From: Alexei Starovoitov Date: Thu, 8 May 2014 21:10:51 +0000 (-0700) Subject: net: filter: make BPF conversion more readable X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9739eef13c926645fbf88bcb77e66442fa75d688;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git 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 Signed-off-by: David S. Miller --- diff --git a/include/linux/filter.h b/include/linux/filter.h index ed1efab10b8f..4457b383961c 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 eb020a7d6f55..9aaa05ad8fe3 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: