linux.git/net/core/skbuff.c, branch v6.14

ipvs: Always clear ipvs_property flag in skb_scrub_packet()

2025-02-25T12:15:17+00:00

We found an issue when using bpf_redirect with ipvs NAT mode after
commit ff70202b2d1a ("dev_forward_skb: do not scrub skb mark within
the same name space"). Particularly, we use bpf_redirect to return
the skb directly back to the netif it comes from, i.e., xnet is
false in skb_scrub_packet(), and then ipvs_property is preserved
and SNAT is skipped in the rx path.

ipvs_property has been already cleared when netns is changed in
commit 2b5ec1a5f973 ("netfilter/ipvs: clear ipvs_property flag when
SKB net namespace changed"). This patch just clears it in spite of
netns.

Fixes: 2b5ec1a5f973 ("netfilter/ipvs: clear ipvs_property flag when SKB net namespace changed")
Signed-off-by: Philo Lu 
Acked-by: Julian Anastasov 
Link: https://patch.msgid.link/20250222033518.126087-1-lulie@linux.alibaba.com
Signed-off-by: Paolo Abeni

Revert "net: skb: introduce and use a single page frag cache"

2025-02-20T09:53:25+00:00

After the previous commit is finally safe to revert commit dbae2b062824
("net: skb: introduce and use a single page frag cache"): do it here.

The intended goal of such change was to counter a performance regression
introduced by commit 3226b158e67c ("net: avoid 32 x truesize
under-estimation for tiny skbs").

Unfortunately, the blamed commit introduces another regression for the
virtio_net driver. Such a driver calls napi_alloc_skb() with a tiny
size, so that the whole head frag could fit a 512-byte block.

The single page frag cache uses a 1K fragment for such allocation, and
the additional overhead, under small UDP packets flood, makes the page
allocator a bottleneck.

Thanks to commit bf9f1baa279f ("net: add dedicated kmem_cache for
typical/small skb->head"), this revert does not re-introduce the
original regression. Actually, in the relevant test on top of this
revert, I measure a small but noticeable positive delta, just above
noise level.

The revert itself required some additional mangling due to recent updates
in the affected code.

Suggested-by: Eric Dumazet 
Fixes: dbae2b062824 ("net: skb: introduce and use a single page frag cache")
Reviewed-by: Eric Dumazet 
Signed-off-by: Paolo Abeni

net: allow small head cache usage with large MAX_SKB_FRAGS values

2025-02-20T09:53:17+00:00

Sabrina reported the following splat:

    WARNING: CPU: 0 PID: 1 at net/core/dev.c:6935 netif_napi_add_weight_locked+0x8f2/0xba0
    Modules linked in:
    CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc1-net-00092-g011b03359038 #996
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
    RIP: 0010:netif_napi_add_weight_locked+0x8f2/0xba0
    Code: e8 c3 e6 6a fe 48 83 c4 28 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc c7 44 24 10 ff ff ff ff e9 8f fb ff ff e8 9e e6 6a fe <0f> 0b e9 d3 fe ff ff e8 92 e6 6a fe 48 8b 04 24 be ff ff ff ff 48
    RSP: 0000:ffffc9000001fc60 EFLAGS: 00010293
    RAX: 0000000000000000 RBX: ffff88806ce48128 RCX: 1ffff11001664b9e
    RDX: ffff888008f00040 RSI: ffffffff8317ca42 RDI: ffff88800b325cb6
    RBP: ffff88800b325c40 R08: 0000000000000001 R09: ffffed100167502c
    R10: ffff88800b3a8163 R11: 0000000000000000 R12: ffff88800ac1c168
    R13: ffff88800ac1c168 R14: ffff88800ac1c168 R15: 0000000000000007
    FS:  0000000000000000(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffff888008201000 CR3: 0000000004c94001 CR4: 0000000000370ef0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
    
    gro_cells_init+0x1ba/0x270
    xfrm_input_init+0x4b/0x2a0
    xfrm_init+0x38/0x50
    ip_rt_init+0x2d7/0x350
    ip_init+0xf/0x20
    inet_init+0x406/0x590
    do_one_initcall+0x9d/0x2e0
    do_initcalls+0x23b/0x280
    kernel_init_freeable+0x445/0x490
    kernel_init+0x20/0x1d0
    ret_from_fork+0x46/0x80
    ret_from_fork_asm+0x1a/0x30
    
    irq event stamp: 584330
    hardirqs last  enabled at (584338): [] __up_console_sem+0x77/0xb0
    hardirqs last disabled at (584345): [] __up_console_sem+0x5c/0xb0
    softirqs last  enabled at (583242): [] netlink_insert+0x14d/0x470
    softirqs last disabled at (583754): [] netif_napi_add_weight_locked+0x77d/0xba0

on kernel built with MAX_SKB_FRAGS=45, where SKB_WITH_OVERHEAD(1024)
is smaller than GRO_MAX_HEAD.

Such built additionally contains the revert of the single page frag cache
so that napi_get_frags() ends up using the page frag allocator, triggering
the splat.

Note that the underlying issue is independent from the mentioned
revert; address it ensuring that the small head cache will fit either TCP
and GRO allocation and updating napi_alloc_skb() and __netdev_alloc_skb()
to select kmalloc() usage for any allocation fitting such cache.

Reported-by: Sabrina Dubroca 
Suggested-by: Eric Dumazet 
Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS")
Reviewed-by: Eric Dumazet 
Signed-off-by: Paolo Abeni

bpf, xdp: constify some bpf_prog * function arguments

2024-12-06T02:41:06+00:00

In lots of places, bpf_prog pointer is used only for tracing or other
stuff that doesn't modify the structure itself. Same for net_device.
Address at least some of them and add `const` attributes there. The
object code didn't change, but that may prevent unwanted data
modifications and also allow more helpers to have const arguments.

Reviewed-by: Toke Høiland-Jørgensen 
Signed-off-by: Alexander Lobakin 
Signed-off-by: Jakub Kicinski

mm: page_frag: avoid caller accessing 'page_frag_cache' directly

2024-11-11T18:56:27+00:00

Use appropriate frag_page API instead of caller accessing
'page_frag_cache' directly.

CC: Andrew Morton 
CC: Linux-MM 
Signed-off-by: Yunsheng Lin 
Reviewed-by: Alexander Duyck 
Acked-by: Chuck Lever 
Link: https://patch.msgid.link/20241028115343.3405838-5-linyunsheng@huawei.com
Signed-off-by: Jakub Kicinski

net-timestamp: namespacify the sysctl_tstamp_allow_data

2024-10-08T22:33:11+00:00

Let it be tuned in per netns by admins.

Signed-off-by: Jason Xing 
Reviewed-by: Kuniyuki Iwashima 
Reviewed-by: Eric Dumazet 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20241005222609.94980-1-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski

net: add support for skbs with unreadable frags

2024-09-12T03:44:31+00:00

For device memory TCP, we expect the skb headers to be available in host
memory for access, and we expect the skb frags to be in device memory
and unaccessible to the host. We expect there to be no mixing and
matching of device memory frags (unaccessible) with host memory frags
(accessible) in the same skb.

Add a skb->devmem flag which indicates whether the frags in this skb
are device memory frags or not.

__skb_fill_netmem_desc() now checks frags added to skbs for net_iov,
and marks the skb as skb->devmem accordingly.

Add checks through the network stack to avoid accessing the frags of
devmem skbs and avoid coalescing devmem skbs with non devmem skbs.

Signed-off-by: Willem de Bruijn 
Signed-off-by: Kaiyuan Zhang 
Signed-off-by: Mina Almasry 
Reviewed-by: Eric Dumazet 
Reviewed-by: Jakub Kicinski 
Link: https://patch.msgid.link/20240910171458.219195-9-almasrymina@google.com
Signed-off-by: Jakub Kicinski

net: support non paged skb frags

2024-09-12T03:44:31+00:00

Make skb_frag_page() fail in the case where the frag is not backed
by a page, and fix its relevant callers to handle this case.

Signed-off-by: Mina Almasry 
Reviewed-by: Eric Dumazet 
Reviewed-by: Jakub Kicinski 
Link: https://patch.msgid.link/20240910171458.219195-8-almasrymina@google.com
Signed-off-by: Jakub Kicinski

page_pool: devmem support

2024-09-12T03:44:31+00:00

Convert netmem to be a union of struct page and struct netmem. Overload
the LSB of struct netmem* to indicate that it's a net_iov, otherwise
it's a page.

Currently these entries in struct page are rented by the page_pool and
used exclusively by the net stack:

struct {
	unsigned long pp_magic;
	struct page_pool *pp;
	unsigned long _pp_mapping_pad;
	unsigned long dma_addr;
	atomic_long_t pp_ref_count;
};

Mirror these (and only these) entries into struct net_iov and implement
netmem helpers that can access these common fields regardless of
whether the underlying type is page or net_iov.

Implement checks for net_iov in netmem helpers which delegate to mm
APIs, to ensure net_iov are never passed to the mm stack.

Signed-off-by: Mina Almasry 
Reviewed-by: Pavel Begunkov 
Acked-by: Jakub Kicinski 
Link: https://patch.msgid.link/20240910171458.219195-6-almasrymina@google.com
Signed-off-by: Jakub Kicinski

Merge tag 'ipsec-next-2024-09-10' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next

2024-09-11T02:00:47+00:00

Steffen Klassert says:

====================
pull request (net-next): ipsec-next 2024-09-10

1) Remove an unneeded WARN_ON on packet offload.
   From Patrisious Haddad.

2) Add a copy from skb_seq_state to buffer function.
   This is needed for the upcomming IPTFS patchset.
   From Christian Hopps.

3) Spelling fix in xfrm.h.
   From Simon Horman.

4) Speed up xfrm policy insertions.
   From Florian Westphal.

5) Add and revert a patch to support xfrm interfaces
   for packet offload. This patch was just half cooked.

6) Extend usage of the new xfrm_policy_is_dead_or_sk helper.
   From Florian Westphal.

7) Update comments on sdb and xfrm_policy.
   From Florian Westphal.

8) Fix a null pointer dereference in the new policy insertion
   code From Florian Westphal.

9) Fix an uninitialized variable in the new policy insertion
   code. From Nathan Chancellor.

* tag 'ipsec-next-2024-09-10' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next:
  xfrm: policy: Restore dir assignments in xfrm_hash_rebuild()
  xfrm: policy: fix null dereference
  Revert "xfrm: add SA information to the offloaded packet"
  xfrm: minor update to sdb and xfrm_policy comments
  xfrm: policy: use recently added helper in more places
  xfrm: add SA information to the offloaded packet
  xfrm: policy: remove remaining use of inexact list
  xfrm: switch migrate to xfrm_policy_lookup_bytype
  xfrm: policy: don't iterate inexact policies twice at insert time
  selftests: add xfrm policy insertion speed test script
  xfrm: Correct spelling in xfrm.h
  net: add copy from skb_seq_state to buffer function
  xfrm: Remove documentation WARN_ON to limit return values for offloaded SA
====================

Link: https://patch.msgid.link/20240910065507.2436394-1-steffen.klassert@secunet.com
Signed-off-by: Jakub Kicinski