[PATCH net-next 3/5] bpf: allow option for setting bpf_l4_csum_replace from scratch
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2017-01-24 00:06:54
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
When programs need to calculate the csum from scratch for small UDP packets and use bpf_l4_csum_replace() to feed the result from helpers like bpf_csum_diff(), then we need a flag besides BPF_F_MARK_MANGLED_0 that would ignore the case of current csum being 0, and which would still allow for the helper to set the csum and transform when needed to CSUM_MANGLED_0. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> --- include/uapi/linux/bpf.h | 1 + net/core/filter.c | 7 ++++--- 2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bd30684..e07fd5a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h@@ -522,6 +522,7 @@ enum bpf_func_id { /* BPF_FUNC_l4_csum_replace flags. */ #define BPF_F_PSEUDO_HDR (1ULL << 4) #define BPF_F_MARK_MANGLED_0 (1ULL << 5) +#define BPF_F_MARK_ENFORCE (1ULL << 6) /* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */ #define BPF_F_INGRESS (1ULL << 0)
diff --git a/net/core/filter.c b/net/core/filter.c
index e2263da..1e00737 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c@@ -1522,10 +1522,11 @@ static inline void bpf_pull_mac_rcsum(struct sk_buff *skb) { bool is_pseudo = flags & BPF_F_PSEUDO_HDR; bool is_mmzero = flags & BPF_F_MARK_MANGLED_0; + bool do_mforce = flags & BPF_F_MARK_ENFORCE; __sum16 *ptr; - if (unlikely(flags & ~(BPF_F_MARK_MANGLED_0 | BPF_F_PSEUDO_HDR | - BPF_F_HDR_FIELD_MASK))) + if (unlikely(flags & ~(BPF_F_MARK_MANGLED_0 | BPF_F_MARK_ENFORCE | + BPF_F_PSEUDO_HDR | BPF_F_HDR_FIELD_MASK))) return -EINVAL; if (unlikely(offset > 0xffff || offset & 1)) return -EFAULT;
@@ -1533,7 +1534,7 @@ static inline void bpf_pull_mac_rcsum(struct sk_buff *skb) return -EFAULT; ptr = (__sum16 *)(skb->data + offset); - if (is_mmzero && !*ptr) + if (is_mmzero && !do_mforce && !*ptr) return 0; switch (flags & BPF_F_HDR_FIELD_MASK) {
--
1.9.3