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AJvYcCXhGfiSaI/jb5NCRk4KBN91niYh/4u7EoVxlF/28Winc9nFL1wnERQXu1U2vyu5rN06qcHLyEE+xi80RNKzARf9ypTM6JUluOY6LIJ/BubyhuRBEv/JMCLfFGzm/vvTRgPcONhP X-Gm-Message-State: AOJu0YzjuPV8jH3rgHYZUY3+q2jzdAyiDtAbsMLskVUwWZGAKKtzF6rH uLfPOfy9PZuKUCfJvo7aakPvIvCfWg/wOHxCOWR4iF0oMH9rxLPD X-Received: by 2002:a05:6000:1a43:b0:34a:5663:410 with SMTP id t3-20020a0560001a4300b0034a56630410mr4506887wry.5.1714046411120; Thu, 25 Apr 2024 05:00:11 -0700 (PDT) Received: from debian ([146.70.204.204]) by smtp.gmail.com with ESMTPSA id e37-20020a5d5965000000b0034a44c615ddsm17752847wri.88.2024.04.25.05.00.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Apr 2024 05:00:10 -0700 (PDT) Message-ID: Date: Thu, 25 Apr 2024 13:59:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH net v3 1/2] net: gro: fix udp bad offset in socket lookup by adding {inner_}network_offset to napi_gro_cb To: Willem de Bruijn , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org, alobakin@pm.me, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240424163045.123528-1-richardbgobert@gmail.com> <20240424163045.123528-2-richardbgobert@gmail.com> <6629bcc9486a3_1bd6b02949c@willemb.c.googlers.com.notmuch> From: Richard Gobert In-Reply-To: <6629bcc9486a3_1bd6b02949c@willemb.c.googlers.com.notmuch> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Willem de Bruijn wrote: > Richard Gobert wrote: >> Commits a602456 ("udp: Add GRO functions to UDP socket") and 57c67ff ("udp: >> additional GRO support") introduce incorrect usage of {ip,ipv6}_hdr in the >> complete phase of gro. The functions always return skb->network_header, >> which in the case of encapsulated packets at the gro complete phase, is >> always set to the innermost L3 of the packet. That means that calling >> {ip,ipv6}_hdr for skbs which completed the GRO receive phase (both in >> gro_list and *_gro_complete) when parsing an encapsulated packet's _outer_ >> L3/L4 may return an unexpected value. >> >> This incorrect usage leads to a bug in GRO's UDP socket lookup. >> udp{4,6}_lib_lookup_skb functions use ip_hdr/ipv6_hdr respectively. These >> *_hdr functions return network_header which will point to the innermost L3, >> resulting in the wrong offset being used in __udp{4,6}_lib_lookup with >> encapsulated packets. >> >> This patch adds network_offset and inner_network_offset to napi_gro_cb, and >> makes sure both are set correctly. >> >> To fix the issue, network_offsets union is used inside napi_gro_cb, in >> which both the outer and the inner network offsets are saved. >> >> Reproduction example: >> >> Endpoint configuration example (fou + local address bind) >> >> # ip fou add port 6666 ipproto 4 >> # ip link add name tun1 type ipip remote 2.2.2.1 local 2.2.2.2 encap fou encap-dport 5555 encap-sport 6666 mode ipip >> # ip link set tun1 up >> # ip a add 1.1.1.2/24 dev tun1 >> >> Netperf TCP_STREAM result on net-next before patch is applied: >> >> net-next main, GRO enabled: >> $ netperf -H 1.1.1.2 -t TCP_STREAM -l 5 >> Recv Send Send >> Socket Socket Message Elapsed >> Size Size Size Time Throughput >> bytes bytes bytes secs. 10^6bits/sec >> >> 131072 16384 16384 5.28 2.37 >> >> net-next main, GRO disabled: >> $ netperf -H 1.1.1.2 -t TCP_STREAM -l 5 >> Recv Send Send >> Socket Socket Message Elapsed >> Size Size Size Time Throughput >> bytes bytes bytes secs. 10^6bits/sec >> >> 131072 16384 16384 5.01 2745.06 >> >> patch applied, GRO enabled: >> $ netperf -H 1.1.1.2 -t TCP_STREAM -l 5 >> Recv Send Send >> Socket Socket Message Elapsed >> Size Size Size Time Throughput >> bytes bytes bytes secs. 10^6bits/sec >> >> 131072 16384 16384 5.01 2877.38 >> >> Fixes: 57c67ff4bd92 ("udp: additional GRO support") >> Signed-off-by: Richard Gobert >> --- >> include/net/gro.h | 18 ++++++++++++++++-- >> net/8021q/vlan_core.c | 2 ++ >> net/core/gro.c | 1 + >> net/ipv4/af_inet.c | 5 +---- >> net/ipv4/tcp_offload.c | 3 ++- >> net/ipv4/udp.c | 3 ++- >> net/ipv4/udp_offload.c | 3 ++- >> net/ipv6/ip6_offload.c | 6 +++--- >> net/ipv6/tcpv6_offload.c | 3 ++- >> net/ipv6/udp.c | 3 ++- >> net/ipv6/udp_offload.c | 3 ++- >> 11 files changed, 35 insertions(+), 15 deletions(-) >> >> diff --git a/include/net/gro.h b/include/net/gro.h >> index 50f1e403dbbb..1faff23b66e8 100644 >> --- a/include/net/gro.h >> +++ b/include/net/gro.h >> @@ -87,6 +87,15 @@ struct napi_gro_cb { >> >> /* used to support CHECKSUM_COMPLETE for tunneling protocols */ >> __wsum csum; >> + >> + /* L3 offsets */ >> + union { >> + struct { >> + u16 network_offset; >> + u16 inner_network_offset; >> + }; >> + u16 network_offsets[2]; >> + }; >> }; >> >> #define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb) >> @@ -172,12 +181,17 @@ static inline void *skb_gro_header(struct sk_buff *skb, unsigned int hlen, >> return ptr; >> } >> >> +static inline int skb_gro_network_offset(const struct sk_buff *skb) >> +{ >> + return NAPI_GRO_CB(skb)->network_offsets[NAPI_GRO_CB(skb)->encap_mark]; >> +} >> + >> static inline void *skb_gro_network_header(const struct sk_buff *skb) >> { >> if (skb_gro_may_pull(skb, skb_gro_offset(skb))) >> - return skb_gro_header_fast(skb, skb_network_offset(skb)); >> + return skb_gro_header_fast(skb, skb_gro_network_offset(skb)); >> >> - return skb_network_header(skb); >> + return skb->data + skb_gro_network_offset(skb); >> } >> >> static inline __wsum inet_gro_compute_pseudo(const struct sk_buff *skb, >> diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c >> index f00158234505..9404dd551dfd 100644 >> --- a/net/8021q/vlan_core.c >> +++ b/net/8021q/vlan_core.c >> @@ -478,6 +478,8 @@ static struct sk_buff *vlan_gro_receive(struct list_head *head, >> if (unlikely(!vhdr)) >> goto out; >> >> + NAPI_GRO_CB(skb)->network_offsets[NAPI_GRO_CB(skb)->encap_mark] = hlen; >> + >> type = vhdr->h_vlan_encapsulated_proto; >> >> ptype = gro_find_receive_by_type(type); >> diff --git a/net/core/gro.c b/net/core/gro.c >> index 83f35d99a682..c7901253a1a8 100644 >> --- a/net/core/gro.c >> +++ b/net/core/gro.c >> @@ -371,6 +371,7 @@ static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff) >> const skb_frag_t *frag0; >> unsigned int headlen; >> >> + NAPI_GRO_CB(skb)->network_offset = 0; >> NAPI_GRO_CB(skb)->data_offset = 0; >> headlen = skb_headlen(skb); >> NAPI_GRO_CB(skb)->frag0 = skb->data; >> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c >> index 55bd72997b31..2daf635ab99e 100644 >> --- a/net/ipv4/af_inet.c >> +++ b/net/ipv4/af_inet.c >> @@ -1568,10 +1568,7 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb) >> >> NAPI_GRO_CB(skb)->is_atomic = !!(iph->frag_off & htons(IP_DF)); >> NAPI_GRO_CB(skb)->flush |= flush; >> - skb_set_network_header(skb, off); >> - /* The above will be needed by the transport layer if there is one >> - * immediately following this IP hdr. >> - */ >> + NAPI_GRO_CB(skb)->inner_network_offset = off; >> >> /* Note : No need to call skb_gro_postpull_rcsum() here, >> * as we already checked checksum over ipv4 header was 0 >> diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c >> index ebe4722bb020..be8ddf6da88c 100644 >> --- a/net/ipv4/tcp_offload.c >> +++ b/net/ipv4/tcp_offload.c >> @@ -332,7 +332,8 @@ struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) >> >> INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) >> { >> - const struct iphdr *iph = ip_hdr(skb); >> + const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation]; >> + const struct iphdr *iph = (struct iphdr *)(skb->data + offset); >> struct tcphdr *th = tcp_hdr(skb); >> >> th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, >> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c >> index c02bf011d4a6..1399fce82b3f 100644 >> --- a/net/ipv4/udp.c >> +++ b/net/ipv4/udp.c >> @@ -532,7 +532,8 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb, >> struct sock *udp4_lib_lookup_skb(const struct sk_buff *skb, >> __be16 sport, __be16 dport) >> { >> - const struct iphdr *iph = ip_hdr(skb); >> + const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation]; >> + const struct iphdr *iph = (struct iphdr *)(skb->data + offset); >> struct net *net = dev_net(skb->dev); >> int iif, sdif; >> >> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c >> index 3498dd1d0694..fd29d21d579c 100644 >> --- a/net/ipv4/udp_offload.c >> +++ b/net/ipv4/udp_offload.c >> @@ -718,7 +718,8 @@ EXPORT_SYMBOL(udp_gro_complete); >> >> INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff) >> { >> - const struct iphdr *iph = ip_hdr(skb); >> + const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation]; >> + const struct iphdr *iph = (struct iphdr *)(skb->data + offset); >> struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); >> >> /* do fraglist only if there is no outer UDP encap (or we already processed it) */ >> diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c >> index b41e35af69ea..5d6b875a4638 100644 >> --- a/net/ipv6/ip6_offload.c >> +++ b/net/ipv6/ip6_offload.c >> @@ -67,7 +67,7 @@ static int ipv6_gro_pull_exthdrs(struct sk_buff *skb, int off, int proto) >> off += len; >> } >> >> - skb_gro_pull(skb, off - skb_network_offset(skb)); >> + skb_gro_pull(skb, off - skb_gro_network_offset(skb)); >> return proto; >> } >> >> @@ -236,7 +236,7 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head, >> if (unlikely(!iph)) >> goto out; >> >> - skb_set_network_header(skb, off); >> + NAPI_GRO_CB(skb)->inner_network_offset = off; >> >> flush += ntohs(iph->payload_len) != skb->len - hlen; >> >> @@ -259,7 +259,7 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head, >> NAPI_GRO_CB(skb)->proto = proto; >> >> flush--; >> - nlen = skb_network_header_len(skb); >> + nlen = skb_gro_offset(skb) - off; >> >> list_for_each_entry(p, head, list) { >> const struct ipv6hdr *iph2; >> diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c >> index 4b07d1e6c952..e70d60e0f86f 100644 >> --- a/net/ipv6/tcpv6_offload.c >> +++ b/net/ipv6/tcpv6_offload.c >> @@ -29,7 +29,8 @@ struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb) >> >> INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff) >> { >> - const struct ipv6hdr *iph = ipv6_hdr(skb); >> + const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation]; >> + const struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + offset); >> struct tcphdr *th = tcp_hdr(skb); >> > > Only udp code is affected, as only that can be used as tunnel. > > For bug fixes, let's try to avoid touching other code. Also that vlan. > > As a minimal patch all that is needed is the following, right? > > - add the fields > - store in inet_gro_receive + ipv6_gro_receive > - read in udp[46]_gro_complete and udp[46]_lib_lookup_skb > This approach is smaller, thanks for writing it down. What do you think about doing this and still writing to inner_network_offset exclusively in {inet,ipv6}_gro_receive? I still prefer it for reasons discussed in the previous series. The code line in vlan_gro_receive will still be there, but that will be the only addition to your snippet.