From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: [PATCH net-next v2 4/5] net: filter: make register namings more comprehensible Date: Thu, 24 Apr 2014 08:45:26 +0200 Message-ID: <1398321927-8845-5-git-send-email-dborkman@redhat.com> References: <1398321927-8845-1-git-send-email-dborkman@redhat.com> Cc: ast@plumgrid.com, netdev@vger.kernel.org To: davem@davemloft.net Return-path: Received: from mx1.redhat.com ([209.132.183.28]:52179 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752440AbaDXGpz (ORCPT ); Thu, 24 Apr 2014 02:45:55 -0400 In-Reply-To: <1398321927-8845-1-git-send-email-dborkman@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: The current code is a bit hard to parse on which registers can be used, how they are mapped and all play together. It makes much more sense to define this a bit more clearly so that the code is a bit more intuitive. This patch cleans this up, and makes naming a bit more consistent among the code. This also allows for moving some of the defines into the header file. Clearing of A and X registers in __sk_run_filter() do not get a particular register name assigned as they have not an 'official' function, but rather just result from the concrete initial mapping. Since for BPF helper functions for BPF_CALL we already use small letters, so be consistent here as well. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov --- include/linux/filter.h | 44 ++++++++-- net/core/filter.c | 215 +++++++++++++++++++++++++------------------------ 2 files changed, 145 insertions(+), 114 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index e58b687..947dc33 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -40,16 +40,47 @@ /* Placeholder/dummy for 0 */ #define BPF_0 0 +/* Register numbers */ +enum { + BPF_REG_0 = 0, + BPF_REG_1, + BPF_REG_2, + BPF_REG_3, + BPF_REG_4, + BPF_REG_5, + BPF_REG_6, + BPF_REG_7, + BPF_REG_8, + BPF_REG_9, + BPF_REG_10, + __MAX_BPF_REG, +}; + /* BPF has 10 general purpose 64-bit registers and stack frame. */ -#define MAX_BPF_REG 11 +#define MAX_BPF_REG __MAX_BPF_REG + +/* ArgX, context and stack frame pointer register positions. Note, + * Arg1, Arg2, Arg3, etc are used as argument mappings of function + * calls in BPF_CALL instruction. + */ +#define BPF_REG_ARG1 BPF_REG_1 +#define BPF_REG_ARG2 BPF_REG_2 +#define BPF_REG_ARG3 BPF_REG_3 +#define BPF_REG_ARG4 BPF_REG_4 +#define BPF_REG_ARG5 BPF_REG_5 +#define BPF_REG_CTX BPF_REG_6 +#define BPF_REG_FP BPF_REG_10 + +/* Additional register mappings for converted user programs. */ +#define BPF_REG_A BPF_REG_0 +#define BPF_REG_X BPF_REG_7 +#define BPF_REG_TMP BPF_REG_8 /* BPF program can access up to 512 bytes of stack space. */ #define MAX_BPF_STACK 512 -/* Arg1, context and stack frame pointer register positions. */ -#define ARG1_REG 1 -#define CTX_REG 6 -#define FP_REG 10 +/* Macro to invoke filter function. */ +#define SK_RUN_FILTER(filter, ctx) (*filter->bpf_func)(ctx, filter->insnsi) struct sock_filter_int { __u8 code; /* opcode */ @@ -97,9 +128,6 @@ static inline unsigned int sk_filter_prog_size(const struct sock_fprog *fprog) return fprog->len * sizeof(fprog->filter[0]); } -#define SK_RUN_FILTER(filter, ctx) \ - (*filter->bpf_func)(ctx, filter->insnsi) - int sk_filter(struct sock *sk, struct sk_buff *skb); u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx, diff --git a/net/core/filter.c b/net/core/filter.c index e5e7717..eada3d5 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -45,6 +45,27 @@ #include #include +/* Registers */ +#define R0 regs[BPF_REG_0] +#define R1 regs[BPF_REG_1] +#define R2 regs[BPF_REG_2] +#define R3 regs[BPF_REG_3] +#define R4 regs[BPF_REG_4] +#define R5 regs[BPF_REG_5] +#define R6 regs[BPF_REG_6] +#define R7 regs[BPF_REG_7] +#define R8 regs[BPF_REG_8] +#define R9 regs[BPF_REG_9] +#define R10 regs[BPF_REG_10] + +/* Named registers */ +#define A regs[insn->a_reg] +#define X regs[insn->x_reg] +#define FP regs[BPF_REG_FP] +#define ARG1 regs[BPF_REG_ARG1] +#define CTX regs[BPF_REG_CTX] +#define K insn->imm + /* No hurry in this branch * * Exported for the bpf jit load helper. @@ -123,13 +144,6 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) return 0; } -/* Register mappings for user programs. */ -#define A_REG 0 -#define X_REG 7 -#define TMP_REG 8 -#define ARG2_REG 2 -#define ARG3_REG 3 - /** * __sk_run_filter - run a filter on a given context * @ctx: buffer to run the filter on @@ -143,17 +157,6 @@ unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn) { u64 stack[MAX_BPF_STACK / sizeof(u64)]; u64 regs[MAX_BPF_REG], tmp; - void *ptr; - int off; - -#define K insn->imm -#define A regs[insn->a_reg] -#define X regs[insn->x_reg] -#define R0 regs[0] - -#define CONT ({insn++; goto select_insn; }) -#define CONT_JMP ({insn++; goto select_insn; }) - static const void *jumptable[256] = { [0 ... 255] = &&default_label, /* Now overwrite non-defaults ... */ @@ -247,11 +250,18 @@ unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn) DL(LD, IND, B), #undef DL }; + void *ptr; + int off; - regs[FP_REG] = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)]; - regs[ARG1_REG] = (u64) (unsigned long) ctx; - regs[A_REG] = 0; - regs[X_REG] = 0; +#define CONT ({ insn++; goto select_insn; }) +#define CONT_JMP ({ insn++; goto select_insn; }) + + FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)]; + ARG1 = (u64) (unsigned long) ctx; + + /* Register for user BPF programs need to be reset first. */ + regs[BPF_REG_A] = 0; + regs[BPF_REG_X] = 0; select_insn: goto *jumptable[insn->code]; @@ -376,8 +386,7 @@ select_insn: /* Function call scratches R1-R5 registers, preserves R6-R9, * and stores return value into R0. */ - R0 = (__bpf_call_base + insn->imm)(regs[1], regs[2], regs[3], - regs[4], regs[5]); + R0 = (__bpf_call_base + insn->imm)(R1, R2, R3, R4, R5); CONT; /* JMP */ @@ -501,7 +510,7 @@ select_insn: load_word: /* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are only * appearing in the programs where ctx == skb. All programs - * keep 'ctx' in regs[CTX_REG] == R6, sk_convert_filter() + * keep 'ctx' in regs[BPF_REG_CTX] == R6, sk_convert_filter() * saves it in R6, internal BPF verifier will check that * R6 == ctx. * @@ -557,13 +566,6 @@ load_byte: /* If we ever reach this, we have a bug somewhere. */ WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code); return 0; -#undef CONT_JMP -#undef CONT - -#undef R0 -#undef X -#undef A -#undef K } u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx, @@ -595,12 +597,12 @@ static unsigned int pkt_type_offset(void) return -1; } -static u64 __skb_get_pay_offset(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) +static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) { return __skb_get_poff((struct sk_buff *)(long) ctx); } -static u64 __skb_get_nlattr(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) +static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) { struct sk_buff *skb = (struct sk_buff *)(long) ctx; struct nlattr *nla; @@ -611,17 +613,17 @@ static u64 __skb_get_nlattr(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) if (unlikely(skb->len < sizeof(struct nlattr))) return 0; - if (unlikely(A > skb->len - sizeof(struct nlattr))) + if (unlikely(a > skb->len - sizeof(struct nlattr))) return 0; - nla = nla_find((struct nlattr *) &skb->data[A], skb->len - A, X); + nla = nla_find((struct nlattr *) &skb->data[a], skb->len - a, x); if (nla) return (void *) nla - (void *) skb->data; return 0; } -static u64 __skb_get_nlattr_nest(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) +static u64 __skb_get_nlattr_nest(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) { struct sk_buff *skb = (struct sk_buff *)(long) ctx; struct nlattr *nla; @@ -632,27 +634,27 @@ static u64 __skb_get_nlattr_nest(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) if (unlikely(skb->len < sizeof(struct nlattr))) return 0; - if (unlikely(A > skb->len - sizeof(struct nlattr))) + if (unlikely(a > skb->len - sizeof(struct nlattr))) return 0; - nla = (struct nlattr *) &skb->data[A]; - if (unlikely(nla->nla_len > skb->len - A)) + nla = (struct nlattr *) &skb->data[a]; + if (unlikely(nla->nla_len > skb->len - a)) return 0; - nla = nla_find_nested(nla, X); + nla = nla_find_nested(nla, x); if (nla) return (void *) nla - (void *) skb->data; return 0; } -static u64 __get_raw_cpu_id(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) +static u64 __get_raw_cpu_id(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) { return raw_smp_processor_id(); } /* note that this only generates 32-bit random numbers */ -static u64 __get_random_u32(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) +static u64 __get_random_u32(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) { return prandom_u32(); } @@ -667,28 +669,28 @@ static bool convert_bpf_extensions(struct sock_filter *fp, BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); insn->code = BPF_LDX | BPF_MEM | BPF_H; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, protocol); insn++; /* A = ntohs(A) [emitting a nop or swap16] */ insn->code = BPF_ALU | BPF_END | BPF_FROM_BE; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = 16; break; case SKF_AD_OFF + SKF_AD_PKTTYPE: insn->code = BPF_LDX | BPF_MEM | BPF_B; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = pkt_type_offset(); if (insn->off < 0) return false; insn++; insn->code = BPF_ALU | BPF_AND | BPF_K; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = PKT_TYPE_MAX; break; @@ -698,13 +700,13 @@ static bool convert_bpf_extensions(struct sock_filter *fp, insn->code = BPF_LDX | BPF_MEM | BPF_DW; else insn->code = BPF_LDX | BPF_MEM | BPF_W; - insn->a_reg = TMP_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_TMP; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, dev); insn++; insn->code = BPF_JMP | BPF_JNE | BPF_K; - insn->a_reg = TMP_REG; + insn->a_reg = BPF_REG_TMP; insn->imm = 0; insn->off = 1; insn++; @@ -715,8 +717,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2); - insn->a_reg = A_REG; - insn->x_reg = TMP_REG; + 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; @@ -731,8 +733,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); insn->code = BPF_LDX | BPF_MEM | BPF_W; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, mark); break; @@ -740,8 +742,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4); insn->code = BPF_LDX | BPF_MEM | BPF_W; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, hash); break; @@ -749,8 +751,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); insn->code = BPF_LDX | BPF_MEM | BPF_H; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, queue_mapping); break; @@ -759,8 +761,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); insn->code = BPF_LDX | BPF_MEM | BPF_H; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, vlan_tci); insn++; @@ -768,16 +770,16 @@ static bool convert_bpf_extensions(struct sock_filter *fp, if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) { insn->code = BPF_ALU | BPF_AND | BPF_K; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = ~VLAN_TAG_PRESENT; } else { insn->code = BPF_ALU | BPF_RSH | BPF_K; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = 12; insn++; insn->code = BPF_ALU | BPF_AND | BPF_K; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = 1; } break; @@ -789,20 +791,20 @@ static bool convert_bpf_extensions(struct sock_filter *fp, case SKF_AD_OFF + SKF_AD_RANDOM: /* arg1 = ctx */ insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = ARG1_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_ARG1; + insn->x_reg = BPF_REG_CTX; insn++; /* arg2 = A */ insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = ARG2_REG; - insn->x_reg = A_REG; + insn->a_reg = BPF_REG_ARG2; + insn->x_reg = BPF_REG_A; insn++; /* arg3 = X */ insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = ARG3_REG; - insn->x_reg = X_REG; + insn->a_reg = BPF_REG_ARG3; + insn->x_reg = BPF_REG_X; insn++; /* Emit call(ctx, arg2=A, arg3=X) */ @@ -828,8 +830,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, case SKF_AD_OFF + SKF_AD_ALU_XOR_X: insn->code = BPF_ALU | BPF_XOR | BPF_X; - insn->a_reg = A_REG; - insn->x_reg = X_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_X; break; default: @@ -879,7 +881,7 @@ int sk_convert_filter(struct sock_filter *prog, int len, u8 bpf_src; BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK); - BUILD_BUG_ON(FP_REG + 1 != MAX_BPF_REG); + BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); if (len <= 0 || len >= BPF_MAXINSNS) return -EINVAL; @@ -896,8 +898,8 @@ do_pass: if (new_insn) { new_insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - new_insn->a_reg = CTX_REG; - new_insn->x_reg = ARG1_REG; + new_insn->a_reg = BPF_REG_CTX; + new_insn->x_reg = BPF_REG_ARG1; } new_insn++; @@ -947,8 +949,8 @@ do_pass: break; insn->code = fp->code; - insn->a_reg = A_REG; - insn->x_reg = X_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_X; insn->imm = fp->k; break; @@ -982,16 +984,16 @@ do_pass: * in compare insn. */ insn->code = BPF_ALU | BPF_MOV | BPF_K; - insn->a_reg = TMP_REG; + insn->a_reg = BPF_REG_TMP; insn->imm = fp->k; insn++; - insn->a_reg = A_REG; - insn->x_reg = TMP_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_TMP; bpf_src = BPF_X; } else { - insn->a_reg = A_REG; - insn->x_reg = X_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_X; insn->imm = fp->k; bpf_src = BPF_SRC(fp->code); } @@ -1026,33 +1028,33 @@ 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 = TMP_REG; - insn->x_reg = A_REG; + insn->a_reg = BPF_REG_TMP; + insn->x_reg = BPF_REG_A; insn++; insn->code = BPF_LD | BPF_ABS | BPF_B; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = fp->k; insn++; insn->code = BPF_ALU | BPF_AND | BPF_K; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = 0xf; insn++; insn->code = BPF_ALU | BPF_LSH | BPF_K; - insn->a_reg = A_REG; + insn->a_reg = BPF_REG_A; insn->imm = 2; insn++; insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = X_REG; - insn->x_reg = A_REG; + insn->a_reg = BPF_REG_X; + insn->x_reg = BPF_REG_A; insn++; insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = A_REG; - insn->x_reg = TMP_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_TMP; break; /* RET_K, RET_A are remaped into 2 insns. */ @@ -1062,7 +1064,7 @@ do_pass: (BPF_RVAL(fp->code) == BPF_K ? BPF_K : BPF_X); insn->a_reg = 0; - insn->x_reg = A_REG; + insn->x_reg = BPF_REG_A; insn->imm = fp->k; insn++; @@ -1073,8 +1075,9 @@ do_pass: case BPF_ST: case BPF_STX: insn->code = BPF_STX | BPF_MEM | BPF_W; - insn->a_reg = FP_REG; - insn->x_reg = fp->code == BPF_ST ? A_REG : X_REG; + 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; break; @@ -1083,8 +1086,8 @@ do_pass: case BPF_LDX | BPF_MEM: insn->code = BPF_LDX | BPF_MEM | BPF_W; insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ? - A_REG : X_REG; - insn->x_reg = FP_REG; + BPF_REG_A : BPF_REG_X; + insn->x_reg = BPF_REG_FP; insn->off = -(BPF_MEMWORDS - fp->k) * 4; break; @@ -1093,22 +1096,22 @@ do_pass: case BPF_LDX | BPF_IMM: insn->code = BPF_ALU | BPF_MOV | BPF_K; insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ? - A_REG : X_REG; + BPF_REG_A : BPF_REG_X; insn->imm = fp->k; break; /* X = A */ case BPF_MISC | BPF_TAX: insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = X_REG; - insn->x_reg = A_REG; + insn->a_reg = BPF_REG_X; + insn->x_reg = BPF_REG_A; break; /* A = X */ case BPF_MISC | BPF_TXA: insn->code = BPF_ALU64 | BPF_MOV | BPF_X; - insn->a_reg = A_REG; - insn->x_reg = X_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_X; break; /* A = skb->len or X = skb->len */ @@ -1116,16 +1119,16 @@ do_pass: case BPF_LDX | BPF_W | BPF_LEN: insn->code = BPF_LDX | BPF_MEM | BPF_W; insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ? - A_REG : X_REG; - insn->x_reg = CTX_REG; + BPF_REG_A : BPF_REG_X; + insn->x_reg = BPF_REG_CTX; insn->off = offsetof(struct sk_buff, len); break; /* access seccomp_data fields */ case BPF_LDX | BPF_ABS | BPF_W: insn->code = BPF_LDX | BPF_MEM | BPF_W; - insn->a_reg = A_REG; - insn->x_reg = CTX_REG; + insn->a_reg = BPF_REG_A; + insn->x_reg = BPF_REG_CTX; insn->off = fp->k; break; -- 1.7.11.7