From d91ee87d8d85a0808c01787e8b4a6b48f2ba487b Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 23 May 2016 14:51:59 -0500 Subject: vfs: Pass data, ns, and ns->userns to mount_ns Today what is normally called data (the mount options) is not passed to fill_super through mount_ns. Pass the mount options and the namespace separately to mount_ns so that filesystems such as proc that have mount options, can use mount_ns. Pass the user namespace to mount_ns so that the standard permission check that verifies the mounter has permissions over the namespace can be performed in mount_ns instead of in each filesystems .mount method. Thus removing the duplication between mqueuefs and proc in terms of permission checks. The extra permission check does not currently affect the rpc_pipefs filesystem and the nfsd filesystem as those filesystems do not currently allow unprivileged mounts. Without unpvileged mounts it is guaranteed that the caller has already passed capable(CAP_SYS_ADMIN) which guarantees extra permission check will pass. Update rpc_pipefs and the nfsd filesystem to ensure that the network namespace reference is always taken in fill_super and always put in kill_sb so that the logic is simpler and so that errors originating inside of fill_super do not cause a network namespace leak. Acked-by: Seth Forshee Signed-off-by: "Eric W. Biederman" diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 9690cb4..5a6ae25 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1154,20 +1154,15 @@ static int nfsd_fill_super(struct super_block * sb, void * data, int silent) #endif /* last one */ {""} }; - struct net *net = data; - int ret; - - ret = simple_fill_super(sb, 0x6e667364, nfsd_files); - if (ret) - return ret; - sb->s_fs_info = get_net(net); - return 0; + get_net(sb->s_fs_info); + return simple_fill_super(sb, 0x6e667364, nfsd_files); } static struct dentry *nfsd_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { - return mount_ns(fs_type, flags, current->nsproxy->net_ns, nfsd_fill_super); + struct net *net = current->nsproxy->net_ns; + return mount_ns(fs_type, flags, data, net, net->user_ns, nfsd_fill_super); } static void nfsd_umount(struct super_block *sb) diff --git a/fs/super.c b/fs/super.c index d78b984..fd65667 100644 --- a/fs/super.c +++ b/fs/super.c @@ -918,12 +918,19 @@ static int ns_set_super(struct super_block *sb, void *data) return set_anon_super(sb, NULL); } -struct dentry *mount_ns(struct file_system_type *fs_type, int flags, - void *data, int (*fill_super)(struct super_block *, void *, int)) +struct dentry *mount_ns(struct file_system_type *fs_type, + int flags, void *data, void *ns, struct user_namespace *user_ns, + int (*fill_super)(struct super_block *, void *, int)) { struct super_block *sb; - sb = sget(fs_type, ns_test_super, ns_set_super, flags, data); + /* Don't allow mounting unless the caller has CAP_SYS_ADMIN + * over the namespace. + */ + if (!(flags & MS_KERNMOUNT) && !ns_capable(user_ns, CAP_SYS_ADMIN)) + return ERR_PTR(-EPERM); + + sb = sget(fs_type, ns_test_super, ns_set_super, flags, ns); if (IS_ERR(sb)) return ERR_CAST(sb); diff --git a/include/linux/fs.h b/include/linux/fs.h index 71988dd..1ce006a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2034,8 +2034,9 @@ struct file_system_type { #define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME) -extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags, - void *data, int (*fill_super)(struct super_block *, void *, int)); +extern struct dentry *mount_ns(struct file_system_type *fs_type, + int flags, void *data, void *ns, struct user_namespace *user_ns, + int (*fill_super)(struct super_block *, void *, int)); extern struct dentry *mount_bdev(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, int (*fill_super)(struct super_block *, void *, int)); diff --git a/ipc/mqueue.c b/ipc/mqueue.c index ade739f..60d9708 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -305,7 +305,7 @@ err: static int mqueue_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; - struct ipc_namespace *ns = data; + struct ipc_namespace *ns = sb->s_fs_info; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; @@ -326,17 +326,14 @@ static struct dentry *mqueue_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { - if (!(flags & MS_KERNMOUNT)) { - struct ipc_namespace *ns = current->nsproxy->ipc_ns; - /* Don't allow mounting unless the caller has CAP_SYS_ADMIN - * over the ipc namespace. - */ - if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) - return ERR_PTR(-EPERM); - - data = ns; + struct ipc_namespace *ns; + if (flags & MS_KERNMOUNT) { + ns = data; + data = NULL; + } else { + ns = current->nsproxy->ipc_ns; } - return mount_ns(fs_type, flags, data, mqueue_fill_super); + return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super); } static void init_once(void *foo) diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index fc48eca..84f98cb 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -1386,7 +1386,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; struct dentry *root, *gssd_dentry; - struct net *net = data; + struct net *net = get_net(sb->s_fs_info); struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); int err; @@ -1419,7 +1419,6 @@ rpc_fill_super(struct super_block *sb, void *data, int silent) sb); if (err) goto err_depopulate; - sb->s_fs_info = get_net(net); mutex_unlock(&sn->pipefs_sb_lock); return 0; @@ -1448,7 +1447,8 @@ static struct dentry * rpc_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { - return mount_ns(fs_type, flags, current->nsproxy->net_ns, rpc_fill_super); + struct net *net = current->nsproxy->net_ns; + return mount_ns(fs_type, flags, data, net, net->user_ns, rpc_fill_super); } static void rpc_kill_sb(struct super_block *sb) @@ -1468,9 +1468,9 @@ static void rpc_kill_sb(struct super_block *sb) RPC_PIPEFS_UMOUNT, sb); mutex_unlock(&sn->pipefs_sb_lock); - put_net(net); out: kill_litter_super(sb); + put_net(net); } static struct file_system_type rpc_pipe_fs_type = { -- cgit v0.10.2