bpf_do_misc_fixups() now queues its patches and applies them at once. Check the xlated code for forward and backward jumps to a patched insn, jumps over patches, and a may_goto whose jump leaves its own patch and crosses another one.
Signed-off-by: Qiliang Yuan <[email protected]> --- tools/testing/selftests/bpf/prog_tests/verifier.c | 2 + .../selftests/bpf/progs/verifier_patch_list.c | 120 +++++++++++++++++++++ 2 files changed, 122 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index 8a6d341b754ac..af107b0c1595e 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -90,6 +90,7 @@ #include "verifier_netfilter_retcode.skel.h" #include "verifier_bpf_fastcall.skel.h" #include "verifier_or_jmp32_k.skel.h" +#include "verifier_patch_list.skel.h" #include "verifier_percpu_addr.skel.h" #include "verifier_precision.skel.h" #include "verifier_prevent_map_lookup.skel.h" @@ -273,6 +274,7 @@ void test_verifier_netfilter_ctx(void) { RUN(verifier_netfilter_ctx); } void test_verifier_netfilter_retcode(void) { RUN(verifier_netfilter_retcode); } void test_verifier_bpf_fastcall(void) { RUN(verifier_bpf_fastcall); } void test_verifier_or_jmp32_k(void) { RUN(verifier_or_jmp32_k); } +void test_verifier_patch_list(void) { RUN(verifier_patch_list); } void test_verifier_percpu_addr(void) { RUN(verifier_percpu_addr); } void test_verifier_precision(void) { RUN(verifier_precision); } void test_verifier_prevent_map_lookup(void) { RUN(verifier_prevent_map_lookup); } diff --git a/tools/testing/selftests/bpf/progs/verifier_patch_list.c b/tools/testing/selftests/bpf/progs/verifier_patch_list.c new file mode 100644 index 0000000000000..268cebd179984 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_patch_list.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include "../../../include/linux/filter.h" +#include "bpf_misc.h" + +/* + * bpf_do_misc_fixups() guards each division by a register against division + * by zero with a 4 insn patch. Jumps to a patched insn must land on the + * first insn of its patch, other jumps must follow the insns they target. + */ + +SEC("raw_tp") +__description("patch list: forward jumps to and over patched insns") +__arch_x86_64 +__arch_arm64 +__success +__xlated("0: call") +__xlated("1: r1 = r0") +__xlated("2: r0 = 7") +__xlated("3: if r1 > 0x5 goto pc+1") +__xlated("4: r0 = 9") +__xlated("5: if r1 != 0x0 goto pc+2") +__xlated("6: w0 ^= w0") +__xlated("7: goto pc+1") +__xlated("8: r0 /= r1") +__xlated("9: if r0 > 0x3 goto pc+4") +__xlated("10: if r1 != 0x0 goto pc+2") +__xlated("11: w0 ^= w0") +__xlated("12: goto pc+1") +__xlated("13: r0 /= r1") +__xlated("14: exit") +__naked void patch_list_forward(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = r0;" + "r0 = 7;" + "if r1 > 5 goto l0_%=;" + "r0 = 9;" +"l0_%=:" + "r0 /= r1;" + "if r0 > 3 goto l1_%=;" + "r0 /= r1;" +"l1_%=:" + "exit;" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("raw_tp") +__description("patch list: backward jump to a patched insn") +__arch_x86_64 +__arch_arm64 +__success +__xlated("0: call") +__xlated("1: r1 = r0") +__xlated("2: r2 = 0") +__xlated("3: if r1 != 0x0 goto pc+2") +__xlated("4: w0 ^= w0") +__xlated("5: goto pc+1") +__xlated("6: r0 /= r1") +__xlated("7: r2 += 1") +__xlated("8: if r2 < 0x3 goto pc-6") +__xlated("9: exit") +__naked void patch_list_backward(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = r0;" + "r2 = 0;" +"l0_%=:" + "r0 /= r1;" + "r2 += 1;" + "if r2 < 3 goto l0_%=;" + "exit;" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +/* The jump of may_goto leaves its own patch and crosses another one. */ +SEC("raw_tp") +__description("patch list: may_goto between patched insns") +__arch_x86_64 +__success +__xlated("0: *(u64 *)(r10 -16) = 65535") +__xlated("1: *(u64 *)(r10 -8) = 0") +__xlated("2: call") +__xlated("3: r1 = r0") +__xlated("4: if r1 != 0x0 goto pc+2") +__xlated("5: w0 ^= w0") +__xlated("6: goto pc+1") +__xlated("7: r0 /= r1") +__xlated("8: r12 = *(u64 *)(r10 -16)") +__xlated("9: if r12 == 0x0 goto pc+9") +__xlated("...") +__xlated("15: if r1 != 0x0 goto pc+2") +__xlated("16: w0 ^= w0") +__xlated("17: goto pc+1") +__xlated("18: r0 /= r1") +__xlated("19: exit") +__naked void patch_list_may_goto(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = r0;" + "r0 /= r1;" + ".8byte %[may_goto];" + "r0 /= r1;" + "exit;" + : + : __imm(bpf_get_prandom_u32), + __imm_insn(may_goto, BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, 1 /* offset */, 0)) + : __clobber_all); +} + +char _license[] SEC("license") = "GPL"; -- 2.43.0
