From 732fa32330667a80ce4985ca81b6e9d6b2ad2072 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Thu, 11 Feb 2021 09:20:29 +0100 Subject: [PATCH 1/2] selftests/bpf: Convert test_xdp_redirect.sh to bash MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The test_xdp_redirect.sh script uses a bash feature, '&>'. On systems, e.g. Debian, where '/bin/sh' is dash, this will not work as expected. Use bash in the shebang to get the expected behavior. Further, using 'set -e' means that the error of a command cannot be captured without the command being executed with '&&' or '||'. Let us restructure the ping-commands, and use them as an if-expression, so that we can capture the return value. v4: Added missing Fixes:, and removed local variables. (Andrii) v3: Reintroduced /bin/bash, and kept 'set -e'. (Andrii) v2: Kept /bin/sh and removed bashisms. (Randy) Fixes: 996139e801fd ("selftests: bpf: add a test for XDP redirect") Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210211082029.1687666-1-bjorn.topel@gmail.com --- tools/testing/selftests/bpf/test_xdp_redirect.sh | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/bpf/test_xdp_redirect.sh b/tools/testing/selftests/bpf/test_xdp_redirect.sh index dd80f0c84afb..c033850886f4 100755 --- a/tools/testing/selftests/bpf/test_xdp_redirect.sh +++ b/tools/testing/selftests/bpf/test_xdp_redirect.sh @@ -1,4 +1,4 @@ -#!/bin/sh +#!/bin/bash # Create 2 namespaces with two veth peers, and # forward packets in-between using generic XDP # @@ -57,12 +57,8 @@ test_xdp_redirect() ip link set dev veth1 $xdpmode obj test_xdp_redirect.o sec redirect_to_222 &> /dev/null ip link set dev veth2 $xdpmode obj test_xdp_redirect.o sec redirect_to_111 &> /dev/null - ip netns exec ns1 ping -c 1 10.1.1.22 &> /dev/null - local ret1=$? - ip netns exec ns2 ping -c 1 10.1.1.11 &> /dev/null - local ret2=$? - - if [ $ret1 -eq 0 -a $ret2 -eq 0 ]; then + if ip netns exec ns1 ping -c 1 10.1.1.22 &> /dev/null && + ip netns exec ns2 ping -c 1 10.1.1.11 &> /dev/null; then echo "selftests: test_xdp_redirect $xdpmode [PASS]"; else ret=1 From 9b00f1b78809309163dda2d044d9e94a3c0248a3 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 10 Feb 2021 14:14:42 +0100 Subject: [PATCH 2/2] bpf: Fix truncation handling for mod32 dst reg wrt zero Recently noticed that when mod32 with a known src reg of 0 is performed, then the dst register is 32-bit truncated in verifier: 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 0: (b7) r0 = 0 1: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0 1: (b7) r1 = -1 2: R0_w=inv0 R1_w=inv-1 R10=fp0 2: (b4) w2 = -1 3: R0_w=inv0 R1_w=inv-1 R2_w=inv4294967295 R10=fp0 3: (9c) w1 %= w0 4: R0_w=inv0 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 4: (b7) r0 = 1 5: R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 5: (1d) if r1 == r2 goto pc+1 R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 6: R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 6: (b7) r0 = 2 7: R0_w=inv2 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 7: (95) exit 7: R0=inv1 R1=inv(id=0,umin_value=4294967295,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2=inv4294967295 R10=fp0 7: (95) exit However, as a runtime result, we get 2 instead of 1, meaning the dst register does not contain (u32)-1 in this case. The reason is fairly straight forward given the 0 test leaves the dst register as-is: # ./bpftool p d x i 23 0: (b7) r0 = 0 1: (b7) r1 = -1 2: (b4) w2 = -1 3: (16) if w0 == 0x0 goto pc+1 4: (9c) w1 %= w0 5: (b7) r0 = 1 6: (1d) if r1 == r2 goto pc+1 7: (b7) r0 = 2 8: (95) exit This was originally not an issue given the dst register was marked as completely unknown (aka 64 bit unknown). However, after 468f6eafa6c4 ("bpf: fix 32-bit ALU op verification") the verifier casts the register output to 32 bit, and hence it becomes 32 bit unknown. Note that for the case where the src register is unknown, the dst register is marked 64 bit unknown. After the fix, the register is truncated by the runtime and the test passes: # ./bpftool p d x i 23 0: (b7) r0 = 0 1: (b7) r1 = -1 2: (b4) w2 = -1 3: (16) if w0 == 0x0 goto pc+2 4: (9c) w1 %= w0 5: (05) goto pc+1 6: (bc) w1 = w1 7: (b7) r0 = 1 8: (1d) if r1 == r2 goto pc+1 9: (b7) r0 = 2 10: (95) exit Semantics also match with {R,W}x mod{64,32} 0 -> {R,W}x. Invalid div has always been {R,W}x div{64,32} 0 -> 0. Rewrites are as follows: mod32: mod64: (16) if w0 == 0x0 goto pc+2 (15) if r0 == 0x0 goto pc+1 (9c) w1 %= w0 (9f) r1 %= r0 (05) goto pc+1 (bc) w1 = w1 Fixes: 468f6eafa6c4 ("bpf: fix 32-bit ALU op verification") Signed-off-by: Daniel Borkmann Reviewed-by: John Fastabend Acked-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 37581919e050..20babdd06278 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11006,7 +11006,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) bool isdiv = BPF_OP(insn->code) == BPF_DIV; struct bpf_insn *patchlet; struct bpf_insn chk_and_div[] = { - /* Rx div 0 -> 0 */ + /* [R,W]x div 0 -> 0 */ BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JNE | BPF_K, insn->src_reg, 0, 2, 0), @@ -11015,16 +11015,18 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) *insn, }; struct bpf_insn chk_and_mod[] = { - /* Rx mod 0 -> Rx */ + /* [R,W]x mod 0 -> [R,W]x */ BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JEQ | BPF_K, insn->src_reg, - 0, 1, 0), + 0, 1 + (is64 ? 0 : 1), 0), *insn, + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + BPF_MOV32_REG(insn->dst_reg, insn->dst_reg), }; patchlet = isdiv ? chk_and_div : chk_and_mod; cnt = isdiv ? ARRAY_SIZE(chk_and_div) : - ARRAY_SIZE(chk_and_mod); + ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0); new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt); if (!new_prog)