diff options
| author | Jakub Sitnicki | 2022-02-09 19:43:32 +0100 |
|---|---|---|
| committer | Alexei Starovoitov | 2022-02-09 11:40:45 -0800 |
| commit | 9a69e2b385f443f244a7e8b8bcafe5ccfb0866b4 (patch) | |
| tree | 22d7aa445e1664fd4ecbd2a0ad3c8eaef0cf84af | |
| parent | dc37dc617fabfb1c3a16d49f5d8cc20e9e3608ca (diff) | |
bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide
remote_port is another case of a BPF context field documented as a 32-bit
value in network byte order for which the BPF context access converter
generates a load of a zero-padded 16-bit integer in network byte order.
First such case was dst_port in bpf_sock which got addressed in commit
4421a582718a ("bpf: Make dst_port field in struct bpf_sock 16-bit wide").
Loading 4-bytes from the remote_port offset and converting the value with
bpf_ntohl() leads to surprising results, as the expected value is shifted
by 16 bits.
Reduce the confusion by splitting the field in two - a 16-bit field holding
a big-endian integer, and a 16-bit zero-padding anonymous field that
follows it.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220209184333.654927-2-jakub@cloudflare.com
| -rw-r--r-- | include/uapi/linux/bpf.h | 3 | ||||
| -rw-r--r-- | net/bpf/test_run.c | 4 | ||||
| -rw-r--r-- | net/core/filter.c | 3 |
3 files changed, 6 insertions, 4 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index a7f0ddedac1f..afe3d0d7f5f2 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -6453,7 +6453,8 @@ struct bpf_sk_lookup { __u32 protocol; /* IP protocol (IPPROTO_TCP, IPPROTO_UDP) */ __u32 remote_ip4; /* Network byte order */ __u32 remote_ip6[4]; /* Network byte order */ - __u32 remote_port; /* Network byte order */ + __be16 remote_port; /* Network byte order */ + __u16 :16; /* Zero padding */ __u32 local_ip4; /* Network byte order */ __u32 local_ip6[4]; /* Network byte order */ __u32 local_port; /* Host byte order */ diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index cb150f756f3d..f08034500813 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -1147,7 +1147,7 @@ int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kat if (!range_is_zero(user_ctx, offsetofend(typeof(*user_ctx), local_port), sizeof(*user_ctx))) goto out; - if (user_ctx->local_port > U16_MAX || user_ctx->remote_port > U16_MAX) { + if (user_ctx->local_port > U16_MAX) { ret = -ERANGE; goto out; } @@ -1155,7 +1155,7 @@ int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kat ctx.family = (u16)user_ctx->family; ctx.protocol = (u16)user_ctx->protocol; ctx.dport = (u16)user_ctx->local_port; - ctx.sport = (__force __be16)user_ctx->remote_port; + ctx.sport = user_ctx->remote_port; switch (ctx.family) { case AF_INET: diff --git a/net/core/filter.c b/net/core/filter.c index 99a05199a806..83f06d3b2c52 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -10843,7 +10843,8 @@ static bool sk_lookup_is_valid_access(int off, int size, case bpf_ctx_range(struct bpf_sk_lookup, local_ip4): case bpf_ctx_range_till(struct bpf_sk_lookup, remote_ip6[0], remote_ip6[3]): case bpf_ctx_range_till(struct bpf_sk_lookup, local_ip6[0], local_ip6[3]): - case bpf_ctx_range(struct bpf_sk_lookup, remote_port): + case offsetof(struct bpf_sk_lookup, remote_port) ... + offsetof(struct bpf_sk_lookup, local_ip4) - 1: case bpf_ctx_range(struct bpf_sk_lookup, local_port): case bpf_ctx_range(struct bpf_sk_lookup, ingress_ifindex): bpf_ctx_record_field_size(info, sizeof(__u32)); |