diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2019-08-20 17:50:25 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-21 07:16:59 +0200 |
| commit | d9f79f0ace550f450851a5c07f88eed585b46214 (patch) | |
| tree | 1bc4f84b333cc6b0ef5c74b73ca4ab71f415bd14 /net | |
| parent | 7d4201ff9f7302a7a91a6171b47362b5b0003661 (diff) | |
bpf: allow narrow loads of some sk_reuseport_md fields with offset > 0
[ Upstream commit 2c238177bd7f4b14bdf7447cc1cd9bb791f147e6 ]
test_select_reuseport fails on s390 due to verifier rejecting
test_select_reuseport_kern.o with the following message:
; data_check.eth_protocol = reuse_md->eth_protocol;
18: (69) r1 = *(u16 *)(r6 +22)
invalid bpf_context access off=22 size=2
This is because on big-endian machines casts from __u32 to __u16 are
generated by referencing the respective variable as __u16 with an offset
of 2 (as opposed to 0 on little-endian machines).
The verifier already has all the infrastructure in place to allow such
accesses, it's just that they are not explicitly enabled for
eth_protocol field. Enable them for eth_protocol field by using
bpf_ctx_range instead of offsetof.
Ditto for ip_protocol, bind_inany and len, since they already allow
narrowing, and the same problem can arise when working with them.
Fixes: 2dbb9b9e6df6 ("bpf: Introduce BPF_PROG_TYPE_SK_REUSEPORT")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/filter.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index c996380f2959..e6fa88506c00 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7234,13 +7234,13 @@ sk_reuseport_is_valid_access(int off, int size, return size == size_default; /* Fields that allow narrowing */ - case offsetof(struct sk_reuseport_md, eth_protocol): + case bpf_ctx_range(struct sk_reuseport_md, eth_protocol): if (size < FIELD_SIZEOF(struct sk_buff, protocol)) return false; /* fall through */ - case offsetof(struct sk_reuseport_md, ip_protocol): - case offsetof(struct sk_reuseport_md, bind_inany): - case offsetof(struct sk_reuseport_md, len): + case bpf_ctx_range(struct sk_reuseport_md, ip_protocol): + case bpf_ctx_range(struct sk_reuseport_md, bind_inany): + case bpf_ctx_range(struct sk_reuseport_md, len): bpf_ctx_record_field_size(info, size_default); return bpf_ctx_narrow_access_ok(off, size, size_default); |