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

Since commit cd17d7770578 ("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 <[email protected]>
Cc: Yonghong Song <[email protected]>
Fixes: cd17d7770578 ("bpf/tools: sync bpf.h")
Reported-by: kernel test robot <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Signed-off-by: Stanislav Fomichev <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index ead27aebf491..c318385aba51 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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);