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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org Subject: [PATCH v6 5/6] bpf: clear decap state on skb_adjust_room shrink path Date: Mon, 4 May 2026 11:17:58 +0100 Message-Id: <20260504101759.3319427-6-nhudson@akamai.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260504101759.3319427-1-nhudson@akamai.com> References: <20260504101759.3319427-1-nhudson@akamai.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-04_03,2026-04-30_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 adultscore=0 mlxlogscore=999 malwarescore=0 lowpriorityscore=0 suspectscore=0 phishscore=0 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2604200000 definitions=main-2605040108 X-Authority-Analysis: v=2.4 cv=Z8fc2nRA c=1 sm=1 tr=0 ts=69f87266 cx=c_pps a=StLZT/nZ0R8Xs+spdojYmg==:117 a=StLZT/nZ0R8Xs+spdojYmg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Ifg-1AOnLHOf1gn6spyb:22 a=d4nn1RXdvEacMIURMw2s:22 a=X7Ea-ya5AAAA:8 a=cwecSWJ0lc1IdipTo1IA:9 X-Proofpoint-ORIG-GUID: W2qgSKo2dGQBrqp-aY1PbFNDgv8VsgTG X-Proofpoint-GUID: W2qgSKo2dGQBrqp-aY1PbFNDgv8VsgTG X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA0MDEwOSBTYWx0ZWRfX+7C7TCAvpm14 29rdzmtSDcoiJ/8b648FAYkoKEXQxPpWy54taiunF0PJLwP0TY/Un06nRTGqPzckaTOk21UqXBh 6pidY4ahsikqV3bYUGIL0z/8XEt9w7quxIoZU0O16F1DZcxQSXVZOyLrWk0qEonlonEwbwzKv+J G90Qx2aFnTFwXG9WP+hkvi83I96mVJu70Omt223M4s2SebRIuJENFCVgrbuLNQ+uLHVqIcfRMGW XfRtIrExiufMePJudfM4SxIH6xRxajnHEkBmcVuAPQScsC3gsIkYMMWCpfIYyb8HCICPIfLgc1q 7r3107aoTUcUbf5f66I7489N9O2N3cWoHxOo29ikN1MR6e8+2JMO7LPnQx+ShxCb0RBftM1PLhZ RhrIvTVZd5Yy3oWhIFY5Dh3WbV4Plut5fKYbq34lEDCSsylKvr2+u88MNUX4u0jK+VSkQaLWC+V IvrtQqkZsIZ9X1nz/ZQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-04_03,2026-04-30_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 suspectscore=0 phishscore=0 clxscore=1015 adultscore=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605040109 On shrink in bpf_skb_adjust_room(), apply decapsulation state updates according to BPF_F_ADJ_ROOM_DECAP_* flags. For GSO skbs, clear only the tunnel gso_type bits that correspond to the requested decap layer: - DECAP_L4_UDP: SKB_GSO_UDP_TUNNEL{,_CSUM} - DECAP_L4_GRE: SKB_GSO_GRE{,_CSUM} - DECAP_IPXIP4: SKB_GSO_IPXIP4 - DECAP_IPXIP6: SKB_GSO_IPXIP6 Then clear skb->encapsulation only if no tunnel GSO bits remain, keeping encapsulation set for cases such as ESP-in-UDP where tunnel state remains. For non-GSO skbs, there are no tunnel GSO bits to consult, so clear skb->encapsulation directly when DECAP_L4_* or DECAP_IPXIP_* flags are set. This keeps decap state handling consistent between GSO and non-GSO packets. Co-developed-by: Max Tottenham Signed-off-by: Max Tottenham Co-developed-by: Anna Glasgall Signed-off-by: Anna Glasgall Signed-off-by: Nick Hudson --- net/core/filter.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 185a11f425fa..3213732dff84 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3666,9 +3666,48 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) skb_increase_gso_size(shinfo, len_diff); + /* Selective GSO flag clearing based on decap type. + * Only clear the flags for the tunnel layer being removed. + */ + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_UDP) && + (shinfo->gso_type & (SKB_GSO_UDP_TUNNEL | + SKB_GSO_UDP_TUNNEL_CSUM))) + shinfo->gso_type &= ~(SKB_GSO_UDP_TUNNEL | + SKB_GSO_UDP_TUNNEL_CSUM); + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_GRE) && + (shinfo->gso_type & (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) + shinfo->gso_type &= ~(SKB_GSO_GRE | + SKB_GSO_GRE_CSUM); + if ((flags & BPF_F_ADJ_ROOM_DECAP_IPXIP4) && + (shinfo->gso_type & SKB_GSO_IPXIP4)) + shinfo->gso_type &= ~SKB_GSO_IPXIP4; + if ((flags & BPF_F_ADJ_ROOM_DECAP_IPXIP6) && + (shinfo->gso_type & SKB_GSO_IPXIP6)) + shinfo->gso_type &= ~SKB_GSO_IPXIP6; + + /* Clear encapsulation flag only when no tunnel GSO flags remain */ + if (flags & (BPF_F_ADJ_ROOM_DECAP_L4_MASK | + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK)) { + if (!(shinfo->gso_type & (SKB_GSO_UDP_TUNNEL | + SKB_GSO_UDP_TUNNEL_CSUM | + SKB_GSO_GRE | + SKB_GSO_GRE_CSUM | + SKB_GSO_IPXIP4 | + SKB_GSO_IPXIP6 | + SKB_GSO_ESP))) + if (skb->encapsulation) + skb->encapsulation = 0; + } + /* Header must be checked, and gso_segs recomputed. */ shinfo->gso_type |= SKB_GSO_DODGY; shinfo->gso_segs = 0; + } else { + /* For non-GSO packets, clear encapsulation if decap flags are set */ + if ((flags & (BPF_F_ADJ_ROOM_DECAP_L4_MASK | + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK)) && + skb->encapsulation) + skb->encapsulation = 0; } return 0; -- 2.34.1