fuse: Ensure posix acls are translated outside of init_user_ns

Ensure the translation happens by failing to read or write
posix acls when the filesystem has not indicated it supports
posix acls.

This ensures that modern cached posix acl support is available
and used when dealing with posix acls.  This is important
because only that path has the code to convernt the uids and
gids in posix acls into the user namespace of a fuse filesystem.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index f630951df8dc727f53f15e406fb4fa917a6e1a7e..5256ad333b05309dda9b2816cc99a0961ca8d63e 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -985,6 +985,7 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size);
 int fuse_removexattr(struct inode *inode, const char *name);
 extern const struct xattr_handler *fuse_xattr_handlers[];
 extern const struct xattr_handler *fuse_acl_xattr_handlers[];
+extern const struct xattr_handler *fuse_no_acl_xattr_handlers[];
 
 struct posix_acl;
 struct posix_acl *fuse_get_acl(struct inode *inode, int type);

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 1643043d4fe59d85d83a3d4aa88fa034949a3c96..22c76cf8c2e39ea6a0d36139f3fb3ee0db2db1da 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1100,6 +1100,13 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
            file->f_cred->user_ns != sb->s_user_ns)
                goto err_fput;
 
+       /*
+        * If we are not in the initial user namespace posix
+        * acls must be translated.
+        */
+       if (sb->s_user_ns != &init_user_ns)
+               sb->s_xattr = fuse_no_acl_xattr_handlers;
+
        fc = kmalloc(sizeof(*fc), GFP_KERNEL);
        err = -ENOMEM;
        if (!fc)

diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 3caac46b08b0eeaad1493024d7102c81c2f41661..433717640f78dfab8abb5e3d460a3a8589b528bf 100644 (file)
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -192,6 +192,26 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
        return fuse_setxattr(inode, name, value, size, flags);
 }
 
+static bool no_xattr_list(struct dentry *dentry)
+{
+       return false;
+}
+
+static int no_xattr_get(const struct xattr_handler *handler,
+                       struct dentry *dentry, struct inode *inode,
+                       const char *name, void *value, size_t size)
+{
+       return -EOPNOTSUPP;
+}
+
+static int no_xattr_set(const struct xattr_handler *handler,
+                       struct dentry *dentry, struct inode *nodee,
+                       const char *name, const void *value,
+                       size_t size, int flags)
+{
+       return -EOPNOTSUPP;
+}
+
 static const struct xattr_handler fuse_xattr_handler = {
        .prefix = "",
        .get    = fuse_xattr_get,
@@ -209,3 +229,26 @@ const struct xattr_handler *fuse_acl_xattr_handlers[] = {
        &fuse_xattr_handler,
        NULL
 };
+
+static const struct xattr_handler fuse_no_acl_access_xattr_handler = {
+       .name  = XATTR_NAME_POSIX_ACL_ACCESS,
+       .flags = ACL_TYPE_ACCESS,
+       .list  = no_xattr_list,
+       .get   = no_xattr_get,
+       .set   = no_xattr_set,
+};
+
+static const struct xattr_handler fuse_no_acl_default_xattr_handler = {
+       .name  = XATTR_NAME_POSIX_ACL_DEFAULT,
+       .flags = ACL_TYPE_ACCESS,
+       .list  = no_xattr_list,
+       .get   = no_xattr_get,
+       .set   = no_xattr_set,
+};
+
+const struct xattr_handler *fuse_no_acl_xattr_handlers[] = {
+       &fuse_no_acl_access_xattr_handler,
+       &fuse_no_acl_default_xattr_handler,
+       &fuse_xattr_handler,
+       NULL
+};