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Message-ID:
<AM6PR03MB50801CAD7F39745C2B8850D799202@AM6PR03MB5080.eurprd03.prod.outlook.com>
Date: Tue, 19 Nov 2024 17:54:02 +0000
From: Juntong Deng <juntong.deng@...look.com>
To: ast@...nel.org,
daniel@...earbox.net,
john.fastabend@...il.com,
andrii@...nel.org,
martin.lau@...ux.dev,
eddyz87@...il.com,
song@...nel.org,
yonghong.song@...ux.dev,
kpsingh@...nel.org,
sdf@...ichev.me,
haoluo@...gle.com,
jolsa@...nel.org,
memxor@...il.com,
snorcht@...il.com,
brauner@...nel.org
Cc: bpf@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Subject: [PATCH bpf-next v4 5/5] selftests/bpf: Add tests for bpf_fget_task() kfunc
This patch adds test cases for bpf_fget_task() kfunc.
test_bpf_fget_task is used to test obtaining struct file based on
the file descriptor in the current process.
bpf_fget_task_null_task and bpf_fget_task_untrusted_task are used to
test the failure cases of passing NULL or untrusted pointer as argument.
Signed-off-by: Juntong Deng <juntong.deng@...look.com>
---
.../testing/selftests/bpf/bpf_experimental.h | 8 +++
.../selftests/bpf/prog_tests/fs_kfuncs.c | 46 +++++++++++++++++
.../selftests/bpf/progs/fs_kfuncs_failure.c | 33 +++++++++++++
.../selftests/bpf/progs/test_fget_task.c | 49 +++++++++++++++++++
4 files changed, 136 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/fs_kfuncs_failure.c
create mode 100644 tools/testing/selftests/bpf/progs/test_fget_task.c
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index ce1520c56b55..e0c9e7d9ba0a 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -221,6 +221,14 @@ extern void bpf_put_file(struct file *file) __ksym;
*/
extern int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz) __ksym;
+/* Description
+ * Get a pointer to the struct file corresponding to the task file descriptor
+ * Note that this function acquires a reference to struct file.
+ * Returns
+ * The corresponding struct file pointer if found, otherwise returns NULL
+ */
+extern struct file *bpf_fget_task(struct task_struct *task, unsigned int fd) __ksym;
+
/* This macro must be used to mark the exception callback corresponding to the
* main program. For example:
*
diff --git a/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c b/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c
index 5a0b51157451..83dfe64aa3fb 100644
--- a/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c
+++ b/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c
@@ -9,6 +9,8 @@
#include <test_progs.h>
#include "test_get_xattr.skel.h"
#include "test_fsverity.skel.h"
+#include "test_fget_task.skel.h"
+#include "fs_kfuncs_failure.skel.h"
static const char testfile[] = "/tmp/test_progs_fs_kfuncs";
@@ -139,6 +141,45 @@ static void test_fsverity(void)
remove(testfile);
}
+static void test_fget_task(void)
+{
+ int pipefd[2], prog_fd, err = 0;
+ struct test_fget_task *skel;
+ struct bpf_program *prog;
+
+ skel = test_fget_task__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "open_and_load"))
+ return;
+
+ if (!ASSERT_OK(skel->bss->err, "pre_test_err"))
+ goto cleanup_skel;
+
+ prog = bpf_object__find_program_by_name(skel->obj, "test_bpf_fget_task");
+ if (!ASSERT_OK_PTR(prog, "find_program_by_name"))
+ goto cleanup_skel;
+
+ prog_fd = bpf_program__fd(prog);
+ if (!ASSERT_GT(prog_fd, -1, "bpf_program__fd"))
+ goto cleanup_skel;
+
+ if (pipe(pipefd) < 0)
+ goto cleanup_skel;
+
+ skel->bss->test_fd1 = pipefd[0];
+ skel->bss->test_fd2 = pipefd[1];
+
+ err = bpf_prog_test_run_opts(prog_fd, NULL);
+ if (!ASSERT_OK(err, "prog_test_run"))
+ goto cleanup_pipe;
+
+ ASSERT_OK(skel->bss->err, "run_bpf_fget_task_test_failure");
+cleanup_pipe:
+ close(pipefd[0]);
+ close(pipefd[1]);
+cleanup_skel:
+ test_fget_task__destroy(skel);
+}
+
void test_fs_kfuncs(void)
{
if (test__start_subtest("xattr"))
@@ -146,4 +187,9 @@ void test_fs_kfuncs(void)
if (test__start_subtest("fsverity"))
test_fsverity();
+
+ if (test__start_subtest("fget_task"))
+ test_fget_task();
+
+ RUN_TESTS(fs_kfuncs_failure);
}
diff --git a/tools/testing/selftests/bpf/progs/fs_kfuncs_failure.c b/tools/testing/selftests/bpf/progs/fs_kfuncs_failure.c
new file mode 100644
index 000000000000..57aa6d2787ac
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fs_kfuncs_failure.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("syscall")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int bpf_fget_task_null_task(void *ctx)
+{
+ struct task_struct *task = NULL;
+
+ bpf_fget_task(task, 1);
+
+ return 0;
+}
+
+SEC("syscall")
+__failure __msg("R1 must be referenced or trusted")
+int bpf_fget_task_untrusted_task(void *ctx)
+{
+ struct task_struct *task;
+
+ task = bpf_get_current_task_btf()->parent;
+
+ bpf_fget_task(task, 1);
+
+ return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_fget_task.c b/tools/testing/selftests/bpf/progs/test_fget_task.c
new file mode 100644
index 000000000000..ec40360ac1b2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_fget_task.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+#include "task_kfunc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+int err, test_fd1, test_fd2;
+
+SEC("syscall")
+int test_bpf_fget_task(void *ctx)
+{
+ struct task_struct *task;
+ struct file *file;
+
+ task = bpf_get_current_task_btf();
+ if (task == NULL) {
+ err = 1;
+ return 0;
+ }
+
+ file = bpf_fget_task(task, test_fd1);
+ if (file == NULL) {
+ err = 2;
+ return 0;
+ }
+
+ bpf_put_file(file);
+
+ file = bpf_fget_task(task, test_fd2);
+ if (file == NULL) {
+ err = 3;
+ return 0;
+ }
+
+ bpf_put_file(file);
+
+ file = bpf_fget_task(task, 9999);
+ if (file != NULL) {
+ err = 4;
+ bpf_put_file(file);
+ }
+
+ return 0;
+}
--
2.39.5
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