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sock: Make sk_protocol a 16-bit value
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Match the 16-bit width of skbuff->protocol. Fills an 8-bit hole so
sizeof(struct sock) does not change.

Also take care of BPF field access for sk_type/sk_protocol. Both of them
are now outside the bitfield, so we can use load instructions without
further shifting/masking.

v5 -> v6:
 - update eBPF accessors, too (Intel's kbuild test robot)
v2 -> v3:
 - keep 'sk_type' 2 bytes aligned (Eric)
v1 -> v2:
 - preserve sk_pacing_shift as bit field (Eric)

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Mat Martineau authored and David S. Miller committed Jan 10, 2020
1 parent e9cdced commit bf97651
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Showing 3 changed files with 28 additions and 59 deletions.
25 changes: 5 additions & 20 deletions include/net/sock.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -436,30 +436,15 @@ struct sock {
* Because of non atomicity rules, all
* changes are protected by socket lock.
*/
unsigned int __sk_flags_offset[0];
#ifdef __BIG_ENDIAN_BITFIELD
#define SK_FL_PROTO_SHIFT 16
#define SK_FL_PROTO_MASK 0x00ff0000

#define SK_FL_TYPE_SHIFT 0
#define SK_FL_TYPE_MASK 0x0000ffff
#else
#define SK_FL_PROTO_SHIFT 8
#define SK_FL_PROTO_MASK 0x0000ff00

#define SK_FL_TYPE_SHIFT 16
#define SK_FL_TYPE_MASK 0xffff0000
#endif

unsigned int sk_padding : 1,
u8 sk_padding : 1,
sk_kern_sock : 1,
sk_no_check_tx : 1,
sk_no_check_rx : 1,
sk_userlocks : 4,
sk_protocol : 8,
sk_type : 16;
u16 sk_gso_max_segs;
sk_userlocks : 4;
u8 sk_pacing_shift;
u16 sk_type;
u16 sk_protocol;
u16 sk_gso_max_segs;
unsigned long sk_lingertime;
struct proto *sk_prot_creator;
rwlock_t sk_callback_lock;
Expand Down
2 changes: 1 addition & 1 deletion include/trace/events/sock.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ TRACE_EVENT(inet_sock_set_state,
__field(__u16, sport)
__field(__u16, dport)
__field(__u16, family)
__field(__u8, protocol)
__field(__u16, protocol)
__array(__u8, saddr, 4)
__array(__u8, daddr, 4)
__array(__u8, saddr_v6, 16)
Expand Down
60 changes: 22 additions & 38 deletions net/core/filter.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7607,21 +7607,21 @@ u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
break;

case offsetof(struct bpf_sock, type):
BUILD_BUG_ON(HWEIGHT32(SK_FL_TYPE_MASK) != BITS_PER_BYTE * 2);
*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
offsetof(struct sock, __sk_flags_offset));
*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_TYPE_MASK);
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, SK_FL_TYPE_SHIFT);
*target_size = 2;
*insn++ = BPF_LDX_MEM(
BPF_FIELD_SIZEOF(struct sock, sk_type),
si->dst_reg, si->src_reg,
bpf_target_off(struct sock, sk_type,
sizeof_field(struct sock, sk_type),
target_size));
break;

case offsetof(struct bpf_sock, protocol):
BUILD_BUG_ON(HWEIGHT32(SK_FL_PROTO_MASK) != BITS_PER_BYTE);
*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
offsetof(struct sock, __sk_flags_offset));
*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_PROTO_MASK);
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, SK_FL_PROTO_SHIFT);
*target_size = 1;
*insn++ = BPF_LDX_MEM(
BPF_FIELD_SIZEOF(struct sock, sk_protocol),
si->dst_reg, si->src_reg,
bpf_target_off(struct sock, sk_protocol,
sizeof_field(struct sock, sk_protocol),
target_size));
break;

case offsetof(struct bpf_sock, src_ip4):
Expand Down Expand Up @@ -7903,20 +7903,13 @@ static u32 sock_addr_convert_ctx_access(enum bpf_access_type type,
break;

case offsetof(struct bpf_sock_addr, type):
SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF(
struct bpf_sock_addr_kern, struct sock, sk,
__sk_flags_offset, BPF_W, 0);
*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_TYPE_MASK);
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, SK_FL_TYPE_SHIFT);
SOCK_ADDR_LOAD_NESTED_FIELD(struct bpf_sock_addr_kern,
struct sock, sk, sk_type);
break;

case offsetof(struct bpf_sock_addr, protocol):
SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF(
struct bpf_sock_addr_kern, struct sock, sk,
__sk_flags_offset, BPF_W, 0);
*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_PROTO_MASK);
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg,
SK_FL_PROTO_SHIFT);
SOCK_ADDR_LOAD_NESTED_FIELD(struct bpf_sock_addr_kern,
struct sock, sk, sk_protocol);
break;

case offsetof(struct bpf_sock_addr, msg_src_ip4):
Expand Down Expand Up @@ -8835,11 +8828,11 @@ sk_reuseport_is_valid_access(int off, int size,
skb, \
SKB_FIELD)

#define SK_REUSEPORT_LOAD_SK_FIELD_SIZE_OFF(SK_FIELD, BPF_SIZE, EXTRA_OFF) \
SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF(struct sk_reuseport_kern, \
struct sock, \
sk, \
SK_FIELD, BPF_SIZE, EXTRA_OFF)
#define SK_REUSEPORT_LOAD_SK_FIELD(SK_FIELD) \
SOCK_ADDR_LOAD_NESTED_FIELD(struct sk_reuseport_kern, \
struct sock, \
sk, \
SK_FIELD)

static u32 sk_reuseport_convert_ctx_access(enum bpf_access_type type,
const struct bpf_insn *si,
Expand All @@ -8863,16 +8856,7 @@ static u32 sk_reuseport_convert_ctx_access(enum bpf_access_type type,
break;

case offsetof(struct sk_reuseport_md, ip_protocol):
BUILD_BUG_ON(HWEIGHT32(SK_FL_PROTO_MASK) != BITS_PER_BYTE);
SK_REUSEPORT_LOAD_SK_FIELD_SIZE_OFF(__sk_flags_offset,
BPF_W, 0);
*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_PROTO_MASK);
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg,
SK_FL_PROTO_SHIFT);
/* SK_FL_PROTO_MASK and SK_FL_PROTO_SHIFT are endian
* aware. No further narrowing or masking is needed.
*/
*target_size = 1;
SK_REUSEPORT_LOAD_SK_FIELD(sk_protocol);
break;

case offsetof(struct sk_reuseport_md, data_end):
Expand Down

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