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Date: Thu, 8 May 2014 14:10:51 -0700
From: Alexei Starovoitov <ast@...mgrid.com>
To: "David S. Miller" <davem@...emloft.net>
Cc: Daniel Borkmann <dborkman@...hat.com>,
Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org
Subject: [PATCH net-next 1/3] net: filter: make BPF conversion more readable
Introduce BPF helper macros to define instructions
(similar to old BPF_STMT/BPF_JUMP macros)
Use them while converting classic BPF to internal
and in BPF testsuite later.
Signed-off-by: Alexei Starovoitov <ast@...mgrid.com>
---
include/linux/filter.h | 51 +++++++++++++++++
net/core/filter.c | 142 +++++++++++++++++-------------------------------
2 files changed, 101 insertions(+), 92 deletions(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 69086f0f7d01..9d5ae0a2c954 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -79,6 +79,57 @@ enum {
/* BPF program can access up to 512 bytes of stack space. */
#define MAX_BPF_STACK 512
+/* bpf_add|sub|...: a += x, bpf_mov: a = x */
+#define BPF_ALU64_REG(op, a, x) \
+ ((struct sock_filter_int) {BPF_ALU64|BPF_OP(op)|BPF_X, a, x, 0, 0})
+#define BPF_ALU32_REG(op, a, x) \
+ ((struct sock_filter_int) {BPF_ALU|BPF_OP(op)|BPF_X, a, x, 0, 0})
+
+/* bpf_add|sub|...: a += imm, bpf_mov: a = imm */
+#define BPF_ALU64_IMM(op, a, imm) \
+ ((struct sock_filter_int) {BPF_ALU64|BPF_OP(op)|BPF_K, a, 0, 0, imm})
+#define BPF_ALU32_IMM(op, a, imm) \
+ ((struct sock_filter_int) {BPF_ALU|BPF_OP(op)|BPF_K, a, 0, 0, imm})
+
+/* R0 = *(uint *) (skb->data + off) */
+#define BPF_LD_ABS(size, off) \
+ ((struct sock_filter_int) {BPF_LD|BPF_SIZE(size)|BPF_ABS, 0, 0, 0, off})
+
+/* R0 = *(uint *) (skb->data + x + off) */
+#define BPF_LD_IND(size, x, off) \
+ ((struct sock_filter_int) {BPF_LD|BPF_SIZE(size)|BPF_IND, 0, x, 0, off})
+
+/* a = *(uint *) (x + off) */
+#define BPF_LDX_MEM(sz, a, x, off) \
+ ((struct sock_filter_int) {BPF_LDX|BPF_SIZE(sz)|BPF_MEM, a, x, off, 0})
+
+/* if (a 'op' x) goto pc+off */
+#define BPF_JMP_REG(op, a, x, off) \
+ ((struct sock_filter_int) {BPF_JMP|BPF_OP(op)|BPF_X, a, x, off, 0})
+
+/* if (a 'op' imm) goto pc+off */
+#define BPF_JMP_IMM(op, a, imm, off) \
+ ((struct sock_filter_int) {BPF_JMP|BPF_OP(op)|BPF_K, a, 0, off, imm})
+
+#define BPF_EXIT_INSN() \
+ ((struct sock_filter_int) {BPF_JMP|BPF_EXIT, 0, 0, 0, 0})
+
+static inline int size_to_bpf(int size)
+{
+ switch (size) {
+ case 1:
+ return BPF_B;
+ case 2:
+ return BPF_H;
+ case 4:
+ return BPF_W;
+ case 8:
+ return BPF_DW;
+ default:
+ return -EINVAL;
+ }
+}
+
/* Macro to invoke filter function. */
#define SK_RUN_FILTER(filter, ctx) (*filter->bpf_func)(ctx, filter->insnsi)
diff --git a/net/core/filter.c b/net/core/filter.c
index 7f36c81e81a5..6ab6987c0501 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -668,10 +668,9 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
case SKF_AD_OFF + SKF_AD_PROTOCOL:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
- insn->code = BPF_LDX | BPF_MEM | BPF_H;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = offsetof(struct sk_buff, protocol);
+ /* A = *(u16 *) (ctx + offsetof(protocol)) */
+ *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
+ offsetof(struct sk_buff, protocol));
insn++;
/* A = ntohs(A) [emitting a nop or swap16] */
@@ -681,37 +680,27 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
break;
case SKF_AD_OFF + SKF_AD_PKTTYPE:
- insn->code = BPF_LDX | BPF_MEM | BPF_B;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = pkt_type_offset();
+ *insn = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX,
+ pkt_type_offset());
if (insn->off < 0)
return false;
insn++;
- insn->code = BPF_ALU | BPF_AND | BPF_K;
- insn->a_reg = BPF_REG_A;
- insn->imm = PKT_TYPE_MAX;
+ *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, PKT_TYPE_MAX);
break;
case SKF_AD_OFF + SKF_AD_IFINDEX:
case SKF_AD_OFF + SKF_AD_HATYPE:
- if (FIELD_SIZEOF(struct sk_buff, dev) == 8)
- insn->code = BPF_LDX | BPF_MEM | BPF_DW;
- else
- insn->code = BPF_LDX | BPF_MEM | BPF_W;
- insn->a_reg = BPF_REG_TMP;
- insn->x_reg = BPF_REG_CTX;
- insn->off = offsetof(struct sk_buff, dev);
+ *insn = BPF_LDX_MEM(size_to_bpf(FIELD_SIZEOF(struct sk_buff, dev)),
+ BPF_REG_TMP, BPF_REG_CTX,
+ offsetof(struct sk_buff, dev));
insn++;
- insn->code = BPF_JMP | BPF_JNE | BPF_K;
- insn->a_reg = BPF_REG_TMP;
- insn->imm = 0;
- insn->off = 1;
+ /* if (tmp != 0) goto pc+1 */
+ *insn = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1);
insn++;
- insn->code = BPF_JMP | BPF_EXIT;
+ *insn = BPF_EXIT_INSN();
insn++;
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
@@ -732,55 +721,45 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
case SKF_AD_OFF + SKF_AD_MARK:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
- insn->code = BPF_LDX | BPF_MEM | BPF_W;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = offsetof(struct sk_buff, mark);
+ *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX,
+ offsetof(struct sk_buff, mark));
break;
case SKF_AD_OFF + SKF_AD_RXHASH:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
- insn->code = BPF_LDX | BPF_MEM | BPF_W;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = offsetof(struct sk_buff, hash);
+ *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX,
+ offsetof(struct sk_buff, hash));
break;
case SKF_AD_OFF + SKF_AD_QUEUE:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
- insn->code = BPF_LDX | BPF_MEM | BPF_H;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = offsetof(struct sk_buff, queue_mapping);
+ *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
+ offsetof(struct sk_buff, queue_mapping));
break;
case SKF_AD_OFF + SKF_AD_VLAN_TAG:
case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
- insn->code = BPF_LDX | BPF_MEM | BPF_H;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = offsetof(struct sk_buff, vlan_tci);
+ /* A = *(u16 *) (ctx + offsetof(vlan_tci)) */
+ *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
+ offsetof(struct sk_buff, vlan_tci));
insn++;
BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) {
- insn->code = BPF_ALU | BPF_AND | BPF_K;
- insn->a_reg = BPF_REG_A;
- insn->imm = ~VLAN_TAG_PRESENT;
+ *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A,
+ ~VLAN_TAG_PRESENT);
} else {
- insn->code = BPF_ALU | BPF_RSH | BPF_K;
- insn->a_reg = BPF_REG_A;
- insn->imm = 12;
+ /* A >>= 12 */
+ *insn = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12);
insn++;
- insn->code = BPF_ALU | BPF_AND | BPF_K;
- insn->a_reg = BPF_REG_A;
- insn->imm = 1;
+ /* A &= 1 */
+ *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 1);
}
break;
@@ -790,21 +769,15 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
case SKF_AD_OFF + SKF_AD_CPU:
case SKF_AD_OFF + SKF_AD_RANDOM:
/* arg1 = ctx */
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_ARG1;
- insn->x_reg = BPF_REG_CTX;
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG1, BPF_REG_CTX);
insn++;
/* arg2 = A */
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_ARG2;
- insn->x_reg = BPF_REG_A;
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG2, BPF_REG_A);
insn++;
/* arg3 = X */
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_ARG3;
- insn->x_reg = BPF_REG_X;
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG3, BPF_REG_X);
insn++;
/* Emit call(ctx, arg2=A, arg3=X) */
@@ -829,9 +802,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
break;
case SKF_AD_OFF + SKF_AD_ALU_XOR_X:
- insn->code = BPF_ALU | BPF_XOR | BPF_X;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_X;
+ /* A ^= X */
+ *insn = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_X);
break;
default:
@@ -897,9 +869,7 @@ do_pass:
fp = prog;
if (new_insn) {
- new_insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- new_insn->a_reg = BPF_REG_CTX;
- new_insn->x_reg = BPF_REG_ARG1;
+ *new_insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_CTX, BPF_REG_ARG1);
}
new_insn++;
@@ -1027,34 +997,28 @@ do_pass:
/* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */
case BPF_LDX | BPF_MSH | BPF_B:
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_TMP;
- insn->x_reg = BPF_REG_A;
+ /* tmp = A */
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_TMP, BPF_REG_A);
insn++;
- insn->code = BPF_LD | BPF_ABS | BPF_B;
- insn->a_reg = BPF_REG_A;
- insn->imm = fp->k;
+ /* A = R0 = *(u8 *) (skb->data + K) */
+ *insn = BPF_LD_ABS(BPF_B, fp->k);
insn++;
- insn->code = BPF_ALU | BPF_AND | BPF_K;
- insn->a_reg = BPF_REG_A;
- insn->imm = 0xf;
+ /* A &= 0xf */
+ *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf);
insn++;
- insn->code = BPF_ALU | BPF_LSH | BPF_K;
- insn->a_reg = BPF_REG_A;
- insn->imm = 2;
+ /* A <<= 2 */
+ *insn = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2);
insn++;
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_X;
- insn->x_reg = BPF_REG_A;
+ /* X = A */
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_X, BPF_REG_A);
insn++;
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_TMP;
+ /* A = tmp */
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_A, BPF_REG_TMP);
break;
/* RET_K, RET_A are remaped into 2 insns. */
@@ -1068,7 +1032,7 @@ do_pass:
insn->imm = fp->k;
insn++;
- insn->code = BPF_JMP | BPF_EXIT;
+ *insn = BPF_EXIT_INSN();
break;
/* Store to stack. */
@@ -1102,16 +1066,12 @@ do_pass:
/* X = A */
case BPF_MISC | BPF_TAX:
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_X;
- insn->x_reg = BPF_REG_A;
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_X, BPF_REG_A);
break;
/* A = X */
case BPF_MISC | BPF_TXA:
- insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_X;
+ *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_A, BPF_REG_X);
break;
/* A = skb->len or X = skb->len */
@@ -1126,10 +1086,8 @@ do_pass:
/* access seccomp_data fields */
case BPF_LDX | BPF_ABS | BPF_W:
- insn->code = BPF_LDX | BPF_MEM | BPF_W;
- insn->a_reg = BPF_REG_A;
- insn->x_reg = BPF_REG_CTX;
- insn->off = fp->k;
+ /* A = *(u32 *) (ctx + K) */
+ *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, fp->k);
break;
default:
--
1.7.9.5
--
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