This is a note to let you know that I've just added the patch titled
ovl: fix regression in showing lowerdir mount option
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ovl-fix-regression-in-showing-lowerdir-mount-option.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 816477eab8a0efd3989b6e6de7119180ef42dcdc
Author: Amir Goldstein <amir73il@xxxxxxxxx>
Date: Wed Oct 11 17:07:03 2023 +0300
ovl: fix regression in showing lowerdir mount option
[ Upstream commit 32db510708507f6133f496ff385cbd841d8f9098 ]
Before commit b36a5780cb44 ("ovl: modify layer parameter parsing"),
spaces and commas in lowerdir mount option value used to be escaped using
seq_show_option().
In current upstream, when lowerdir value has a space, it is not escaped
in /proc/mounts, e.g.:
none /mnt overlay rw,relatime,lowerdir=l l,upperdir=u,workdir=w 0 0
which results in broken output of the mount utility:
none on /mnt type overlay (rw,relatime,lowerdir=l)
Store the original lowerdir mount options before unescaping and show
them using the same escaping used for seq_show_option() in addition to
escaping the colon separator character.
Fixes: b36a5780cb44 ("ovl: modify layer parameter parsing")
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index eb7d2c88ddece..8e1b27288afd4 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -339,6 +339,18 @@ The specified lower directories will be stacked beginning from the
rightmost one and going left. In the above example lower1 will be the
top, lower2 the middle and lower3 the bottom layer.
+Note: directory names containing colons can be provided as lower layer by
+escaping the colons with a single backslash. For example:
+
+ mount -t overlay overlay -olowerdir=/a\:lower\:\:dir /merged
+
+Since kernel version v6.5, directory names containing colons can also
+be provided as lower layer using the fsconfig syscall from new mount api:
+
+ fsconfig(fs_fd, FSCONFIG_SET_STRING, "lowerdir", "/a:lower::dir", 0);
+
+In the latter case, colons in lower layer directory names will be escaped
+as an octal characters (\072) when displayed in /proc/self/mountinfo.
Metadata only copy up
---------------------
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index e6edad7542e88..644badb13fe01 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -155,7 +155,8 @@ static ssize_t ovl_parse_param_split_lowerdirs(char *str)
for (s = d = str;; s++, d++) {
if (*s == '\\') {
- s++;
+ /* keep esc chars in split lowerdir */
+ *d++ = *s++;
} else if (*s == ':') {
bool next_colon = (*(s + 1) == ':');
@@ -230,7 +231,7 @@ static void ovl_unescape(char *s)
}
}
-static int ovl_mount_dir(const char *name, struct path *path)
+static int ovl_mount_dir(const char *name, struct path *path, bool upper)
{
int err = -ENOMEM;
char *tmp = kstrdup(name, GFP_KERNEL);
@@ -239,7 +240,7 @@ static int ovl_mount_dir(const char *name, struct path *path)
ovl_unescape(tmp);
err = ovl_mount_dir_noesc(tmp, path);
- if (!err && path->dentry->d_flags & DCACHE_OP_REAL) {
+ if (!err && upper && path->dentry->d_flags & DCACHE_OP_REAL) {
pr_err("filesystem on '%s' not supported as upperdir\n",
tmp);
path_put_init(path);
@@ -260,7 +261,7 @@ static int ovl_parse_param_upperdir(const char *name, struct fs_context *fc,
struct path path;
char *dup;
- err = ovl_mount_dir(name, &path);
+ err = ovl_mount_dir(name, &path, true);
if (err)
return err;
@@ -417,7 +418,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
l = &ctx->lower[nr];
memset(l, 0, sizeof(*l));
- err = ovl_mount_dir_noesc(dup_iter, &l->path);
+ err = ovl_mount_dir(dup_iter, &l->path, false);
if (err)
goto out_put;
@@ -858,16 +859,23 @@ int ovl_show_options(struct seq_file *m, struct dentry *dentry)
struct super_block *sb = dentry->d_sb;
struct ovl_fs *ofs = sb->s_fs_info;
size_t nr, nr_merged_lower = ofs->numlayer - ofs->numdatalayer;
- char **lowerdatadirs = &ofs->config.lowerdirs[nr_merged_lower];
-
- /* lowerdirs[] starts from offset 1 */
- seq_printf(m, ",lowerdir=%s", ofs->config.lowerdirs[1]);
- /* dump regular lower layers */
- for (nr = 2; nr < nr_merged_lower; nr++)
- seq_printf(m, ":%s", ofs->config.lowerdirs[nr]);
- /* dump data lower layers */
- for (nr = 0; nr < ofs->numdatalayer; nr++)
- seq_printf(m, "::%s", lowerdatadirs[nr]);
+
+ /*
+ * lowerdirs[] starts from offset 1, then
+ * >= 0 regular lower layers prefixed with : and
+ * >= 0 data-only lower layers prefixed with ::
+ *
+ * we need to escase comma and space like seq_show_option() does and
+ * we also need to escape the colon separator from lowerdir paths.
+ */
+ seq_puts(m, ",lowerdir=");
+ for (nr = 1; nr < ofs->numlayer; nr++) {
+ if (nr > 1)
+ seq_putc(m, ':');
+ if (nr >= nr_merged_lower)
+ seq_putc(m, ':');
+ seq_escape(m, ofs->config.lowerdirs[nr], ":, \t\n\\");
+ }
if (ofs->config.upperdir) {
seq_show_option(m, "upperdir", ofs->config.upperdir);
seq_show_option(m, "workdir", ofs->config.workdir);
