From ecfc3fcabbb5291d1e61600a3dac6cdbfdb04cb1 Mon Sep 17 00:00:00 2001 From: YueHaibing Date: Wed, 10 Apr 2019 21:49:23 +0800 Subject: [PATCH 1/6] MIPS: eBPF: Make ebpf_to_mips_reg() static Fix sparse warning: arch/mips/net/ebpf_jit.c:196:5: warning: symbol 'ebpf_to_mips_reg' was not declared. Should it be static? Reported-by: Hulk Robot Signed-off-by: YueHaibing Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov --- arch/mips/net/ebpf_jit.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c index 0effd3cba9a7..98bf0c222b5f 100644 --- a/arch/mips/net/ebpf_jit.c +++ b/arch/mips/net/ebpf_jit.c @@ -186,8 +186,9 @@ enum which_ebpf_reg { * separate frame pointer, so BPF_REG_10 relative accesses are * adjusted to be $sp relative. */ -int ebpf_to_mips_reg(struct jit_ctx *ctx, const struct bpf_insn *insn, - enum which_ebpf_reg w) +static int ebpf_to_mips_reg(struct jit_ctx *ctx, + const struct bpf_insn *insn, + enum which_ebpf_reg w) { int ebpf_reg = (w == src_reg || w == src_reg_no_fp) ? insn->src_reg : insn->dst_reg; From 8694d8c1f82cccec9380e0d3720b84eee315dfb7 Mon Sep 17 00:00:00 2001 From: Alban Crequy Date: Fri, 12 Apr 2019 14:40:50 +0200 Subject: [PATCH 2/6] tools: bpftool: fix infinite loop in map create "bpftool map create" has an infinite loop on "while (argc)". The error case is missing. Symptoms: when forgetting to type the keyword 'type' in front of 'hash': $ sudo bpftool map create /sys/fs/bpf/dir/foobar hash key 8 value 8 entries 128 (infinite loop, taking all the CPU) ^C After the patch: $ sudo bpftool map create /sys/fs/bpf/dir/foobar hash key 8 value 8 entries 128 Error: unknown arg hash Fixes: 0b592b5a01be ("tools: bpftool: add map create command") Signed-off-by: Alban Crequy Reviewed-by: Quentin Monnet Acked-by: Song Liu Reviewed-by: Jakub Kicinski Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov --- tools/bpf/bpftool/map.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index e0c650d91784..994a7e0d16fb 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -1151,6 +1151,9 @@ static int do_create(int argc, char **argv) return -1; } NEXT_ARG(); + } else { + p_err("unknown arg %s", *argv); + return -1; } } From 39391377f8ecf2fa4569e2fede624dc091bcd859 Mon Sep 17 00:00:00 2001 From: Matteo Croce Date: Sat, 13 Apr 2019 03:37:32 +0200 Subject: [PATCH 3/6] libbpf: add binary to gitignore Some binaries are generated when building libbpf from tools/lib/bpf/, namely libbpf.so.0.0.2 and libbpf.so.0. Add them to the local .gitignore. Signed-off-by: Matteo Croce Reviewed-by: Jakub Kicinski Acked-by: Song Liu Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/.gitignore | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/lib/bpf/.gitignore b/tools/lib/bpf/.gitignore index 4db74758c674..fecb78afea3f 100644 --- a/tools/lib/bpf/.gitignore +++ b/tools/lib/bpf/.gitignore @@ -1,3 +1,4 @@ libbpf_version.h FEATURE-DUMP.libbpf test_libbpf +libbpf.so.* From c6a9efa1d8353d8960d152e7d469d952b01495c0 Mon Sep 17 00:00:00 2001 From: Paul Chaignon Date: Wed, 24 Apr 2019 21:50:42 +0200 Subject: [PATCH 4/6] bpf: mark registers in all frames after pkt/null checks In case of a null check on a pointer inside a subprog, we should mark all registers with this pointer as either safe or unknown, in both the current and previous frames. Currently, only spilled registers and registers in the current frame are marked. Packet bound checks in subprogs have the same issue. This patch fixes it to mark registers in previous frames as well. A good reproducer for null checks looks as follow: 1: ptr = bpf_map_lookup_elem(map, &key); 2: ret = subprog(ptr) { 3: return ptr != NULL; 4: } 5: if (ret) 6: value = *ptr; With the above, the verifier will complain on line 6 because it sees ptr as map_value_or_null despite the null check in subprog 1. Note that this patch fixes another resulting bug when using bpf_sk_release(): 1: sk = bpf_sk_lookup_tcp(...); 2: subprog(sk) { 3: if (sk) 4: bpf_sk_release(sk); 5: } 6: if (!sk) 7: return 0; 8: return 1; In the above, mark_ptr_or_null_regs will warn on line 6 because it will try to free the reference state, even though it was already freed on line 3. Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)") Signed-off-by: Paul Chaignon Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 76 ++++++++++++++++++++++++++----------------- 1 file changed, 46 insertions(+), 30 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6c5a41f7f338..09d5d972c9ff 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4138,15 +4138,35 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) return 0; } +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) +{ + struct bpf_reg_state *reg; + int i; + + for (i = 0; i < MAX_BPF_REG; i++) { + reg = &state->regs[i]; + if (reg->type == type && reg->id == dst_reg->id) + /* keep the maximum range already checked */ + reg->range = max(reg->range, new_range); + } + + bpf_for_each_spilled_reg(i, state, reg) { + if (!reg) + continue; + if (reg->type == type && reg->id == dst_reg->id) + reg->range = max(reg->range, new_range); + } +} + static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, struct bpf_reg_state *dst_reg, enum bpf_reg_type type, bool range_right_open) { - struct bpf_func_state *state = vstate->frame[vstate->curframe]; - struct bpf_reg_state *regs = state->regs, *reg; u16 new_range; - int i, j; + int i; if (dst_reg->off < 0 || (dst_reg->off == 0 && range_right_open)) @@ -4211,20 +4231,9 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, * the range won't allow anything. * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. */ - for (i = 0; i < MAX_BPF_REG; i++) - if (regs[i].type == type && regs[i].id == dst_reg->id) - /* keep the maximum range already checked */ - regs[i].range = max(regs[i].range, new_range); - - for (j = 0; j <= vstate->curframe; j++) { - state = vstate->frame[j]; - bpf_for_each_spilled_reg(i, state, reg) { - if (!reg) - continue; - if (reg->type == type && reg->id == dst_reg->id) - reg->range = max(reg->range, new_range); - } - } + for (i = 0; i <= vstate->curframe; i++) + __find_good_pkt_pointers(vstate->frame[i], dst_reg, type, + new_range); } /* compute branch direction of the expression "if (reg opcode val) goto target;" @@ -4698,6 +4707,22 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state, } } +static void __mark_ptr_or_null_regs(struct bpf_func_state *state, u32 id, + bool is_null) +{ + struct bpf_reg_state *reg; + int i; + + for (i = 0; i < MAX_BPF_REG; i++) + mark_ptr_or_null_reg(state, &state->regs[i], id, is_null); + + bpf_for_each_spilled_reg(i, state, reg) { + if (!reg) + continue; + mark_ptr_or_null_reg(state, reg, id, is_null); + } +} + /* The logic is similar to find_good_pkt_pointers(), both could eventually * be folded together at some point. */ @@ -4705,10 +4730,10 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, bool is_null) { struct bpf_func_state *state = vstate->frame[vstate->curframe]; - struct bpf_reg_state *reg, *regs = state->regs; + struct bpf_reg_state *regs = state->regs; u32 ref_obj_id = regs[regno].ref_obj_id; u32 id = regs[regno].id; - int i, j; + int i; if (ref_obj_id && ref_obj_id == id && is_null) /* regs[regno] is in the " == NULL" branch. @@ -4717,17 +4742,8 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, */ WARN_ON_ONCE(release_reference_state(state, id)); - for (i = 0; i < MAX_BPF_REG; i++) - mark_ptr_or_null_reg(state, ®s[i], id, is_null); - - for (j = 0; j <= vstate->curframe; j++) { - state = vstate->frame[j]; - bpf_for_each_spilled_reg(i, state, reg) { - if (!reg) - continue; - mark_ptr_or_null_reg(state, reg, id, is_null); - } - } + for (i = 0; i <= vstate->curframe; i++) + __mark_ptr_or_null_regs(vstate->frame[i], id, is_null); } static bool try_match_pkt_pointers(const struct bpf_insn *insn, From 6dd7f14080473b655c247863e61b7c34424f0c83 Mon Sep 17 00:00:00 2001 From: Paul Chaignon Date: Wed, 24 Apr 2019 21:51:26 +0200 Subject: [PATCH 5/6] selftests/bpf: test cases for pkt/null checks in subprogs The first test case, for pointer null checks, is equivalent to the following pseudo-code. It checks that the verifier does not complain on line 6 and recognizes that ptr isn't null. 1: ptr = bpf_map_lookup_elem(map, &key); 2: ret = subprog(ptr) { 3: return ptr != NULL; 4: } 5: if (ret) 6: value = *ptr; The second test case, for packet bound checks, is equivalent to the following pseudo-code. It checks that the verifier does not complain on line 7 and recognizes that the packet is at least 1 byte long. 1: pkt_end = ctx.pkt_end; 2: ptr = ctx.pkt + 8; 3: ret = subprog(ptr, pkt_end) { 4: return ptr <= pkt_end; 5: } 6: if (ret) 7: value = *(u8 *)ctx.pkt; Signed-off-by: Paul Chaignon Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/verifier/calls.c | 25 +++++++++++++++++++ .../bpf/verifier/direct_packet_access.c | 22 ++++++++++++++++ 2 files changed, 47 insertions(+) diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c index fb11240b758b..9093a8f64dc6 100644 --- a/tools/testing/selftests/bpf/verifier/calls.c +++ b/tools/testing/selftests/bpf/verifier/calls.c @@ -374,6 +374,31 @@ .prog_type = BPF_PROG_TYPE_XDP, .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, }, +{ + "calls: ptr null check in subprog", + .insns = { + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6, 0), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .errstr_unpriv = "function calls to other bpf functions are allowed for root only", + .fixup_map_hash_48b = { 3 }, + .result_unpriv = REJECT, + .result = ACCEPT, + .retval = 0, +}, { "calls: two calls with args", .insns = { diff --git a/tools/testing/selftests/bpf/verifier/direct_packet_access.c b/tools/testing/selftests/bpf/verifier/direct_packet_access.c index e3fc22e672c2..d5c596fdc4b9 100644 --- a/tools/testing/selftests/bpf/verifier/direct_packet_access.c +++ b/tools/testing/selftests/bpf/verifier/direct_packet_access.c @@ -631,3 +631,25 @@ .errstr = "invalid access to packet", .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, +{ + "direct packet access: test29 (reg > pkt_end in subprog)", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1, + offsetof(struct __sk_buff, data)), + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct __sk_buff, data_end)), + BPF_MOV64_REG(BPF_REG_3, BPF_REG_6), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, 8), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 4), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_REG(BPF_JGT, BPF_REG_3, BPF_REG_2, 1), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, +}, From 0edd6b64d1939e9e9168ff27947995bb7751db5d Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 23 Apr 2019 21:55:59 +0200 Subject: [PATCH 6/6] bpf: Fix preempt_enable_no_resched() abuse Unless the very next line is schedule(), or implies it, one must not use preempt_enable_no_resched(). It can cause a preemption to go missing and thereby cause arbitrary delays, breaking the PREEMPT=y invariant. Cc: Roman Gushchin Cc: Alexei Starovoitov Cc: Daniel Borkmann Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f02367faa58d..944ccc310201 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -510,7 +510,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, } \ _out: \ rcu_read_unlock(); \ - preempt_enable_no_resched(); \ + preempt_enable(); \ _ret; \ })