From 6841de8b0d03cc9a4e0e928453623c13ee754f77 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 11 Aug 2016 18:17:16 -0700 Subject: bpf: allow helpers access the packet directly The helper functions like bpf_map_lookup_elem(map, key) were only allowing 'key' to point to the initialized stack area. That is causing performance degradation when programs need to process millions of packets per second and need to copy contents of the packet into the stack just to pass the stack pointer into the lookup() function. Allow such helpers read from the packet directly. All helpers that expect ARG_PTR_TO_MAP_KEY, ARG_PTR_TO_MAP_VALUE, ARG_PTR_TO_STACK assume byte aligned pointer, so no alignment concerns, only need to check that helper will not be accessing beyond the packet range verified by the prior 'if (ptr < data_end)' condition. For now allow this feature for XDP programs only. Later it can be relaxed for the clsact programs as well. Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/bpf/verifier.c | 61 ++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 43 insertions(+), 18 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d504722ebfa4..0cc46f1df358 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -930,14 +930,14 @@ static int check_func_arg(struct verifier_env *env, u32 regno, enum bpf_arg_type arg_type, struct bpf_call_arg_meta *meta) { - struct reg_state *reg = env->cur_state.regs + regno; - enum bpf_reg_type expected_type; + struct reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; + enum bpf_reg_type expected_type, type = reg->type; int err = 0; if (arg_type == ARG_DONTCARE) return 0; - if (reg->type == NOT_INIT) { + if (type == NOT_INIT) { verbose("R%d !read_ok\n", regno); return -EACCES; } @@ -950,16 +950,29 @@ static int check_func_arg(struct verifier_env *env, u32 regno, return 0; } + if (type == PTR_TO_PACKET && !may_write_pkt_data(env->prog->type)) { + verbose("helper access to the packet is not allowed for clsact\n"); + return -EACCES; + } + if (arg_type == ARG_PTR_TO_MAP_KEY || arg_type == ARG_PTR_TO_MAP_VALUE) { expected_type = PTR_TO_STACK; + if (type != PTR_TO_PACKET && type != expected_type) + goto err_type; } else if (arg_type == ARG_CONST_STACK_SIZE || arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { expected_type = CONST_IMM; + if (type != expected_type) + goto err_type; } else if (arg_type == ARG_CONST_MAP_PTR) { expected_type = CONST_PTR_TO_MAP; + if (type != expected_type) + goto err_type; } else if (arg_type == ARG_PTR_TO_CTX) { expected_type = PTR_TO_CTX; + if (type != expected_type) + goto err_type; } else if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_RAW_STACK) { expected_type = PTR_TO_STACK; @@ -967,20 +980,16 @@ static int check_func_arg(struct verifier_env *env, u32 regno, * passed in as argument, it's a CONST_IMM type. Final test * happens during stack boundary checking. */ - if (reg->type == CONST_IMM && reg->imm == 0) - expected_type = CONST_IMM; + if (type == CONST_IMM && reg->imm == 0) + /* final test in check_stack_boundary() */; + else if (type != PTR_TO_PACKET && type != expected_type) + goto err_type; meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK; } else { verbose("unsupported arg_type %d\n", arg_type); return -EFAULT; } - if (reg->type != expected_type) { - verbose("R%d type=%s expected=%s\n", regno, - reg_type_str[reg->type], reg_type_str[expected_type]); - return -EACCES; - } - if (arg_type == ARG_CONST_MAP_PTR) { /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ meta->map_ptr = reg->map_ptr; @@ -998,8 +1007,13 @@ static int check_func_arg(struct verifier_env *env, u32 regno, verbose("invalid map_ptr to access map->key\n"); return -EACCES; } - err = check_stack_boundary(env, regno, meta->map_ptr->key_size, - false, NULL); + if (type == PTR_TO_PACKET) + err = check_packet_access(env, regno, 0, + meta->map_ptr->key_size); + else + err = check_stack_boundary(env, regno, + meta->map_ptr->key_size, + false, NULL); } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { /* bpf_map_xxx(..., map_ptr, ..., value) call: * check [value, value + map->value_size) validity @@ -1009,9 +1023,13 @@ static int check_func_arg(struct verifier_env *env, u32 regno, verbose("invalid map_ptr to access map->value\n"); return -EACCES; } - err = check_stack_boundary(env, regno, - meta->map_ptr->value_size, - false, NULL); + if (type == PTR_TO_PACKET) + err = check_packet_access(env, regno, 0, + meta->map_ptr->value_size); + else + err = check_stack_boundary(env, regno, + meta->map_ptr->value_size, + false, NULL); } else if (arg_type == ARG_CONST_STACK_SIZE || arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO); @@ -1025,11 +1043,18 @@ static int check_func_arg(struct verifier_env *env, u32 regno, verbose("ARG_CONST_STACK_SIZE cannot be first argument\n"); return -EACCES; } - err = check_stack_boundary(env, regno - 1, reg->imm, - zero_size_allowed, meta); + if (regs[regno - 1].type == PTR_TO_PACKET) + err = check_packet_access(env, regno - 1, 0, reg->imm); + else + err = check_stack_boundary(env, regno - 1, reg->imm, + zero_size_allowed, meta); } return err; +err_type: + verbose("R%d type=%s expected=%s\n", regno, + reg_type_str[type], reg_type_str[expected_type]); + return -EACCES; } static int check_map_func_compatibility(struct bpf_map *map, int func_id) -- cgit From 1633ac0a2e774a9af339b9290ef33cd97a918c54 Mon Sep 17 00:00:00 2001 From: Aaron Yue Date: Thu, 11 Aug 2016 18:17:17 -0700 Subject: samples/bpf: add verifier tests for the helper access to the packet test various corner cases of the helper function access to the packet via crafted XDP programs. Signed-off-by: Aaron Yue Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- samples/bpf/test_verifier.c | 114 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 110 insertions(+), 4 deletions(-) diff --git a/samples/bpf/test_verifier.c b/samples/bpf/test_verifier.c index fe2fcec98c1f..78c6f131d94f 100644 --- a/samples/bpf/test_verifier.c +++ b/samples/bpf/test_verifier.c @@ -1449,7 +1449,7 @@ static struct bpf_test tests[] = { .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, { - "pkt: test1", + "direct packet access: test1", .insns = { BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, offsetof(struct __sk_buff, data)), @@ -1466,7 +1466,7 @@ static struct bpf_test tests[] = { .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, { - "pkt: test2", + "direct packet access: test2", .insns = { BPF_MOV64_IMM(BPF_REG_0, 1), BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1, @@ -1499,7 +1499,7 @@ static struct bpf_test tests[] = { .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, { - "pkt: test3", + "direct packet access: test3", .insns = { BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, offsetof(struct __sk_buff, data)), @@ -1511,7 +1511,7 @@ static struct bpf_test tests[] = { .prog_type = BPF_PROG_TYPE_SOCKET_FILTER, }, { - "pkt: test4", + "direct packet access: test4", .insns = { BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, offsetof(struct __sk_buff, data)), @@ -1528,6 +1528,112 @@ static struct bpf_test tests[] = { .result = REJECT, .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, + { + "helper access to packet: test1, valid packet_ptr range", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct xdp_md, data)), + BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1, + offsetof(struct xdp_md, data_end)), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_2), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 8), + BPF_JMP_REG(BPF_JGT, BPF_REG_1, BPF_REG_3, 5), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_MOV64_REG(BPF_REG_3, BPF_REG_2), + BPF_MOV64_IMM(BPF_REG_4, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_update_elem), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup = {5}, + .result_unpriv = ACCEPT, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_XDP, + }, + { + "helper access to packet: test2, unchecked packet_ptr", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct xdp_md, data)), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup = {1}, + .result = REJECT, + .errstr = "invalid access to packet", + .prog_type = BPF_PROG_TYPE_XDP, + }, + { + "helper access to packet: test3, variable add", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct xdp_md, data)), + BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1, + offsetof(struct xdp_md, data_end)), + BPF_MOV64_REG(BPF_REG_4, BPF_REG_2), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 8), + BPF_JMP_REG(BPF_JGT, BPF_REG_4, BPF_REG_3, 10), + BPF_LDX_MEM(BPF_B, BPF_REG_5, BPF_REG_2, 0), + BPF_MOV64_REG(BPF_REG_4, BPF_REG_2), + BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_5), + BPF_MOV64_REG(BPF_REG_5, BPF_REG_4), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, 8), + BPF_JMP_REG(BPF_JGT, BPF_REG_5, BPF_REG_3, 4), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_4), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup = {11}, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_XDP, + }, + { + "helper access to packet: test4, packet_ptr with bad range", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct xdp_md, data)), + BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1, + offsetof(struct xdp_md, data_end)), + BPF_MOV64_REG(BPF_REG_4, BPF_REG_2), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4), + BPF_JMP_REG(BPF_JGT, BPF_REG_4, BPF_REG_3, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup = {7}, + .result = REJECT, + .errstr = "invalid access to packet", + .prog_type = BPF_PROG_TYPE_XDP, + }, + { + "helper access to packet: test5, packet_ptr with too short range", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct xdp_md, data)), + BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1, + offsetof(struct xdp_md, data_end)), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, 1), + BPF_MOV64_REG(BPF_REG_4, BPF_REG_2), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 7), + BPF_JMP_REG(BPF_JGT, BPF_REG_4, BPF_REG_3, 3), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup = {6}, + .result = REJECT, + .errstr = "invalid access to packet", + .prog_type = BPF_PROG_TYPE_XDP, + }, }; static int probe_filter_length(struct bpf_insn *fp) -- cgit From 8937bd80fce64a25be23c7790459d93f7b1e9b79 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 11 Aug 2016 18:17:18 -0700 Subject: bpf: allow bpf_get_prandom_u32() to be used in tracing bpf_get_prandom_u32() was initially introduced for socket filters and later requested numberous times to be added to tracing bpf programs for the same reason as in socket filters: to be able to randomly select incoming events. Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/trace/bpf_trace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 6b794d6669a7..ad35213b8405 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -437,6 +437,8 @@ static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) return bpf_get_probe_write_proto(); case BPF_FUNC_current_task_under_cgroup: return &bpf_current_task_under_cgroup_proto; + case BPF_FUNC_get_prandom_u32: + return &bpf_get_prandom_u32_proto; default: return NULL; } -- cgit