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bpf: allow wide (u64) aligned stores for some fields of bpf_sock_addr

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Since commit cd17d77705 ("bpf/tools: sync bpf.h") clang decided
that it can do a single u64 store into user_ip6[2] instead of two
separate u32 ones:

 #  17: (18) r2 = 0x100000000000000
 #  ; ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
 #  19: (7b) *(u64 *)(r1 +16) = r2
 #  invalid bpf_context access off=16 size=8

>From the compiler point of view it does look like a correct thing
to do, so let's support it on the kernel side.

Credit to Andrii Nakryiko for a proper implementation of
bpf_ctx_wide_store_ok.

Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Fixes: cd17d77705 ("bpf/tools: sync bpf.h")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev
2019-07-01 10:38:39 -07:00
committed by Daniel Borkmann
parent d2850ce0bd
commit 600c70bad6
3 changed files with 23 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
include/uapi/linux/bpf.h
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@@ -3247,7 +3247,7 @@ struct bpf_sock_addr {
__u32 user_ip4; /* Allows 1,2,4-byte read and 4-byte write.
* Stored in network byte order.
*/
__u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write.
__u32 user_ip6[4]; /* Allows 1,2,4-byte read and 4,8-byte write.
* Stored in network byte order.
*/
__u32 user_port; /* Allows 4-byte read and write.
@@ -3256,10 +3256,10 @@ struct bpf_sock_addr {
__u32 family; /* Allows 4-byte read, but no write */
__u32 type; /* Allows 4-byte read, but no write */
__u32 protocol; /* Allows 4-byte read, but no write */
__u32 msg_src_ip4; /* Allows 1,2,4-byte read an 4-byte write.
__u32 msg_src_ip4; /* Allows 1,2,4-byte read and 4-byte write.
* Stored in network byte order.
*/
__u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write.
__u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read and 4,8-byte write.
* Stored in network byte order.
*/
__bpf_md_ptr(struct bpf_sock *, sk);