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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org Subject: [PATCH bpf-next v7 4/6] bpf: allow new DECAP flags and add guard rails Date: Wed, 12 Aug 2026 09:31:13 +0100 Message-Id: <20260812083115.73100-5-nhudson@akamai.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260812083115.73100-1-nhudson@akamai.com> References: <20260812083115.73100-1-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:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-12_02,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 bulkscore=0 spamscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2606160000 definitions=main-2608120066 X-Proofpoint-ORIG-GUID: 40AOGrOOpRmJ8bDUCVflWPYq7tDyGkpL X-Authority-Analysis: v=2.4 cv=b/KCJNGx c=1 sm=1 tr=0 ts=6a7c2f64 cx=c_pps a=NpDlK6FjLPvvy7XAFEyJFw==:117 a=NpDlK6FjLPvvy7XAFEyJFw==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Ifg-1AOnLHOf1gn6spyb:22 a=d4nn1RXdvEacMIURMw2s:22 a=X7Ea-ya5AAAA:8 a=1XWaLZrsAAAA:8 a=Hfnf2daL9bryszF4jIsA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODEyMDA2NyBTYWx0ZWRfX+CttmMnKIYvv MKwoSd/dS4Kke/fIScGoQQehUxI8f91BbaHxXClOc9MrHRJ5C4zkjkNrWggeotUjWhuyulL2ehK xkSkQZIBgRc3NDl8g4pP22lEK/wOAwc= X-Proofpoint-GUID: 40AOGrOOpRmJ8bDUCVflWPYq7tDyGkpL X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEyMDA2NyBTYWx0ZWRfX8X+5McIoztYv P7dHoQ7AtAmxS+93suQp/IRZZ9jx7EdetOTCv3KzSfIMW/i+a3oT2GB2goCgriHqUppTwV16kvC WvnpzYbtRUuDiQLznaGKO9XQJAfeflEgZZacV4JZhX/v/Go7nm/KzYGSZHu16PWgwDJ6tDstj7a kuR2rnEqeoSdgsWuZDCL7JgQxw3u3d2+m1+TrtjAzm9Ppf8kb209aPysfDMFDPzRKUd4CHunub5 QVawuk2UoHU6KnZpXv8yesl+waMFULS26cDWCbYy/PcnhV37xQm4oXCLKWD8aS40RQzCdFXOsDn a9qlk1Gw59hyf32tykRtAs9JpFGWxT/hWaEe/i26ef3BJVnN22MtRSBSO8TouCITF5djlNM+YVe VZlw5+3ArxpNHiNLcyPWxRca1bZJNuuGa/50HYV+pfugJssPPxXuX2uCo2gZK9FNQpfWrfOhbpp uKtqankgl3LvpkW/gHw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-12_02,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 suspectscore=0 phishscore=0 bulkscore=0 impostorscore=0 clxscore=1015 malwarescore=0 adultscore=0 lowpriorityscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606160001 definitions=main-2608120067 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 89e516049c85..981b75941e7f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include #include @@ -3572,6 +3573,12 @@ 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 | \ @@ -3579,7 +3586,9 @@ 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 | \ @@ -3827,6 +3836,8 @@ 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; @@ -3835,6 +3846,37 @@ 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