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bpf: Support narrow loads from bpf_sock_addr.user_port

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bpf_sock_addr.user_port supports only 4-byte load and it leads to ugly
code in BPF programs, like:

	volatile __u32 user_port = ctx->user_port;
	__u16 port = bpf_ntohs(user_port);

Since otherwise clang may optimize the load to be 2-byte and it's
rejected by verifier.

Add support for 1- and 2-byte loads same way as it's supported for other
fields in bpf_sock_addr like user_ip4, msg_src_ip4, etc.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/c1e983f4c17573032601d0b2b1f9d1274f24bc16.1589420814.git.rdna@fb.com
This commit is contained in:
Andrey Ignatov 2020-05-13 18:50:27 -07:00 committed by Andrii Nakryiko
parent 70e6075d1d
commit 3cd9cac8fb
1 changed files with 1 additions and 1 deletions
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2
include/uapi/linux/bpf.h
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@ -3728,7 +3728,7 @@ struct bpf_sock_addr {
__u32 user_ip6[4]; /* Allows 1,2,4,8-byte read and 4,8-byte write.
* Stored in network byte order.
*/
__u32 user_port; /* Allows 4-byte read and write.
__u32 user_port; /* Allows 1,2,4-byte read and 4-byte write.
* Stored in network byte order
*/
__u32 family; /* Allows 4-byte read, but no write */