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Mon, 04 May 2026 11:18:09 +0100 (BST) Received: from pps.filterd (prod-mail-ppoint1.akamai.com [127.0.0.1]) by prod-mail-ppoint1.akamai.com (8.18.1.7/8.18.1.7) with ESMTP id 644ACMPl005971; Mon, 4 May 2026 06:18:08 -0400 Received: from prod-mail-relay01.akamai.com ([172.27.118.31]) by prod-mail-ppoint1.akamai.com (PPS) with ESMTP id 4dwckwq08s-1; Mon, 04 May 2026 06:18:08 -0400 (EDT) Received: from muc-lhvdhd.munich.corp.akamai.com (muc-lhvdhd.munich.corp.akamai.com [172.29.0.147]) by prod-mail-relay01.akamai.com (Postfix) with ESMTP id B469C84; Mon, 4 May 2026 10:18:06 +0000 (UTC) From: Nick Hudson To: bpf@vger.kernel.org, netdev@vger.kernel.org, Willem de Bruijn , Martin KaFai Lau Cc: Nick Hudson , Max Tottenham , Anna Glasgall , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , linux-kernel@vger.kernel.org Subject: [PATCH v6 3/6] bpf: add BPF_F_ADJ_ROOM_DECAP_* flags for tunnel decapsulation Date: Mon, 4 May 2026 11:17:56 +0100 Message-Id: <20260504101759.3319427-4-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=608 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=UulT8ewB c=1 sm=1 tr=0 ts=69f87261 cx=c_pps a=StLZT/nZ0R8Xs+spdojYmg==:117 a=StLZT/nZ0R8Xs+spdojYmg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Ifg-1AOnLHOf1gn6spyb:22 a=VcQvXEo1OZcA_IiPcy3B:22 a=X7Ea-ya5AAAA:8 a=1XWaLZrsAAAA:8 a=KfGVUnEDJfcTcdlxACkA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA0MDEwOSBTYWx0ZWRfX1MZ+z1MXANBJ Npefq0zhzvxUb73gzbbEHgGqt7EMHpbwTH869uhDPr5gVnBjeLoFBe6UKxiElrEve+koMqwxdTd qMtCdHPoMwenwyevZKA2amjwMzIEkRhCYaOUHehfd/+oJviWV543zMEEY1k2mrWHPesDR12Sj2D ERvOSBs4w0AX6L5kJ43Wn9by/9Amu1ZzOs9bSeHA1bYHiUZ6FO1xncc38zWgLbmqedFyenV9yfp BxoS3SHBctbDfL6RKbzduGuANA19k2AU9WLW37p/RIAyYCjBshaAqfQtNR8z+WCziUSLcI1IIfM 89YxW57AuISSvBKF97YH+zkOp2U+adQxVRhQRxJOsLsHRYBxRGiD7gHel175nZEItvnnSHZLtne doMzO6InbABJmraTUxT//rvpZj8vMWjVUWY/9+jnogYD8KyKpbNynX73O0hFxYiY0bURKMNTftc 3xDnP+jypW3GYZyrBhg== X-Proofpoint-ORIG-GUID: e_yXvawwBzRrmS-I3P4Zt9_evSy_qy5t X-Proofpoint-GUID: e_yXvawwBzRrmS-I3P4Zt9_evSy_qy5t 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 phishscore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 clxscore=1015 suspectscore=0 adultscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605040109 Add new bpf_skb_adjust_room() decapsulation flags: - BPF_F_ADJ_ROOM_DECAP_L4_GRE - BPF_F_ADJ_ROOM_DECAP_L4_UDP - BPF_F_ADJ_ROOM_DECAP_IPXIP4 - BPF_F_ADJ_ROOM_DECAP_IPXIP6 These flags let BPF programs describe which tunnel layer is being removed, so later changes can update tunnel-related GSO state accordingly during decapsulation. This patch only introduces the UAPI flag definitions and helper documentation. 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 Reviewed-by: Willem de Bruijn --- include/uapi/linux/bpf.h | 34 ++++++++++++++++++++++++++++++++-- tools/include/uapi/linux/bpf.h | 34 ++++++++++++++++++++++++++++++++-- 2 files changed, 64 insertions(+), 4 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index c021ed8d7b44..4a53e731c554 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3010,8 +3010,34 @@ union bpf_attr { * * * **BPF_F_ADJ_ROOM_DECAP_L3_IPV4**, * **BPF_F_ADJ_ROOM_DECAP_L3_IPV6**: - * Indicate the new IP header version after decapsulating the outer - * IP header. Used when the inner and outer IP versions are different. + * Indicate the new IP header version after decapsulating the + * outer IP header. Used when the inner and outer IP versions + * are different. These flags only trigger a protocol change + * without clearing any tunnel-specific GSO flags. + * + * * **BPF_F_ADJ_ROOM_DECAP_L4_GRE**: + * Clear GRE tunnel GSO flags (SKB_GSO_GRE and SKB_GSO_GRE_CSUM) + * when decapsulating a GRE tunnel. + * + * * **BPF_F_ADJ_ROOM_DECAP_L4_UDP**: + * Clear UDP tunnel GSO flags (SKB_GSO_UDP_TUNNEL and + * SKB_GSO_UDP_TUNNEL_CSUM) when decapsulating a UDP tunnel. + * + * * **BPF_F_ADJ_ROOM_DECAP_IPXIP4**: + * Clear IPIP/SIT tunnel GSO flag (SKB_GSO_IPXIP4) when decapsulating + * a tunnel with an outer IPv4 header (IPv4-in-IPv4 or IPv6-in-IPv4). + * + * * **BPF_F_ADJ_ROOM_DECAP_IPXIP6**: + * Clear IPv6 encapsulation tunnel GSO flag (SKB_GSO_IPXIP6) when + * decapsulating a tunnel with an outer IPv6 header (IPv6-in-IPv6 + * or IPv4-in-IPv6). + * + * When using the decapsulation flags above, the skb->encapsulation + * flag is automatically cleared if all tunnel-specific GSO flags + * (SKB_GSO_UDP_TUNNEL, SKB_GSO_UDP_TUNNEL_CSUM, SKB_GSO_GRE, + * SKB_GSO_GRE_CSUM, SKB_GSO_IPXIP4, SKB_GSO_IPXIP6) have been + * removed from the packet. This handles cases where all tunnel + * layers have been decapsulated. * * A call to this helper is susceptible to change the underlying * packet buffer. Therefore, at load time, all checks on pointers @@ -6221,6 +6247,10 @@ enum bpf_adj_room_flags { BPF_F_ADJ_ROOM_ENCAP_L2_ETH = (1ULL << 6), BPF_F_ADJ_ROOM_DECAP_L3_IPV4 = (1ULL << 7), BPF_F_ADJ_ROOM_DECAP_L3_IPV6 = (1ULL << 8), + BPF_F_ADJ_ROOM_DECAP_L4_GRE = (1ULL << 9), + BPF_F_ADJ_ROOM_DECAP_L4_UDP = (1ULL << 10), + BPF_F_ADJ_ROOM_DECAP_IPXIP4 = (1ULL << 11), + BPF_F_ADJ_ROOM_DECAP_IPXIP6 = (1ULL << 12), }; enum { diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index ca35ed622ed5..f4c2fbd8fe68 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3010,8 +3010,34 @@ union bpf_attr { * * * **BPF_F_ADJ_ROOM_DECAP_L3_IPV4**, * **BPF_F_ADJ_ROOM_DECAP_L3_IPV6**: - * Indicate the new IP header version after decapsulating the outer - * IP header. Used when the inner and outer IP versions are different. + * Indicate the new IP header version after decapsulating the + * outer IP header. Used when the inner and outer IP versions + * are different. These flags only trigger a protocol change + * without clearing any tunnel-specific GSO flags. + * + * * **BPF_F_ADJ_ROOM_DECAP_L4_GRE**: + * Clear GRE tunnel GSO flags (SKB_GSO_GRE and SKB_GSO_GRE_CSUM) + * when decapsulating a GRE tunnel. + * + * * **BPF_F_ADJ_ROOM_DECAP_L4_UDP**: + * Clear UDP tunnel GSO flags (SKB_GSO_UDP_TUNNEL and + * SKB_GSO_UDP_TUNNEL_CSUM) when decapsulating a UDP tunnel. + * + * * **BPF_F_ADJ_ROOM_DECAP_IPXIP4**: + * Clear IPIP/SIT tunnel GSO flag (SKB_GSO_IPXIP4) when decapsulating + * a tunnel with an outer IPv4 header (IPv4-in-IPv4 or IPv6-in-IPv4). + * + * * **BPF_F_ADJ_ROOM_DECAP_IPXIP6**: + * Clear IPv6 encapsulation tunnel GSO flag (SKB_GSO_IPXIP6) when + * decapsulating a tunnel with an outer IPv6 header (IPv6-in-IPv6 + * or IPv4-in-IPv6). + * + * When using the decapsulation flags above, the skb->encapsulation + * flag is automatically cleared if all tunnel-specific GSO flags + * (SKB_GSO_UDP_TUNNEL, SKB_GSO_UDP_TUNNEL_CSUM, SKB_GSO_GRE, + * SKB_GSO_GRE_CSUM, SKB_GSO_IPXIP4, SKB_GSO_IPXIP6) have been + * removed from the packet. This handles cases where all tunnel + * layers have been decapsulated. * * A call to this helper is susceptible to change the underlying * packet buffer. Therefore, at load time, all checks on pointers @@ -6221,6 +6247,10 @@ enum bpf_adj_room_flags { BPF_F_ADJ_ROOM_ENCAP_L2_ETH = (1ULL << 6), BPF_F_ADJ_ROOM_DECAP_L3_IPV4 = (1ULL << 7), BPF_F_ADJ_ROOM_DECAP_L3_IPV6 = (1ULL << 8), + BPF_F_ADJ_ROOM_DECAP_L4_GRE = (1ULL << 9), + BPF_F_ADJ_ROOM_DECAP_L4_UDP = (1ULL << 10), + BPF_F_ADJ_ROOM_DECAP_IPXIP4 = (1ULL << 11), + BPF_F_ADJ_ROOM_DECAP_IPXIP6 = (1ULL << 12), }; enum { -- 2.34.1