net: add skb_defer_max sysctl

commit 68822bdf76f1 ("net: generalize skb freeing
deferral to per-cpu lists") added another per-cpu
cache of skbs. It was expected to be small,
and an IPI was forced wh

net: add skb_defer_max sysctl

commit 68822bdf76f1 ("net: generalize skb freeing
deferral to per-cpu lists") added another per-cpu
cache of skbs. It was expected to be small,
and an IPI was forced whenever the list reached 128
skbs.

We might need to be able to control more precisely
queue capacity and added latency.

An IPI is generated whenever queue reaches half capacity.

Default value of the new limit is 64.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: fix possible race in skb_attempt_defer_free()

A cpu can observe sd->defer_count reaching 128,
and call smp_call_function_single_async()

Problem is that the remote CPU can clear sd->defer_count

net: fix possible race in skb_attempt_defer_free()

A cpu can observe sd->defer_count reaching 128,
and call smp_call_function_single_async()

Problem is that the remote CPU can clear sd->defer_count
before the IPI is run/acknowledged.

Other cpus can queue more packets and also decide
to call smp_call_function_single_async() while the pending
IPI was not yet delivered.

This is a common issue with smp_call_function_single_async().
Callers must ensure correct synchronization and serialization.

I triggered this issue while experimenting smaller threshold.
Performing the call to smp_call_function_single_async()
under sd->defer_lock protection did not solve the problem.

Commit 5a18ceca6350 ("smp: Allow smp_call_function_single_async()
to insert locked csd") replaced an informative WARN_ON_ONCE()
with a return of -EBUSY, which is often ignored.
Test of CSD_FLAG_LOCK presence is racy anyway.

Fixes: 68822bdf76f1 ("net: generalize skb freeing deferral to per-cpu lists")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: skb: check the boundrary of drop reason in kfree_skb_reason()

Sometimes, we may forget to reset skb drop reason to NOT_SPECIFIED after
we make it the return value of the functions with return t

net: skb: check the boundrary of drop reason in kfree_skb_reason()

Sometimes, we may forget to reset skb drop reason to NOT_SPECIFIED after
we make it the return value of the functions with return type of enum
skb_drop_reason, such as tcp_inbound_md5_hash. Therefore, its value can
be SKB_NOT_DROPPED_YET(0), which is invalid for kfree_skb_reason().

So we check the range of drop reason in kfree_skb_reason() with
DEBUG_NET_WARN_ON_ONCE().

Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: fix wrong network header length

When clatd starts with ebpf offloaing, and NETIF_F_GRO_FRAGLIST is enable,
several skbs are gathered in skb_shinfo(skb)->frag_list. The first skb's
ipv6 header w

net: fix wrong network header length

When clatd starts with ebpf offloaing, and NETIF_F_GRO_FRAGLIST is enable,
several skbs are gathered in skb_shinfo(skb)->frag_list. The first skb's
ipv6 header will be changed to ipv4 after bpf_skb_proto_6_to_4,
network_header\transport_header\mac_header have been updated as ipv4 acts,
but other skbs in frag_list didnot update anything, just ipv6 packets.

udp_queue_rcv_skb will call skb_segment_list to traverse other skbs in
frag_list and make sure right udp payload is delivered to user space.
Unfortunately, other skbs in frag_list who are still ipv6 packets are
updated like the first skb and will have wrong transport header length.

e.g.before bpf_skb_proto_6_to_4,the first skb and other skbs in frag_list
has the same network_header(24)& transport_header(64), after
bpf_skb_proto_6_to_4, ipv6 protocol has been changed to ipv4, the first
skb's network_header is 44,transport_header is 64, other skbs in frag_list
didnot change.After skb_segment_list, the other skbs in frag_list has
different network_header(24) and transport_header(44), so there will be 20
bytes different from original,that is difference between ipv6 header and
ipv4 header. Just change transport_header to be the same with original.

Actually, there are two solutions to fix it, one is traversing all skbs
and changing every skb header in bpf_skb_proto_6_to_4, the other is
modifying frag_list skb's header in skb_segment_list. Considering
efficiency, adopt the second one--- when the first skb and other skbs in
frag_list has different network_header length, restore them to make sure
right udp payload is delivered to user space.

Signed-off-by: Lina Wang <lina.wang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: Make msg_zerocopy_alloc static

msg_zerocopy_alloc is only used by msg_zerocopy_realloc; remove the
export and make static in skbuff.c

Signed-off-by: David Ahern <dsahern@kernel.org>
Acked-by:

net: Make msg_zerocopy_alloc static

msg_zerocopy_alloc is only used by msg_zerocopy_realloc; remove the
export and make static in skbuff.c

Signed-off-by: David Ahern <dsahern@kernel.org>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/r/20220504170947.18773-1-dsahern@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

tcp: optimise skb_zerocopy_iter_stream()

It's expensive to make a copy of 40B struct iov_iter to the point it
was taking 0.2-0.5% of all cycles in my tests. iov_iter_revert() should
be fine as it's

tcp: optimise skb_zerocopy_iter_stream()

It's expensive to make a copy of 40B struct iov_iter to the point it
was taking 0.2-0.5% of all cycles in my tests. iov_iter_revert() should
be fine as it's a simple case without nested reverts/truncates.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a7e1690c00c5dfe700c30eb9a8a81ec59f6545dd.1650884401.git.asml.silence@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

net: inline skb_zerocopy_iter_dgram

skb_zerocopy_iter_dgram() is a small proxy function, inline it. For
that, move __zerocopy_sg_from_iter into linux/skbuff.h

Signed-off-by: Pavel Begunkov <asml.si

net: inline skb_zerocopy_iter_dgram

skb_zerocopy_iter_dgram() is a small proxy function, inline it. For
that, move __zerocopy_sg_from_iter into linux/skbuff.h

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: generalize skb freeing deferral to per-cpu lists

Logic added in commit f35f821935d8 ("tcp: defer skb freeing after socket
lock is released") helped bulk TCP flows to move the cost of skbs
frees

net: generalize skb freeing deferral to per-cpu lists

Logic added in commit f35f821935d8 ("tcp: defer skb freeing after socket
lock is released") helped bulk TCP flows to move the cost of skbs
frees outside of critical section where socket lock was held.

But for RPC traffic, or hosts with RFS enabled, the solution is far from
being ideal.

For RPC traffic, recvmsg() has to return to user space right after
skb payload has been consumed, meaning that BH handler has no chance
to pick the skb before recvmsg() thread. This issue is more visible
with BIG TCP, as more RPC fit one skb.

For RFS, even if BH handler picks the skbs, they are still picked
from the cpu on which user thread is running.

Ideally, it is better to free the skbs (and associated page frags)
on the cpu that originally allocated them.

This patch removes the per socket anchor (sk->defer_list) and
instead uses a per-cpu list, which will hold more skbs per round.

This new per-cpu list is drained at the end of net_action_rx(),
after incoming packets have been processed, to lower latencies.

In normal conditions, skbs are added to the per-cpu list with
no further action. In the (unlikely) cases where the cpu does not
run net_action_rx() handler fast enough, we use an IPI to raise
NET_RX_SOFTIRQ on the remote cpu.

Also, we do not bother draining the per-cpu list from dev_cpu_dead()
This is because skbs in this list have no requirement on how fast
they should be freed.

Note that we can add in the future a small per-cpu cache
if we see any contention on sd->defer_lock.

Tested on a pair of hosts with 100Gbit NIC, RFS enabled,
and /proc/sys/net/ipv4/tcp_rmem[2] tuned to 16MB to work around
page recycling strategy used by NIC driver (its page pool capacity
being too small compared to number of skbs/pages held in sockets
receive queues)

Note that this tuning was only done to demonstrate worse
conditions for skb freeing for this particular test.
These conditions can happen in more general production workload.

10 runs of one TCP_STREAM flow

Before:
Average throughput: 49685 Mbit.

Kernel profiles on cpu running user thread recvmsg() show high cost for
skb freeing related functions (*)

57.81% [kernel] [k] copy_user_enhanced_fast_string
(*) 12.87% [kernel] [k] skb_release_data
(*) 4.25% [kernel] [k] __free_one_page
(*) 3.57% [kernel] [k] __list_del_entry_valid
1.85% [kernel] [k] __netif_receive_skb_core
1.60% [kernel] [k] __skb_datagram_iter
(*) 1.59% [kernel] [k] free_unref_page_commit
(*) 1.16% [kernel] [k] __slab_free
1.16% [kernel] [k] _copy_to_iter
(*) 1.01% [kernel] [k] kfree
(*) 0.88% [kernel] [k] free_unref_page
0.57% [kernel] [k] ip6_rcv_core
0.55% [kernel] [k] ip6t_do_table
0.54% [kernel] [k] flush_smp_call_function_queue
(*) 0.54% [kernel] [k] free_pcppages_bulk
0.51% [kernel] [k] llist_reverse_order
0.38% [kernel] [k] process_backlog
(*) 0.38% [kernel] [k] free_pcp_prepare
0.37% [kernel] [k] tcp_recvmsg_locked
(*) 0.37% [kernel] [k] __list_add_valid
0.34% [kernel] [k] sock_rfree
0.34% [kernel] [k] _raw_spin_lock_irq
(*) 0.33% [kernel] [k] __page_cache_release
0.33% [kernel] [k] tcp_v6_rcv
(*) 0.33% [kernel] [k] __put_page
(*) 0.29% [kernel] [k] __mod_zone_page_state
0.27% [kernel] [k] _raw_spin_lock

After patch:
Average throughput: 73076 Mbit.

Kernel profiles on cpu running user thread recvmsg() looks better:

81.35% [kernel] [k] copy_user_enhanced_fast_string
1.95% [kernel] [k] _copy_to_iter
1.95% [kernel] [k] __skb_datagram_iter
1.27% [kernel] [k] __netif_receive_skb_core
1.03% [kernel] [k] ip6t_do_table
0.60% [kernel] [k] sock_rfree
0.50% [kernel] [k] tcp_v6_rcv
0.47% [kernel] [k] ip6_rcv_core
0.45% [kernel] [k] read_tsc
0.44% [kernel] [k] _raw_spin_lock_irqsave
0.37% [kernel] [k] _raw_spin_lock
0.37% [kernel] [k] native_irq_return_iret
0.33% [kernel] [k] __inet6_lookup_established
0.31% [kernel] [k] ip6_protocol_deliver_rcu
0.29% [kernel] [k] tcp_rcv_established
0.29% [kernel] [k] llist_reverse_order

v2: kdoc issue (kernel bots)
do not defer if (alloc_cpu == smp_processor_id()) (Paolo)
replace the sk_buff_head with a single-linked list (Jakub)
add a READ_ONCE()/WRITE_ONCE() for the lockless read of sd->defer_list

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20220422201237.416238-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

net: Change skb_ensure_writable()'s write_len param to unsigned int type

Both pskb_may_pull() and skb_clone_writable()'s length parameters are of
type unsigned int already. Therefore, change this fu

net: Change skb_ensure_writable()'s write_len param to unsigned int type

Both pskb_may_pull() and skb_clone_writable()'s length parameters are of
type unsigned int already. Therefore, change this function's write_len
param to unsigned int type.

Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220416105801.88708-3-liujian56@huawei.com

show more ...

skbuff: fix coalescing for page_pool fragment recycling

Fix a use-after-free when using page_pool with page fragments. We
encountered this problem during normal RX in the hns3 driver:

(1) Initially

skbuff: fix coalescing for page_pool fragment recycling

Fix a use-after-free when using page_pool with page fragments. We
encountered this problem during normal RX in the hns3 driver:

(1) Initially we have three descriptors in the RX queue. The first one
allocates PAGE1 through page_pool, and the other two allocate one
half of PAGE2 each. Page references look like this:

RX_BD1 _______ PAGE1
RX_BD2 _______ PAGE2
RX_BD3 _________/

(2) Handle RX on the first descriptor. Allocate SKB1, eventually added
to the receive queue by tcp_queue_rcv().

(3) Handle RX on the second descriptor. Allocate SKB2 and pass it to
netif_receive_skb():

netif_receive_skb(SKB2)
ip_rcv(SKB2)
SKB3 = skb_clone(SKB2)

SKB2 and SKB3 share a reference to PAGE2 through
skb_shinfo()->dataref. The other ref to PAGE2 is still held by
RX_BD3:

SKB2 ---+- PAGE2
SKB3 __/ /
RX_BD3 _________/

(3b) Now while handling TCP, coalesce SKB3 with SKB1:

tcp_v4_rcv(SKB3)
tcp_try_coalesce(to=SKB1, from=SKB3) // succeeds
kfree_skb_partial(SKB3)
skb_release_data(SKB3) // drops one dataref

SKB1 _____ PAGE1
\____
SKB2 _____ PAGE2
/
RX_BD3 _________/

In skb_try_coalesce(), __skb_frag_ref() takes a page reference to
PAGE2, where it should instead have increased the page_pool frag
reference, pp_frag_count. Without coalescing, when releasing both
SKB2 and SKB3, a single reference to PAGE2 would be dropped. Now
when releasing SKB1 and SKB2, two references to PAGE2 will be
dropped, resulting in underflow.

(3c) Drop SKB2:

af_packet_rcv(SKB2)
consume_skb(SKB2)
skb_release_data(SKB2) // drops second dataref
page_pool_return_skb_page(PAGE2) // drops one pp_frag_count

SKB1 _____ PAGE1
\____
PAGE2
/
RX_BD3 _________/

(4) Userspace calls recvmsg()
Copies SKB1 and releases it. Since SKB3 was coalesced with SKB1, we
release the SKB3 page as well:

tcp_eat_recv_skb(SKB1)
skb_release_data(SKB1)
page_pool_return_skb_page(PAGE1)
page_pool_return_skb_page(PAGE2) // drops second pp_frag_count

(5) PAGE2 is freed, but the third RX descriptor was still using it!
In our case this causes IOMMU faults, but it would silently corrupt
memory if the IOMMU was disabled.

Change the logic that checks whether pp_recycle SKBs can be coalesced.
We still reject differing pp_recycle between 'from' and 'to' SKBs, but
in order to avoid the situation described above, we also reject
coalescing when both 'from' and 'to' are pp_recycled and 'from' is
cloned.

The new logic allows coalescing a cloned pp_recycle SKB into a page
refcounted one, because in this case the release (4) will drop the right
reference, the one taken by skb_try_coalesce().

Fixes: 53e0961da1c7 ("page_pool: add frag page recycling support in page pool")
Suggested-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: skb: introduce the function kfree_skb_list_reason()

To report reasons of skb drops, introduce the function
kfree_skb_list_reason() and make kfree_skb_list() an inline call to
it. This function

net: skb: introduce the function kfree_skb_list_reason()

To report reasons of skb drops, introduce the function
kfree_skb_list_reason() and make kfree_skb_list() an inline call to
it. This function will be used in the next commit in
__dev_xmit_skb().

Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: Clear mono_delivery_time bit in __skb_tstamp_tx()

In __skb_tstamp_tx(), it may clone the egress skb and queues the clone to
the sk_error_queue. The outgoing skb may have the mono delivery_time

net: Clear mono_delivery_time bit in __skb_tstamp_tx()

In __skb_tstamp_tx(), it may clone the egress skb and queues the clone to
the sk_error_queue. The outgoing skb may have the mono delivery_time
while the (rcv) timestamp is expected for the clone, so the
skb->mono_delivery_time bit needs to be cleared from the clone.

This patch adds the skb->mono_delivery_time clearing to the existing
__net_timestamp() and use it in __skb_tstamp_tx().
The __net_timestamp() fast path usage in dev.c is changed to directly
call ktime_get_real() since the mono_delivery_time bit is not set at
that point.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: Add skb_clear_tstamp() to keep the mono delivery_time

Right now, skb->tstamp is reset to 0 whenever the skb is forwarded.

If skb->tstamp has the mono delivery_time, clearing it can hurt
the pe

net: Add skb_clear_tstamp() to keep the mono delivery_time

Right now, skb->tstamp is reset to 0 whenever the skb is forwarded.

If skb->tstamp has the mono delivery_time, clearing it can hurt
the performance when it finally transmits out to fq@phy-dev.

The earlier patch added a skb->mono_delivery_time bit to
flag the skb->tstamp carrying the mono delivery_time.

This patch adds skb_clear_tstamp() helper which keeps
the mono delivery_time and clears everything else.

The delivery_time clearing will be postponed until the stack knows the
skb will be delivered locally. It will be done in a latter patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: fix up skbs delta_truesize in UDP GRO frag_list

The truesize for a UDP GRO packet is added by main skb and skbs in main
skb's frag_list:
skb_gro_receive_list
p->truesize += skb->truesiz

net: fix up skbs delta_truesize in UDP GRO frag_list

The truesize for a UDP GRO packet is added by main skb and skbs in main
skb's frag_list:
skb_gro_receive_list
p->truesize += skb->truesize;

The commit 53475c5dd856 ("net: fix use-after-free when UDP GRO with
shared fraglist") introduced a truesize increase for frag_list skbs.
When uncloning skb, it will call pskb_expand_head and trusesize for
frag_list skbs may increase. This can occur when allocators uses
__netdev_alloc_skb and not jump into __alloc_skb. This flow does not
use ksize(len) to calculate truesize while pskb_expand_head uses.
skb_segment_list
err = skb_unclone(nskb, GFP_ATOMIC);
pskb_expand_head
if (!skb->sk || skb->destructor == sock_edemux)
skb->truesize += size - osize;

If we uses increased truesize adding as delta_truesize, it will be
larger than before and even larger than previous total truesize value
if skbs in frag_list are abundant. The main skb truesize will become
smaller and even a minus value or a huge value for an unsigned int
parameter. Then the following memory check will drop this abnormal skb.

To avoid this error we should use the original truesize to segment the
main skb.

Fixes: 53475c5dd856 ("net: fix use-after-free when UDP GRO with shared fraglist")
Signed-off-by: lena wang <lena.wang@mediatek.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/1646133431-8948-1-git-send-email-lena.wang@mediatek.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

net: preserve skb_end_offset() in skb_unclone_keeptruesize()

syzbot found another way to trigger the infamous WARN_ON_ONCE(delta < len)
in skb_try_coalesce() [1]

I was able to root cause the issue

net: preserve skb_end_offset() in skb_unclone_keeptruesize()

syzbot found another way to trigger the infamous WARN_ON_ONCE(delta < len)
in skb_try_coalesce() [1]

I was able to root cause the issue to kfence.

When kfence is in action, the following assertion is no longer true:

int size = xxxx;
void *ptr1 = kmalloc(size, gfp);
void *ptr2 = kmalloc(size, gfp);

if (ptr1 && ptr2)
ASSERT(ksize(ptr1) == ksize(ptr2));

We attempted to fix these issues in the blamed commits, but forgot
that TCP was possibly shifting data after skb_unclone_keeptruesize()
has been used, notably from tcp_retrans_try_collapse().

So we not only need to keep same skb->truesize value,
we also need to make sure TCP wont fill new tailroom
that pskb_expand_head() was able to get from a
addr = kmalloc(...) followed by ksize(addr)

Split skb_unclone_keeptruesize() into two parts:

1) Inline skb_unclone_keeptruesize() for the common case,
when skb is not cloned.

2) Out of line __skb_unclone_keeptruesize() for the 'slow path'.

WARNING: CPU: 1 PID: 6490 at net/core/skbuff.c:5295 skb_try_coalesce+0x1235/0x1560 net/core/skbuff.c:5295
Modules linked in:
CPU: 1 PID: 6490 Comm: syz-executor161 Not tainted 5.17.0-rc4-syzkaller-00229-g4f12b742eb2b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:skb_try_coalesce+0x1235/0x1560 net/core/skbuff.c:5295
Code: bf 01 00 00 00 0f b7 c0 89 c6 89 44 24 20 e8 62 24 4e fa 8b 44 24 20 83 e8 01 0f 85 e5 f0 ff ff e9 87 f4 ff ff e8 cb 20 4e fa <0f> 0b e9 06 f9 ff ff e8 af b2 95 fa e9 69 f0 ff ff e8 95 b2 95 fa
RSP: 0018:ffffc900063af268 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000ffffffd5 RCX: 0000000000000000
RDX: ffff88806fc05700 RSI: ffffffff872abd55 RDI: 0000000000000003
RBP: ffff88806e675500 R08: 00000000ffffffd5 R09: 0000000000000000
R10: ffffffff872ab659 R11: 0000000000000000 R12: ffff88806dd554e8
R13: ffff88806dd9bac0 R14: ffff88806dd9a2c0 R15: 0000000000000155
FS: 00007f18014f9700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020002000 CR3: 000000006be7a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tcp_try_coalesce net/ipv4/tcp_input.c:4651 [inline]
tcp_try_coalesce+0x393/0x920 net/ipv4/tcp_input.c:4630
tcp_queue_rcv+0x8a/0x6e0 net/ipv4/tcp_input.c:4914
tcp_data_queue+0x11fd/0x4bb0 net/ipv4/tcp_input.c:5025
tcp_rcv_established+0x81e/0x1ff0 net/ipv4/tcp_input.c:5947
tcp_v4_do_rcv+0x65e/0x980 net/ipv4/tcp_ipv4.c:1719
sk_backlog_rcv include/net/sock.h:1037 [inline]
__release_sock+0x134/0x3b0 net/core/sock.c:2779
release_sock+0x54/0x1b0 net/core/sock.c:3311
sk_wait_data+0x177/0x450 net/core/sock.c:2821
tcp_recvmsg_locked+0xe28/0x1fd0 net/ipv4/tcp.c:2457
tcp_recvmsg+0x137/0x610 net/ipv4/tcp.c:2572
inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:850
sock_recvmsg_nosec net/socket.c:948 [inline]
sock_recvmsg net/socket.c:966 [inline]
sock_recvmsg net/socket.c:962 [inline]
____sys_recvmsg+0x2c4/0x600 net/socket.c:2632
___sys_recvmsg+0x127/0x200 net/socket.c:2674
__sys_recvmsg+0xe2/0x1a0 net/socket.c:2704
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: c4777efa751d ("net: add and use skb_unclone_keeptruesize() helper")
Fixes: 097b9146c0e2 ("net: fix up truesize of cloned skb in skb_prepare_for_shift()")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: add skb_set_end_offset() helper

We have multiple places where this helper is convenient,
and plan using it in the following patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-

net: add skb_set_end_offset() helper

We have multiple places where this helper is convenient,
and plan using it in the following patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: __pskb_pull_tail() & pskb_carve_frag_list() drop_monitor friends

Whenever one of these functions pull all data from an skb in a frag_list,
use consume_skb() instead of kfree_skb() to avoid poll

net: __pskb_pull_tail() & pskb_carve_frag_list() drop_monitor friends

Whenever one of these functions pull all data from an skb in a frag_list,
use consume_skb() instead of kfree_skb() to avoid polluting drop
monitoring.

Fixes: 6fa01ccd8830 ("skbuff: Add pskb_extract() helper function")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220220154052.1308469-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net-timestamp: convert sk->sk_tskey to atomic_t

UDP sendmsg() can be lockless, this is causing all kinds
of data races.

This patch converts sk->sk_tskey to remove one of these races.

BUG: KCSAN: d

net-timestamp: convert sk->sk_tskey to atomic_t

UDP sendmsg() can be lockless, this is causing all kinds
of data races.

This patch converts sk->sk_tskey to remove one of these races.

BUG: KCSAN: data-race in __ip_append_data / __ip_append_data

read to 0xffff8881035d4b6c of 4 bytes by task 8877 on cpu 1:
__ip_append_data+0x1c1/0x1de0 net/ipv4/ip_output.c:994
ip_make_skb+0x13f/0x2d0 net/ipv4/ip_output.c:1636
udp_sendmsg+0x12bd/0x14c0 net/ipv4/udp.c:1249
inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg net/socket.c:725 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2413
___sys_sendmsg net/socket.c:2467 [inline]
__sys_sendmmsg+0x267/0x4c0 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2579
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881035d4b6c of 4 bytes by task 8880 on cpu 0:
__ip_append_data+0x1d8/0x1de0 net/ipv4/ip_output.c:994
ip_make_skb+0x13f/0x2d0 net/ipv4/ip_output.c:1636
udp_sendmsg+0x12bd/0x14c0 net/ipv4/udp.c:1249
inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg net/socket.c:725 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2413
___sys_sendmsg net/socket.c:2467 [inline]
__sys_sendmmsg+0x267/0x4c0 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2579
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000054d -> 0x0000054e

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8880 Comm: syz-executor.5 Not tainted 5.17.0-rc2-syzkaller-00167-gdcb85f85fa6f-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 09c2d251b707 ("net-timestamp: add key to disambiguate concurrent datagrams")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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skbuff: cleanup double word in comment

Remove the second 'to'.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: skb: introduce kfree_skb_reason()

Introduce the interface kfree_skb_reason(), which is able to pass
the reason why the skb is dropped to 'kfree_skb' tracepoint.

Add the 'reason' field to 'trac

net: skb: introduce kfree_skb_reason()

Introduce the interface kfree_skb_reason(), which is able to pass
the reason why the skb is dropped to 'kfree_skb' tracepoint.

Add the 'reason' field to 'trace_kfree_skb', therefor user can get
more detail information about abnormal skb with 'drop_monitor' or
eBPF.

All drop reasons are defined in the enum 'skb_drop_reason', and
they will be print as string in 'kfree_skb' tracepoint in format
of 'reason: XXX'.

( Maybe the reasons should be defined in a uapi header file, so that
user space can use them? )

Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: Fix double 0x prefix print in SKB dump

When printing netdev features %pNF already takes care of the 0x prefix,
remove the explicit one.

Fixes: 6413139dfc64 ("skbuff: increase verbosity when du

net: Fix double 0x prefix print in SKB dump

When printing netdev features %pNF already takes care of the 0x prefix,
remove the explicit one.

Fixes: 6413139dfc64 ("skbuff: increase verbosity when dumping skb data")
Signed-off-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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skbuff: introduce skb_pull_data

Like skb_pull but returns the original data pointer before pulling the
data after performing a check against sbk->len.

This allows to change code that does "struct f

skbuff: introduce skb_pull_data

Like skb_pull but returns the original data pointer before pulling the
data after performing a check against sbk->len.

This allows to change code that does "struct foo *p = (void *)skb->data;"
which is hard to audit and error prone, to:

p = skb_pull_data(skb, sizeof(*p));
if (!p)
return;

Which is both safer and cleaner.

Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

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skbuff: Switch structure bounds to struct_group()

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentiona

skbuff: Switch structure bounds to struct_group()

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.

Replace the existing empty member position markers "headers_start" and
"headers_end" with a struct_group(). This will allow memcpy() and sizeof()
to more easily reason about sizes, and improve readability.

"pahole" shows no size nor member offset changes to struct sk_buff.
"objdump -d" shows no object code changes (outside of WARNs affected by
source line number changes).

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com> # drivers/net/wireguard/*
Link: https://lore.kernel.org/lkml/20210728035006.GD35706@embeddedor
Signed-off-by: David S. Miller <davem@davemloft.net>

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net: gro: move skb_gro_receive into net/core/gro.c

net/core/gro.c will contain all core gro functions,
to shrink net/core/skbuff.c and net/core/dev.c

Signed-off-by: Eric Dumazet <edumazet@google.co

net: gro: move skb_gro_receive into net/core/gro.c

net/core/gro.c will contain all core gro functions,
to shrink net/core/skbuff.c and net/core/dev.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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net: gro: move skb_gro_receive_list to udp_offload.c

This helper is used once, no need to keep it in fat net/core/skbuff.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S.

net: gro: move skb_gro_receive_list to udp_offload.c

This helper is used once, no need to keep it in fat net/core/skbuff.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...