diff options
| -rw-r--r-- | fs/Makefile | 2 | ||||
| -rw-r--r-- | fs/internal.h | 5 | ||||
| -rw-r--r-- | fs/namespace.c | 9 | ||||
| -rw-r--r-- | fs/nsfs.c | 161 | ||||
| -rw-r--r-- | fs/proc/inode.c | 5 | ||||
| -rw-r--r-- | fs/proc/namespaces.c | 152 | ||||
| -rw-r--r-- | include/linux/ns_common.h | 1 | ||||
| -rw-r--r-- | include/linux/proc_ns.h | 31 | ||||
| -rw-r--r-- | include/uapi/linux/magic.h | 1 | ||||
| -rw-r--r-- | init/main.c | 2 |
10 files changed, 208 insertions, 161 deletions
diff --git a/fs/Makefile b/fs/Makefile index 34a1b9dea6d..34393376eaa 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -11,7 +11,7 @@ obj-y := open.o read_write.o file_table.o super.o \ attr.o bad_inode.o file.o filesystems.o namespace.o \ seq_file.o xattr.o libfs.o fs-writeback.o \ pnode.o splice.o sync.o utimes.o \ - stack.o fs_struct.o statfs.o fs_pin.o + stack.o fs_struct.o statfs.o fs_pin.o nsfs.o ifeq ($(CONFIG_BLOCK),y) obj-y += buffer.o block_dev.o direct-io.o mpage.o diff --git a/fs/internal.h b/fs/internal.h index 757ba2abf21..e9a61fe6757 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -147,3 +147,8 @@ extern const struct file_operations pipefifo_fops; */ extern void sb_pin_kill(struct super_block *sb); extern void mnt_pin_kill(struct mount *m); + +/* + * fs/nsfs.c + */ +extern struct dentry_operations ns_dentry_operations; diff --git a/fs/namespace.c b/fs/namespace.c index 9dfb4cac0c4..30df6e7dd80 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1569,8 +1569,8 @@ SYSCALL_DEFINE1(oldumount, char __user *, name) static bool is_mnt_ns_file(struct dentry *dentry) { /* Is this a proxy for a mount namespace? */ - struct inode *inode = dentry->d_inode; - return proc_ns_inode(inode) && dentry->d_fsdata == &mntns_operations; + return dentry->d_op == &ns_dentry_operations && + dentry->d_fsdata == &mntns_operations; } struct mnt_namespace *to_mnt_ns(struct ns_common *ns) @@ -2016,7 +2016,10 @@ static int do_loopback(struct path *path, const char *old_name, if (IS_MNT_UNBINDABLE(old)) goto out2; - if (!check_mnt(parent) || !check_mnt(old)) + if (!check_mnt(parent)) + goto out2; + + if (!check_mnt(old) && old_path.dentry->d_op != &ns_dentry_operations) goto out2; if (!recurse && has_locked_children(old, old_path.dentry)) diff --git a/fs/nsfs.c b/fs/nsfs.c new file mode 100644 index 00000000000..af1b24fa899 --- /dev/null +++ b/fs/nsfs.c @@ -0,0 +1,161 @@ +#include <linux/mount.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/proc_ns.h> +#include <linux/magic.h> +#include <linux/ktime.h> + +static struct vfsmount *nsfs_mnt; + +static const struct file_operations ns_file_operations = { + .llseek = no_llseek, +}; + +static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) +{ + struct inode *inode = dentry->d_inode; + const struct proc_ns_operations *ns_ops = dentry->d_fsdata; + + return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]", + ns_ops->name, inode->i_ino); +} + +static void ns_prune_dentry(struct dentry *dentry) +{ + struct inode *inode = dentry->d_inode; + if (inode) { + struct ns_common *ns = inode->i_private; + atomic_long_set(&ns->stashed, 0); + } +} + +const struct dentry_operations ns_dentry_operations = +{ + .d_prune = ns_prune_dentry, + .d_delete = always_delete_dentry, + .d_dname = ns_dname, +}; + +static void nsfs_evict(struct inode *inode) +{ + struct ns_common *ns = inode->i_private; + clear_inode(inode); + ns->ops->put(ns); +} + +void *ns_get_path(struct path *path, struct task_struct *task, + const struct proc_ns_operations *ns_ops) +{ + struct vfsmount *mnt = mntget(nsfs_mnt); + struct qstr qname = { .name = "", }; + struct dentry *dentry; + struct inode *inode; + struct ns_common *ns; + unsigned long d; + +again: + ns = ns_ops->get(task); + if (!ns) { + mntput(mnt); + return ERR_PTR(-ENOENT); + } + rcu_read_lock(); + d = atomic_long_read(&ns->stashed); + if (!d) + goto slow; + dentry = (struct dentry *)d; + if (!lockref_get_not_dead(&dentry->d_lockref)) + goto slow; + rcu_read_unlock(); + ns_ops->put(ns); +got_it: + path->mnt = mnt; + path->dentry = dentry; + return NULL; +slow: + rcu_read_unlock(); + inode = new_inode_pseudo(mnt->mnt_sb); + if (!inode) { + ns_ops->put(ns); + mntput(mnt); + return ERR_PTR(-ENOMEM); + } + inode->i_ino = ns->inum; + inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; + inode->i_flags |= S_IMMUTABLE; + inode->i_mode = S_IFREG | S_IRUGO; + inode->i_fop = &ns_file_operations; + inode->i_private = ns; + + dentry = d_alloc_pseudo(mnt->mnt_sb, &qname); + if (!dentry) { + iput(inode); + mntput(mnt); + return ERR_PTR(-ENOMEM); + } + d_instantiate(dentry, inode); + dentry->d_fsdata = (void *)ns_ops; + d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry); + if (d) { + d_delete(dentry); /* make sure ->d_prune() does nothing */ + dput(dentry); + cpu_relax(); + goto again; + } + goto got_it; +} + +int ns_get_name(char *buf, size_t size, struct task_struct *task, + const struct proc_ns_operations *ns_ops) +{ + struct ns_common *ns; + int res = -ENOENT; + ns = ns_ops->get(task); + if (ns) { + res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum); + ns_ops->put(ns); + } + return res; +} + +struct file *proc_ns_fget(int fd) +{ + struct file *file; + + file = fget(fd); + if (!file) + return ERR_PTR(-EBADF); + + if (file->f_op != &ns_file_operations) + goto out_invalid; + + return file; + +out_invalid: + fput(file); + return ERR_PTR(-EINVAL); +} + +static const struct super_operations nsfs_ops = { + .statfs = simple_statfs, + .evict_inode = nsfs_evict, +}; +static struct dentry *nsfs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_pseudo(fs_type, "nsfs:", &nsfs_ops, + &ns_dentry_operations, NSFS_MAGIC); +} +static struct file_system_type nsfs = { + .name = "nsfs", + .mount = nsfs_mount, + .kill_sb = kill_anon_super, +}; + +void __init nsfs_init(void) +{ + nsfs_mnt = kern_mount(&nsfs); + if (IS_ERR(nsfs_mnt)) + panic("can't set nsfs up\n"); + nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER; +} diff --git a/fs/proc/inode.c b/fs/proc/inode.c index a212996e098..57a9be9a666 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -32,7 +32,6 @@ static void proc_evict_inode(struct inode *inode) { struct proc_dir_entry *de; struct ctl_table_header *head; - struct ns_common *ns; truncate_inode_pages_final(&inode->i_data); clear_inode(inode); @@ -49,10 +48,6 @@ static void proc_evict_inode(struct inode *inode) RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL); sysctl_head_put(head); } - /* Release any associated namespace */ - ns = PROC_I(inode)->ns.ns; - if (ns && ns->ops) - ns->ops->put(ns); } static struct kmem_cache * proc_inode_cachep; diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 18fc1cf899d..aaaac77abad 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -1,10 +1,6 @@ #include <linux/proc_fs.h> #include <linux/nsproxy.h> -#include <linux/sched.h> #include <linux/ptrace.h> -#include <linux/fs_struct.h> -#include <linux/mount.h> -#include <linux/path.h> #include <linux/namei.h> #include <linux/file.h> #include <linux/utsname.h> @@ -34,139 +30,45 @@ static const struct proc_ns_operations *ns_entries[] = { &mntns_operations, }; -static const struct file_operations ns_file_operations = { - .llseek = no_llseek, -}; - -static const struct inode_operations ns_inode_operations = { - .setattr = proc_setattr, -}; - -static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) -{ - struct inode *inode = dentry->d_inode; - const struct proc_ns_operations *ns_ops = dentry->d_fsdata; - - return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]", - ns_ops->name, inode->i_ino); -} - -const struct dentry_operations ns_dentry_operations = -{ - .d_delete = always_delete_dentry, - .d_dname = ns_dname, -}; - -static struct dentry *proc_ns_get_dentry(struct super_block *sb, - struct task_struct *task, const struct proc_ns_operations *ns_ops) -{ - struct dentry *dentry, *result; - struct inode *inode; - struct proc_inode *ei; - struct qstr qname = { .name = "", }; - struct ns_common *ns; - - ns = ns_ops->get(task); - if (!ns) - return ERR_PTR(-ENOENT); - - dentry = d_alloc_pseudo(sb, &qname); - if (!dentry) { - ns_ops->put(ns); - return ERR_PTR(-ENOMEM); - } - dentry->d_fsdata = (void *)ns_ops; - - inode = iget_locked(sb, ns->inum); - if (!inode) { - dput(dentry); - ns_ops->put(ns); - return ERR_PTR(-ENOMEM); - } - - ei = PROC_I(inode); - if (inode->i_state & I_NEW) { - inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; - inode->i_op = &ns_inode_operations; - inode->i_mode = S_IFREG | S_IRUGO; - inode->i_fop = &ns_file_operations; - ei->ns.ns_ops = ns_ops; - ei->ns.ns = ns; - unlock_new_inode(inode); - } else { - ns_ops->put(ns); - } - - d_set_d_op(dentry, &ns_dentry_operations); - result = d_instantiate_unique(dentry, inode); - if (result) { - dput(dentry); - dentry = result; - } - - return dentry; -} - static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd) { struct inode *inode = dentry->d_inode; - struct super_block *sb = inode->i_sb; - struct proc_inode *ei = PROC_I(inode); + const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns.ns_ops; struct task_struct *task; struct path ns_path; void *error = ERR_PTR(-EACCES); task = get_proc_task(inode); if (!task) - goto out; + return error; - if (!ptrace_may_access(task, PTRACE_MODE_READ)) - goto out_put_task; - - ns_path.dentry = proc_ns_get_dentry(sb, task, ei->ns.ns_ops); - if (IS_ERR(ns_path.dentry)) { - error = ERR_CAST(ns_path.dentry); - goto out_put_task; + if (ptrace_may_access(task, PTRACE_MODE_READ)) { + error = ns_get_path(&ns_path, task, ns_ops); + if (!error) + nd_jump_link(nd, &ns_path); } - - ns_path.mnt = mntget(nd->path.mnt); - nd_jump_link(nd, &ns_path); - error = NULL; - -out_put_task: put_task_struct(task); -out: return error; } static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen) { struct inode *inode = dentry->d_inode; - struct proc_inode *ei = PROC_I(inode); - const struct proc_ns_operations *ns_ops = ei->ns.ns_ops; + const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns.ns_ops; struct task_struct *task; - struct ns_common *ns; char name[50]; int res = -EACCES; task = get_proc_task(inode); if (!task) - goto out; - - if (!ptrace_may_access(task, PTRACE_MODE_READ)) - goto out_put_task; + return res; - res = -ENOENT; - ns = ns_ops->get(task); - if (!ns) - goto out_put_task; - - snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns->inum); - res = readlink_copy(buffer, buflen, name); - ns_ops->put(ns); -out_put_task: + if (ptrace_may_access(task, PTRACE_MODE_READ)) { + res = ns_get_name(name, sizeof(name), task, ns_ops); + if (res >= 0) + res = readlink_copy(buffer, buflen, name); + } put_task_struct(task); -out: return res; } @@ -268,31 +170,3 @@ const struct inode_operations proc_ns_dir_inode_operations = { .getattr = pid_getattr, .setattr = proc_setattr, }; - -struct file *proc_ns_fget(int fd) -{ - struct file *file; - - file = fget(fd); - if (!file) - return ERR_PTR(-EBADF); - - if (file->f_op != &ns_file_operations) - goto out_invalid; - - return file; - -out_invalid: - fput(file); - return ERR_PTR(-EINVAL); -} - -struct ns_common *get_proc_ns(struct inode *inode) -{ - return PROC_I(inode)->ns.ns; -} - -bool proc_ns_inode(struct inode *inode) -{ - return inode->i_fop == &ns_file_operations; -} diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index ce23cf4bbe6..85a5c8c16be 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -4,6 +4,7 @@ struct proc_ns_operations; struct ns_common { + atomic_long_t stashed; const struct proc_ns_operations *ops; unsigned int inum; }; diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h index 2837ff41cfe..42dfc615dbf 100644 --- a/include/linux/proc_ns.h +++ b/include/linux/proc_ns.h @@ -4,9 +4,11 @@ #ifndef _LINUX_PROC_NS_H #define _LINUX_PROC_NS_H +#include <linux/ns_common.h> + struct pid_namespace; struct nsproxy; -struct ns_common; +struct path; struct proc_ns_operations { const char *name; @@ -38,35 +40,38 @@ enum { extern int pid_ns_prepare_proc(struct pid_namespace *ns); extern void pid_ns_release_proc(struct pid_namespace *ns); -extern struct file *proc_ns_fget(int fd); -extern struct ns_common *get_proc_ns(struct inode *); extern int proc_alloc_inum(unsigned int *pino); extern void proc_free_inum(unsigned int inum); -extern bool proc_ns_inode(struct inode *inode); #else /* CONFIG_PROC_FS */ static inline int pid_ns_prepare_proc(struct pid_namespace *ns) { return 0; } static inline void pid_ns_release_proc(struct pid_namespace *ns) {} -static inline struct file *proc_ns_fget(int fd) -{ - return ERR_PTR(-EINVAL); -} - -static inline struct ns_common *get_proc_ns(struct inode *inode) { return NULL; } - static inline int proc_alloc_inum(unsigned int *inum) { *inum = 1; return 0; } static inline void proc_free_inum(unsigned int inum) {} -static inline bool proc_ns_inode(struct inode *inode) { return false; } #endif /* CONFIG_PROC_FS */ -#define ns_alloc_inum(ns) proc_alloc_inum(&(ns)->inum) +static inline int ns_alloc_inum(struct ns_common *ns) +{ + atomic_long_set(&ns->stashed, 0); + return proc_alloc_inum(&ns->inum); +} + #define ns_free_inum(ns) proc_free_inum((ns)->inum) +extern struct file *proc_ns_fget(int fd); +#define get_proc_ns(inode) ((struct ns_common *)(inode)->i_private) +extern void *ns_get_path(struct path *path, struct task_struct *task, + const struct proc_ns_operations *ns_ops); + +extern int ns_get_name(char *buf, size_t size, struct task_struct *task, + const struct proc_ns_operations *ns_ops); +extern void nsfs_init(void); + #endif /* _LINUX_PROC_NS_H */ diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index 77c60311a6c..7d664ea85eb 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -72,5 +72,6 @@ #define MTD_INODE_FS_MAGIC 0x11307854 #define ANON_INODE_FS_MAGIC 0x09041934 #define BTRFS_TEST_MAGIC 0x73727279 +#define NSFS_MAGIC 0x6e736673 #endif /* __LINUX_MAGIC_H__ */ diff --git a/init/main.c b/init/main.c index 800a0daede7..bcc75057ea8 100644 --- a/init/main.c +++ b/init/main.c @@ -78,6 +78,7 @@ #include <linux/context_tracking.h> #include <linux/random.h> #include <linux/list.h> +#include <linux/proc_ns.h> #include <asm/io.h> #include <asm/bugs.h> @@ -660,6 +661,7 @@ asmlinkage __visible void __init start_kernel(void) /* rootfs populating might need page-writeback */ page_writeback_init(); proc_root_init(); + nsfs_init(); cgroup_init(); cpuset_init(); taskstats_init_early(); |