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net: filter: get rid of BPF_S_* enum
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This patch finally allows us to get rid of the BPF_S_* enum.
Currently, the code performs unnecessary encode and decode
workarounds in seccomp and filter migration itself when a filter
is being attached in order to overcome BPF_S_* encoding which
is not used anymore by the new interpreter resp. JIT compilers.

Keeping it around would mean that also in future we would need
to extend and maintain this enum and related encoders/decoders.
We can get rid of all that and save us these operations during
filter attaching. Naturally, also JIT compilers need to be updated
by this.

Before JIT conversion is being done, each compiler checks if A
is being loaded at startup to obtain information if it needs to
emit instructions to clear A first. Since BPF extensions are a
subset of BPF_LD | BPF_{W,H,B} | BPF_ABS variants, case statements
for extensions can be removed at that point. To ease and minimalize
code changes in the classic JITs, we have introduced bpf_anc_helper().

Tested with test_bpf on x86_64 (JIT, int), s390x (JIT, int),
arm (JIT, int), i368 (int), ppc64 (JIT, int); for sparc we
unfortunately didn't have access, but changes are analogous to
the rest.

Joint work with Alexei Starovoitov.

Signed-off-by: Daniel Borkmann <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Mircea Gherzan <[email protected]>
Cc: Kees Cook <[email protected]>
Acked-by: Chema Gonzalez <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@davem330
Daniel Borkmann authored and davem330 committed Jun 2, 2014
1 parent d50bc15 commit 3480593
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Showing 8 changed files with 498 additions and 649 deletions.
139 changes: 67 additions & 72 deletions arch/arm/net/bpf_jit_32.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ static u16 saved_regs(struct jit_ctx *ctx)
u16 ret = 0;

if ((ctx->skf->len > 1) ||
(ctx->skf->insns[0].code == BPF_S_RET_A))
(ctx->skf->insns[0].code == (BPF_RET | BPF_A)))
ret |= 1 << r_A;

#ifdef CONFIG_FRAME_POINTER
Expand Down Expand Up @@ -164,18 +164,10 @@ static inline int mem_words_used(struct jit_ctx *ctx)
static inline bool is_load_to_a(u16 inst)
{
switch (inst) {
case BPF_S_LD_W_LEN:
case BPF_S_LD_W_ABS:
case BPF_S_LD_H_ABS:
case BPF_S_LD_B_ABS:
case BPF_S_ANC_CPU:
case BPF_S_ANC_IFINDEX:
case BPF_S_ANC_MARK:
case BPF_S_ANC_PROTOCOL:
case BPF_S_ANC_RXHASH:
case BPF_S_ANC_VLAN_TAG:
case BPF_S_ANC_VLAN_TAG_PRESENT:
case BPF_S_ANC_QUEUE:
case BPF_LD | BPF_W | BPF_LEN:
case BPF_LD | BPF_W | BPF_ABS:
case BPF_LD | BPF_H | BPF_ABS:
case BPF_LD | BPF_B | BPF_ABS:
return true;
default:
return false;
Expand Down Expand Up @@ -215,7 +207,7 @@ static void build_prologue(struct jit_ctx *ctx)
emit(ARM_MOV_I(r_X, 0), ctx);

/* do not leak kernel data to userspace */
if ((first_inst != BPF_S_RET_K) && !(is_load_to_a(first_inst)))
if ((first_inst != (BPF_RET | BPF_K)) && !(is_load_to_a(first_inst)))
emit(ARM_MOV_I(r_A, 0), ctx);

/* stack space for the BPF_MEM words */
Expand Down Expand Up @@ -480,36 +472,39 @@ static int build_body(struct jit_ctx *ctx)
u32 k;

for (i = 0; i < prog->len; i++) {
u16 code;

inst = &(prog->insns[i]);
/* K as an immediate value operand */
k = inst->k;
code = bpf_anc_helper(inst);

/* compute offsets only in the fake pass */
if (ctx->target == NULL)
ctx->offsets[i] = ctx->idx * 4;

switch (inst->code) {
case BPF_S_LD_IMM:
switch (code) {
case BPF_LD | BPF_IMM:
emit_mov_i(r_A, k, ctx);
break;
case BPF_S_LD_W_LEN:
case BPF_LD | BPF_W | BPF_LEN:
ctx->seen |= SEEN_SKB;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
emit(ARM_LDR_I(r_A, r_skb,
offsetof(struct sk_buff, len)), ctx);
break;
case BPF_S_LD_MEM:
case BPF_LD | BPF_MEM:
/* A = scratch[k] */
ctx->seen |= SEEN_MEM_WORD(k);
emit(ARM_LDR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
break;
case BPF_S_LD_W_ABS:
case BPF_LD | BPF_W | BPF_ABS:
load_order = 2;
goto load;
case BPF_S_LD_H_ABS:
case BPF_LD | BPF_H | BPF_ABS:
load_order = 1;
goto load;
case BPF_S_LD_B_ABS:
case BPF_LD | BPF_B | BPF_ABS:
load_order = 0;
load:
/* the interpreter will deal with the negative K */
Expand Down Expand Up @@ -552,31 +547,31 @@ static int build_body(struct jit_ctx *ctx)
emit_err_ret(ARM_COND_NE, ctx);
emit(ARM_MOV_R(r_A, ARM_R0), ctx);
break;
case BPF_S_LD_W_IND:
case BPF_LD | BPF_W | BPF_IND:
load_order = 2;
goto load_ind;
case BPF_S_LD_H_IND:
case BPF_LD | BPF_H | BPF_IND:
load_order = 1;
goto load_ind;
case BPF_S_LD_B_IND:
case BPF_LD | BPF_B | BPF_IND:
load_order = 0;
load_ind:
OP_IMM3(ARM_ADD, r_off, r_X, k, ctx);
goto load_common;
case BPF_S_LDX_IMM:
case BPF_LDX | BPF_IMM:
ctx->seen |= SEEN_X;
emit_mov_i(r_X, k, ctx);
break;
case BPF_S_LDX_W_LEN:
case BPF_LDX | BPF_W | BPF_LEN:
ctx->seen |= SEEN_X | SEEN_SKB;
emit(ARM_LDR_I(r_X, r_skb,
offsetof(struct sk_buff, len)), ctx);
break;
case BPF_S_LDX_MEM:
case BPF_LDX | BPF_MEM:
ctx->seen |= SEEN_X | SEEN_MEM_WORD(k);
emit(ARM_LDR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
break;
case BPF_S_LDX_B_MSH:
case BPF_LDX | BPF_B | BPF_MSH:
/* x = ((*(frame + k)) & 0xf) << 2; */
ctx->seen |= SEEN_X | SEEN_DATA | SEEN_CALL;
/* the interpreter should deal with the negative K */
Expand Down Expand Up @@ -606,113 +601,113 @@ static int build_body(struct jit_ctx *ctx)
emit(ARM_AND_I(r_X, ARM_R0, 0x00f), ctx);
emit(ARM_LSL_I(r_X, r_X, 2), ctx);
break;
case BPF_S_ST:
case BPF_ST:
ctx->seen |= SEEN_MEM_WORD(k);
emit(ARM_STR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
break;
case BPF_S_STX:
case BPF_STX:
update_on_xread(ctx);
ctx->seen |= SEEN_MEM_WORD(k);
emit(ARM_STR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
break;
case BPF_S_ALU_ADD_K:
case BPF_ALU | BPF_ADD | BPF_K:
/* A += K */
OP_IMM3(ARM_ADD, r_A, r_A, k, ctx);
break;
case BPF_S_ALU_ADD_X:
case BPF_ALU | BPF_ADD | BPF_X:
update_on_xread(ctx);
emit(ARM_ADD_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_SUB_K:
case BPF_ALU | BPF_SUB | BPF_K:
/* A -= K */
OP_IMM3(ARM_SUB, r_A, r_A, k, ctx);
break;
case BPF_S_ALU_SUB_X:
case BPF_ALU | BPF_SUB | BPF_X:
update_on_xread(ctx);
emit(ARM_SUB_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_MUL_K:
case BPF_ALU | BPF_MUL | BPF_K:
/* A *= K */
emit_mov_i(r_scratch, k, ctx);
emit(ARM_MUL(r_A, r_A, r_scratch), ctx);
break;
case BPF_S_ALU_MUL_X:
case BPF_ALU | BPF_MUL | BPF_X:
update_on_xread(ctx);
emit(ARM_MUL(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_DIV_K:
case BPF_ALU | BPF_DIV | BPF_K:
if (k == 1)
break;
emit_mov_i(r_scratch, k, ctx);
emit_udiv(r_A, r_A, r_scratch, ctx);
break;
case BPF_S_ALU_DIV_X:
case BPF_ALU | BPF_DIV | BPF_X:
update_on_xread(ctx);
emit(ARM_CMP_I(r_X, 0), ctx);
emit_err_ret(ARM_COND_EQ, ctx);
emit_udiv(r_A, r_A, r_X, ctx);
break;
case BPF_S_ALU_OR_K:
case BPF_ALU | BPF_OR | BPF_K:
/* A |= K */
OP_IMM3(ARM_ORR, r_A, r_A, k, ctx);
break;
case BPF_S_ALU_OR_X:
case BPF_ALU | BPF_OR | BPF_X:
update_on_xread(ctx);
emit(ARM_ORR_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_XOR_K:
case BPF_ALU | BPF_XOR | BPF_K:
/* A ^= K; */
OP_IMM3(ARM_EOR, r_A, r_A, k, ctx);
break;
case BPF_S_ANC_ALU_XOR_X:
case BPF_S_ALU_XOR_X:
case BPF_ANC | SKF_AD_ALU_XOR_X:
case BPF_ALU | BPF_XOR | BPF_X:
/* A ^= X */
update_on_xread(ctx);
emit(ARM_EOR_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_AND_K:
case BPF_ALU | BPF_AND | BPF_K:
/* A &= K */
OP_IMM3(ARM_AND, r_A, r_A, k, ctx);
break;
case BPF_S_ALU_AND_X:
case BPF_ALU | BPF_AND | BPF_X:
update_on_xread(ctx);
emit(ARM_AND_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_LSH_K:
case BPF_ALU | BPF_LSH | BPF_K:
if (unlikely(k > 31))
return -1;
emit(ARM_LSL_I(r_A, r_A, k), ctx);
break;
case BPF_S_ALU_LSH_X:
case BPF_ALU | BPF_LSH | BPF_X:
update_on_xread(ctx);
emit(ARM_LSL_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_RSH_K:
case BPF_ALU | BPF_RSH | BPF_K:
if (unlikely(k > 31))
return -1;
emit(ARM_LSR_I(r_A, r_A, k), ctx);
break;
case BPF_S_ALU_RSH_X:
case BPF_ALU | BPF_RSH | BPF_X:
update_on_xread(ctx);
emit(ARM_LSR_R(r_A, r_A, r_X), ctx);
break;
case BPF_S_ALU_NEG:
case BPF_ALU | BPF_NEG:
/* A = -A */
emit(ARM_RSB_I(r_A, r_A, 0), ctx);
break;
case BPF_S_JMP_JA:
case BPF_JMP | BPF_JA:
/* pc += K */
emit(ARM_B(b_imm(i + k + 1, ctx)), ctx);
break;
case BPF_S_JMP_JEQ_K:
case BPF_JMP | BPF_JEQ | BPF_K:
/* pc += (A == K) ? pc->jt : pc->jf */
condt = ARM_COND_EQ;
goto cmp_imm;
case BPF_S_JMP_JGT_K:
case BPF_JMP | BPF_JGT | BPF_K:
/* pc += (A > K) ? pc->jt : pc->jf */
condt = ARM_COND_HI;
goto cmp_imm;
case BPF_S_JMP_JGE_K:
case BPF_JMP | BPF_JGE | BPF_K:
/* pc += (A >= K) ? pc->jt : pc->jf */
condt = ARM_COND_HS;
cmp_imm:
Expand All @@ -731,22 +726,22 @@ static int build_body(struct jit_ctx *ctx)
_emit(condt ^ 1, ARM_B(b_imm(i + inst->jf + 1,
ctx)), ctx);
break;
case BPF_S_JMP_JEQ_X:
case BPF_JMP | BPF_JEQ | BPF_X:
/* pc += (A == X) ? pc->jt : pc->jf */
condt = ARM_COND_EQ;
goto cmp_x;
case BPF_S_JMP_JGT_X:
case BPF_JMP | BPF_JGT | BPF_X:
/* pc += (A > X) ? pc->jt : pc->jf */
condt = ARM_COND_HI;
goto cmp_x;
case BPF_S_JMP_JGE_X:
case BPF_JMP | BPF_JGE | BPF_X:
/* pc += (A >= X) ? pc->jt : pc->jf */
condt = ARM_COND_CS;
cmp_x:
update_on_xread(ctx);
emit(ARM_CMP_R(r_A, r_X), ctx);
goto cond_jump;
case BPF_S_JMP_JSET_K:
case BPF_JMP | BPF_JSET | BPF_K:
/* pc += (A & K) ? pc->jt : pc->jf */
condt = ARM_COND_NE;
/* not set iff all zeroes iff Z==1 iff EQ */
Expand All @@ -759,34 +754,34 @@ static int build_body(struct jit_ctx *ctx)
emit(ARM_TST_I(r_A, imm12), ctx);
}
goto cond_jump;
case BPF_S_JMP_JSET_X:
case BPF_JMP | BPF_JSET | BPF_X:
/* pc += (A & X) ? pc->jt : pc->jf */
update_on_xread(ctx);
condt = ARM_COND_NE;
emit(ARM_TST_R(r_A, r_X), ctx);
goto cond_jump;
case BPF_S_RET_A:
case BPF_RET | BPF_A:
emit(ARM_MOV_R(ARM_R0, r_A), ctx);
goto b_epilogue;
case BPF_S_RET_K:
case BPF_RET | BPF_K:
if ((k == 0) && (ctx->ret0_fp_idx < 0))
ctx->ret0_fp_idx = i;
emit_mov_i(ARM_R0, k, ctx);
b_epilogue:
if (i != ctx->skf->len - 1)
emit(ARM_B(b_imm(prog->len, ctx)), ctx);
break;
case BPF_S_MISC_TAX:
case BPF_MISC | BPF_TAX:
/* X = A */
ctx->seen |= SEEN_X;
emit(ARM_MOV_R(r_X, r_A), ctx);
break;
case BPF_S_MISC_TXA:
case BPF_MISC | BPF_TXA:
/* A = X */
update_on_xread(ctx);
emit(ARM_MOV_R(r_A, r_X), ctx);
break;
case BPF_S_ANC_PROTOCOL:
case BPF_ANC | SKF_AD_PROTOCOL:
/* A = ntohs(skb->protocol) */
ctx->seen |= SEEN_SKB;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
Expand All @@ -795,15 +790,15 @@ static int build_body(struct jit_ctx *ctx)
emit(ARM_LDRH_I(r_scratch, r_skb, off), ctx);
emit_swap16(r_A, r_scratch, ctx);
break;
case BPF_S_ANC_CPU:
case BPF_ANC | SKF_AD_CPU:
/* r_scratch = current_thread_info() */
OP_IMM3(ARM_BIC, r_scratch, ARM_SP, THREAD_SIZE - 1, ctx);
/* A = current_thread_info()->cpu */
BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4);
off = offsetof(struct thread_info, cpu);
emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
break;
case BPF_S_ANC_IFINDEX:
case BPF_ANC | SKF_AD_IFINDEX:
/* A = skb->dev->ifindex */
ctx->seen |= SEEN_SKB;
off = offsetof(struct sk_buff, dev);
Expand All @@ -817,30 +812,30 @@ static int build_body(struct jit_ctx *ctx)
off = offsetof(struct net_device, ifindex);
emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
break;
case BPF_S_ANC_MARK:
case BPF_ANC | SKF_AD_MARK:
ctx->seen |= SEEN_SKB;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
off = offsetof(struct sk_buff, mark);
emit(ARM_LDR_I(r_A, r_skb, off), ctx);
break;
case BPF_S_ANC_RXHASH:
case BPF_ANC | SKF_AD_RXHASH:
ctx->seen |= SEEN_SKB;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
off = offsetof(struct sk_buff, hash);
emit(ARM_LDR_I(r_A, r_skb, off), ctx);
break;
case BPF_S_ANC_VLAN_TAG:
case BPF_S_ANC_VLAN_TAG_PRESENT:
case BPF_ANC | SKF_AD_VLAN_TAG:
case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
ctx->seen |= SEEN_SKB;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
off = offsetof(struct sk_buff, vlan_tci);
emit(ARM_LDRH_I(r_A, r_skb, off), ctx);
if (inst->code == BPF_S_ANC_VLAN_TAG)
if (code == (BPF_ANC | SKF_AD_VLAN_TAG))
OP_IMM3(ARM_AND, r_A, r_A, VLAN_VID_MASK, ctx);
else
OP_IMM3(ARM_AND, r_A, r_A, VLAN_TAG_PRESENT, ctx);
break;
case BPF_S_ANC_QUEUE:
case BPF_ANC | SKF_AD_QUEUE:
ctx->seen |= SEEN_SKB;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
queue_mapping) != 2);
Expand Down
2 changes: 1 addition & 1 deletion arch/powerpc/net/bpf_jit_64.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ sk_load_byte_positive_offset:
blr

/*
* BPF_S_LDX_B_MSH: ldxb 4*([offset]&0xf)
* BPF_LDX | BPF_B | BPF_MSH: ldxb 4*([offset]&0xf)
* r_addr is the offset value
*/
.globl sk_load_byte_msh
Expand Down
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