From: Bill O'Donnell <billodo@redhat.com>
Date: Wed, 21 Jun 2017 19:40:35 +0000 (-0500)
Subject: xfs_growfs: ensure target path is an active xfs mountpoint
X-Git-Tag: v4.12.0-rc1~24
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b97815a0321072a7154ecab63e297af84066fc78;p=thirdparty%2Fxfsprogs-dev.git

xfs_growfs: ensure target path is an active xfs mountpoint

xfs_growfs manpage clearly states that the target path must be
an active xfs mountpoint.

Current behavior allows xfs_growfs to proceed if the target path
resides anywhere on a mounted xfs filesystem. This could lead to
unexpected results. Unless the target path is an active xfs
mountpoint, reject it. Create a new fs table lookup function which
matches only active xfs mount points, not any file residing within
those mountpoints.

Signed-off-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

diff --git a/growfs/xfs_growfs.c b/growfs/xfs_growfs.c
index a294e144c..366176b71 100644
--- a/growfs/xfs_growfs.c
+++ b/growfs/xfs_growfs.c
@@ -133,6 +133,7 @@ main(int argc, char **argv)
 	int			spinodes;
 	int			rmapbt_enabled;
 	int			reflink_enabled;
+	char			rpath[PATH_MAX];
 
 	progname = basename(argv[0]);
 	setlocale(LC_ALL, "");
@@ -202,7 +203,14 @@ main(int argc, char **argv)
 		aflag = 1;
 
 	fs_table_initialise(0, NULL, 0, NULL);
-	fs = fs_table_lookup(argv[optind], FS_MOUNT_POINT);
+
+	if (!realpath(argv[optind], rpath)) {
+		fprintf(stderr, _("%s: path resolution failed for %s: %s\n"),
+			progname, argv[optind], strerror(errno));
+		return 1;
+	}
+
+	fs = fs_table_lookup_mount(rpath);
 	if (!fs) {
 		fprintf(stderr, _("%s: %s is not a mounted XFS filesystem\n"),
 			progname, argv[optind]);
diff --git a/include/path.h b/include/path.h
index d077bac4f..1d3a902e0 100644
--- a/include/path.h
+++ b/include/path.h
@@ -56,6 +56,7 @@ extern void fs_table_insert_project_path(char *__dir, uint __projid);
 
 
 extern fs_path_t *fs_table_lookup(const char *__dir, uint __flags);
+extern fs_path_t *fs_table_lookup_mount(const char *__dir);
 
 typedef struct fs_cursor {
 	uint		count;		/* total count of mount entries	*/
diff --git a/libxcmd/paths.c b/libxcmd/paths.c
index 816acc22b..b767e9dce 100644
--- a/libxcmd/paths.c
+++ b/libxcmd/paths.c
@@ -65,6 +65,9 @@ fs_device_number(
  * Find the FS table entry for the given path.  The "flags" argument
  * is a mask containing FS_MOUNT_POINT or FS_PROJECT_PATH (or both)
  * to indicate the type of table entry sought.
+ * fs_table_lookup() finds the fs table entry for the filesystem hosting
+ * the file represented in the "dir" argument. To compare against actual
+ * mount point entries, use fs_table_lookup_mount() instead.
  */
 struct fs_path *
 fs_table_lookup(
@@ -86,6 +89,34 @@ fs_table_lookup(
 	return NULL;
 }
 
+/*
+ * Find the FS table entry describing an actual mount for the given path.
+ * Unlike fs_table_lookup(), fs_table_lookup_mount() compares the "dir"
+ * argument to actual mount point entries in the table. Accordingly, it
+ * will find matches only if the "dir" argument is indeed mounted.
+ */
+struct fs_path *
+fs_table_lookup_mount(
+	const char	*dir)
+{
+	uint		i;
+	dev_t		dev = 0;
+	char		rpath[PATH_MAX];
+
+	if (fs_device_number(dir, &dev))
+		return NULL;
+
+	for (i = 0; i < fs_count; i++) {
+		if (fs_table[i].fs_flags != FS_MOUNT_POINT)
+			continue;
+		if (!realpath(fs_table[i].fs_dir, rpath))
+			continue;
+		if (strcmp(rpath, dir) == 0)
+			return &fs_table[i];
+	}
+	return NULL;
+}
+
 static int
 fs_table_insert(
 	char		*dir,