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 <vfsmount,dentry> pair it gets
from ns_get_path().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 18fc1cf..aaaac77 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 @@
&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;
+ return res;
- if (!ptrace_may_access(task, PTRACE_MODE_READ))
- goto out_put_task;
-
- 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 @@
.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;
-}