On Tue, 6 Sept 2022 at 17:13, Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> wrote: > > We need to also export the kfunc set to the syscall program type, > and then add a couple of eBPF programs that are testing those calls. > > The first one checks for valid access, and the second one is OK > from a static analysis point of view but fails at run time because > we are trying to access outside of the allocated memory. > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> > > --- CI is failing for test_progs-no_alu32: https://github.com/kernel-patches/bpf/runs/8220916615?check_suite_focus=true > > changes in v11: > - use new way of declaring tests > > changes in v10: > - use new definitions for tests in an array > - add a new kfunc syscall_test_null_fail test > > no changes in v9 > > no changes in v8 > > changes in v7: > - add 1 more case to ensure we can read the entire sizeof(ctx) > - add a test case for when the context is NULL > > new in v6 > --- > net/bpf/test_run.c | 1 + > .../selftests/bpf/prog_tests/kfunc_call.c | 143 +++++++++++++++++- > .../selftests/bpf/progs/kfunc_call_fail.c | 39 +++++ > .../selftests/bpf/progs/kfunc_call_test.c | 38 +++++ > 4 files changed, 214 insertions(+), 7 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/kfunc_call_fail.c > > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c > index 25d8ecf105aa..f16baf977a21 100644 > --- a/net/bpf/test_run.c > +++ b/net/bpf/test_run.c > @@ -1634,6 +1634,7 @@ static int __init bpf_prog_test_run_init(void) > > ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_prog_test_kfunc_set); > ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_prog_test_kfunc_set); > + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_prog_test_kfunc_set); > return ret ?: register_btf_id_dtor_kfuncs(bpf_prog_test_dtor_kfunc, > ARRAY_SIZE(bpf_prog_test_dtor_kfunc), > THIS_MODULE); > diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_call.c b/tools/testing/selftests/bpf/prog_tests/kfunc_call.c > index 9dfbe5355a2d..d5881c3331a8 100644 > --- a/tools/testing/selftests/bpf/prog_tests/kfunc_call.c > +++ b/tools/testing/selftests/bpf/prog_tests/kfunc_call.c > @@ -2,6 +2,7 @@ > /* Copyright (c) 2021 Facebook */ > #include <test_progs.h> > #include <network_helpers.h> > +#include "kfunc_call_fail.skel.h" > #include "kfunc_call_test.skel.h" > #include "kfunc_call_test.lskel.h" > #include "kfunc_call_test_subprog.skel.h" > @@ -10,37 +11,96 @@ > > #include "cap_helpers.h" > > +static size_t log_buf_sz = 1048576; /* 1 MB */ > +static char obj_log_buf[1048576]; > + > +enum kfunc_test_type { > + tc_test = 0, > + syscall_test, > + syscall_null_ctx_test, > +}; > + > struct kfunc_test_params { > const char *prog_name; > unsigned long lskel_prog_desc_offset; > int retval; > + enum kfunc_test_type test_type; > + const char *expected_err_msg; > }; > > -#define TC_TEST(name, __retval) \ > +#define __BPF_TEST_SUCCESS(name, __retval, type) \ > { \ > .prog_name = #name, \ > .lskel_prog_desc_offset = offsetof(struct kfunc_call_test_lskel, progs.name), \ > .retval = __retval, \ > + .test_type = type, \ > + .expected_err_msg = NULL, \ > + } > + > +#define __BPF_TEST_FAIL(name, __retval, type, error_msg) \ > + { \ > + .prog_name = #name, \ > + .lskel_prog_desc_offset = 0 /* unused when test is failing */, \ > + .retval = __retval, \ > + .test_type = type, \ > + .expected_err_msg = error_msg, \ > } > > +#define TC_TEST(name, retval) __BPF_TEST_SUCCESS(name, retval, tc_test) > +#define SYSCALL_TEST(name, retval) __BPF_TEST_SUCCESS(name, retval, syscall_test) > +#define SYSCALL_NULL_CTX_TEST(name, retval) __BPF_TEST_SUCCESS(name, retval, syscall_null_ctx_test) > + > +#define SYSCALL_NULL_CTX_FAIL(name, retval, error_msg) \ > + __BPF_TEST_FAIL(name, retval, syscall_null_ctx_test, error_msg) > + > static struct kfunc_test_params kfunc_tests[] = { > + /* failure cases: > + * if retval is 0 -> the program will fail to load and the error message is an error > + * if retval is not 0 -> the program can be loaded but running it will gives the > + * provided return value. The error message is thus the one > + * from a successful load > + */ > + SYSCALL_NULL_CTX_FAIL(kfunc_syscall_test_fail, -EINVAL, "processed 4 insns"), > + SYSCALL_NULL_CTX_FAIL(kfunc_syscall_test_null_fail, -EINVAL, "processed 4 insns"), > + > + /* success cases */ > TC_TEST(kfunc_call_test1, 12), > TC_TEST(kfunc_call_test2, 3), > TC_TEST(kfunc_call_test_ref_btf_id, 0), > + SYSCALL_TEST(kfunc_syscall_test, 0), > + SYSCALL_NULL_CTX_TEST(kfunc_syscall_test_null, 0), > +}; > + > +struct syscall_test_args { > + __u8 data[16]; > + size_t size; > }; > > static void verify_success(struct kfunc_test_params *param) > { > struct kfunc_call_test_lskel *lskel = NULL; > + LIBBPF_OPTS(bpf_test_run_opts, topts); > struct bpf_prog_desc *lskel_prog; > struct kfunc_call_test *skel; > struct bpf_program *prog; > int prog_fd, err; > - LIBBPF_OPTS(bpf_test_run_opts, topts, > - .data_in = &pkt_v4, > - .data_size_in = sizeof(pkt_v4), > - .repeat = 1, > - ); > + struct syscall_test_args args = { > + .size = 10, > + }; > + > + switch (param->test_type) { > + case syscall_test: > + topts.ctx_in = &args; > + topts.ctx_size_in = sizeof(args); > + /* fallthrough */ > + case syscall_null_ctx_test: > + break; > + case tc_test: > + topts.data_in = &pkt_v4; > + topts.data_size_in = sizeof(pkt_v4); > + topts.repeat = 1; > + break; > + } > > /* first test with normal libbpf */ > skel = kfunc_call_test__open_and_load(); > @@ -79,6 +139,72 @@ static void verify_success(struct kfunc_test_params *param) > kfunc_call_test_lskel__destroy(lskel); > } > > +static void verify_fail(struct kfunc_test_params *param) > +{ > + LIBBPF_OPTS(bpf_object_open_opts, opts); > + LIBBPF_OPTS(bpf_test_run_opts, topts); > + struct bpf_program *prog; > + struct kfunc_call_fail *skel; > + int prog_fd, err; > + struct syscall_test_args args = { > + .size = 10, > + }; > + > + opts.kernel_log_buf = obj_log_buf; > + opts.kernel_log_size = log_buf_sz; > + opts.kernel_log_level = 1; > + > + switch (param->test_type) { > + case syscall_test: > + topts.ctx_in = &args; > + topts.ctx_size_in = sizeof(args); > + /* fallthrough */ > + case syscall_null_ctx_test: > + break; > + case tc_test: > + topts.data_in = &pkt_v4; > + topts.data_size_in = sizeof(pkt_v4); > + break; > + topts.repeat = 1; > + } > + > + skel = kfunc_call_fail__open_opts(&opts); > + if (!ASSERT_OK_PTR(skel, "kfunc_call_fail__open_opts")) > + goto cleanup; > + > + prog = bpf_object__find_program_by_name(skel->obj, param->prog_name); > + if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name")) > + goto cleanup; > + > + bpf_program__set_autoload(prog, true); > + > + err = kfunc_call_fail__load(skel); > + if (!param->retval) { > + /* the verifier is supposed to complain and refuses to load */ > + if (!ASSERT_ERR(err, "unexpected load success")) > + goto out_err; > + > + } else { > + /* the program is loaded but must dynamically fail */ > + if (!ASSERT_OK(err, "unexpected load error")) > + goto out_err; > + > + prog_fd = bpf_program__fd(prog); > + err = bpf_prog_test_run_opts(prog_fd, &topts); > + if (!ASSERT_EQ(err, param->retval, param->prog_name)) > + goto out_err; > + } > + > +out_err: > + if (!ASSERT_OK_PTR(strstr(obj_log_buf, param->expected_err_msg), "expected_err_msg")) { > + fprintf(stderr, "Expected err_msg: %s\n", param->expected_err_msg); > + fprintf(stderr, "Verifier output: %s\n", obj_log_buf); > + } > + > +cleanup: > + kfunc_call_fail__destroy(skel); > +} > + > static void test_main(void) > { > int i; > @@ -87,7 +213,10 @@ static void test_main(void) > if (!test__start_subtest(kfunc_tests[i].prog_name)) > continue; > > - verify_success(&kfunc_tests[i]); > + if (!kfunc_tests[i].expected_err_msg) > + verify_success(&kfunc_tests[i]); > + else > + verify_fail(&kfunc_tests[i]); > } > } > > diff --git a/tools/testing/selftests/bpf/progs/kfunc_call_fail.c b/tools/testing/selftests/bpf/progs/kfunc_call_fail.c > new file mode 100644 > index 000000000000..4168027f2ab1 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/kfunc_call_fail.c > @@ -0,0 +1,39 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2021 Facebook */ > +#include <vmlinux.h> > +#include <bpf/bpf_helpers.h> > + > +extern void bpf_kfunc_call_test_mem_len_pass1(void *mem, int len) __ksym; > + > +struct syscall_test_args { > + __u8 data[16]; > + size_t size; > +}; > + > +SEC("?syscall") > +int kfunc_syscall_test_fail(struct syscall_test_args *args) > +{ > + bpf_kfunc_call_test_mem_len_pass1(&args->data, sizeof(*args) + 1); > + > + return 0; > +} > + > +SEC("?syscall") > +int kfunc_syscall_test_null_fail(struct syscall_test_args *args) > +{ > + /* Must be called with args as a NULL pointer > + * we do not check for it to have the verifier consider that > + * the pointer might not be null, and so we can load it. > + * > + * So the following can not be added: > + * > + * if (args) > + * return -22; > + */ > + > + bpf_kfunc_call_test_mem_len_pass1(args, sizeof(*args)); > + > + return 0; > +} > + > +char _license[] SEC("license") = "GPL"; > diff --git a/tools/testing/selftests/bpf/progs/kfunc_call_test.c b/tools/testing/selftests/bpf/progs/kfunc_call_test.c > index 5aecbb9fdc68..94c05267e5e7 100644 > --- a/tools/testing/selftests/bpf/progs/kfunc_call_test.c > +++ b/tools/testing/selftests/bpf/progs/kfunc_call_test.c > @@ -92,4 +92,42 @@ int kfunc_call_test_pass(struct __sk_buff *skb) > return 0; > } > > +struct syscall_test_args { > + __u8 data[16]; > + size_t size; > +}; > + > +SEC("syscall") > +int kfunc_syscall_test(struct syscall_test_args *args) > +{ > + const int size = args->size; > + > + if (size > sizeof(args->data)) > + return -7; /* -E2BIG */ > + Looks like it is due to this. Verifier is confused because: r7 = args->data; r1 = r7; then it does r1 <<= 32; r1 >>=32; clearing upper 32 bits, so both r1 and r7 lose the id association which propagates the bounds of r1 learnt from comparison of it with sizeof(args->data); > + bpf_kfunc_call_test_mem_len_pass1(&args->data, sizeof(args->data)); > + bpf_kfunc_call_test_mem_len_pass1(&args->data, sizeof(*args)); Later llvm assigns r7 to r2 for this call's 2nd arg. At this point the verifier still thinks r7 is unbounded, while to make a call with mem, len pair you need non-negative min value. Easiest way might be to just do args->size & sizeof(args->data), as the verifier log says. You might still keep the error above. Others may have better ideas/insights. > + bpf_kfunc_call_test_mem_len_pass1(&args->data, size); > + > + return 0; > +} > + > +SEC("syscall") > +int kfunc_syscall_test_null(struct syscall_test_args *args) > +{ > + /* Must be called with args as a NULL pointer > + * we do not check for it to have the verifier consider that > + * the pointer might not be null, and so we can load it. > + * > + * So the following can not be added: > + * > + * if (args) > + * return -22; > + */ > + > + bpf_kfunc_call_test_mem_len_pass1(args, 0); > + > + return 0; > +} > + > char _license[] SEC("license") = "GPL"; > -- > 2.36.1 >
