From c7c7a1a18af4c3bb7749d33e3df3acdf0a95bbb5 Mon Sep 17 00:00:00 2001 From: Tycho Andersen Date: Thu, 21 Jan 2021 14:19:28 +0100 Subject: xattr: handle idmapped mounts When interacting with extended attributes the vfs verifies that the caller is privileged over the inode with which the extended attribute is associated. For posix access and posix default extended attributes a uid or gid can be stored on-disk. Let the functions handle posix extended attributes on idmapped mounts. If the inode is accessed through an idmapped mount we need to map it according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. This has no effect for e.g. security xattrs since they don't store uids or gids and don't perform permission checks on them like posix acls do. Link: https://lore.kernel.org/r/20210121131959.646623-10-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Reviewed-by: James Morris Signed-off-by: Tycho Andersen Signed-off-by: Christian Brauner --- fs/cachefiles/xattr.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) (limited to 'fs/cachefiles/xattr.c') diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c index 72e42438f3d7..a591b5e09637 100644 --- a/fs/cachefiles/xattr.c +++ b/fs/cachefiles/xattr.c @@ -39,8 +39,8 @@ int cachefiles_check_object_type(struct cachefiles_object *object) _enter("%p{%s}", object, type); /* attempt to install a type label directly */ - ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2, - XATTR_CREATE); + ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache, type, + 2, XATTR_CREATE); if (ret == 0) { _debug("SET"); /* we succeeded */ goto error; @@ -54,7 +54,8 @@ int cachefiles_check_object_type(struct cachefiles_object *object) } /* read the current type label */ - ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3); + ret = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, xtype, + 3); if (ret < 0) { if (ret == -ERANGE) goto bad_type_length; @@ -110,9 +111,8 @@ int cachefiles_set_object_xattr(struct cachefiles_object *object, _debug("SET #%u", auxdata->len); clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags); - ret = vfs_setxattr(dentry, cachefiles_xattr_cache, - &auxdata->type, auxdata->len, - XATTR_CREATE); + ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache, + &auxdata->type, auxdata->len, XATTR_CREATE); if (ret < 0 && ret != -ENOMEM) cachefiles_io_error_obj( object, @@ -140,9 +140,8 @@ int cachefiles_update_object_xattr(struct cachefiles_object *object, _debug("SET #%u", auxdata->len); clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags); - ret = vfs_setxattr(dentry, cachefiles_xattr_cache, - &auxdata->type, auxdata->len, - XATTR_REPLACE); + ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache, + &auxdata->type, auxdata->len, XATTR_REPLACE); if (ret < 0 && ret != -ENOMEM) cachefiles_io_error_obj( object, @@ -171,7 +170,7 @@ int cachefiles_check_auxdata(struct cachefiles_object *object) if (!auxbuf) return -ENOMEM; - xlen = vfs_getxattr(dentry, cachefiles_xattr_cache, + xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, &auxbuf->type, 512 + 1); ret = -ESTALE; if (xlen < 1 || @@ -213,7 +212,7 @@ int cachefiles_check_object_xattr(struct cachefiles_object *object, } /* read the current type label */ - ret = vfs_getxattr(dentry, cachefiles_xattr_cache, + ret = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, &auxbuf->type, 512 + 1); if (ret < 0) { if (ret == -ENODATA) @@ -270,9 +269,9 @@ int cachefiles_check_object_xattr(struct cachefiles_object *object, } /* update the current label */ - ret = vfs_setxattr(dentry, cachefiles_xattr_cache, - &auxdata->type, auxdata->len, - XATTR_REPLACE); + ret = vfs_setxattr(&init_user_ns, dentry, + cachefiles_xattr_cache, &auxdata->type, + auxdata->len, XATTR_REPLACE); if (ret < 0) { cachefiles_io_error_obj(object, "Can't update xattr on %lu" @@ -309,7 +308,7 @@ int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, { int ret; - ret = vfs_removexattr(dentry, cachefiles_xattr_cache); + ret = vfs_removexattr(&init_user_ns, dentry, cachefiles_xattr_cache); if (ret < 0) { if (ret == -ENOENT || ret == -ENODATA) ret = 0; -- cgit v1.2.3