/* * Linux Socket Filter - Kernel level socket filtering * * Based on the design of the Berkeley Packet Filter. The new * internal format has been designed by PLUMgrid: * * Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com * * Authors: * * Jay Schulist * Alexei Starovoitov * Daniel Borkmann * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Andi Kleen - Fix a few bad bugs and races. * Kris Katterjohn - Added many additional checks in sk_chk_filter() */ #include #include #include /* Registers */ #define BPF_R0 regs[BPF_REG_0] #define BPF_R1 regs[BPF_REG_1] #define BPF_R2 regs[BPF_REG_2] #define BPF_R3 regs[BPF_REG_3] #define BPF_R4 regs[BPF_REG_4] #define BPF_R5 regs[BPF_REG_5] #define BPF_R6 regs[BPF_REG_6] #define BPF_R7 regs[BPF_REG_7] #define BPF_R8 regs[BPF_REG_8] #define BPF_R9 regs[BPF_REG_9] #define BPF_R10 regs[BPF_REG_10] /* Named registers */ #define DST regs[insn->dst_reg] #define SRC regs[insn->src_reg] #define FP regs[BPF_REG_FP] #define ARG1 regs[BPF_REG_ARG1] #define CTX regs[BPF_REG_CTX] #define IMM insn->imm /* No hurry in this branch * * Exported for the bpf jit load helper. */ void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size) { u8 *ptr = NULL; if (k >= SKF_NET_OFF) ptr = skb_network_header(skb) + k - SKF_NET_OFF; else if (k >= SKF_LL_OFF) ptr = skb_mac_header(skb) + k - SKF_LL_OFF; if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb)) return ptr; return NULL; } /* Base function for offset calculation. Needs to go into .text section, * therefore keeping it non-static as well; will also be used by JITs * anyway later on, so do not let the compiler omit it. */ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) { return 0; } /** * __sk_run_filter - run a filter on a given context * @ctx: buffer to run the filter on * @insn: filter to apply * * Decode and apply filter instructions to the skb->data. Return length to * keep, 0 for none. @ctx is the data we are operating on, @insn is the * array of filter instructions. */ static unsigned int __sk_run_filter(void *ctx, const struct bpf_insn *insn) { u64 stack[MAX_BPF_STACK / sizeof(u64)]; u64 regs[MAX_BPF_REG], tmp; static const void *jumptable[256] = { [0 ... 255] = &&default_label, /* Now overwrite non-defaults ... */ /* 32 bit ALU operations */ [BPF_ALU | BPF_ADD | BPF_X] = &&ALU_ADD_X, [BPF_ALU | BPF_ADD | BPF_K] = &&ALU_ADD_K, [BPF_ALU | BPF_SUB | BPF_X] = &&ALU_SUB_X, [BPF_ALU | BPF_SUB | BPF_K] = &&ALU_SUB_K, [BPF_ALU | BPF_AND | BPF_X] = &&ALU_AND_X, [BPF_ALU | BPF_AND | BPF_K] = &&ALU_AND_K, [BPF_ALU | BPF_OR | BPF_X] = &&ALU_OR_X, [BPF_ALU | BPF_OR | BPF_K] = &&ALU_OR_K, [BPF_ALU | BPF_LSH | BPF_X] = &&ALU_LSH_X, [BPF_ALU | BPF_LSH | BPF_K] = &&ALU_LSH_K, [BPF_ALU | BPF_RSH | BPF_X] = &&ALU_RSH_X, [BPF_ALU | BPF_RSH | BPF_K] = &&ALU_RSH_K, [BPF_ALU | BPF_XOR | BPF_X] = &&ALU_XOR_X, [BPF_ALU | BPF_XOR | BPF_K] = &&ALU_XOR_K, [BPF_ALU | BPF_MUL | BPF_X] = &&ALU_MUL_X, [BPF_ALU | BPF_MUL | BPF_K] = &&ALU_MUL_K, [BPF_ALU | BPF_MOV | BPF_X] = &&ALU_MOV_X, [BPF_ALU | BPF_MOV | BPF_K] = &&ALU_MOV_K, [BPF_ALU | BPF_DIV | BPF_X] = &&ALU_DIV_X, [BPF_ALU | BPF_DIV | BPF_K] = &&ALU_DIV_K, [BPF_ALU | BPF_MOD | BPF_X] = &&ALU_MOD_X, [BPF_ALU | BPF_MOD | BPF_K] = &&ALU_MOD_K, [BPF_ALU | BPF_NEG] = &&ALU_NEG, [BPF_ALU | BPF_END | BPF_TO_BE] = &&ALU_END_TO_BE, [BPF_ALU | BPF_END | BPF_TO_LE] = &&ALU_END_TO_LE, /* 64 bit ALU operations */ [BPF_ALU64 | BPF_ADD | BPF_X] = &&ALU64_ADD_X, [BPF_ALU64 | BPF_ADD | BPF_K] = &&ALU64_ADD_K, [BPF_ALU64 | BPF_SUB | BPF_X] = &&ALU64_SUB_X, [BPF_ALU64 | BPF_SUB | BPF_K] = &&ALU64_SUB_K, [BPF_ALU64 | BPF_AND | BPF_X] = &&ALU64_AND_X, [BPF_ALU64 | BPF_AND | BPF_K] = &&ALU64_AND_K, [BPF_ALU64 | BPF_OR | BPF_X] = &&ALU64_OR_X, [BPF_ALU64 | BPF_OR | BPF_K] = &&ALU64_OR_K, [BPF_ALU64 | BPF_LSH | BPF_X] = &&ALU64_LSH_X, [BPF_ALU64 | BPF_LSH | BPF_K] = &&ALU64_LSH_K, [BPF_ALU64 | BPF_RSH | BPF_X] = &&ALU64_RSH_X, [BPF_ALU64 | BPF_RSH | BPF_K] = &&ALU64_RSH_K, [BPF_ALU64 | BPF_XOR | BPF_X] = &&ALU64_XOR_X, [BPF_ALU64 | BPF_XOR | BPF_K] = &&ALU64_XOR_K, [BPF_ALU64 | BPF_MUL | BPF_X] = &&ALU64_MUL_X, [BPF_ALU64 | BPF_MUL | BPF_K] = &&ALU64_MUL_K, [BPF_ALU64 | BPF_MOV | BPF_X] = &&ALU64_MOV_X, [BPF_ALU64 | BPF_MOV | BPF_K] = &&ALU64_MOV_K, [BPF_ALU64 | BPF_ARSH | BPF_X] = &&ALU64_ARSH_X, [BPF_ALU64 | BPF_ARSH | BPF_K] = &&ALU64_ARSH_K, [BPF_ALU64 | BPF_DIV | BPF_X] = &&ALU64_DIV_X, [BPF_ALU64 | BPF_DIV | BPF_K] = &&ALU64_DIV_K, [BPF_ALU64 | BPF_MOD | BPF_X] = &&ALU64_MOD_X, [BPF_ALU64 | BPF_MOD | BPF_K] = &&ALU64_MOD_K, [BPF_ALU64 | BPF_NEG] = &&ALU64_NEG, /* Call instruction */ [BPF_JMP | BPF_CALL] = &&JMP_CALL, /* Jumps */ [BPF_JMP | BPF_JA] = &&JMP_JA, [BPF_JMP | BPF_JEQ | BPF_X] = &&JMP_JEQ_X, [BPF_JMP | BPF_JEQ | BPF_K] = &&JMP_JEQ_K, [BPF_JMP | BPF_JNE | BPF_X] = &&JMP_JNE_X, [BPF_JMP | BPF_JNE | BPF_K] = &&JMP_JNE_K, [BPF_JMP | BPF_JGT | BPF_X] = &&JMP_JGT_X, [BPF_JMP | BPF_JGT | BPF_K] = &&JMP_JGT_K, [BPF_JMP | BPF_JGE | BPF_X] = &&JMP_JGE_X, [BPF_JMP | BPF_JGE | BPF_K] = &&JMP_JGE_K, [BPF_JMP | BPF_JSGT | BPF_X] = &&JMP_JSGT_X, [BPF_JMP | BPF_JSGT | BPF_K] = &&JMP_JSGT_K, [BPF_JMP | BPF_JSGE | BPF_X] = &&JMP_JSGE_X, [BPF_JMP | BPF_JSGE | BPF_K] = &&JMP_JSGE_K, [BPF_JMP | BPF_JSET | BPF_X] = &&JMP_JSET_X, [BPF_JMP | BPF_JSET | BPF_K] = &&JMP_JSET_K, /* Program return */ [BPF_JMP | BPF_EXIT] = &&JMP_EXIT, /* Store instructions */ [BPF_STX | BPF_MEM | BPF_B] = &&STX_MEM_B, [BPF_STX | BPF_MEM | BPF_H] = &&STX_MEM_H, [BPF_STX | BPF_MEM | BPF_W] = &&STX_MEM_W, [BPF_STX | BPF_MEM | BPF_DW] = &&STX_MEM_DW, [BPF_STX | BPF_XADD | BPF_W] = &&STX_XADD_W, [BPF_STX | BPF_XADD | BPF_DW] = &&STX_XADD_DW, [BPF_ST | BPF_MEM | BPF_B] = &&ST_MEM_B, [BPF_ST | BPF_MEM | BPF_H] = &&ST_MEM_H, [BPF_ST | BPF_MEM | BPF_W] = &&ST_MEM_W, [BPF_ST | BPF_MEM | BPF_DW] = &&ST_MEM_DW, /* Load instructions */ [BPF_LDX | BPF_MEM | BPF_B] = &&LDX_MEM_B, [BPF_LDX | BPF_MEM | BPF_H] = &&LDX_MEM_H, [BPF_LDX | BPF_MEM | BPF_W] = &&LDX_MEM_W, [BPF_LDX | BPF_MEM | BPF_DW] = &&LDX_MEM_DW, [BPF_LD | BPF_ABS | BPF_W] = &&LD_ABS_W, [BPF_LD | BPF_ABS | BPF_H] = &&LD_ABS_H, [BPF_LD | BPF_ABS | BPF_B] = &&LD_ABS_B, [BPF_LD | BPF_IND | BPF_W] = &&LD_IND_W, [BPF_LD | BPF_IND | BPF_H] = &&LD_IND_H, [BPF_LD | BPF_IND | BPF_B] = &&LD_IND_B, }; void *ptr; int off; #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; /* Registers used in classic BPF programs need to be reset first. */ regs[BPF_REG_A] = 0; regs[BPF_REG_X] = 0; select_insn: goto *jumptable[insn->code]; /* ALU */ #define ALU(OPCODE, OP) \ ALU64_##OPCODE##_X: \ DST = DST OP SRC; \ CONT; \ ALU_##OPCODE##_X: \ DST = (u32) DST OP (u32) SRC; \ CONT; \ ALU64_##OPCODE##_K: \ DST = DST OP IMM; \ CONT; \ ALU_##OPCODE##_K: \ DST = (u32) DST OP (u32) IMM; \ CONT; ALU(ADD, +) ALU(SUB, -) ALU(AND, &) ALU(OR, |) ALU(LSH, <<) ALU(RSH, >>) ALU(XOR, ^) ALU(MUL, *) #undef ALU ALU_NEG: DST = (u32) -DST; CONT; ALU64_NEG: DST = -DST; CONT; ALU_MOV_X: DST = (u32) SRC; CONT; ALU_MOV_K: DST = (u32) IMM; CONT; ALU64_MOV_X: DST = SRC; CONT; ALU64_MOV_K: DST = IMM; CONT; ALU64_ARSH_X: (*(s64 *) &DST) >>= SRC; CONT; ALU64_ARSH_K: (*(s64 *) &DST) >>= IMM; CONT; ALU64_MOD_X: if (unlikely(SRC == 0)) return 0; tmp = DST; DST = do_div(tmp, SRC); CONT; ALU_MOD_X: if (unlikely(SRC == 0)) return 0; tmp = (u32) DST; DST = do_div(tmp, (u32) SRC); CONT; ALU64_MOD_K: tmp = DST; DST = do_div(tmp, IMM); CONT; ALU_MOD_K: tmp = (u32) DST; DST = do_div(tmp, (u32) IMM); CONT; ALU64_DIV_X: if (unlikely(SRC == 0)) return 0; do_div(DST, SRC); CONT; ALU_DIV_X: if (unlikely(SRC == 0)) return 0; tmp = (u32) DST; do_div(tmp, (u32) SRC); DST = (u32) tmp; CONT; ALU64_DIV_K: do_div(DST, IMM); CONT; ALU_DIV_K: tmp = (u32) DST; do_div(tmp, (u32) IMM); DST = (u32) tmp; CONT; ALU_END_TO_BE: switch (IMM) { case 16: DST = (__force u16) cpu_to_be16(DST); break; case 32: DST = (__force u32) cpu_to_be32(DST); break; case 64: DST = (__force u64) cpu_to_be64(DST); break; } CONT; ALU_END_TO_LE: switch (IMM) { case 16: DST = (__force u16) cpu_to_le16(DST); break; case 32: DST = (__force u32) cpu_to_le32(DST); break; case 64: DST = (__force u64) cpu_to_le64(DST); break; } CONT; /* CALL */ JMP_CALL: /* Function call scratches BPF_R1-BPF_R5 registers, * preserves BPF_R6-BPF_R9, and stores return value * into BPF_R0. */ BPF_R0 = (__bpf_call_base + insn->imm)(BPF_R1, BPF_R2, BPF_R3, BPF_R4, BPF_R5); CONT; /* JMP */ JMP_JA: insn += insn->off; CONT; JMP_JEQ_X: if (DST == SRC) { insn += insn->off; CONT_JMP; } CONT; JMP_JEQ_K: if (DST == IMM) { insn += insn->off; CONT_JMP; } CONT; JMP_JNE_X: if (DST != SRC) { insn += insn->off; CONT_JMP; } CONT; JMP_JNE_K: if (DST != IMM) { insn += insn->off; CONT_JMP; } CONT; JMP_JGT_X: if (DST > SRC) { insn += insn->off; CONT_JMP; } CONT; JMP_JGT_K: if (DST > IMM) { insn += insn->off; CONT_JMP; } CONT; JMP_JGE_X: if (DST >= SRC) { insn += insn->off; CONT_JMP; } CONT; JMP_JGE_K: if (DST >= IMM) { insn += insn->off; CONT_JMP; } CONT; JMP_JSGT_X: if (((s64) DST) > ((s64) SRC)) { insn += insn->off; CONT_JMP; } CONT; JMP_JSGT_K: if (((s64) DST) > ((s64) IMM)) { insn += insn->off; CONT_JMP; } CONT; JMP_JSGE_X: if (((s64) DST) >= ((s64) SRC)) { insn += insn->off; CONT_JMP; } CONT; JMP_JSGE_K: if (((s64) DST) >= ((s64) IMM)) { insn += insn->off; CONT_JMP; } CONT; JMP_JSET_X: if (DST & SRC) { insn += insn->off; CONT_JMP; } CONT; JMP_JSET_K: if (DST & IMM) { insn += insn->off; CONT_JMP; } CONT; JMP_EXIT: return BPF_R0; /* STX and ST and LDX*/ #define LDST(SIZEOP, SIZE) \ STX_MEM_##SIZEOP: \ *(SIZE *)(unsigned long) (DST + insn->off) = SRC; \ CONT; \ ST_MEM_##SIZEOP: \ *(SIZE *)(unsigned long) (DST + insn->off) = IMM; \ CONT; \ LDX_MEM_##SIZEOP: \ DST = *(SIZE *)(unsigned long) (SRC + insn->off); \ CONT; LDST(B, u8) LDST(H, u16) LDST(W, u32) LDST(DW, u64) #undef LDST STX_XADD_W: /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */ atomic_add((u32) SRC, (atomic_t *)(unsigned long) (DST + insn->off)); CONT; STX_XADD_DW: /* lock xadd *(u64 *)(dst_reg + off16) += src_reg */ atomic64_add((u64) SRC, (atomic64_t *)(unsigned long) (DST + insn->off)); CONT; LD_ABS_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + imm32)) */ off = IMM; 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[BPF_REG_CTX] * == BPF_R6, sk_convert_filter() saves it in BPF_R6, * internal BPF verifier will check that BPF_R6 == * ctx. * * BPF_ABS and BPF_IND are wrappers of function calls, * so they scratch BPF_R1-BPF_R5 registers, preserve * BPF_R6-BPF_R9, and store return value into BPF_R0. * * Implicit input: * ctx == skb == BPF_R6 == CTX * * Explicit input: * SRC == any register * IMM == 32-bit immediate * * Output: * BPF_R0 - 8/16/32-bit skb data converted to cpu endianness */ ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 4, &tmp); if (likely(ptr != NULL)) { BPF_R0 = get_unaligned_be32(ptr); CONT; } return 0; LD_ABS_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + imm32)) */ off = IMM; load_half: ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 2, &tmp); if (likely(ptr != NULL)) { BPF_R0 = get_unaligned_be16(ptr); CONT; } return 0; LD_ABS_B: /* BPF_R0 = *(u8 *) (skb->data + imm32) */ off = IMM; load_byte: ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 1, &tmp); if (likely(ptr != NULL)) { BPF_R0 = *(u8 *)ptr; CONT; } return 0; LD_IND_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + src_reg + imm32)) */ off = IMM + SRC; goto load_word; LD_IND_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + src_reg + imm32)) */ off = IMM + SRC; goto load_half; LD_IND_B: /* BPF_R0 = *(u8 *) (skb->data + src_reg + imm32) */ off = IMM + SRC; goto load_byte; default_label: /* If we ever reach this, we have a bug somewhere. */ WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code); return 0; } void __weak bpf_int_jit_compile(struct sk_filter *prog) { } /** * sk_filter_select_runtime - select execution runtime for BPF program * @fp: sk_filter populated with internal BPF program * * try to JIT internal BPF program, if JIT is not available select interpreter * BPF program will be executed via SK_RUN_FILTER() macro */ void sk_filter_select_runtime(struct sk_filter *fp) { fp->bpf_func = (void *) __sk_run_filter; /* Probe if internal BPF can be JITed */ bpf_int_jit_compile(fp); } EXPORT_SYMBOL_GPL(sk_filter_select_runtime); /* free internal BPF program */ void sk_filter_free(struct sk_filter *fp) { bpf_jit_free(fp); } EXPORT_SYMBOL_GPL(sk_filter_free);