diff options
-rw-r--r-- | include/linux/bpf_verifier.h | 2 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 129 |
2 files changed, 108 insertions, 23 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 391bc1480dfb..f49165f9229c 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -45,7 +45,7 @@ struct bpf_reg_state { enum bpf_reg_type type; union { /* valid when type == PTR_TO_PACKET */ - u16 range; + int range; /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | * PTR_TO_MAP_VALUE_OR_NULL diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e4dcc23b52c0..510a54471f13 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2978,7 +2978,9 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, regno); return -EACCES; } - err = __check_mem_access(env, regno, off, size, reg->range, + + err = reg->range < 0 ? -EINVAL : + __check_mem_access(env, regno, off, size, reg->range, zero_size_allowed); if (err) { verbose(env, "R%d offset is outside of the packet\n", regno); @@ -5018,6 +5020,32 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env) __clear_all_pkt_pointers(env, vstate->frame[i]); } +enum { + AT_PKT_END = -1, + BEYOND_PKT_END = -2, +}; + +static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open) +{ + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *reg = &state->regs[regn]; + + if (reg->type != PTR_TO_PACKET) + /* PTR_TO_PACKET_META is not supported yet */ + return; + + /* The 'reg' is pkt > pkt_end or pkt >= pkt_end. + * How far beyond pkt_end it goes is unknown. + * if (!range_open) it's the case of pkt >= pkt_end + * if (range_open) it's the case of pkt > pkt_end + * hence this pointer is at least 1 byte bigger than pkt_end + */ + if (range_open) + reg->range = BEYOND_PKT_END; + else + reg->range = AT_PKT_END; +} + static void release_reg_references(struct bpf_verifier_env *env, struct bpf_func_state *state, int ref_obj_id) @@ -7193,7 +7221,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) static void __find_good_pkt_pointers(struct bpf_func_state *state, struct bpf_reg_state *dst_reg, - enum bpf_reg_type type, u16 new_range) + enum bpf_reg_type type, int new_range) { struct bpf_reg_state *reg; int i; @@ -7218,8 +7246,7 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, enum bpf_reg_type type, bool range_right_open) { - u16 new_range; - int i; + int new_range, i; if (dst_reg->off < 0 || (dst_reg->off == 0 && range_right_open)) @@ -7470,6 +7497,67 @@ static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, return is_branch64_taken(reg, val, opcode); } +static int flip_opcode(u32 opcode) +{ + /* How can we transform "a <op> b" into "b <op> a"? */ + static const u8 opcode_flip[16] = { + /* these stay the same */ + [BPF_JEQ >> 4] = BPF_JEQ, + [BPF_JNE >> 4] = BPF_JNE, + [BPF_JSET >> 4] = BPF_JSET, + /* these swap "lesser" and "greater" (L and G in the opcodes) */ + [BPF_JGE >> 4] = BPF_JLE, + [BPF_JGT >> 4] = BPF_JLT, + [BPF_JLE >> 4] = BPF_JGE, + [BPF_JLT >> 4] = BPF_JGT, + [BPF_JSGE >> 4] = BPF_JSLE, + [BPF_JSGT >> 4] = BPF_JSLT, + [BPF_JSLE >> 4] = BPF_JSGE, + [BPF_JSLT >> 4] = BPF_JSGT + }; + return opcode_flip[opcode >> 4]; +} + +static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg, + u8 opcode) +{ + struct bpf_reg_state *pkt; + + if (src_reg->type == PTR_TO_PACKET_END) { + pkt = dst_reg; + } else if (dst_reg->type == PTR_TO_PACKET_END) { + pkt = src_reg; + opcode = flip_opcode(opcode); + } else { + return -1; + } + + if (pkt->range >= 0) + return -1; + + switch (opcode) { + case BPF_JLE: + /* pkt <= pkt_end */ + fallthrough; + case BPF_JGT: + /* pkt > pkt_end */ + if (pkt->range == BEYOND_PKT_END) + /* pkt has at last one extra byte beyond pkt_end */ + return opcode == BPF_JGT; + break; + case BPF_JLT: + /* pkt < pkt_end */ + fallthrough; + case BPF_JGE: + /* pkt >= pkt_end */ + if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END) + return opcode == BPF_JGE; + break; + } + return -1; +} + /* Adjusts the register min/max values in the case that the dst_reg is the * variable register that we are working on, and src_reg is a constant or we're * simply doing a BPF_K check. @@ -7640,23 +7728,7 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, u64 val, u32 val32, u8 opcode, bool is_jmp32) { - /* How can we transform "a <op> b" into "b <op> a"? */ - static const u8 opcode_flip[16] = { - /* these stay the same */ - [BPF_JEQ >> 4] = BPF_JEQ, - [BPF_JNE >> 4] = BPF_JNE, - [BPF_JSET >> 4] = BPF_JSET, - /* these swap "lesser" and "greater" (L and G in the opcodes) */ - [BPF_JGE >> 4] = BPF_JLE, - [BPF_JGT >> 4] = BPF_JLT, - [BPF_JLE >> 4] = BPF_JGE, - [BPF_JLT >> 4] = BPF_JGT, - [BPF_JSGE >> 4] = BPF_JSLE, - [BPF_JSGT >> 4] = BPF_JSLT, - [BPF_JSLE >> 4] = BPF_JSGE, - [BPF_JSLT >> 4] = BPF_JSGT - }; - opcode = opcode_flip[opcode >> 4]; + opcode = flip_opcode(opcode); /* This uses zero as "not present in table"; luckily the zero opcode, * BPF_JA, can't get here. */ @@ -7825,6 +7897,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' > pkt_end, pkt_meta' > pkt_data */ find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, false); + mark_pkt_end(other_branch, insn->dst_reg, true); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -7832,6 +7905,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end > pkt_data', pkt_data > pkt_meta' */ find_good_pkt_pointers(other_branch, src_reg, src_reg->type, true); + mark_pkt_end(this_branch, insn->src_reg, false); } else { return false; } @@ -7844,6 +7918,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' < pkt_end, pkt_meta' < pkt_data */ find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, true); + mark_pkt_end(this_branch, insn->dst_reg, false); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -7851,6 +7926,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end < pkt_data', pkt_data > pkt_meta' */ find_good_pkt_pointers(this_branch, src_reg, src_reg->type, false); + mark_pkt_end(other_branch, insn->src_reg, true); } else { return false; } @@ -7863,6 +7939,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */ find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, true); + mark_pkt_end(other_branch, insn->dst_reg, false); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -7870,6 +7947,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */ find_good_pkt_pointers(other_branch, src_reg, src_reg->type, false); + mark_pkt_end(this_branch, insn->src_reg, true); } else { return false; } @@ -7882,6 +7960,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */ find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, false); + mark_pkt_end(this_branch, insn->dst_reg, true); } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) || (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && @@ -7889,6 +7968,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */ find_good_pkt_pointers(this_branch, src_reg, src_reg->type, true); + mark_pkt_end(other_branch, insn->src_reg, false); } else { return false; } @@ -7988,6 +8068,10 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, src_reg->var_off.value, opcode, is_jmp32); + } else if (reg_is_pkt_pointer_any(dst_reg) && + reg_is_pkt_pointer_any(src_reg) && + !is_jmp32) { + pred = is_pkt_ptr_branch_taken(dst_reg, src_reg, opcode); } if (pred >= 0) { @@ -7996,7 +8080,8 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, */ if (!__is_pointer_value(false, dst_reg)) err = mark_chain_precision(env, insn->dst_reg); - if (BPF_SRC(insn->code) == BPF_X && !err) + if (BPF_SRC(insn->code) == BPF_X && !err && + !__is_pointer_value(false, src_reg)) err = mark_chain_precision(env, insn->src_reg); if (err) return err; |