diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2017-01-12 11:51:33 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-01-12 10:00:31 -0500 |
| commit | 62c7989b24dbd348c2507ee6458ebf5637d6ddb5 (patch) | |
| tree | 352050f1913fae4683e564607374618338c1c773 /net/core | |
| parent | 6b8cc1d11ef75c5b9c530b3d0d148f3c2dd25f93 (diff) | |
bpf: allow b/h/w/dw access for bpf's cb in ctx
When structs are used to store temporary state in cb[] buffer that is
used with programs and among tail calls, then the generated code will
not always access the buffer in bpf_w chunks. We can ease programming
of it and let this act more natural by allowing for aligned b/h/w/dw
sized access for cb[] ctx member. Various test cases are attached as
well for the selftest suite. Potentially, this can also be reused for
other program types to pass data around.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 8cfbdefbfb1c..90383860e224 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2776,11 +2776,33 @@ static bool __is_valid_access(int off, int size) { if (off < 0 || off >= sizeof(struct __sk_buff)) return false; + /* The verifier guarantees that size > 0. */ if (off % size != 0) return false; - if (size != sizeof(__u32)) - return false; + + switch (off) { + case offsetof(struct __sk_buff, cb[0]) ... + offsetof(struct __sk_buff, cb[4]) + sizeof(__u32) - 1: + if (size == sizeof(__u16) && + off > offsetof(struct __sk_buff, cb[4]) + sizeof(__u16)) + return false; + if (size == sizeof(__u32) && + off > offsetof(struct __sk_buff, cb[4])) + return false; + if (size == sizeof(__u64) && + off > offsetof(struct __sk_buff, cb[2])) + return false; + if (size != sizeof(__u8) && + size != sizeof(__u16) && + size != sizeof(__u32) && + size != sizeof(__u64)) + return false; + break; + default: + if (size != sizeof(__u32)) + return false; + } return true; } @@ -2799,7 +2821,7 @@ static bool sk_filter_is_valid_access(int off, int size, if (type == BPF_WRITE) { switch (off) { case offsetof(struct __sk_buff, cb[0]) ... - offsetof(struct __sk_buff, cb[4]): + offsetof(struct __sk_buff, cb[4]) + sizeof(__u32) - 1: break; default: return false; @@ -2823,7 +2845,7 @@ static bool lwt_is_valid_access(int off, int size, case offsetof(struct __sk_buff, mark): case offsetof(struct __sk_buff, priority): case offsetof(struct __sk_buff, cb[0]) ... - offsetof(struct __sk_buff, cb[4]): + offsetof(struct __sk_buff, cb[4]) + sizeof(__u32) - 1: break; default: return false; @@ -2915,7 +2937,7 @@ static bool tc_cls_act_is_valid_access(int off, int size, case offsetof(struct __sk_buff, tc_index): case offsetof(struct __sk_buff, priority): case offsetof(struct __sk_buff, cb[0]) ... - offsetof(struct __sk_buff, cb[4]): + offsetof(struct __sk_buff, cb[4]) + sizeof(__u32) - 1: case offsetof(struct __sk_buff, tc_classid): break; default: @@ -3066,8 +3088,11 @@ static u32 sk_filter_convert_ctx_access(enum bpf_access_type type, si->dst_reg, si->src_reg, insn); case offsetof(struct __sk_buff, cb[0]) ... - offsetof(struct __sk_buff, cb[4]): + offsetof(struct __sk_buff, cb[4]) + sizeof(__u32) - 1: BUILD_BUG_ON(FIELD_SIZEOF(struct qdisc_skb_cb, data) < 20); + BUILD_BUG_ON((offsetof(struct sk_buff, cb) + + offsetof(struct qdisc_skb_cb, data)) % + sizeof(__u64)); prog->cb_access = 1; off = si->off; @@ -3075,10 +3100,10 @@ static u32 sk_filter_convert_ctx_access(enum bpf_access_type type, off += offsetof(struct sk_buff, cb); off += offsetof(struct qdisc_skb_cb, data); if (type == BPF_WRITE) - *insn++ = BPF_STX_MEM(BPF_W, si->dst_reg, + *insn++ = BPF_STX_MEM(BPF_SIZE(si->code), si->dst_reg, si->src_reg, off); else - *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, + *insn++ = BPF_LDX_MEM(BPF_SIZE(si->code), si->dst_reg, si->src_reg, off); break; |