From 78fee0b6846f27872321338db6afe280f059ae99 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Sat, 25 Jun 2016 01:51:52 +0200 Subject: [PATCH] orangefs: fix namespace handling In orangefs_inode_getxattr(), an fsuid is written to dmesg. The kuid is converted to a userspace uid via from_kuid(current_user_ns(), [...]), but since dmesg is global, init_user_ns should be used here instead. In copy_attributes_from_inode(), op_alloc() and fill_default_sys_attrs(), upcall structures are populated with uids/gids that have been mapped into the caller's namespace. However, those upcall structures are read by another process (the userspace filesystem driver), and that process might be running in another namespace. This effectively lets any user spoof its uid and gid as seen by the userspace filesystem driver. To fix the second issue, I just construct the opcall structures with init_user_ns uids/gids and require the filesystem server to run in the init namespace. Since orangefs is full of global state anyway (as the error message in DUMP_DEVICE_ERROR explains, there can only be one userspace orangefs filesystem driver at once), that shouldn't be a problem. [ Why does orangefs even exist in the kernel if everything does upcalls into userspace? What does orangefs do that couldn't be done with the FUSE interface? If there is no good answer to those questions, I'd prefer to see orangefs kicked out of the kernel. Can that be done for something that shipped in a release? According to commit f7ab093f74bf ("Orangefs: kernel client part 1"), they even already have a FUSE daemon, and the only rational reason (apart from "but most of our users report preferring to use our kernel module instead") given for not wanting to use FUSE is one "in-the-works" feature that could probably be integated into FUSE instead. ] This patch has been compile-tested. Signed-off-by: Jann Horn Signed-off-by: Mike Marshall --- fs/orangefs/devorangefs-req.c | 7 +++++++ fs/orangefs/orangefs-cache.c | 4 ++-- fs/orangefs/orangefs-kernel.h | 4 ++-- fs/orangefs/orangefs-utils.c | 4 ++-- fs/orangefs/xattr.c | 4 ++-- 5 files changed, 15 insertions(+), 8 deletions(-) diff --git a/fs/orangefs/devorangefs-req.c b/fs/orangefs/devorangefs-req.c index db170beba797..a287a66d94e3 100644 --- a/fs/orangefs/devorangefs-req.c +++ b/fs/orangefs/devorangefs-req.c @@ -116,6 +116,13 @@ static int orangefs_devreq_open(struct inode *inode, struct file *file) { int ret = -EINVAL; + /* in order to ensure that the filesystem driver sees correct UIDs */ + if (file->f_cred->user_ns != &init_user_ns) { + gossip_err("%s: device cannot be opened outside init_user_ns\n", + __func__); + goto out; + } + if (!(file->f_flags & O_NONBLOCK)) { gossip_err("%s: device cannot be opened in blocking mode\n", __func__); diff --git a/fs/orangefs/orangefs-cache.c b/fs/orangefs/orangefs-cache.c index 900a2e38e11b..b6edbe9fb309 100644 --- a/fs/orangefs/orangefs-cache.c +++ b/fs/orangefs/orangefs-cache.c @@ -136,10 +136,10 @@ struct orangefs_kernel_op_s *op_alloc(__s32 type) llu(new_op->tag), get_opname_string(new_op)); - new_op->upcall.uid = from_kuid(current_user_ns(), + new_op->upcall.uid = from_kuid(&init_user_ns, current_fsuid()); - new_op->upcall.gid = from_kgid(current_user_ns(), + new_op->upcall.gid = from_kgid(&init_user_ns, current_fsgid()); } else { gossip_err("op_alloc: kmem_cache_zalloc failed!\n"); diff --git a/fs/orangefs/orangefs-kernel.h b/fs/orangefs/orangefs-kernel.h index 7b542f168d44..c1181e5529af 100644 --- a/fs/orangefs/orangefs-kernel.h +++ b/fs/orangefs/orangefs-kernel.h @@ -587,8 +587,8 @@ int service_operation(struct orangefs_kernel_op_s *op, #define fill_default_sys_attrs(sys_attr, type, mode) \ do { \ - sys_attr.owner = from_kuid(current_user_ns(), current_fsuid()); \ - sys_attr.group = from_kgid(current_user_ns(), current_fsgid()); \ + sys_attr.owner = from_kuid(&init_user_ns, current_fsuid()); \ + sys_attr.group = from_kgid(&init_user_ns, current_fsgid()); \ sys_attr.perms = ORANGEFS_util_translate_mode(mode); \ sys_attr.mtime = 0; \ sys_attr.atime = 0; \ diff --git a/fs/orangefs/orangefs-utils.c b/fs/orangefs/orangefs-utils.c index 2d129b5886ee..c5fbc62357c6 100644 --- a/fs/orangefs/orangefs-utils.c +++ b/fs/orangefs/orangefs-utils.c @@ -153,12 +153,12 @@ static inline int copy_attributes_from_inode(struct inode *inode, */ attrs->mask = 0; if (iattr->ia_valid & ATTR_UID) { - attrs->owner = from_kuid(current_user_ns(), iattr->ia_uid); + attrs->owner = from_kuid(&init_user_ns, iattr->ia_uid); attrs->mask |= ORANGEFS_ATTR_SYS_UID; gossip_debug(GOSSIP_UTILS_DEBUG, "(UID) %d\n", attrs->owner); } if (iattr->ia_valid & ATTR_GID) { - attrs->group = from_kgid(current_user_ns(), iattr->ia_gid); + attrs->group = from_kgid(&init_user_ns, iattr->ia_gid); attrs->mask |= ORANGEFS_ATTR_SYS_GID; gossip_debug(GOSSIP_UTILS_DEBUG, "(GID) %d\n", attrs->group); } diff --git a/fs/orangefs/xattr.c b/fs/orangefs/xattr.c index 73a0c3411d4b..2a9f07f06d10 100644 --- a/fs/orangefs/xattr.c +++ b/fs/orangefs/xattr.c @@ -79,8 +79,8 @@ ssize_t orangefs_inode_getxattr(struct inode *inode, const char *name, return -EINVAL; } - fsuid = from_kuid(current_user_ns(), current_fsuid()); - fsgid = from_kgid(current_user_ns(), current_fsgid()); + fsuid = from_kuid(&init_user_ns, current_fsuid()); + fsgid = from_kgid(&init_user_ns, current_fsgid()); gossip_debug(GOSSIP_XATTR_DEBUG, "getxattr on inode %pU, name %s " -- 2.30.2