net: filter: improve filter block macros

Commit 9739eef13c92 ("net: filter: make BPF conversion more readable")
started to introduce helper macros similar to BPF_STMT()/BPF_JUMP()
macros from classic BPF.

However, quite some statements in the filter conversion functions
remained in the old style which gives a mixture of block macros and
non block macros in the code. This patch makes the block macros itself
more readable by using explicit member initialization, and converts
the remaining ones where possible to remain in a more consistent state.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 72 insertions, 124 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 328aaf6ff4d1..842f8393121d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -672,14 +672,10 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
                 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
 
                 /* A = *(u16 *) (ctx + offsetof(protocol)) */
-                *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
-                                    offsetof(struct sk_buff, protocol));
-                insn++;
-
+                *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
+                                      offsetof(struct sk_buff, protocol));
                 /* A = ntohs(A) [emitting a nop or swap16] */
-                insn->code = BPF_ALU | BPF_END | BPF_FROM_BE;
-                insn->a_reg = BPF_REG_A;
-                insn->imm = 16;
+                *insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16);
                 break;
 
         case SKF_AD_OFF + SKF_AD_PKTTYPE:
@@ -688,37 +684,27 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
                 if (insn->off < 0)
                         return false;
                 insn++;
-
                 *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:
-                *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++;
-
-                /* if (tmp != 0) goto pc+1 */
-                *insn = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1);
-                insn++;
-
-                *insn = BPF_EXIT_INSN();
-                insn++;
-
                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
                 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
-
-                insn->a_reg = BPF_REG_A;
-                insn->x_reg = BPF_REG_TMP;
-
-                if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX) {
-                        insn->code = BPF_LDX | BPF_MEM | BPF_W;
-                        insn->off = offsetof(struct net_device, ifindex);
-                } else {
-                        insn->code = BPF_LDX | BPF_MEM | BPF_H;
-                        insn->off = offsetof(struct net_device, type);
-                }
+                BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)) < 0);
+
+                *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)),
+                                      BPF_REG_TMP, BPF_REG_CTX,
+                                      offsetof(struct sk_buff, dev));
+                /* if (tmp != 0) goto pc + 1 */
+                *insn++ = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1);
+                *insn++ = BPF_EXIT_INSN();
+                if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX)
+                        *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_TMP,
+                                            offsetof(struct net_device, ifindex));
+                else
+                        *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_TMP,
+                                            offsetof(struct net_device, type));
                 break;
 
         case SKF_AD_OFF + SKF_AD_MARK:
@@ -745,22 +731,17 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
         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);
-
-                /* 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);
 
+                /* A = *(u16 *) (ctx + offsetof(vlan_tci)) */
+                *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
+                                      offsetof(struct sk_buff, vlan_tci));
                 if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) {
                         *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A,
                                               ~VLAN_TAG_PRESENT);
                 } else {
                         /* A >>= 12 */
-                        *insn = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12);
-                        insn++;
-
+                        *insn++ = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12);
                         /* A &= 1 */
                         *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 1);
                 }
@@ -772,34 +753,27 @@ 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 = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG1, BPF_REG_CTX);
-                insn++;
-
+                *insn++ = BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_CTX);
                 /* arg2 = A */
-                *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG2, BPF_REG_A);
-                insn++;
-
+                *insn++ = BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_A);
                 /* arg3 = X */
-                *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG3, BPF_REG_X);
-                insn++;
-
+                *insn++ = BPF_MOV64_REG(BPF_REG_ARG3, BPF_REG_X);
                 /* Emit call(ctx, arg2=A, arg3=X) */
-                insn->code = BPF_JMP | BPF_CALL;
                 switch (fp->k) {
                 case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
-                        insn->imm = __skb_get_pay_offset - __bpf_call_base;
+                        *insn = BPF_EMIT_CALL(__skb_get_pay_offset);
                         break;
                 case SKF_AD_OFF + SKF_AD_NLATTR:
-                        insn->imm = __skb_get_nlattr - __bpf_call_base;
+                        *insn = BPF_EMIT_CALL(__skb_get_nlattr);
                         break;
                 case SKF_AD_OFF + SKF_AD_NLATTR_NEST:
-                        insn->imm = __skb_get_nlattr_nest - __bpf_call_base;
+                        *insn = BPF_EMIT_CALL(__skb_get_nlattr_nest);
                         break;
                 case SKF_AD_OFF + SKF_AD_CPU:
-                        insn->imm = __get_raw_cpu_id - __bpf_call_base;
+                        *insn = BPF_EMIT_CALL(__get_raw_cpu_id);
                         break;
                 case SKF_AD_OFF + SKF_AD_RANDOM:
-                        insn->imm = __get_random_u32 - __bpf_call_base;
+                        *insn = BPF_EMIT_CALL(__get_random_u32);
                         break;
                 }
                 break;
@@ -871,9 +845,8 @@ do_pass:
         new_insn = new_prog;
         fp = prog;
 
-        if (new_insn) {
-                *new_insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_CTX, BPF_REG_ARG1);
-        }
+        if (new_insn)
+                *new_insn = BPF_MOV64_REG(BPF_REG_CTX, BPF_REG_ARG1);
         new_insn++;
 
         for (i = 0; i < len; fp++, i++) {
@@ -921,17 +894,16 @@ do_pass:
                             convert_bpf_extensions(fp, &insn))
                                 break;
 
-                        insn->code = fp->code;
-                        insn->a_reg = BPF_REG_A;
-                        insn->x_reg = BPF_REG_X;
-                        insn->imm = fp->k;
+                        *insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k);
                         break;
 
-                /* Jump opcodes map as-is, but offsets need adjustment. */
-                case BPF_JMP | BPF_JA:
-                        target = i + fp->k + 1;
-                        insn->code = fp->code;
-#define EMIT_JMP                                                        \
+                /* Jump transformation cannot use BPF block macros
+                 * everywhere as offset calculation and target updates
+                 * require a bit more work than the rest, i.e. jump
+                 * opcodes map as-is, but offsets need adjustment.
+                 */
+
+#define BPF_EMIT_JMP                                                    \
         do {                                                            \
                 if (target >= len || target < 0)                        \
                         goto err;                                       \
@@ -940,7 +912,10 @@ do_pass:
                 insn->off -= insn - tmp_insns;                          \
         } while (0)
 
-                        EMIT_JMP;
+                case BPF_JMP | BPF_JA:
+                        target = i + fp->k + 1;
+                        insn->code = fp->code;
+                        BPF_EMIT_JMP;
                         break;
 
                 case BPF_JMP | BPF_JEQ | BPF_K:
@@ -956,10 +931,7 @@ do_pass:
                                  * immediate into tmp register and use it
                                  * in compare insn.
                                  */
-                                insn->code = BPF_ALU | BPF_MOV | BPF_K;
-                                insn->a_reg = BPF_REG_TMP;
-                                insn->imm = fp->k;
-                                insn++;
+                                *insn++ = BPF_MOV32_IMM(BPF_REG_TMP, fp->k);
 
                                 insn->a_reg = BPF_REG_A;
                                 insn->x_reg = BPF_REG_TMP;
@@ -975,7 +947,7 @@ do_pass:
                         if (fp->jf == 0) {
                                 insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src;
                                 target = i + fp->jt + 1;
-                                EMIT_JMP;
+                                BPF_EMIT_JMP;
                                 break;
                         }
 
@@ -983,116 +955,94 @@ do_pass:
                         if (fp->jt == 0 && BPF_OP(fp->code) == BPF_JEQ) {
                                 insn->code = BPF_JMP | BPF_JNE | bpf_src;
                                 target = i + fp->jf + 1;
-                                EMIT_JMP;
+                                BPF_EMIT_JMP;
                                 break;
                         }
 
                         /* Other jumps are mapped into two insns: Jxx and JA. */
                         target = i + fp->jt + 1;
                         insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src;
-                        EMIT_JMP;
+                        BPF_EMIT_JMP;
                         insn++;
 
                         insn->code = BPF_JMP | BPF_JA;
                         target = i + fp->jf + 1;
-                        EMIT_JMP;
+                        BPF_EMIT_JMP;
                         break;
 
                 /* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */
                 case BPF_LDX | BPF_MSH | BPF_B:
                         /* tmp = A */
-                        *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_TMP, BPF_REG_A);
-                        insn++;
-
+                        *insn++ = BPF_MOV64_REG(BPF_REG_TMP, BPF_REG_A);
                         /* A = BPF_R0 = *(u8 *) (skb->data + K) */
-                        *insn = BPF_LD_ABS(BPF_B, fp->k);
-                        insn++;
-
+                        *insn++ = BPF_LD_ABS(BPF_B, fp->k);
                         /* A &= 0xf */
-                        *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf);
-                        insn++;
-
+                        *insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf);
                         /* A <<= 2 */
-                        *insn = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2);
-                        insn++;
-
+                        *insn++ = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2);
                         /* X = A */
-                        *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_X, BPF_REG_A);
-                        insn++;
-
+                        *insn++ = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A);
                         /* A = tmp */
-                        *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_A, BPF_REG_TMP);
+                        *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_TMP);
                         break;
 
                 /* RET_K, RET_A are remaped into 2 insns. */
                 case BPF_RET | BPF_A:
                 case BPF_RET | BPF_K:
-                        insn->code = BPF_ALU | BPF_MOV |
-                                     (BPF_RVAL(fp->code) == BPF_K ?
-                                      BPF_K : BPF_X);
-                        insn->a_reg = 0;
-                        insn->x_reg = BPF_REG_A;
-                        insn->imm = fp->k;
-                        insn++;
-
+                        *insn++ = BPF_MOV32_RAW(BPF_RVAL(fp->code) == BPF_K ?
+                                                BPF_K : BPF_X, BPF_REG_0,
+                                                BPF_REG_A, fp->k);
                         *insn = BPF_EXIT_INSN();
                         break;
 
                 /* Store to stack. */
                 case BPF_ST:
                 case BPF_STX:
-                        insn->code = BPF_STX | BPF_MEM | BPF_W;
-                        insn->a_reg = BPF_REG_FP;
-                        insn->x_reg = fp->code == BPF_ST ?
-                                      BPF_REG_A : BPF_REG_X;
-                        insn->off = -(BPF_MEMWORDS - fp->k) * 4;
+                        *insn = BPF_STX_MEM(BPF_W, BPF_REG_FP, BPF_CLASS(fp->code) ==
+                                            BPF_ST ? BPF_REG_A : BPF_REG_X,
+                                            -(BPF_MEMWORDS - fp->k) * 4);
                         break;
 
                 /* Load from stack. */
                 case BPF_LD | BPF_MEM:
                 case BPF_LDX | BPF_MEM:
-                        insn->code = BPF_LDX | BPF_MEM | BPF_W;
-                        insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ?
-                                      BPF_REG_A : BPF_REG_X;
-                        insn->x_reg = BPF_REG_FP;
-                        insn->off = -(BPF_MEMWORDS - fp->k) * 4;
+                        *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD  ?
+                                            BPF_REG_A : BPF_REG_X, BPF_REG_FP,
+                                            -(BPF_MEMWORDS - fp->k) * 4);
                         break;
 
                 /* A = K or X = K */
                 case BPF_LD | BPF_IMM:
                 case BPF_LDX | BPF_IMM:
-                        insn->code = BPF_ALU | BPF_MOV | BPF_K;
-                        insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ?
-                                      BPF_REG_A : BPF_REG_X;
-                        insn->imm = fp->k;
+                        *insn = BPF_MOV32_IMM(BPF_CLASS(fp->code) == BPF_LD ?
+                                              BPF_REG_A : BPF_REG_X, fp->k);
                         break;
 
                 /* X = A */
                 case BPF_MISC | BPF_TAX:
-                        *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_X, BPF_REG_A);
+                        *insn = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A);
                         break;
 
                 /* A = X */
                 case BPF_MISC | BPF_TXA:
-                        *insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_A, BPF_REG_X);
+                        *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_X);
                         break;
 
                 /* A = skb->len or X = skb->len */
                 case BPF_LD | BPF_W | BPF_LEN:
                 case BPF_LDX | BPF_W | BPF_LEN:
-                        insn->code = BPF_LDX | BPF_MEM | BPF_W;
-                        insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ?
-                                      BPF_REG_A : BPF_REG_X;
-                        insn->x_reg = BPF_REG_CTX;
-                        insn->off = offsetof(struct sk_buff, len);
+                        *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ?
+                                            BPF_REG_A : BPF_REG_X, BPF_REG_CTX,
+                                            offsetof(struct sk_buff, len));
                         break;
 
-                /* access seccomp_data fields */
+                /* Access seccomp_data fields. */
                 case BPF_LDX | BPF_ABS | BPF_W:
                         /* A = *(u32 *) (ctx + K) */
                         *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, fp->k);
                         break;
 
+                /* Unkown instruction. */
                 default:
                         goto err;
                 }
@@ -1101,7 +1051,6 @@ do_pass:
                 if (new_prog)
                         memcpy(new_insn, tmp_insns,
                                sizeof(*insn) * (insn - tmp_insns));
-
                 new_insn += insn - tmp_insns;
         }
 
@@ -1116,7 +1065,6 @@ do_pass:
                 new_flen = new_insn - new_prog;
                 if (pass > 2)
                         goto err;
-
                 goto do_pass;
         }