selftests/bpf: add freplace of BTF-unreliable main prog test

Add a test validating that freplace'ing another main (entry) BPF program
fails if the target BPF program doesn't have valid/expected func proto BTF.

We extend fexit_bpf2bpf test to allow to specify expected log message
for negative test cases (where freplace program is expected to fail to
load).

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-11-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
index 8ec73fdfcdab949cb65141f895fb3aaa13783e45..f29fc789c14b4c8cf02ae9a6122f9030bb1d5e59 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
+++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
@@ -348,7 +348,8 @@ static void test_func_sockmap_update(void)
 }
 
 static void test_obj_load_failure_common(const char *obj_file,
-                                        const char *target_obj_file)
+                                        const char *target_obj_file,
+                                        const char *exp_msg)
 {
        /*
         * standalone test that asserts failure to load freplace prog
@@ -356,6 +357,7 @@ static void test_obj_load_failure_common(const char *obj_file,
         */
        struct bpf_object *obj = NULL, *pkt_obj;
        struct bpf_program *prog;
+       char log_buf[64 * 1024];
        int err, pkt_fd;
        __u32 duration = 0;
 
@@ -374,11 +376,21 @@ static void test_obj_load_failure_common(const char *obj_file,
        err = bpf_program__set_attach_target(prog, pkt_fd, NULL);
        ASSERT_OK(err, "set_attach_target");
 
+       log_buf[0] = '\0';
+       if (exp_msg)
+               bpf_program__set_log_buf(prog, log_buf, sizeof(log_buf));
+       if (env.verbosity > VERBOSE_NONE)
+               bpf_program__set_log_level(prog, 2);
+
        /* It should fail to load the program */
        err = bpf_object__load(obj);
+       if (env.verbosity > VERBOSE_NONE && exp_msg) /* we overtook log */
+               printf("VERIFIER LOG:\n================\n%s\n================\n", log_buf);
        if (CHECK(!err, "bpf_obj_load should fail", "err %d\n", err))
                goto close_prog;
 
+       if (exp_msg)
+               ASSERT_HAS_SUBSTR(log_buf, exp_msg, "fail_msg");
 close_prog:
        bpf_object__close(obj);
        bpf_object__close(pkt_obj);
@@ -388,14 +400,24 @@ static void test_func_replace_return_code(void)
 {
        /* test invalid return code in the replaced program */
        test_obj_load_failure_common("./freplace_connect_v4_prog.bpf.o",
-                                    "./connect4_prog.bpf.o");
+                                    "./connect4_prog.bpf.o", NULL);
 }
 
 static void test_func_map_prog_compatibility(void)
 {
        /* test with spin lock map value in the replaced program */
        test_obj_load_failure_common("./freplace_attach_probe.bpf.o",
-                                    "./test_attach_probe.bpf.o");
+                                    "./test_attach_probe.bpf.o", NULL);
+}
+
+static void test_func_replace_unreliable(void)
+{
+       /* freplace'ing unreliable main prog should fail with error
+        * "Cannot replace static functions"
+        */
+       test_obj_load_failure_common("freplace_unreliable_prog.bpf.o",
+                                    "./verifier_btf_unreliable_prog.bpf.o",
+                                    "Cannot replace static functions");
 }
 
 static void test_func_replace_global_func(void)
@@ -563,6 +585,8 @@ void serial_test_fexit_bpf2bpf(void)
                test_func_replace_return_code();
        if (test__start_subtest("func_map_prog_compatibility"))
                test_func_map_prog_compatibility();
+       if (test__start_subtest("func_replace_unreliable"))
+               test_func_replace_unreliable();
        if (test__start_subtest("func_replace_multi"))
                test_func_replace_multi();
        if (test__start_subtest("fmod_ret_freplace"))

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index ac49ec25211d1d2ba15f025314c3dd31c6d96251..d62c5bf00e71da9bd25c8d14d23eb664ca13b667 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -14,6 +14,7 @@
 #include "verifier_bpf_get_stack.skel.h"
 #include "verifier_bswap.skel.h"
 #include "verifier_btf_ctx_access.skel.h"
+#include "verifier_btf_unreliable_prog.skel.h"
 #include "verifier_cfg.skel.h"
 #include "verifier_cgroup_inv_retcode.skel.h"
 #include "verifier_cgroup_skb.skel.h"
@@ -125,6 +126,7 @@ void test_verifier_bounds_mix_sign_unsign(void) { RUN(verifier_bounds_mix_sign_u
 void test_verifier_bpf_get_stack(void)        { RUN(verifier_bpf_get_stack); }
 void test_verifier_bswap(void)                { RUN(verifier_bswap); }
 void test_verifier_btf_ctx_access(void)       { RUN(verifier_btf_ctx_access); }
+void test_verifier_btf_unreliable_prog(void)  { RUN(verifier_btf_unreliable_prog); }
 void test_verifier_cfg(void)                  { RUN(verifier_cfg); }
 void test_verifier_cgroup_inv_retcode(void)   { RUN(verifier_cgroup_inv_retcode); }
 void test_verifier_cgroup_skb(void)           { RUN(verifier_cgroup_skb); }

diff --git a/tools/testing/selftests/bpf/progs/freplace_unreliable_prog.c b/tools/testing/selftests/bpf/progs/freplace_unreliable_prog.c
new file mode 100644 (file)
index 0000000..624078a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/freplace_unreliable_prog.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+SEC("freplace/btf_unreliable_kprobe")
+/* context type is what BPF verifier expects for kprobe context, but target
+ * program has `stuct whatever *ctx` argument, so freplace operation will be
+ * rejected with the following message:
+ *
+ * arg0 replace_btf_unreliable_kprobe(struct pt_regs *) doesn't match btf_unreliable_kprobe(struct whatever *)
+ */
+int replace_btf_unreliable_kprobe(bpf_user_pt_regs_t *ctx)
+{
+       return 0;
+}
+
+char _license[] SEC("license") = "GPL";

diff --git a/tools/testing/selftests/bpf/progs/verifier_btf_unreliable_prog.c b/tools/testing/selftests/bpf/progs/verifier_btf_unreliable_prog.c
new file mode 100644 (file)
index 0000000..36e033a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_btf_unreliable_prog.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017 Facebook
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "bpf_misc.h"
+
+struct whatever {};
+
+SEC("kprobe")
+__success __log_level(2)
+/* context type is wrong, making it impossible to freplace this program */
+int btf_unreliable_kprobe(struct whatever *ctx)
+{
+       return 0;
+}
+
+char _license[] SEC("license") = "GPL";