diff options
| author | Andrey Ignatov <rdna@fb.com> | 2020-05-13 18:50:27 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-05-14 18:30:57 -0700 |
| commit | 7aebfa1b3885b5aa29fcb4a596d0485ac463bbe8 (patch) | |
| tree | 63b1598db717838cec551892a04b6245c316539e | |
| parent | 6a09815428547657f3ffd2f5c31ac2a191e7fdf3 (diff) | |
bpf: Support narrow loads from bpf_sock_addr.user_port
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
| -rw-r--r-- | include/uapi/linux/bpf.h | 2 | ||||
| -rw-r--r-- | net/core/filter.c | 15 | ||||
| -rw-r--r-- | tools/include/uapi/linux/bpf.h | 2 |
3 files changed, 9 insertions, 10 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index bfb31c1be219..85cfdffde182 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -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 */ diff --git a/net/core/filter.c b/net/core/filter.c index da0634979f53..1fe8c0c2d408 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7029,6 +7029,7 @@ static bool sock_addr_is_valid_access(int off, int size, case bpf_ctx_range(struct bpf_sock_addr, msg_src_ip4): case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0], msg_src_ip6[3]): + case bpf_ctx_range(struct bpf_sock_addr, user_port): if (type == BPF_READ) { bpf_ctx_record_field_size(info, size_default); @@ -7059,10 +7060,6 @@ static bool sock_addr_is_valid_access(int off, int size, return false; } break; - case bpf_ctx_range(struct bpf_sock_addr, user_port): - if (size != size_default) - return false; - break; case offsetof(struct bpf_sock_addr, sk): if (type != BPF_READ) return false; @@ -7958,8 +7955,8 @@ static u32 sock_addr_convert_ctx_access(enum bpf_access_type type, struct bpf_insn *insn_buf, struct bpf_prog *prog, u32 *target_size) { + int off, port_size = sizeof_field(struct sockaddr_in6, sin6_port); struct bpf_insn *insn = insn_buf; - int off; switch (si->off) { case offsetof(struct bpf_sock_addr, user_family): @@ -7994,9 +7991,11 @@ static u32 sock_addr_convert_ctx_access(enum bpf_access_type type, offsetof(struct sockaddr_in6, sin6_port)); BUILD_BUG_ON(sizeof_field(struct sockaddr_in, sin_port) != sizeof_field(struct sockaddr_in6, sin6_port)); - SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD(struct bpf_sock_addr_kern, - struct sockaddr_in6, uaddr, - sin6_port, tmp_reg); + /* Account for sin6_port being smaller than user_port. */ + port_size = min(port_size, BPF_LDST_BYTES(si)); + SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD_SIZE_OFF( + struct bpf_sock_addr_kern, struct sockaddr_in6, uaddr, + sin6_port, bytes_to_bpf_size(port_size), 0, tmp_reg); break; case offsetof(struct bpf_sock_addr, family): diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index bfb31c1be219..85cfdffde182 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -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 */ |