ovl: Do not lose security.capability xattr over metadata file copy-up
commit 993a0b2aec52754f0897b1dab4c453be8217cae5 upstream.
If a file has been copied up metadata only, and later data is copied up,
upper loses any security.capability xattr it has (underlying filesystem
clears it as upon file write).
From a user's point of view, this is just a file copy-up and that should
not result in losing security.capability xattr. Hence, before data copy
up, save security.capability xattr (if any) and restore it on upper after
data copy up is complete.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Fixes: 0c2888749363 ("ovl: A new xattr OVL_XATTR_METACOPY for file on upper")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index ace4fe4..c9a2e3c 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -867,28 +867,49 @@
return (oe->numlower > 1);
}
+ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value,
+ size_t padding)
+{
+ ssize_t res;
+ char *buf = NULL;
+
+ res = vfs_getxattr(dentry, name, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return -ENODATA;
+ goto fail;
+ }
+
+ if (res != 0) {
+ buf = kzalloc(res + padding, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ res = vfs_getxattr(dentry, name, buf, res);
+ if (res < 0)
+ goto fail;
+ }
+ *value = buf;
+
+ return res;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get xattr %s: err=%zi)\n",
+ name, res);
+ kfree(buf);
+ return res;
+}
+
char *ovl_get_redirect_xattr(struct dentry *dentry, int padding)
{
int res;
char *s, *next, *buf = NULL;
- res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
- if (res < 0) {
- if (res == -ENODATA || res == -EOPNOTSUPP)
- return NULL;
- goto fail;
- }
-
- buf = kzalloc(res + padding + 1, GFP_KERNEL);
- if (!buf)
- return ERR_PTR(-ENOMEM);
-
- if (res == 0)
- goto invalid;
-
- res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
+ res = ovl_getxattr(dentry, OVL_XATTR_REDIRECT, &buf, padding + 1);
+ if (res == -ENODATA)
+ return NULL;
if (res < 0)
- goto fail;
+ return ERR_PTR(res);
if (res == 0)
goto invalid;
@@ -904,15 +925,9 @@
}
return buf;
-
-err_free:
- kfree(buf);
- return ERR_PTR(res);
-fail:
- pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res);
- goto err_free;
invalid:
pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
res = -EINVAL;
- goto err_free;
+ kfree(buf);
+ return ERR_PTR(res);
}