* [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags
[not found] <20260317121429.2399539-1-nhudson@akamai.com>
@ 2026-03-17 12:14 ` Nick Hudson
2026-03-17 13:27 ` Willem de Bruijn
2026-03-17 12:14 ` [PATCH v1 4/5] bpf: add guard rails for new DECAP flags Nick Hudson
2026-03-17 12:14 ` [PATCH v1 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room Nick Hudson
2 siblings, 1 reply; 8+ messages in thread
From: Nick Hudson @ 2026-03-17 12:14 UTC (permalink / raw)
To: bpf
Cc: Willem de Bruijn, Nick Hudson, Max Tottenham, Anna Glasgall,
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev, linux-kernel
Introduce helper masks for bpf_skb_adjust_room() decapsulation flags
to simplify validation and keep flag handling readable:
- BPF_F_ADJ_ROOM_DECAP_L4_MASK
- BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK
- BPF_F_ADJ_ROOM_ENCAP_MASK
- BPF_F_ADJ_ROOM_DECAP_MASK
Also fold these masks into BPF_F_ADJ_ROOM_MASK and per-path flag
validation checks.
This is a refactoring/plumbing change; functional decapsulation and
GSO behavior updates are handled in later patches.
Co-developed-by: Max Tottenham <mtottenh@akamai.com>
Signed-off-by: Max Tottenham <mtottenh@akamai.com>
Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Nick Hudson <nhudson@akamai.com>
---
net/core/filter.c | 33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 0d5d5a17acb2..ac7e1068fe4c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3483,14 +3483,27 @@ 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_MASK (BPF_F_ADJ_ROOM_FIXED_GSO | \
- BPF_F_ADJ_ROOM_ENCAP_L3_MASK | \
+#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 | \
BPF_F_ADJ_ROOM_ENCAP_L2_ETH | \
BPF_F_ADJ_ROOM_ENCAP_L2( \
- BPF_ADJ_ROOM_ENCAP_L2_MASK) | \
- BPF_F_ADJ_ROOM_DECAP_L3_MASK)
+ BPF_ADJ_ROOM_ENCAP_L2_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 | \
+ BPF_F_ADJ_ROOM_DECAP_MASK | \
+ BPF_F_ADJ_ROOM_NO_CSUM_RESET)
static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
u64 flags)
@@ -3502,6 +3515,11 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
unsigned int gso_type = SKB_GSO_DODGY;
int ret;
+ if (unlikely(flags & ~(BPF_F_ADJ_ROOM_ENCAP_MASK |
+ BPF_F_ADJ_ROOM_NO_CSUM_RESET |
+ BPF_F_ADJ_ROOM_FIXED_GSO)))
+ return -EINVAL;
+
if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
/* udp gso_size delineates datagrams, only allow if fixed */
if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) ||
@@ -3611,8 +3629,8 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff,
{
int ret;
- if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO |
- BPF_F_ADJ_ROOM_DECAP_L3_MASK |
+ if (unlikely(flags & ~(BPF_F_ADJ_ROOM_DECAP_MASK |
+ BPF_F_ADJ_ROOM_FIXED_GSO |
BPF_F_ADJ_ROOM_NO_CSUM_RESET)))
return -EINVAL;
@@ -3708,8 +3726,7 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
u32 off;
int ret;
- if (unlikely(flags & ~(BPF_F_ADJ_ROOM_MASK |
- BPF_F_ADJ_ROOM_NO_CSUM_RESET)))
+ if (unlikely(flags & ~BPF_F_ADJ_ROOM_MASK))
return -EINVAL;
if (unlikely(len_diff_abs > 0xfffU))
return -EFAULT;
--
2.34.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH v1 4/5] bpf: add guard rails for new DECAP flags
[not found] <20260317121429.2399539-1-nhudson@akamai.com>
2026-03-17 12:14 ` [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags Nick Hudson
@ 2026-03-17 12:14 ` Nick Hudson
2026-03-17 13:30 ` Willem de Bruijn
2026-03-17 12:14 ` [PATCH v1 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room Nick Hudson
2 siblings, 1 reply; 8+ messages in thread
From: Nick Hudson @ 2026-03-17 12:14 UTC (permalink / raw)
To: bpf
Cc: Willem de Bruijn, Nick Hudson, Max Tottenham, Anna Glasgall,
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev, linux-kernel
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 <mtottenh@akamai.com>
Signed-off-by: Max Tottenham <mtottenh@akamai.com>
Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Nick Hudson <nhudson@akamai.com>
---
net/core/filter.c | 45 ++++++++++++++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 9 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index ac7e1068fe4c..437e0da34f84 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -56,6 +56,7 @@
#include <net/sock_reuseport.h>
#include <net/busy_poll.h>
#include <net/tcp.h>
+#include <net/gre.h>
#include <net/xfrm.h>
#include <net/udp.h>
#include <linux/bpf_trace.h>
@@ -3745,20 +3746,46 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
return -ENOTSUPP;
}
- if (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) {
+ if (flags & BPF_F_ADJ_ROOM_DECAP_MASK) {
+ u32 len_decap_min = 0;
+
if (!shrink)
return -EINVAL;
- switch (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) {
- case BPF_F_ADJ_ROOM_DECAP_L3_IPV4:
+ if ((flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) ==
+ 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;
+
+ if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) &&
+ (flags & BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK))
+ return -EINVAL;
+
+ if (mode == BPF_ADJ_ROOM_MAC)
+ len_decap_min += proto == htons(ETH_P_IP) ?
+ sizeof(struct iphdr) : sizeof(struct ipv6hdr);
+
+ 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 (len_diff_abs < len_decap_min)
+ return -EINVAL;
+
+ if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV4)
len_min = sizeof(struct iphdr);
- break;
- case BPF_F_ADJ_ROOM_DECAP_L3_IPV6:
+
+ if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV6)
len_min = sizeof(struct ipv6hdr);
- break;
- default:
- return -EINVAL;
- }
}
len_cur = skb->len - skb_network_offset(skb);
--
2.34.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH v1 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room
[not found] <20260317121429.2399539-1-nhudson@akamai.com>
2026-03-17 12:14 ` [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags Nick Hudson
2026-03-17 12:14 ` [PATCH v1 4/5] bpf: add guard rails for new DECAP flags Nick Hudson
@ 2026-03-17 12:14 ` Nick Hudson
2026-03-17 13:02 ` bot+bpf-ci
2 siblings, 1 reply; 8+ messages in thread
From: Nick Hudson @ 2026-03-17 12:14 UTC (permalink / raw)
To: bpf
Cc: Willem de Bruijn, Nick Hudson, Max Tottenham, Anna Glasgall,
Martin KaFai Lau, Daniel Borkmann, Alexei Starovoitov,
Andrii Nakryiko, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev, linux-kernel
On shrink in bpf_skb_adjust_room(), clear tunnel-specific GSO flags
according to the decapsulation flags:
- BPF_F_ADJ_ROOM_DECAP_L4_UDP clears SKB_GSO_UDP_TUNNEL{,_CSUM}
- BPF_F_ADJ_ROOM_DECAP_L4_GRE clears SKB_GSO_GRE{,_CSUM}
- BPF_F_ADJ_ROOM_DECAP_IPXIP4 clears SKB_GSO_IPXIP4
- BPF_F_ADJ_ROOM_DECAP_IPXIP6 clears SKB_GSO_IPXIP6
When all tunnel-related GSO bits are cleared, also clear
skb->encapsulation.
Co-developed-by: Max Tottenham <mtottenh@akamai.com>
Signed-off-by: Max Tottenham <mtottenh@akamai.com>
Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Nick Hudson <nhudson@akamai.com>
---
net/core/filter.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/net/core/filter.c b/net/core/filter.c
index 437e0da34f84..8a7c06a10dd4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3665,6 +3665,37 @@ 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_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)))
+ if (skb->encapsulation)
+ skb->encapsulation = 0;
+ }
+
/* Header must be checked, and gso_segs recomputed. */
shinfo->gso_type |= SKB_GSO_DODGY;
shinfo->gso_segs = 0;
--
2.34.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v1 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room
2026-03-17 12:14 ` [PATCH v1 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room Nick Hudson
@ 2026-03-17 13:02 ` bot+bpf-ci
0 siblings, 0 replies; 8+ messages in thread
From: bot+bpf-ci @ 2026-03-17 13:02 UTC (permalink / raw)
To: nhudson, bpf
Cc: willemdebruijn.kernel, nhudson, mtottenh, aglasgal, martin.lau,
daniel, ast, andrii, davem, edumazet, kuba, pabeni, netdev,
linux-kernel, ast, andrii, daniel, martin.lau, eddyz87,
yonghong.song, clm, ihor.solodrai
[-- Attachment #1: Type: text/plain, Size: 2457 bytes --]
> diff --git a/net/core/filter.c b/net/core/filter.c
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -3665,6 +3665,37 @@ 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);
Should SKB_GSO_TUNNEL_REMCSUM also be cleared here when decapping
a UDP tunnel?
VXLAN and Geneve set SKB_GSO_TUNNEL_REMCSUM alongside
SKB_GSO_UDP_TUNNEL during encapsulation:
net/ipv4/udp_offload.c:udp_gro_complete():
skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
drivers/net/vxlan/vxlan_core.c:vxlan_build_skb():
type |= SKB_GSO_TUNNEL_REMCSUM;
After clearing SKB_GSO_UDP_TUNNEL{,_CSUM} but not TUNNEL_REMCSUM,
the gso_type has an orphaned tunnel flag with no associated tunnel
type.
> +
> + /* Clear encapsulation flag only when no tunnel GSO flags remain */
> + if (flags & BPF_F_ADJ_ROOM_DECAP_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)))
This check does not include SKB_GSO_TUNNEL_REMCSUM. If a packet
had both SKB_GSO_UDP_TUNNEL and SKB_GSO_TUNNEL_REMCSUM set, the
L4_UDP clearing above removes UDP_TUNNEL but leaves REMCSUM. This
check then concludes no tunnel GSO flags remain and clears
skb->encapsulation, even though a tunnel-related GSO bit is still
present.
The kernel's own UDP tunnel segmentation in
__skb_udp_tunnel_segment() explicitly handles TUNNEL_REMCSUM as
part of tunnel processing:
remcsum = !!(skb_shinfo(skb)->gso_type &
SKB_GSO_TUNNEL_REMCSUM);
Would it make sense to include TUNNEL_REMCSUM in both the L4_UDP
clearing and this encapsulation check?
> + if (skb->encapsulation)
> + skb->encapsulation = 0;
> + }
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/23194329334
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags
2026-03-17 12:14 ` [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags Nick Hudson
@ 2026-03-17 13:27 ` Willem de Bruijn
2026-03-17 13:47 ` Hudson, Nick
0 siblings, 1 reply; 8+ messages in thread
From: Willem de Bruijn @ 2026-03-17 13:27 UTC (permalink / raw)
To: Nick Hudson, bpf
Cc: Willem de Bruijn, Nick Hudson, Max Tottenham, Anna Glasgall,
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev, linux-kernel
Nick Hudson wrote:
> Introduce helper masks for bpf_skb_adjust_room() decapsulation flags
> to simplify validation and keep flag handling readable:
>
> - BPF_F_ADJ_ROOM_DECAP_L4_MASK
> - BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK
> - BPF_F_ADJ_ROOM_ENCAP_MASK
> - BPF_F_ADJ_ROOM_DECAP_MASK
>
> Also fold these masks into BPF_F_ADJ_ROOM_MASK and per-path flag
> validation checks.
>
> This is a refactoring/plumbing change; functional decapsulation and
> GSO behavior updates are handled in later patches.
>
> Co-developed-by: Max Tottenham <mtottenh@akamai.com>
> Signed-off-by: Max Tottenham <mtottenh@akamai.com>
> Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
> Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
> Signed-off-by: Nick Hudson <nhudson@akamai.com>
Only patches 3 through 5 were sent to the netdev list.
Please resubmit the entire series (after the customary 24 hr min) to
the full list.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v1 4/5] bpf: add guard rails for new DECAP flags
2026-03-17 12:14 ` [PATCH v1 4/5] bpf: add guard rails for new DECAP flags Nick Hudson
@ 2026-03-17 13:30 ` Willem de Bruijn
0 siblings, 0 replies; 8+ messages in thread
From: Willem de Bruijn @ 2026-03-17 13:30 UTC (permalink / raw)
To: Nick Hudson, bpf
Cc: Willem de Bruijn, Nick Hudson, Max Tottenham, Anna Glasgall,
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev, linux-kernel
Nick Hudson wrote:
> 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 <mtottenh@akamai.com>
> Signed-off-by: Max Tottenham <mtottenh@akamai.com>
> Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
> Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
> Signed-off-by: Nick Hudson <nhudson@akamai.com>
This patch probably should come before 3, as 3 enables the features
without the guard rails in place.
> ---
> net/core/filter.c | 45 ++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 36 insertions(+), 9 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index ac7e1068fe4c..437e0da34f84 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -56,6 +56,7 @@
> #include <net/sock_reuseport.h>
> #include <net/busy_poll.h>
> #include <net/tcp.h>
> +#include <net/gre.h>
> #include <net/xfrm.h>
> #include <net/udp.h>
> #include <linux/bpf_trace.h>
> @@ -3745,20 +3746,46 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
> return -ENOTSUPP;
> }
>
> - if (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) {
> + if (flags & BPF_F_ADJ_ROOM_DECAP_MASK) {
> + u32 len_decap_min = 0;
> +
> if (!shrink)
> return -EINVAL;
>
> - switch (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) {
> - case BPF_F_ADJ_ROOM_DECAP_L3_IPV4:
> + if ((flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) ==
> + 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;
> +
Are these equality tests shorthand based on knowledge that each only
have two options, so equality implies more than one option set? That
is not obvious/self documenting. Please add a brief comment.
> + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) &&
> + (flags & BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK))
> + return -EINVAL;
> +
> + if (mode == BPF_ADJ_ROOM_MAC)
> + len_decap_min += proto == htons(ETH_P_IP) ?
> + sizeof(struct iphdr) : sizeof(struct ipv6hdr);
MAC is not a GSO related decap, can be used for insertion/deletion of
L2.5 headers. This should be dropped.
> +
> + 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 (len_diff_abs < len_decap_min)
> + return -EINVAL;
> +
> + if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV4)
> len_min = sizeof(struct iphdr);
> - break;
> - case BPF_F_ADJ_ROOM_DECAP_L3_IPV6:
> +
> + if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV6)
> len_min = sizeof(struct ipv6hdr);
> - break;
> - default:
> - return -EINVAL;
> - }
> }
>
> len_cur = skb->len - skb_network_offset(skb);
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags
2026-03-17 13:27 ` Willem de Bruijn
@ 2026-03-17 13:47 ` Hudson, Nick
2026-03-17 14:01 ` Willem de Bruijn
0 siblings, 1 reply; 8+ messages in thread
From: Hudson, Nick @ 2026-03-17 13:47 UTC (permalink / raw)
To: Willem de Bruijn
Cc: bpf@vger.kernel.org, Tottenham, Max, Glasgall, Anna,
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
[-- Attachment #1: Type: text/plain, Size: 1374 bytes --]
> On 17 Mar 2026, at 13:27, Willem de Bruijn <willemdebruijn.kernel@gmail.com> wrote:
>
> !-------------------------------------------------------------------|
> This Message Is From an External Sender
> This message came from outside your organization.
> |-------------------------------------------------------------------!
>
> Nick Hudson wrote:
>> Introduce helper masks for bpf_skb_adjust_room() decapsulation flags
>> to simplify validation and keep flag handling readable:
>>
>> - BPF_F_ADJ_ROOM_DECAP_L4_MASK
>> - BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK
>> - BPF_F_ADJ_ROOM_ENCAP_MASK
>> - BPF_F_ADJ_ROOM_DECAP_MASK
>>
>> Also fold these masks into BPF_F_ADJ_ROOM_MASK and per-path flag
>> validation checks.
>>
>> This is a refactoring/plumbing change; functional decapsulation and
>> GSO behavior updates are handled in later patches.
>>
>> Co-developed-by: Max Tottenham <mtottenh@akamai.com>
>> Signed-off-by: Max Tottenham <mtottenh@akamai.com>
>> Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
>> Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
>> Signed-off-by: Nick Hudson <nhudson@akamai.com>
>
> Only patches 3 through 5 were sent to the netdev list.
oops.
>
> Please resubmit the entire series (after the customary 24 hr min) to
> the full list.
Will do… as v2 with patch re-order you mentioned?
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags
2026-03-17 13:47 ` Hudson, Nick
@ 2026-03-17 14:01 ` Willem de Bruijn
0 siblings, 0 replies; 8+ messages in thread
From: Willem de Bruijn @ 2026-03-17 14:01 UTC (permalink / raw)
To: Hudson, Nick, Willem de Bruijn
Cc: bpf@vger.kernel.org, Tottenham, Max, Glasgall, Anna,
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Hudson, Nick wrote:
>
>
> > On 17 Mar 2026, at 13:27, Willem de Bruijn <willemdebruijn.kernel@gmail.com> wrote:
> >
> > !-------------------------------------------------------------------|
> > This Message Is From an External Sender
> > This message came from outside your organization.
> > |-------------------------------------------------------------------!
> >
> > Nick Hudson wrote:
> >> Introduce helper masks for bpf_skb_adjust_room() decapsulation flags
> >> to simplify validation and keep flag handling readable:
> >>
> >> - BPF_F_ADJ_ROOM_DECAP_L4_MASK
> >> - BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK
> >> - BPF_F_ADJ_ROOM_ENCAP_MASK
> >> - BPF_F_ADJ_ROOM_DECAP_MASK
> >>
> >> Also fold these masks into BPF_F_ADJ_ROOM_MASK and per-path flag
> >> validation checks.
> >>
> >> This is a refactoring/plumbing change; functional decapsulation and
> >> GSO behavior updates are handled in later patches.
> >>
> >> Co-developed-by: Max Tottenham <mtottenh@akamai.com>
> >> Signed-off-by: Max Tottenham <mtottenh@akamai.com>
> >> Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
> >> Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
> >> Signed-off-by: Nick Hudson <nhudson@akamai.com>
> >
> > Only patches 3 through 5 were sent to the netdev list.
>
> oops.
>
> >
> > Please resubmit the entire series (after the customary 24 hr min) to
> > the full list.
>
> Will do… as v2 with patch re-order you mentioned?
Yes
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2026-03-17 14:01 UTC | newest]
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2026-03-17 12:14 ` [PATCH v1 3/5] bpf: add helper masks for ADJ_ROOM decap flags Nick Hudson
2026-03-17 13:27 ` Willem de Bruijn
2026-03-17 13:47 ` Hudson, Nick
2026-03-17 14:01 ` Willem de Bruijn
2026-03-17 12:14 ` [PATCH v1 4/5] bpf: add guard rails for new DECAP flags Nick Hudson
2026-03-17 13:30 ` Willem de Bruijn
2026-03-17 12:14 ` [PATCH v1 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room Nick Hudson
2026-03-17 13:02 ` bot+bpf-ci
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