Signed-off-by: Paolo Abeni 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

bpf, sockmap: Incorrectly handling copied_seq

2023-06-05T07:29:42+00:00

[ Upstream commit e5c6de5fa025882babf89cecbed80acf49b987fa ]

The read_skb() logic is incrementing the tcp->copied_seq which is used for
among other things calculating how many outstanding bytes can be read by
the application. This results in application errors, if the application
does an ioctl(FIONREAD) we return zero because this is calculated from
the copied_seq value.

To fix this we move tcp->copied_seq accounting into the recv handler so
that we update these when the recvmsg() hook is called and data is in
fact copied into user buffers. This gives an accurate FIONREAD value
as expected and improves ACK handling. Before we were calling the
tcp_rcv_space_adjust() which would update 'number of bytes copied to
user in last RTT' which is wrong for programs returning SK_PASS. The
bytes are only copied to the user when recvmsg is handled.

Doing the fix for recvmsg is straightforward, but fixing redirect and
SK_DROP pkts is a bit tricker. Build a tcp_psock_eat() helper and then
call this from skmsg handlers. This fixes another issue where a broken
socket with a BPF program doing a resubmit could hang the receiver. This
happened because although read_skb() consumed the skb through sock_drop()
it did not update the copied_seq. Now if a single reccv socket is
redirecting to many sockets (for example for lb) the receiver sk will be
hung even though we might expect it to continue. The hang comes from
not updating the copied_seq numbers and memory pressure resulting from
that.

We have a slight layer problem of calling tcp_eat_skb even if its not
a TCP socket. To fix we could refactor and create per type receiver
handlers. I decided this is more work than we want in the fix and we
already have some small tweaks depending on caller that use the
helper skb_bpf_strparser(). So we extend that a bit and always set
the strparser bit when it is in use and then we can gate the
seq_copied updates on this.

Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Signed-off-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Jakub Sitnicki 
Link: https://lore.kernel.org/bpf/20230523025618.113937-9-john.fastabend@gmail.com
Signed-off-by: Sasha Levin

bpf, sockmap: Wake up polling after data copy

2023-06-05T07:29:42+00:00

[ Upstream commit 6df7f764cd3cf5a03a4a47b23be47e57e41fcd85 ]

When TCP stack has data ready to read sk_data_ready() is called. Sockmap
overwrites this with its own handler to call into BPF verdict program.
But, the original TCP socket had sock_def_readable that would additionally
wake up any user space waiters with sk_wake_async().

Sockmap saved the callback when the socket was created so call the saved
data ready callback and then we can wake up any epoll() logic waiting
on the read.

Note we call on 'copied >= 0' to account for returning 0 when a FIN is
received because we need to wake up user for this as well so they
can do the recvmsg() -> 0 and detect the shutdown.

Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Signed-off-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Jakub Sitnicki 
Link: https://lore.kernel.org/bpf/20230523025618.113937-8-john.fastabend@gmail.com
Signed-off-by: Sasha Levin

bpf, sockmap: Improved check for empty queue

2023-06-05T07:29:41+00:00

[ Upstream commit 405df89dd52cbcd69a3cd7d9a10d64de38f854b2 ]

We noticed some rare sk_buffs were stepping past the queue when system was
under memory pressure. The general theory is to skip enqueueing
sk_buffs when its not necessary which is the normal case with a system
that is properly provisioned for the task, no memory pressure and enough
cpu assigned.

But, if we can't allocate memory due to an ENOMEM error when enqueueing
the sk_buff into the sockmap receive queue we push it onto a delayed
workqueue to retry later. When a new sk_buff is received we then check
if that queue is empty. However, there is a problem with simply checking
the queue length. When a sk_buff is being processed from the ingress queue
but not yet on the sockmap msg receive queue its possible to also recv
a sk_buff through normal path. It will check the ingress queue which is
zero and then skip ahead of the pkt being processed.

Previously we used sock lock from both contexts which made the problem
harder to hit, but not impossible.

To fix instead of popping the skb from the queue entirely we peek the
skb from the queue and do the copy there. This ensures checks to the
queue length are non-zero while skb is being processed. Then finally
when the entire skb has been copied to user space queue or another
socket we pop it off the queue. This way the queue length check allows
bypassing the queue only after the list has been completely processed.

To reproduce issue we run NGINX compliance test with sockmap running and
observe some flakes in our testing that we attributed to this issue.

Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Suggested-by: Jakub Sitnicki 
Signed-off-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Tested-by: William Findlay 
Reviewed-by: Jakub Sitnicki 
Link: https://lore.kernel.org/bpf/20230523025618.113937-5-john.fastabend@gmail.com
Signed-off-by: Sasha Levin

bpf, sockmap: Reschedule is now done through backlog

2023-06-05T07:29:40+00:00

[ Upstream commit bce22552f92ea7c577f49839b8e8f7d29afaf880 ]

Now that the backlog manages the reschedule() logic correctly we can drop
the partial fix to reschedule from recvmsg hook.

Rescheduling on recvmsg hook was added to address a corner case where we
still had data in the backlog state but had nothing to kick it and
reschedule the backlog worker to run and finish copying data out of the
state. This had a couple limitations, first it required user space to
kick it introducing an unnecessary EBUSY and retry. Second it only
handled the ingress case and egress redirects would still be hung.

With the correct fix, pushing the reschedule logic down to where the
enomem error occurs we can drop this fix.

Fixes: bec217197b412 ("skmsg: Schedule psock work if the cached skb exists on the psock")
Signed-off-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Jakub Sitnicki 
Link: https://lore.kernel.org/bpf/20230523025618.113937-4-john.fastabend@gmail.com
Signed-off-by: Sasha Levin

bpf, sockmap: Convert schedule_work into delayed_work

2023-06-05T07:29:40+00:00

[ Upstream commit 29173d07f79883ac94f5570294f98af3d4287382 ]

Sk_buffs are fed into sockmap verdict programs either from a strparser
(when the user might want to decide how framing of skb is done by attaching
another parser program) or directly through tcp_read_sock. The
tcp_read_sock is the preferred method for performance when the BPF logic is
a stream parser.

The flow for Cilium's common use case with a stream parser is,

 tcp_read_sock()
  sk_psock_verdict_recv
    ret = bpf_prog_run_pin_on_cpu()
    sk_psock_verdict_apply(sock, skb, ret)
     // if system is under memory pressure or app is slow we may
     // need to queue skb. Do this queuing through ingress_skb and
     // then kick timer to wake up handler
     skb_queue_tail(ingress_skb, skb)
     schedule_work(work);

The work queue is wired up to sk_psock_backlog(). This will then walk the
ingress_skb skb list that holds our sk_buffs that could not be handled,
but should be OK to run at some later point. However, its possible that
the workqueue doing this work still hits an error when sending the skb.
When this happens the skbuff is requeued on a temporary 'state' struct
kept with the workqueue. This is necessary because its possible to
partially send an skbuff before hitting an error and we need to know how
and where to restart when the workqueue runs next.

Now for the trouble, we don't rekick the workqueue. This can cause a
stall where the skbuff we just cached on the state variable might never
be sent. This happens when its the last packet in a flow and no further
packets come along that would cause the system to kick the workqueue from
that side.

To fix we could do simple schedule_work(), but while under memory pressure
it makes sense to back off some instead of continue to retry repeatedly. So
instead to fix convert schedule_work to schedule_delayed_work and add
backoff logic to reschedule from backlog queue on errors. Its not obvious
though what a good backoff is so use '1'.

To test we observed some flakes whil running NGINX compliance test with
sockmap we attributed these failed test to this bug and subsequent issue.

>From on list discussion. This commit

 bec217197b41("skmsg: Schedule psock work if the cached skb exists on the psock")

was intended to address similar race, but had a couple cases it missed.
Most obvious it only accounted for receiving traffic on the local socket
so if redirecting into another socket we could still get an sk_buff stuck
here. Next it missed the case where copied=0 in the recv() handler and
then we wouldn't kick the scheduler. Also its sub-optimal to require
userspace to kick the internal mechanisms of sockmap to wake it up and
copy data to user. It results in an extra syscall and requires the app
to actual handle the EAGAIN correctly.

Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Signed-off-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Tested-by: William Findlay 
Reviewed-by: Jakub Sitnicki 
Link: https://lore.kernel.org/bpf/20230523025618.113937-3-john.fastabend@gmail.com
Signed-off-by: Sasha Levin

bpf, sockmap: Pass skb ownership through read_skb

2023-06-05T07:29:39+00:00

[ Upstream commit 78fa0d61d97a728d306b0c23d353c0e340756437 ]

The read_skb hook calls consume_skb() now, but this means that if the
recv_actor program wants to use the skb it needs to inc the ref cnt
so that the consume_skb() doesn't kfree the sk_buff.

This is problematic because in some error cases under memory pressure
we may need to linearize the sk_buff from sk_psock_skb_ingress_enqueue().
Then we get this,

 skb_linearize()
   __pskb_pull_tail()
     pskb_expand_head()
       BUG_ON(skb_shared(skb))

Because we incremented users refcnt from sk_psock_verdict_recv() we
hit the bug on with refcnt > 1 and trip it.

To fix lets simply pass ownership of the sk_buff through the skb_read
call. Then we can drop the consume from read_skb handlers and assume
the verdict recv does any required kfree.

Bug found while testing in our CI which runs in VMs that hit memory
constraints rather regularly. William tested TCP read_skb handlers.

[  106.536188] ------------[ cut here ]------------
[  106.536197] kernel BUG at net/core/skbuff.c:1693!
[  106.536479] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[  106.536726] CPU: 3 PID: 1495 Comm: curl Not tainted 5.19.0-rc5 #1
[  106.537023] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.16.0-1 04/01/2014
[  106.537467] RIP: 0010:pskb_expand_head+0x269/0x330
[  106.538585] RSP: 0018:ffffc90000138b68 EFLAGS: 00010202
[  106.538839] RAX: 000000000000003f RBX: ffff8881048940e8 RCX: 0000000000000a20
[  106.539186] RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffff8881048940e8
[  106.539529] RBP: ffffc90000138be8 R08: 00000000e161fd1a R09: 0000000000000000
[  106.539877] R10: 0000000000000018 R11: 0000000000000000 R12: ffff8881048940e8
[  106.540222] R13: 0000000000000003 R14: 0000000000000000 R15: ffff8881048940e8
[  106.540568] FS:  00007f277dde9f00(0000) GS:ffff88813bd80000(0000) knlGS:0000000000000000
[  106.540954] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  106.541227] CR2: 00007f277eeede64 CR3: 000000000ad3e000 CR4: 00000000000006e0
[  106.541569] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  106.541915] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  106.542255] Call Trace:
[  106.542383]  
[  106.542487]  __pskb_pull_tail+0x4b/0x3e0
[  106.542681]  skb_ensure_writable+0x85/0xa0
[  106.542882]  sk_skb_pull_data+0x18/0x20
[  106.543084]  bpf_prog_b517a65a242018b0_bpf_skskb_http_verdict+0x3a9/0x4aa9
[  106.543536]  ? migrate_disable+0x66/0x80
[  106.543871]  sk_psock_verdict_recv+0xe2/0x310
[  106.544258]  ? sk_psock_write_space+0x1f0/0x1f0
[  106.544561]  tcp_read_skb+0x7b/0x120
[  106.544740]  tcp_data_queue+0x904/0xee0
[  106.544931]  tcp_rcv_established+0x212/0x7c0
[  106.545142]  tcp_v4_do_rcv+0x174/0x2a0
[  106.545326]  tcp_v4_rcv+0xe70/0xf60
[  106.545500]  ip_protocol_deliver_rcu+0x48/0x290
[  106.545744]  ip_local_deliver_finish+0xa7/0x150

Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Reported-by: William Findlay 
Signed-off-by: John Fastabend 
Signed-off-by: Daniel Borkmann 
Tested-by: William Findlay 
Reviewed-by: Jakub Sitnicki 
Link: https://lore.kernel.org/bpf/20230523025618.113937-2-john.fastabend@gmail.com
Signed-off-by: Sasha Levin