From patchwork Thu May 30 20:16:09 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mina Almasry X-Patchwork-Id: 13680772 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 42258C27C44 for ; Thu, 30 May 2024 20:17:11 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DD3E612B726; Thu, 30 May 2024 20:17:09 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="R6Rz9Bf0"; dkim-atps=neutral Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9BEAE12B6E0 for ; Thu, 30 May 2024 20:16:38 +0000 (UTC) Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-62a23864df0so17533887b3.0 for ; Thu, 30 May 2024 13:16:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1717100197; x=1717704997; darn=lists.freedesktop.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=jum7zENHi0ssaEPHUAwuM/j3Imz9OTlvDM8Z416ekQw=; b=R6Rz9Bf0U7Njj27H/enkW3lJYaJLZJbPiSWOJc6sEECxOXAVkKJxD/VVDqT+ikdLfK WyAeIQN/SY0CirdferTd4jxXD+23nvkG4Y3DaisaEEfiPdKfj3a0imCBaBTdk+d+EEaK ZoTUESUk+K9Wc8tC02b/9tv/wWfOM539NXemLxXu1IoNJFBrGRVh4UbCvRAbxh/xHvQl Jec8pYJ9Lzkvbr8dzdLKSy62ZNrHllQqdkgiG4/NddVwW/yLlE9k/R+63rFgwDpD+uOn n4arPPxcTfwZAsQFuUIbc5glrkj4qI89B36r4LOeJLrt7BS7eFHlN9bU5NtTV/1wJ7PO v+jg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1717100197; x=1717704997; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=jum7zENHi0ssaEPHUAwuM/j3Imz9OTlvDM8Z416ekQw=; b=OXIUR4xIqGkxy2UzeuSXjVSBdizrY6dJoqY7cKPl7BztdedfqJr7wMzwALWzOkmVlH ChbhJZI9uGgq82haWk2qzvdyb4Sb/zdd4DIWplnf/qkdCOI+bmzYMZuZ6iGdsoKhcJli Kaz+mIyMXDpficbGj2T7hTA8zDSdTZ49EmAZxaDF25eJjKHxKg4m4foWGMUDitojZrc4 Udore1gTtlSExfwCNjHpdvcGf/MK2D3hV3yA18lIOttioGTAadM2jyqAKLz/gM5MZXmn 7nZWsklThIfqBiOZU7015aYyG6dJIqiJShBYqjMfImfQ55Dkpw1IOu7oyaXeKIQFRo5u 4E1A== X-Forwarded-Encrypted: i=1; AJvYcCXKOUgl+11l9n3PGje6iuKm+dRZkbfsYelT8OF9kIxS0Utxe4AVzKevSbAMqSlAPs+sE1FGViAXFO1ISzUft8WYmDTEOt/+Na0Wr+baUJUk X-Gm-Message-State: AOJu0Ywzdbjs3uL79/4hPpa/8SLJljiLl8dv9rZKEVXvGRildppFqFiK glLTPNrap3msNcfrj+YeXSgd/gJv9d9tPY4vaXC06cwnkMghWCj6xHq+u0ah/+9/DXHY2OuzuoU 0t5eD+YKBzF+1CMBx3pL03w== X-Google-Smtp-Source: AGHT+IFhORRSsQi/whKDnHHDekjXKn5EjAii6vWoohnOMyxb/IhK1j9ijUfTwuSCDNJeODcMufwTrVjYOwHk4UORkQ== X-Received: from almasrymina.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:4bc5]) (user=almasrymina job=sendgmr) by 2002:a05:690c:c:b0:627:a961:caee with SMTP id 00721157ae682-62c6bbfa2femr9099767b3.4.1717100197518; Thu, 30 May 2024 13:16:37 -0700 (PDT) Date: Thu, 30 May 2024 20:16:09 +0000 In-Reply-To: <20240530201616.1316526-1-almasrymina@google.com> Mime-Version: 1.0 References: <20240530201616.1316526-1-almasrymina@google.com> X-Mailer: git-send-email 2.45.1.288.g0e0cd299f1-goog Message-ID: <20240530201616.1316526-11-almasrymina@google.com> Subject: [PATCH net-next v10 10/14] net: add support for skbs with unreadable frags From: Mina Almasry To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: Mina Almasry , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Donald Hunter , Jonathan Corbet , Richard Henderson , Ivan Kokshaysky , Matt Turner , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Andreas Larsson , Jesper Dangaard Brouer , Ilias Apalodimas , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Steffen Klassert , Herbert Xu , David Ahern , Willem de Bruijn , Shuah Khan , Sumit Semwal , " =?utf-8?q?Christian_K=C3=B6nig?= " , Pavel Begunkov , David Wei , Jason Gunthorpe , Yunsheng Lin , Shailend Chand , Harshitha Ramamurthy , Shakeel Butt , Jeroen de Borst , Praveen Kaligineedi , Willem de Bruijn , Kaiyuan Zhang X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 --- v9: https://lore.kernel.org/netdev/20240403002053.2376017-11-almasrymina@google.com/ - change skb->readable to skb->unreadable (Pavel/David). skb->readable was very complicated, because by default skbs are readable so the flag needed to be set to true in all code paths where new skbs were created or cloned. Forgetting to set skb->readable=true in some paths caused crashes. Flip it to skb->unreadable so that the default 0 value works well, and we only need to set it to true when we add unreadable frags. v6 - skb->dmabuf -> skb->readable (Pavel). Pavel's original suggestion was to remove the skb->dmabuf flag entirely, but when I looked into it closely, I found the issue that if we remove the flag we have to dereference the shinfo(skb) pointer to obtain the first frag, which can cause a performance regression if it dirties the cache line when the shinfo(skb) was not really needed. Instead, I converted the skb->dmabuf flag into a generic skb->readable flag which can be re-used by io_uring. Changes in v1: - Rename devmem -> dmabuf (David). - Flip skb_frags_not_readable (Jakub). --- include/linux/skbuff.h | 19 +++++++++++++++-- include/net/tcp.h | 5 +++-- net/core/datagram.c | 6 ++++++ net/core/gro.c | 5 ++++- net/core/skbuff.c | 48 ++++++++++++++++++++++++++++++++++++++++-- net/ipv4/tcp.c | 3 +++ net/ipv4/tcp_input.c | 13 +++++++++--- net/ipv4/tcp_output.c | 5 ++++- net/packet/af_packet.c | 4 ++-- 9 files changed, 95 insertions(+), 13 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 0a4df0025e6dc..9c9be08f96aa7 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -827,6 +827,8 @@ enum skb_tstamp_type { * @csum_level: indicates the number of consecutive checksums found in * the packet minus one that have been verified as * CHECKSUM_UNNECESSARY (max 3) + * @unreadable: indicates that at least 1 of the fragments in this skb is + * unreadable. * @dst_pending_confirm: need to confirm neighbour * @decrypted: Decrypted SKB * @slow_gro: state present at GRO time, slower prepare step required @@ -1008,7 +1010,7 @@ struct sk_buff { #if IS_ENABLED(CONFIG_IP_SCTP) __u8 csum_not_inet:1; #endif - + __u8 unreadable:1; #if defined(CONFIG_NET_SCHED) || defined(CONFIG_NET_XGRESS) __u16 tc_index; /* traffic control index */ #endif @@ -1800,6 +1802,12 @@ static inline void skb_zcopy_downgrade_managed(struct sk_buff *skb) __skb_zcopy_downgrade_managed(skb); } +/* Return true if frags in this skb are readable by the host. */ +static inline bool skb_frags_readable(const struct sk_buff *skb) +{ + return !skb->unreadable; +} + static inline void skb_mark_not_on_list(struct sk_buff *skb) { skb->next = NULL; @@ -2516,10 +2524,17 @@ static inline void skb_len_add(struct sk_buff *skb, int delta) static inline void __skb_fill_netmem_desc(struct sk_buff *skb, int i, netmem_ref netmem, int off, int size) { - struct page *page = netmem_to_page(netmem); + struct page *page; __skb_fill_netmem_desc_noacc(skb_shinfo(skb), i, netmem, off, size); + if (netmem_is_net_iov(netmem)) { + skb->unreadable = true; + return; + } + + page = netmem_to_page(netmem); + /* Propagate page pfmemalloc to the skb if we can. The problem is * that not all callers have unique ownership of the page but rely * on page_is_pfmemalloc doing the right thing(tm). diff --git a/include/net/tcp.h b/include/net/tcp.h index 32815a40dea16..181a4834a60fc 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1060,7 +1060,7 @@ static inline int tcp_skb_mss(const struct sk_buff *skb) static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) { - return likely(!TCP_SKB_CB(skb)->eor); + return likely(!TCP_SKB_CB(skb)->eor && skb_frags_readable(skb)); } static inline bool tcp_skb_can_collapse(const struct sk_buff *to, @@ -1068,7 +1068,8 @@ static inline bool tcp_skb_can_collapse(const struct sk_buff *to, { return likely(tcp_skb_can_collapse_to(to) && mptcp_skb_can_collapse(to, from) && - skb_pure_zcopy_same(to, from)); + skb_pure_zcopy_same(to, from) && + skb_frags_readable(to) == skb_frags_readable(from)); } /* Events passed to congestion control interface */ diff --git a/net/core/datagram.c b/net/core/datagram.c index e614cfd8e14a5..b29f881df0e83 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -407,6 +407,9 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset, return 0; } + if (!skb_frags_readable(skb)) + goto short_copy; + /* Copy paged appendix. Hmm... why does this look so complicated? */ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end; @@ -619,6 +622,9 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk, if (msg && msg->msg_ubuf && msg->sg_from_iter) return msg->sg_from_iter(sk, skb, from, length); + if (!skb_frags_readable(skb)) + return -EFAULT; + frag = skb_shinfo(skb)->nr_frags; while (length && iov_iter_count(from)) { diff --git a/net/core/gro.c b/net/core/gro.c index 26f09c3e830b7..7b9d018f552bd 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -422,6 +422,9 @@ static void gro_pull_from_frag0(struct sk_buff *skb, int grow) { struct skb_shared_info *pinfo = skb_shinfo(skb); + if (WARN_ON_ONCE(!skb_frags_readable(skb))) + return; + BUG_ON(skb->end - skb->tail < grow); memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow); @@ -443,7 +446,7 @@ static void gro_try_pull_from_frag0(struct sk_buff *skb) { int grow = skb_gro_offset(skb) - skb_headlen(skb); - if (grow > 0) + if (grow > 0 && skb_frags_readable(skb)) gro_pull_from_frag0(skb, grow); } diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 99cf1ee73836d..7257bfbb8d2c2 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1951,6 +1951,9 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) if (skb_shared(skb) || skb_unclone(skb, gfp_mask)) return -EINVAL; + if (!skb_frags_readable(skb)) + return -EFAULT; + if (!num_frags) goto release; @@ -2124,6 +2127,9 @@ struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask) unsigned int size; int headerlen; + if (!skb_frags_readable(skb)) + return NULL; + if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)) return NULL; @@ -2462,6 +2468,9 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb, struct sk_buff *n; int oldheadroom; + if (!skb_frags_readable(skb)) + return NULL; + if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)) return NULL; @@ -2806,6 +2815,9 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta) */ int i, k, eat = (skb->tail + delta) - skb->end; + if (!skb_frags_readable(skb)) + return NULL; + if (eat > 0 || skb_cloned(skb)) { if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0, GFP_ATOMIC)) @@ -2959,6 +2971,9 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) to += copy; } + if (!skb_frags_readable(skb)) + goto fault; + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end; skb_frag_t *f = &skb_shinfo(skb)->frags[i]; @@ -3147,6 +3162,9 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe, /* * then map the fragments */ + if (!skb_frags_readable(skb)) + return false; + for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) { const skb_frag_t *f = &skb_shinfo(skb)->frags[seg]; @@ -3370,6 +3388,9 @@ int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) from += copy; } + if (!skb_frags_readable(skb)) + goto fault; + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; int end; @@ -3449,6 +3470,9 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, pos = copy; } + if (!skb_frags_readable(skb)) + return 0; + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end; skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; @@ -3549,6 +3573,9 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, pos = copy; } + if (!skb_frags_readable(skb)) + return 0; + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end; @@ -4040,6 +4067,7 @@ static inline void skb_split_inside_header(struct sk_buff *skb, skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i]; skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags; + skb1->unreadable = skb->unreadable; skb_shinfo(skb)->nr_frags = 0; skb1->data_len = skb->data_len; skb1->len += skb1->data_len; @@ -4054,6 +4082,7 @@ static inline void skb_split_no_header(struct sk_buff *skb, { int i, k = 0; const int nfrags = skb_shinfo(skb)->nr_frags; + const int unreadable = skb->unreadable; skb_shinfo(skb)->nr_frags = 0; skb1->len = skb1->data_len = skb->len - len; @@ -4087,6 +4116,12 @@ static inline void skb_split_no_header(struct sk_buff *skb, pos += size; } skb_shinfo(skb1)->nr_frags = k; + + if (skb_shinfo(skb)->nr_frags) + skb->unreadable = unreadable; + + if (skb_shinfo(skb1)->nr_frags) + skb1->unreadable = unreadable; } /** @@ -4322,6 +4357,9 @@ unsigned int skb_seq_read(unsigned int consumed, const u8 **data, return block_limit - abs_offset; } + if (!skb_frags_readable(st->cur_skb)) + return 0; + if (st->frag_idx == 0 && !st->frag_data) st->stepped_offset += skb_headlen(st->cur_skb); @@ -5934,7 +5972,10 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, if (to->pp_recycle != from->pp_recycle) return false; - if (len <= skb_tailroom(to)) { + if (skb_frags_readable(from) != skb_frags_readable(to)) + return false; + + if (len <= skb_tailroom(to) && skb_frags_readable(from)) { if (len) BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len)); *delta_truesize = 0; @@ -6111,6 +6152,9 @@ int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len) if (!pskb_may_pull(skb, write_len)) return -ENOMEM; + if (!skb_frags_readable(skb)) + return -EFAULT; + if (!skb_cloned(skb) || skb_clone_writable(skb, write_len)) return 0; @@ -6790,7 +6834,7 @@ void skb_condense(struct sk_buff *skb) { if (skb->data_len) { if (skb->data_len > skb->end - skb->tail || - skb_cloned(skb)) + skb_cloned(skb) || !skb_frags_readable(skb)) return; /* Nice, we can free page frag(s) right now */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 679cb51aaaf2b..55d85b1df0f39 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2154,6 +2154,9 @@ static int tcp_zerocopy_receive(struct sock *sk, skb = tcp_recv_skb(sk, seq, &offset); } + if (!skb_frags_readable(skb)) + break; + if (TCP_SKB_CB(skb)->has_rxtstamp) { tcp_update_recv_tstamps(skb, tss); zc->msg_flags |= TCP_CMSG_TS; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 5aadf64e554d8..2b6c448e274be 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5352,6 +5352,9 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root, for (end_of_skbs = true; skb != NULL && skb != tail; skb = n) { n = tcp_skb_next(skb, list); + if (!skb_frags_readable(skb)) + goto skip_this; + /* No new bits? It is possible on ofo queue. */ if (!before(start, TCP_SKB_CB(skb)->end_seq)) { skb = tcp_collapse_one(sk, skb, list, root); @@ -5372,17 +5375,20 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root, break; } - if (n && n != tail && mptcp_skb_can_collapse(skb, n) && + if (n && n != tail && skb_frags_readable(n) && + mptcp_skb_can_collapse(skb, n) && TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(n)->seq) { end_of_skbs = false; break; } +skip_this: /* Decided to skip this, advance start seq. */ start = TCP_SKB_CB(skb)->end_seq; } if (end_of_skbs || - (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN))) + (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN)) || + !skb_frags_readable(skb)) return; __skb_queue_head_init(&tmp); @@ -5424,7 +5430,8 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root, if (!skb || skb == tail || !mptcp_skb_can_collapse(nskb, skb) || - (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN))) + (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN)) || + !skb_frags_readable(skb)) goto end; if (skb_cmp_decrypted(skb, nskb)) goto end; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index f97e098f18a52..16c7c4839b683 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2344,7 +2344,8 @@ static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) if (unlikely(TCP_SKB_CB(skb)->eor) || tcp_has_tx_tstamp(skb) || - !skb_pure_zcopy_same(skb, next)) + !skb_pure_zcopy_same(skb, next) || + skb_frags_readable(skb) != skb_frags_readable(next)) return false; len -= skb->len; @@ -3264,6 +3265,8 @@ static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) return false; if (skb_cloned(skb)) return false; + if (!skb_frags_readable(skb)) + return false; /* Some heuristics for collapsing over SACK'd could be invented */ if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) return false; diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index fce3908875912..2ad47a6f37619 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2155,7 +2155,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, } } - snaplen = skb->len; + snaplen = skb_frags_readable(skb) ? skb->len : skb_headlen(skb); res = run_filter(skb, sk, snaplen); if (!res) @@ -2275,7 +2275,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, } } - snaplen = skb->len; + snaplen = skb_frags_readable(skb) ? skb->len : skb_headlen(skb); res = run_filter(skb, sk, snaplen); if (!res)