From: Al Viro <[email protected]> New pseudo-filesystem: nsfs. Targets of /proc/*/ns/* live there now. It's not mountable (not even registered, so it's not in /proc/filesystems, etc.). Files on it *are* bindable - we explicitly permit that in do_loopback().
This stuff lives in fs/nsfs.c now; proc_ns_fget() moved there as well. get_proc_ns() is a macro now (it's simply returning ->i_private; would have been an inline, if not for header ordering headache). proc_ns_inode() is an ex-parrot. The interface used in procfs is ns_get_path(path, task, ops) and ns_get_name(buf, size, task, ops). Dentries and inodes are never hashed; a non-counting reference to dentry is stashed in ns_common (removed by ->d_prune()) and reused by ns_get_path() if present. See ns_get_path()/ns_prune_dentry/nsfs_evict() for details of that mechanism. As the result, proc_ns_follow_link() has stopped poking in nd->path.mnt; it does nd_jump_link() on a consistent <vfsmount,dentry> pair it gets from ns_get_path(). Signed-off-by: Al Viro <[email protected]> (cherry picked from VZ8 commit e149ed2b805fefdccf7ccdfc19eca22fdd4514ac) https://jira.sw.ru/browse/PSBM-102357 Signed-off-by: Pavel Tikhomirov <[email protected]> --- fs/Makefile | 2 +- fs/internal.h | 5 ++ fs/namespace.c | 9 +- fs/nsfs.c | 167 ++++++++++++++++++++++++++++++++++++ fs/proc/inode.c | 5 -- fs/proc/namespaces.c | 171 +++++-------------------------------- include/linux/ns_common.h | 1 + include/linux/proc_ns.h | 32 ++++--- include/uapi/linux/magic.h | 1 + init/main.c | 2 + 10 files changed, 221 insertions(+), 174 deletions(-) create mode 100644 fs/nsfs.c diff --git a/fs/Makefile b/fs/Makefile index 15607740ad44..eaf855395381 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 bio.o block_dev.o direct-io.o mpage.o ioprio.o diff --git a/fs/internal.h b/fs/internal.h index e3f25efb6a32..3d3d0b57c8ff 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -170,3 +170,8 @@ loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length, */ extern void group_pin_kill(struct hlist_head *p); 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 b88e6083d8d6..ab4fcd9a5b1f 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1877,8 +1877,8 @@ 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) @@ -2367,7 +2367,10 @@ 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 000000000000..cb8323fac27f --- /dev/null +++ b/fs/nsfs.c @@ -0,0 +1,167 @@ +#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); + } +} + +static int ns_delete_dentry(const struct dentry *dentry) +{ + /* Don't cache namespace inodes when not in use */ + return 1; +} + +const struct dentry_operations ns_dentry_operations = +{ + .d_prune = ns_prune_dentry, + .d_delete = ns_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 8918cf3060a8..fba30eb2aed6 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); @@ -50,10 +49,6 @@ static void proc_evict_inode(struct inode *inode) rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); proc_sys_evict_inode(inode, 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 1f152f9f6ec4..49d459f05546 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> @@ -34,151 +30,50 @@ 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 int ns_delete_dentry(const struct dentry *dentry) -{ - /* Don't cache namespace inodes when not in use */ - return 1; -} - -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 = ns_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; - - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - goto out_put_task; + return error; - 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_FSCREDS)) { + 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 len = -EACCES; task = get_proc_task(inode); if (!task) - goto out; - - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - goto out_put_task; - - len = -ENOENT; - ns = ns_ops->get(task); - if (!ns) - goto out_put_task; - - snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns->inum); - len = strlen(name); - - if (len > buflen) - len = buflen; - if (copy_to_user(buffer, name, len)) - len = -EFAULT; - - ns_ops->put(ns); -out_put_task: + return len; + if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) { + len = ns_get_name(name, sizeof(name), task, ns_ops); + if (len >= 0) { + len = strlen(name); + + if (len > buflen) + len = buflen; + if (copy_to_user(buffer, name, len)) + len = -EFAULT; + } + } put_task_struct(task); -out: return len; } @@ -318,31 +213,3 @@ 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 ce23cf4bbe69..85a5c8c16be9 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 0068daaf7c3c..065d651fde7c 100644 --- a/include/linux/proc_ns.h +++ b/include/linux/proc_ns.h @@ -4,10 +4,13 @@ #ifndef _LINUX_PROC_NS_H #define _LINUX_PROC_NS_H +#include <linux/ns_common.h> + struct super_block; + struct pid_namespace; struct nsproxy; -struct ns_common; +struct path; struct proc_ns_operations { const char *name; @@ -39,11 +42,8 @@ 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); extern bool proc_in_container(struct super_block *sb); @@ -52,24 +52,30 @@ extern bool proc_in_container(struct super_block *sb); 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 8af2941feda3..3ee2a9a9392f 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -76,6 +76,7 @@ #define MTD_INODE_FS_MAGIC 0x11307854 #define ANON_INODE_FS_MAGIC 0x09041934 #define BTRFS_TEST_MAGIC 0x73727279 +#define NSFS_MAGIC 0x6e736673 #define BPF_FS_MAGIC 0xcafe4a11 #endif /* __LINUX_MAGIC_H__ */ diff --git a/init/main.c b/init/main.c index 9d60adf86c36..0c2c6b41f4f0 100644 --- a/init/main.c +++ b/init/main.c @@ -77,6 +77,7 @@ #include <linux/random.h> #include <linux/context_tracking.h> #include <linux/list.h> +#include <linux/proc_ns.h> #include <linux/io.h> #include <linux/jump_label.h> #include <linux/ve.h> @@ -671,6 +672,7 @@ asmlinkage void __init start_kernel(void) #ifdef CONFIG_PROC_FS proc_root_init(); #endif + nsfs_init(); cgroup_init(); ub_init_late(); cpuset_init(); -- 2.24.1 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
