[v4,3/3] idmapped-mounts: Add open with O_TMPFILE operation in setgid test

Commit Message

Yang Xu (Fujitsu) May 7, 2022, 1:05 p.m. UTC

Since we can create temp file by using O_TMPFILE flag and filesystem driver also
has this api, we should also check this operation whether strip S_ISGID.

Reviewed-by: Christian Brauner (Microsoft) <[e-mail]>
Signed-off-by: Yang Xu <[e-mail]>
---
v3->v4: use linkat with AT_EMPTY_PATH to make the temporary file permanent
instead of snprint and link with AT_SYMLINK_FOLLOW
 src/idmapped-mounts/idmapped-mounts.c | 139 ++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)

Patch

diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c
index a1c22da2..8fe06408 100644
--- a/src/idmapped-mounts/idmapped-mounts.c
+++ b/src/idmapped-mounts/idmapped-mounts.c
@@ -51,6 +51,7 @@ 
 #define FILE1_RENAME "file1_rename"
 #define FILE2 "file2"
 #define FILE2_RENAME "file2_rename"
+#define FILE3 "file3"
 #define DIR1 "dir1"
 #define DIR2 "dir2"
 #define DIR3 "dir3"
@@ -340,6 +341,24 @@  out:
 	return fret;
 }
 
+static bool openat_tmpfile_supported(int dirfd)
+{
+	int fd = -1;
+
+	fd = openat(dirfd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+	if (fd == -1) {
+		if (errno == ENOTSUP)
+			return false;
+		else
+			return log_errno(false, "failure: create");
+	}
+
+	if (close(fd))
+		log_stderr("failure: close");
+
+	return true;
+}
+
 /* __expected_uid_gid - check whether file is owned by the provided uid and gid */
 static bool __expected_uid_gid(int dfd, const char *path, int flags,
 			       uid_t expected_uid, gid_t expected_gid, bool log)
@@ -7844,7 +7863,9 @@  static int setgid_create(void)
 {
 	int fret = -1;
 	int file1_fd = -EBADF;
+	int tmpfile_fd = -EBADF;
 	pid_t pid;
+	bool supported = false;
 
 	if (!caps_supported())
 		return 0;
@@ -7869,6 +7890,8 @@  static int setgid_create(void)
 		goto out;
 	}
 
+	supported = openat_tmpfile_supported(t_dir1_fd);
+
 	pid = fork();
 	if (pid < 0) {
 		log_stderr("failure: fork");
@@ -7932,6 +7955,24 @@  static int setgid_create(void)
 		if (unlinkat(t_dir1_fd, CHRDEV1, 0))
 			die("failure: delete");
 
+		/* create tmpfile via filesystem tmpfile api */
+		if (supported) {
+			tmpfile_fd = openat(t_dir1_fd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+			if (tmpfile_fd < 0)
+				die("failure: create");
+			/* link the temporary file into the filesystem, making it permanent */
+			if (linkat(tmpfile_fd, "", t_dir1_fd, FILE3, AT_EMPTY_PATH))
+				die("failure: linkat");
+			if (close(tmpfile_fd))
+				die("failure: close");
+			if (!is_setgid(t_dir1_fd, FILE3, 0))
+				die("failure: is_setgid");
+			if (!expected_uid_gid(t_dir1_fd, FILE3, 0, 0, 0))
+				die("failure: check ownership");
+			if (unlinkat(t_dir1_fd, FILE3, 0))
+				die("failure: delete");
+		}
+
 		exit(EXIT_SUCCESS);
 	}
 	if (wait_for_pid(pid))
@@ -8021,6 +8062,24 @@  static int setgid_create(void)
 		if (unlinkat(t_dir1_fd, CHRDEV1, 0))
 			die("failure: delete");
 
+		/* create tmpfile via filesystem tmpfile api */
+		if (supported) {
+			tmpfile_fd = openat(t_dir1_fd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+			if (tmpfile_fd < 0)
+				die("failure: create");
+			/* link the temporary file into the filesystem, making it permanent */
+			if (linkat(tmpfile_fd, "", t_dir1_fd, FILE3, AT_EMPTY_PATH))
+				die("failure: linkat");
+			if (close(tmpfile_fd))
+				die("failure: close");
+			if (is_setgid(t_dir1_fd, FILE3, 0))
+				die("failure: is_setgid");
+			if (!expected_uid_gid(t_dir1_fd, FILE3, 0, 0, 0))
+				die("failure: check ownership");
+			if (unlinkat(t_dir1_fd, FILE3, 0))
+				die("failure: delete");
+		}
+
 		exit(EXIT_SUCCESS);
 	}
 	if (wait_for_pid(pid))
@@ -8042,6 +8101,8 @@  static int setgid_create_idmapped(void)
 		.attr_set = MOUNT_ATTR_IDMAP,
 	};
 	pid_t pid;
+	int tmpfile_fd = -EBADF;
+	bool supported = false;
 
 	if (!caps_supported())
 		return 0;
@@ -8089,6 +8150,8 @@  static int setgid_create_idmapped(void)
 		goto out;
 	}
 
+	supported = openat_tmpfile_supported(open_tree_fd);
+
 	pid = fork();
 	if (pid < 0) {
 		log_stderr("failure: fork");
@@ -8171,6 +8234,24 @@  static int setgid_create_idmapped(void)
 		if (unlinkat(open_tree_fd, CHRDEV1, 0))
 			die("failure: delete");
 
+		/* create tmpfile via filesystem tmpfile api */
+		if (supported) {
+			tmpfile_fd = openat(open_tree_fd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+			if (tmpfile_fd < 0)
+				die("failure: create");
+			/* link the temporary file into the filesystem, making it permanent */
+			if (linkat(tmpfile_fd, "", t_dir1_fd, FILE3, AT_EMPTY_PATH))
+				die("failure: linkat");
+			if (close(tmpfile_fd))
+				die("failure: close");
+			if (is_setgid(open_tree_fd, FILE3, 0))
+				die("failure: is_setgid");
+			if (!expected_uid_gid(open_tree_fd, FILE3, 0, 10000, 10000))
+				die("failure: check ownership");
+			if  (unlinkat(open_tree_fd, FILE3, 0))
+				die("failure: delete");
+		}
+
 		exit(EXIT_SUCCESS);
 	}
 	if (wait_for_pid(pid))
@@ -8194,6 +8275,8 @@  static int setgid_create_idmapped_in_userns(void)
 		.attr_set = MOUNT_ATTR_IDMAP,
 	};
 	pid_t pid;
+	int tmpfile_fd = -EBADF;
+	bool supported = false;
 
 	if (!caps_supported())
 		return 0;
@@ -8241,6 +8324,8 @@  static int setgid_create_idmapped_in_userns(void)
 		goto out;
 	}
 
+	supported = openat_tmpfile_supported(open_tree_fd);
+
 	pid = fork();
 	if (pid < 0) {
 		log_stderr("failure: fork");
@@ -8307,6 +8392,24 @@  static int setgid_create_idmapped_in_userns(void)
 		if (unlinkat(open_tree_fd, CHRDEV1, 0))
 			die("failure: delete");
 
+		/* create tmpfile via filesystem tmpfile api */
+		if (supported) {
+			tmpfile_fd = openat(open_tree_fd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+			if (tmpfile_fd < 0)
+				die("failure: create");
+			/* link the temporary file into the filesystem, making it permanent */
+			if (linkat(tmpfile_fd, "", t_dir1_fd, FILE3, AT_EMPTY_PATH))
+				die("failure: linkat");
+			if (close(tmpfile_fd))
+				die("failure: close");
+			if (!is_setgid(open_tree_fd, FILE3, 0))
+				die("failure: is_setgid");
+			if (!expected_uid_gid(open_tree_fd, FILE3, 0, 0, 0))
+				die("failure: check ownership");
+			if (unlinkat(open_tree_fd, FILE3, 0))
+				die("failure: delete");
+		}
+
 		exit(EXIT_SUCCESS);
 	}
 	if (wait_for_pid(pid))
@@ -8415,6 +8518,24 @@  static int setgid_create_idmapped_in_userns(void)
 		if (unlinkat(open_tree_fd, CHRDEV1, 0))
 			die("failure: delete");
 
+		/* create tmpfile via filesystem tmpfile api */
+		if (supported) {
+			tmpfile_fd = openat(open_tree_fd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+			if (tmpfile_fd < 0)
+				die("failure: create");
+			/* link the temporary file into the filesystem, making it permanent */
+			if (linkat(tmpfile_fd, "", t_dir1_fd, FILE3, AT_EMPTY_PATH))
+				die("failure: linkat");
+			if (close(tmpfile_fd))
+				die("failure: close");
+			if (is_setgid(open_tree_fd, FILE3, 0))
+				die("failure: is_setgid");
+			if (!expected_uid_gid(open_tree_fd, FILE3, 0, 0, 1000))
+				die("failure: check ownership");
+			if (unlinkat(open_tree_fd, FILE3, 0))
+				die("failure: delete");
+		}
+
 		exit(EXIT_SUCCESS);
 	}
 	if (wait_for_pid(pid))
@@ -8511,6 +8632,24 @@  static int setgid_create_idmapped_in_userns(void)
 		if (unlinkat(open_tree_fd, CHRDEV1, 0))
 			die("failure: delete");
 
+		/* create tmpfile via filesystem tmpfile api */
+		if (supported) {
+			tmpfile_fd = openat(open_tree_fd, ".", O_TMPFILE | O_RDWR, S_IXGRP | S_ISGID);
+			if (tmpfile_fd < 0)
+				die("failure: create");
+			/* link the temporary file into the filesystem, making it permanent */
+			if (linkat(tmpfile_fd, "", t_dir1_fd, FILE3, AT_EMPTY_PATH))
+				die("failure: linkat");
+			if (close(tmpfile_fd))
+				die("failure: close");
+			if (is_setgid(open_tree_fd, FILE3, 0))
+				die("failure: is_setgid");
+			if (!expected_uid_gid(open_tree_fd, FILE3, 0, 0, 0))
+				die("failure: check ownership");
+			if (unlinkat(open_tree_fd, FILE3, 0))
+				die("failure: delete");
+		}
+
 		exit(EXIT_SUCCESS);
 	}
 	if (wait_for_pid(pid))