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Message-ID: <20230811161509.19722-16-larysa.zaremba@intel.com> Date: Fri, 11 Aug 2023 18:15:03 +0200 From: Larysa Zaremba <larysa.zaremba@...el.com> To: bpf@...r.kernel.org Cc: Larysa Zaremba <larysa.zaremba@...el.com>, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org, yhs@...com, john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org, David Ahern <dsahern@...il.com>, Jakub Kicinski <kuba@...nel.org>, Willem de Bruijn <willemb@...gle.com>, Jesper Dangaard Brouer <brouer@...hat.com>, Anatoly Burakov <anatoly.burakov@...el.com>, Alexander Lobakin <alexandr.lobakin@...el.com>, Magnus Karlsson <magnus.karlsson@...il.com>, Maryam Tahhan <mtahhan@...hat.com>, xdp-hints@...-project.net, netdev@...r.kernel.org, Willem de Bruijn <willemdebruijn.kernel@...il.com>, Alexei Starovoitov <alexei.starovoitov@...il.com>, Simon Horman <simon.horman@...igine.com>, Aleksander Lobakin <aleksander.lobakin@...el.com> Subject: [PATCH bpf-next v5 15/21] net, xdp: allow metadata > 32 From: Aleksander Lobakin <aleksander.lobakin@...el.com> When using XDP hints, metadata sometimes has to be much bigger than 32 bytes. Relax the restriction, allow metadata larger than 32 bytes and make __skb_metadata_differs() work with bigger lengths. Now size of metadata is only limited by the fact it is stored as u8 in skb_shared_info, so maximum possible value is 255. Other important conditions, such as having enough space for xdp_frame building, are already checked in bpf_xdp_adjust_meta(). The requirement of having its length aligned to 4 bytes is still valid. Signed-off-by: Aleksander Lobakin <aleksander.lobakin@...el.com> Signed-off-by: Larysa Zaremba <larysa.zaremba@...el.com> --- include/linux/skbuff.h | 13 ++++++++----- include/net/xdp.h | 7 ++++++- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index aa57e2eca33b..0e455678cb8a 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -4216,10 +4216,13 @@ static inline bool __skb_metadata_differs(const struct sk_buff *skb_a, { const void *a = skb_metadata_end(skb_a); const void *b = skb_metadata_end(skb_b); - /* Using more efficient varaiant than plain call to memcmp(). */ -#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 u64 diffs = 0; + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) || + BITS_PER_LONG != 64) + goto slow; + + /* Using more efficient variant than plain call to memcmp(). */ switch (meta_len) { #define __it(x, op) (x -= sizeof(u##op)) #define __it_diff(a, b, op) (*(u##op *)__it(a, op)) ^ (*(u##op *)__it(b, op)) @@ -4239,11 +4242,11 @@ static inline bool __skb_metadata_differs(const struct sk_buff *skb_a, fallthrough; case 4: diffs |= __it_diff(a, b, 32); break; + default: +slow: + return memcmp(a - meta_len, b - meta_len, meta_len); } return diffs; -#else - return memcmp(a - meta_len, b - meta_len, meta_len); -#endif } static inline bool skb_metadata_differs(const struct sk_buff *skb_a, diff --git a/include/net/xdp.h b/include/net/xdp.h index 495c4d2a2c50..05234f156a73 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -369,7 +369,12 @@ xdp_data_meta_unsupported(const struct xdp_buff *xdp) static inline bool xdp_metalen_invalid(unsigned long metalen) { - return (metalen & (sizeof(__u32) - 1)) || (metalen > 32); + typeof(metalen) meta_max; + + meta_max = type_max(typeof_member(struct skb_shared_info, meta_len)); + BUILD_BUG_ON(!__builtin_constant_p(meta_max)); + + return !IS_ALIGNED(metalen, sizeof(u32)) || metalen > meta_max; } struct xdp_attachment_info { -- 2.41.0
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