selftests/filesystems: create setup_userns() helper

Add helper to utils.c and use it in statmount userns tests.

Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/20250509133240.529330-8-amir73il@gmail.com
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/tools/testing/selftests/filesystems/statmount/statmount_test_ns.c b/tools/testing/selftests/filesystems/statmount/statmount_test_ns.c
index 375a521..605a3fa 100644 (file)
--- a/tools/testing/selftests/filesystems/statmount/statmount_test_ns.c
+++ b/tools/testing/selftests/filesystems/statmount/statmount_test_ns.c
@@ -79,66 +79,10 @@ static int get_mnt_ns_id(const char *mnt_ns, uint64_t *mnt_ns_id)
        return NSID_PASS;
 }
 
-static int write_file(const char *path, const char *val)
-{
-       int fd = open(path, O_WRONLY);
-       size_t len = strlen(val);
-       int ret;
-
-       if (fd == -1) {
-               ksft_print_msg("opening %s for write: %s\n", path, strerror(errno));
-               return NSID_ERROR;
-       }
-
-       ret = write(fd, val, len);
-       if (ret == -1) {
-               ksft_print_msg("writing to %s: %s\n", path, strerror(errno));
-               return NSID_ERROR;
-       }
-       if (ret != len) {
-               ksft_print_msg("short write to %s\n", path);
-               return NSID_ERROR;
-       }
-
-       ret = close(fd);
-       if (ret == -1) {
-               ksft_print_msg("closing %s\n", path);
-               return NSID_ERROR;
-       }
-
-       return NSID_PASS;
-}
-
 static int setup_namespace(void)
 {
-       int ret;
-       char buf[32];
-       uid_t uid = getuid();
-       gid_t gid = getgid();
-
-       ret = unshare(CLONE_NEWNS|CLONE_NEWUSER|CLONE_NEWPID);
-       if (ret == -1)
-               ksft_exit_fail_msg("unsharing mountns and userns: %s\n",
-                                  strerror(errno));
-
-       sprintf(buf, "0 %d 1", uid);
-       ret = write_file("/proc/self/uid_map", buf);
-       if (ret != NSID_PASS)
-               return ret;
-       ret = write_file("/proc/self/setgroups", "deny");
-       if (ret != NSID_PASS)
-               return ret;
-       sprintf(buf, "0 %d 1", gid);
-       ret = write_file("/proc/self/gid_map", buf);
-       if (ret != NSID_PASS)
-               return ret;
-
-       ret = mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL);
-       if (ret == -1) {
-               ksft_print_msg("making mount tree private: %s\n",
-                              strerror(errno));
+       if (setup_userns() != 0)
                return NSID_ERROR;
-       }
 
        return NSID_PASS;
 }

diff --git a/tools/testing/selftests/filesystems/utils.c b/tools/testing/selftests/filesystems/utils.c
index 5a114af..c43a69d 100644 (file)
--- a/tools/testing/selftests/filesystems/utils.c
+++ b/tools/testing/selftests/filesystems/utils.c
@@ -18,6 +18,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <sys/xattr.h>
+#include <sys/mount.h>
 
 #include "../kselftest.h"
 #include "wrappers.h"
@@ -449,6 +450,71 @@ out_close:
        return fret;
 }
 
+static int write_file(const char *path, const char *val)
+{
+       int fd = open(path, O_WRONLY);
+       size_t len = strlen(val);
+       int ret;
+
+       if (fd == -1) {
+               ksft_print_msg("opening %s for write: %s\n", path, strerror(errno));
+               return -1;
+       }
+
+       ret = write(fd, val, len);
+       if (ret == -1) {
+               ksft_print_msg("writing to %s: %s\n", path, strerror(errno));
+               return -1;
+       }
+       if (ret != len) {
+               ksft_print_msg("short write to %s\n", path);
+               return -1;
+       }
+
+       ret = close(fd);
+       if (ret == -1) {
+               ksft_print_msg("closing %s\n", path);
+               return -1;
+       }
+
+       return 0;
+}
+
+int setup_userns(void)
+{
+       int ret;
+       char buf[32];
+       uid_t uid = getuid();
+       gid_t gid = getgid();
+
+       ret = unshare(CLONE_NEWNS|CLONE_NEWUSER|CLONE_NEWPID);
+       if (ret) {
+               ksft_exit_fail_msg("unsharing mountns and userns: %s\n",
+                                  strerror(errno));
+               return ret;
+       }
+
+       sprintf(buf, "0 %d 1", uid);
+       ret = write_file("/proc/self/uid_map", buf);
+       if (ret)
+               return ret;
+       ret = write_file("/proc/self/setgroups", "deny");
+       if (ret)
+               return ret;
+       sprintf(buf, "0 %d 1", gid);
+       ret = write_file("/proc/self/gid_map", buf);
+       if (ret)
+               return ret;
+
+       ret = mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL);
+       if (ret) {
+               ksft_print_msg("making mount tree private: %s\n", strerror(errno));
+               return ret;
+       }
+
+       return 0;
+}
+
 /* caps_down - lower all effective caps */
 int caps_down(void)
 {

diff --git a/tools/testing/selftests/filesystems/utils.h b/tools/testing/selftests/filesystems/utils.h
index d9cf145..70f7ccc 100644 (file)
--- a/tools/testing/selftests/filesystems/utils.h
+++ b/tools/testing/selftests/filesystems/utils.h
@@ -27,6 +27,7 @@ extern int caps_down(void);
 extern int cap_down(cap_value_t down);
 
 extern bool switch_ids(uid_t uid, gid_t gid);
+extern int setup_userns(void);
 
 static inline bool switch_userns(int fd, uid_t uid, gid_t gid, bool drop_caps)
 {