On 2026/7/22 15:39, Philo Lu wrote:
From: Daniel Borkmann <[email protected]> commit e0fcb42bc6f41bab2895757d6610616b3820eff7 upstream. Extend the verifier_ld_ind BPF selftests with subprogs containing ld_{abs,ind} and craft the test in a way where the invalid register read is rejected in the fixed case. Also add a success case each, and add additional coverage related to the BTF return type enforcement. # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_ld_ind [...] #611/1 verifier_ld_ind/ld_ind: check calling conv, r1:OK #611/2 verifier_ld_ind/ld_ind: check calling conv, r1 @unpriv:OK #611/3 verifier_ld_ind/ld_ind: check calling conv, r2:OK #611/4 verifier_ld_ind/ld_ind: check calling conv, r2 @unpriv:OK #611/5 verifier_ld_ind/ld_ind: check calling conv, r3:OK #611/6 verifier_ld_ind/ld_ind: check calling conv, r3 @unpriv:OK #611/7 verifier_ld_ind/ld_ind: check calling conv, r4:OK #611/8 verifier_ld_ind/ld_ind: check calling conv, r4 @unpriv:OK #611/9 verifier_ld_ind/ld_ind: check calling conv, r5:OK #611/10 verifier_ld_ind/ld_ind: check calling conv, r5 @unpriv:OK #611/11 verifier_ld_ind/ld_ind: check calling conv, r7:OK #611/12 verifier_ld_ind/ld_ind: check calling conv, r7 @unpriv:OK #611/13 verifier_ld_ind/ld_abs: subprog early exit on ld_abs failure:OK #611/14 verifier_ld_ind/ld_ind: subprog early exit on ld_ind failure:OK #611/15 verifier_ld_ind/ld_abs: subprog with both paths safe:OK #611/16 verifier_ld_ind/ld_ind: subprog with both paths safe:OK #611/17 verifier_ld_ind/ld_abs: reject void return subprog:OK #611/18 verifier_ld_ind/ld_ind: reject void return subprog:OK #611 verifier_ld_ind:OK Summary: 1/18 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Alexei Starovoitov <[email protected]> Signed-off-by: Philo Lu <[email protected]>
Reviewed-by: Pu Lehui <[email protected]>
--- .../selftests/bpf/progs/verifier_ld_ind.c | 142 ++++++++++++++++++ 1 file changed, 142 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_ld_ind.c b/tools/testing/selftests/bpf/progs/verifier_ld_ind.c index c925ba9a2e74c..09e81b99eecb4 100644 --- a/tools/testing/selftests/bpf/progs/verifier_ld_ind.c +++ b/tools/testing/selftests/bpf/progs/verifier_ld_ind.c @@ -107,4 +107,146 @@ __naked void ind_check_calling_conv_r7(void) : __clobber_all); }+/*+ * ld_{abs,ind} subprog that always sets r0=1 on the success path. + * bpf_gen_ld_abs() emits a hidden exit with r0=0 when the load helper + * fails. The verifier must model this failure return so that callers + * account for r0=0 as a possible return value. + */ +__naked __noinline __used +static int ldabs_subprog(void) +{ + asm volatile ( + "r6 = r1;" + ".8byte %[ld_abs];" + "r0 = 1;" + "exit;" + : + : __imm_insn(ld_abs, BPF_LD_ABS(BPF_W, 0)) + : __clobber_all); +} + +__naked __noinline __used +static int ldind_subprog(void) +{ + asm volatile ( + "r6 = r1;" + "r7 = 0;" + ".8byte %[ld_ind];" + "r0 = 1;" + "exit;" + : + : __imm_insn(ld_ind, BPF_LD_IND(BPF_W, BPF_REG_7, 0)) + : __clobber_all); +} + +SEC("socket") +__description("ld_abs: subprog early exit on ld_abs failure") +__failure __msg("R9 !read_ok") +__naked void ld_abs_subprog_early_exit(void) +{ + asm volatile ( + "call ldabs_subprog;" + "if r0 != 0 goto l_exit_%=;" + "r0 = r9;" + "l_exit_%=:" + "r0 = 0;" + "exit;" + ::: __clobber_all); +} + +SEC("socket") +__description("ld_ind: subprog early exit on ld_ind failure") +__failure __msg("R9 !read_ok") +__naked void ld_ind_subprog_early_exit(void) +{ + asm volatile ( + "call ldind_subprog;" + "if r0 != 0 goto l_exit_%=;" + "r0 = r9;" + "l_exit_%=:" + "r0 = 0;" + "exit;" + ::: __clobber_all); +} + +SEC("socket") +__description("ld_abs: subprog with both paths safe") +__success +__naked void ld_abs_subprog_both_paths_safe(void) +{ + asm volatile ( + "call ldabs_subprog;" + "r0 = 0;" + "exit;" + ::: __clobber_all); +} + +SEC("socket") +__description("ld_ind: subprog with both paths safe") +__success +__naked void ld_ind_subprog_both_paths_safe(void) +{ + asm volatile ( + "call ldind_subprog;" + "r0 = 0;" + "exit;" + ::: __clobber_all); +} + +/* + * ld_{abs,ind} in subprogs require scalar (int) return type in BTF. + * A test with void return must be rejected. + */ +__naked __noinline __used +static void ldabs_void_subprog(void) +{ + asm volatile ( + "r6 = r1;" + ".8byte %[ld_abs];" + "r0 = 1;" + "exit;" + : + : __imm_insn(ld_abs, BPF_LD_ABS(BPF_W, 0)) + : __clobber_all); +} + +SEC("socket") +__description("ld_abs: reject void return subprog") +__failure __msg("LD_ABS is only allowed in functions that return 'int'") +__naked void ld_abs_void_subprog_reject(void) +{ + asm volatile ( + "call ldabs_void_subprog;" + "r0 = 0;" + "exit;" + ::: __clobber_all); +} + +__naked __noinline __used +static void ldind_void_subprog(void) +{ + asm volatile ( + "r6 = r1;" + "r7 = 0;" + ".8byte %[ld_ind];" + "r0 = 1;" + "exit;" + : + : __imm_insn(ld_ind, BPF_LD_IND(BPF_W, BPF_REG_7, 0)) + : __clobber_all); +} + +SEC("socket") +__description("ld_ind: reject void return subprog") +__failure __msg("LD_ABS is only allowed in functions that return 'int'") +__naked void ld_ind_void_subprog_reject(void) +{ + asm volatile ( + "call ldind_void_subprog;" + "r0 = 0;" + "exit;" + ::: __clobber_all); +} + char _license[] SEC("license") = "GPL";
