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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org Subject: [PATCH v6 4/6] bpf: allow new DECAP flags and add guard rails Date: Mon, 4 May 2026 11:17:57 +0100 Message-Id: <20260504101759.3319427-5-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-Proofpoint-ORIG-GUID: 7Et7Eu6p9nxIjcr4k4ckPpvsm3Tu5FQd X-Authority-Analysis: v=2.4 cv=dovrzVg4 c=1 sm=1 tr=0 ts=69f87263 cx=c_pps a=StLZT/nZ0R8Xs+spdojYmg==:117 a=StLZT/nZ0R8Xs+spdojYmg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Ifg-1AOnLHOf1gn6spyb:22 a=BYUV7c42er6_Rx9bq0XK:22 a=X7Ea-ya5AAAA:8 a=1XWaLZrsAAAA:8 a=Hfnf2daL9bryszF4jIsA:9 X-Proofpoint-GUID: 7Et7Eu6p9nxIjcr4k4ckPpvsm3Tu5FQd X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA0MDEwOSBTYWx0ZWRfX3AP/ugI4CfUm 87gX6Dj3D26R/cci69TEu0QvcR7eua/qWVZ1u6vvr8kza8sLE1TKCkx4RCVyrU4eefJE0kCkRHf Gr8wa7DO+qUsyaKGywZ9x6CN3coPd/L0etYH33g9AsXyoNto4GKfM0d7S0mozsl14R64sYiVonY cFqClwhKb3zlkDk31AWPXonxAQQ1Hm1LM7vvNTIN0y7XcvNmcS1aZxv/ODXO8ebmEMW8chta3tm n62/G/OMkzNtsO6vjFSY/FgmVdo9mJbZsPcijzTW/dqzopkd8uian1JsnXot5CjKjzl8JhFYgXV rrxp/o6BmAe4KLKpcwKjAyaWe0AaIhyaCO6QnjrFRq64xrE65J5RcGP3j9AyAzjKjo2HIyEVJeY rexPSrBwLnZ+j5M8gI25n7lZnM/pjlqZ+4Qq5OZGcaQL4KWawVJXJz4BqQC9PqVqp+v1vTg4wCZ FEj/MKMhF4kUyhcGfog== 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 malwarescore=0 bulkscore=0 impostorscore=0 phishscore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 clxscore=1015 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605040109 Add checks to require shrink-only decap, reject conflicting decap flag combinations, and verify removed length is sufficient for claimed header decapsulation. 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 --- net/core/filter.c | 44 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index 02d3947cca32..185a11f425fa 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include #include @@ -3484,6 +3485,12 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb) #define BPF_F_ADJ_ROOM_DECAP_L3_MASK (BPF_F_ADJ_ROOM_DECAP_L3_IPV4 | \ BPF_F_ADJ_ROOM_DECAP_L3_IPV6) +#define BPF_F_ADJ_ROOM_DECAP_L4_MASK (BPF_F_ADJ_ROOM_DECAP_L4_UDP | \ + BPF_F_ADJ_ROOM_DECAP_L4_GRE) + +#define BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK (BPF_F_ADJ_ROOM_DECAP_IPXIP4 | \ + BPF_F_ADJ_ROOM_DECAP_IPXIP6) + #define BPF_F_ADJ_ROOM_ENCAP_MASK (BPF_F_ADJ_ROOM_ENCAP_L3_MASK | \ BPF_F_ADJ_ROOM_ENCAP_L4_GRE | \ BPF_F_ADJ_ROOM_ENCAP_L4_UDP | \ @@ -3491,7 +3498,9 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb) BPF_F_ADJ_ROOM_ENCAP_L2( \ BPF_ADJ_ROOM_ENCAP_L2_MASK)) -#define BPF_F_ADJ_ROOM_DECAP_MASK (BPF_F_ADJ_ROOM_DECAP_L3_MASK) +#define BPF_F_ADJ_ROOM_DECAP_MASK (BPF_F_ADJ_ROOM_DECAP_L3_MASK | \ + BPF_F_ADJ_ROOM_DECAP_L4_MASK | \ + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK) #define BPF_F_ADJ_ROOM_MASK (BPF_F_ADJ_ROOM_FIXED_GSO | \ BPF_F_ADJ_ROOM_ENCAP_MASK | \ @@ -3739,6 +3748,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, } if (flags & BPF_F_ADJ_ROOM_DECAP_MASK) { + u32 len_decap_min = 0; + if (!shrink) return -EINVAL; @@ -3747,6 +3758,37 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, BPF_F_ADJ_ROOM_DECAP_L3_MASK) return -EINVAL; + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) == + BPF_F_ADJ_ROOM_DECAP_L4_MASK) + return -EINVAL; + + if ((flags & BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK) == + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK) + return -EINVAL; + + /* Reject mutually exclusive decap tunnel type flags. */ + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) && + (flags & BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK)) + return -EINVAL; + + if (flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) + len_decap_min += bpf_skb_net_base_len(skb); + + if (flags & BPF_F_ADJ_ROOM_DECAP_L4_UDP) + len_decap_min += sizeof(struct udphdr); + + if (flags & BPF_F_ADJ_ROOM_DECAP_L4_GRE) + len_decap_min += sizeof(struct gre_base_hdr); + + if (flags & BPF_F_ADJ_ROOM_DECAP_IPXIP4) + len_decap_min += sizeof(struct iphdr); + + if (flags & BPF_F_ADJ_ROOM_DECAP_IPXIP6) + len_decap_min += sizeof(struct ipv6hdr); + + if (len_diff_abs < len_decap_min) + return -EINVAL; + if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV4) len_min = sizeof(struct iphdr); -- 2.34.1