From e149ed2b805fefdccf7ccdfc19eca22fdd4514ac Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 1 Nov 2014 10:57:28 -0400 Subject: take the targets of /proc/*/ns/* symlinks to separate fs 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 pair it gets from ns_get_path(). Signed-off-by: Al Viro --- fs/proc/inode.c | 5 -- fs/proc/namespaces.c | 152 +++++---------------------------------------------- 2 files changed, 13 insertions(+), 144 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/inode.c b/fs/proc/inode.c index a212996e0987..57a9be9a6668 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 18fc1cf899de..aaaac77abad0 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -1,10 +1,6 @@ #include #include -#include #include -#include -#include -#include #include #include #include @@ -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; -} -- cgit v1.2.3-59-g8ed1b