1 files changed, 78 insertions, 3 deletions

diff --git a/fs/overlayfs/xattrs.c b/fs/overlayfs/xattrs.c
index d20032f8a537..383978e4663c 100644
--- a/fs/overlayfs/xattrs.c
+++ b/fs/overlayfs/xattrs.c
@@ -4,7 +4,19 @@
 #include <linux/xattr.h>
 #include "overlayfs.h"
 
-bool ovl_is_private_xattr(struct super_block *sb, const char *name)
+static bool ovl_is_escaped_xattr(struct super_block *sb, const char *name)
+{
+	struct ovl_fs *ofs = sb->s_fs_info;
+
+	if (ofs->config.userxattr)
+		return strncmp(name, OVL_XATTR_ESCAPE_USER_PREFIX,
+			       OVL_XATTR_ESCAPE_USER_PREFIX_LEN) == 0;
+	else
+		return strncmp(name, OVL_XATTR_ESCAPE_TRUSTED_PREFIX,
+			       OVL_XATTR_ESCAPE_TRUSTED_PREFIX_LEN - 1) == 0;
+}
+
+static bool ovl_is_own_xattr(struct super_block *sb, const char *name)
 {
 	struct ovl_fs *ofs = OVL_FS(sb);
 
@@ -16,6 +28,11 @@ bool ovl_is_private_xattr(struct super_block *sb, const char *name)
 			       OVL_XATTR_TRUSTED_PREFIX_LEN) == 0;
 }
 
+bool ovl_is_private_xattr(struct super_block *sb, const char *name)
+{
+	return ovl_is_own_xattr(sb, name) && !ovl_is_escaped_xattr(sb, name);
+}
+
 static int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 			 const void *value, size_t size, int flags)
 {
@@ -95,10 +112,12 @@ static bool ovl_can_list(struct super_block *sb, const char *s)
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 {
 	struct dentry *realdentry = ovl_dentry_real(dentry);
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
 	ssize_t res;
 	size_t len;
 	char *s;
 	const struct cred *old_cred;
+	size_t prefix_len, name_len;
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	res = vfs_listxattr(realdentry, list, size);
@@ -106,6 +125,9 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 	if (res <= 0 || size == 0)
 		return res;
 
+	prefix_len = ofs->config.userxattr ?
+		OVL_XATTR_USER_PREFIX_LEN : OVL_XATTR_TRUSTED_PREFIX_LEN;
+
 	/* filter out private xattrs */
 	for (s = list, len = res; len;) {
 		size_t slen = strnlen(s, len) + 1;
@@ -118,6 +140,12 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 		if (!ovl_can_list(dentry->d_sb, s)) {
 			res -= slen;
 			memmove(s, s + slen, len);
+		} else if (ovl_is_escaped_xattr(dentry->d_sb, s)) {
+			res -= OVL_XATTR_ESCAPE_PREFIX_LEN;
+			name_len = slen - prefix_len - OVL_XATTR_ESCAPE_PREFIX_LEN;
+			s += prefix_len;
+			memmove(s, s + OVL_XATTR_ESCAPE_PREFIX_LEN, name_len + len);
+			s += name_len;
 		} else {
 			s += slen;
 		}
@@ -126,11 +154,47 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 	return res;
 }
 
+static char *ovl_xattr_escape_name(const char *prefix, const char *name)
+{
+	size_t prefix_len = strlen(prefix);
+	size_t name_len = strlen(name);
+	size_t escaped_len;
+	char *escaped, *s;
+
+	escaped_len = prefix_len + OVL_XATTR_ESCAPE_PREFIX_LEN + name_len;
+	if (escaped_len > XATTR_NAME_MAX)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	escaped = kmalloc(escaped_len + 1, GFP_KERNEL);
+	if (escaped == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	s = escaped;
+	memcpy(s, prefix, prefix_len);
+	s += prefix_len;
+	memcpy(s, OVL_XATTR_ESCAPE_PREFIX, OVL_XATTR_ESCAPE_PREFIX_LEN);
+	s += OVL_XATTR_ESCAPE_PREFIX_LEN;
+	memcpy(s, name, name_len + 1);
+
+	return escaped;
+}
+
 static int ovl_own_xattr_get(const struct xattr_handler *handler,
 			     struct dentry *dentry, struct inode *inode,
 			     const char *name, void *buffer, size_t size)
 {
-	return -EOPNOTSUPP;
+	char *escaped;
+	int r;
+
+	escaped = ovl_xattr_escape_name(handler->prefix, name);
+	if (IS_ERR(escaped))
+		return PTR_ERR(escaped);
+
+	r = ovl_xattr_get(dentry, inode, escaped, buffer, size);
+
+	kfree(escaped);
+
+	return r;
 }
 
 static int ovl_own_xattr_set(const struct xattr_handler *handler,
@@ -139,7 +203,18 @@ static int ovl_own_xattr_set(const struct xattr_handler *handler,
 			     const char *name, const void *value,
 			     size_t size, int flags)
 {
-	return -EOPNOTSUPP;
+	char *escaped;
+	int r;
+
+	escaped = ovl_xattr_escape_name(handler->prefix, name);
+	if (IS_ERR(escaped))
+		return PTR_ERR(escaped);
+
+	r = ovl_xattr_set(dentry, inode, escaped, value, size, flags);
+
+	kfree(escaped);
+
+	return r;
 }
 
 static int ovl_other_xattr_get(const struct xattr_handler *handler,