@@ -536,6 +536,11 @@ int noinline bpf_modify_return_test(int a, int *b)
return a + *b;
}
+int noinline bpf_fentry_shadow_test(int a)
+{
+ return a + 1;
+}
+
u64 noinline bpf_kfunc_call_test1(struct sock *sk, u32 a, u64 b, u32 c, u64 d)
{
return a + b + c + d;
@@ -229,6 +229,13 @@ static const struct btf_kfunc_id_set bpf_testmod_kfunc_set = {
.set = &bpf_testmod_check_kfunc_ids,
};
+noinline int bpf_fentry_shadow_test(int a)
+{
+ return a + 2;
+}
+EXPORT_SYMBOL_GPL(bpf_fentry_shadow_test);
+ALLOW_ERROR_INJECTION(bpf_fentry_shadow_test, ERRNO);
+
extern int bpf_fentry_test1(int a);
static int bpf_testmod_init(void)
new file mode 100644
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Red Hat */
+#include <test_progs.h>
+#include <bpf/btf.h>
+#include "bpf/libbpf_internal.h"
+#include "cgroup_helpers.h"
+
+static const char *module_name = "bpf_testmod";
+static const char *symbol_name = "bpf_fentry_shadow_test";
+
+int get_bpf_testmod_btf_fd(void)
+{
+ struct bpf_btf_info info;
+ char name[64];
+ __u32 id, len;
+ int err, fd;
+
+ while (true) {
+ err = bpf_btf_get_next_id(id, &id);
+ if (err) {
+ log_err("failed to iterate BTF objects");
+ return err;
+ }
+
+ fd = bpf_btf_get_fd_by_id(id);
+ if (fd < 0) {
+ err = -errno;
+ log_err("failed to get FD for BTF object #%d", id);
+ return err;
+ }
+
+ len = sizeof(info);
+ memset(&info, 0, sizeof(info));
+ info.name = ptr_to_u64(name);
+ info.name_len = sizeof(name);
+
+ err = bpf_obj_get_info_by_fd(fd, &info, &len);
+ if (err) {
+ err = -errno;
+ log_err("failed to get info for BTF object #%d", id);
+ close(fd);
+ return err;
+ }
+
+ if (strcmp(name, module_name) == 0)
+ return fd;
+
+ close(fd);
+ }
+ return -ENOENT;
+}
+
+void test_module_fentry_shadow(void)
+{
+ struct btf *vmlinux_btf, *mod_btf;
+ int err, i;
+ int btf_fd[2] = {};
+ int prog_fd[2] = {};
+ int link_fd[2] = {};
+ __s32 btf_id[2] = {};
+
+ const struct bpf_insn trace_program[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+
+ LIBBPF_OPTS(bpf_prog_load_opts, load_opts,
+ .expected_attach_type = BPF_TRACE_FENTRY,
+ );
+
+ LIBBPF_OPTS(bpf_test_run_opts, test_opts);
+
+ vmlinux_btf = btf__load_vmlinux_btf();
+ if (!ASSERT_OK_PTR(vmlinux_btf, "load_vmlinux_btf"))
+ return;
+
+ btf_fd[1] = get_bpf_testmod_btf_fd();
+ if (!ASSERT_GT(btf_fd[1], 0, "get_bpf_testmod_btf_fd"))
+ return;
+
+ mod_btf = btf_get_from_fd(btf_fd[1], vmlinux_btf);
+ if (!ASSERT_OK_PTR(mod_btf, "btf_get_from_fd"))
+ goto out;
+
+ btf_id[0] = btf__find_by_name(vmlinux_btf, symbol_name);
+ if (!ASSERT_GT(btf_id[0], 0, "btf_find_by_name"))
+ goto out;
+
+ btf_id[1] = btf__find_by_name(mod_btf, symbol_name);
+ if (!ASSERT_GT(btf_id[1], 0, "btf_find_by_name"))
+ goto out;
+
+ for (i = 0; i < 2; i++) {
+ load_opts.attach_btf_id = btf_id[i];
+ load_opts.attach_btf_obj_fd = btf_fd[i];
+ prog_fd[i] = bpf_prog_load(BPF_PROG_TYPE_TRACING, NULL, "GPL",
+ trace_program,
+ sizeof(trace_program) / sizeof(struct bpf_insn),
+ &load_opts);
+ if (!ASSERT_GE(prog_fd[i], 0, "bpf_prog_load"))
+ goto out;
+
+ link_fd[i] = bpf_link_create(prog_fd[i], 0, BPF_TRACE_FENTRY, NULL);
+ if (!ASSERT_GE(link_fd[i], 0, "bpf_link_create"))
+ goto out;
+ }
+
+ err = bpf_prog_test_run_opts(prog_fd[0], &test_opts);
+ ASSERT_OK(err, "running test");
+
+out:
+ for (i = 0; i < 2; i++) {
+ if (btf_fd[i])
+ close(btf_fd[i]);
+ if (prog_fd[i])
+ close(prog_fd[i]);
+ if (link_fd[i])
+ close(link_fd[i]);
+ }
+}
Adds a new test that tries to attach a program to fentry of two functions of the same name, one located in vmlinux and the other in bpf_testmod. To avoid conflicts with existing tests, a new function "bpf_fentry_shadow_test" was created both in vmlinux and in bpf_testmod. The previous commit fixed a bug which caused this test to fail. The verifier would always use the vmlinux function's address as the target trampoline address, hence trying to attach two programs to the same trampoline. Signed-off-by: Viktor Malik <vmalik@redhat.com> --- net/bpf/test_run.c | 5 + .../selftests/bpf/bpf_testmod/bpf_testmod.c | 7 + .../bpf/prog_tests/module_attach_shadow.c | 120 ++++++++++++++++++ 3 files changed, 132 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c