![Alexey Dobriyan](/assets/img/avatar_default.png)
Currently lookup for /proc/$PID first goes through spinlock and whole list of misc /proc entries only to confirm that, yes, /proc/42 can not possibly match random proc entry. List is is several dozens entries long (52 entries on my setup). None of this is necessary. Try to convert dentry name to integer first. If it works, it must be /proc/$PID. If it doesn't, it must be random proc entry. Based on patch from Al Viro. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
270 lines
5.6 KiB
C
270 lines
5.6 KiB
C
/*
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* linux/fs/proc/root.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* proc root directory handling functions
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*/
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#include <asm/uaccess.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/user_namespace.h>
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#include <linux/mount.h>
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#include <linux/pid_namespace.h>
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#include <linux/parser.h>
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#include "internal.h"
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static int proc_test_super(struct super_block *sb, void *data)
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{
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return sb->s_fs_info == data;
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}
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static int proc_set_super(struct super_block *sb, void *data)
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{
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int err = set_anon_super(sb, NULL);
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if (!err) {
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struct pid_namespace *ns = (struct pid_namespace *)data;
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sb->s_fs_info = get_pid_ns(ns);
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}
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return err;
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}
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enum {
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Opt_gid, Opt_hidepid, Opt_err,
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};
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static const match_table_t tokens = {
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{Opt_hidepid, "hidepid=%u"},
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{Opt_gid, "gid=%u"},
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{Opt_err, NULL},
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};
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static int proc_parse_options(char *options, struct pid_namespace *pid)
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{
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char *p;
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substring_t args[MAX_OPT_ARGS];
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int option;
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if (!options)
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return 1;
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while ((p = strsep(&options, ",")) != NULL) {
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int token;
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if (!*p)
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continue;
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args[0].to = args[0].from = NULL;
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token = match_token(p, tokens, args);
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switch (token) {
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case Opt_gid:
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if (match_int(&args[0], &option))
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return 0;
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pid->pid_gid = make_kgid(current_user_ns(), option);
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break;
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case Opt_hidepid:
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if (match_int(&args[0], &option))
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return 0;
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if (option < 0 || option > 2) {
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pr_err("proc: hidepid value must be between 0 and 2.\n");
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return 0;
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}
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pid->hide_pid = option;
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break;
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default:
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pr_err("proc: unrecognized mount option \"%s\" "
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"or missing value\n", p);
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return 0;
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}
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}
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return 1;
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}
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int proc_remount(struct super_block *sb, int *flags, char *data)
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{
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struct pid_namespace *pid = sb->s_fs_info;
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sync_filesystem(sb);
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return !proc_parse_options(data, pid);
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}
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static struct dentry *proc_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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int err;
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struct super_block *sb;
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struct pid_namespace *ns;
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char *options;
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if (flags & MS_KERNMOUNT) {
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ns = (struct pid_namespace *)data;
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options = NULL;
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} else {
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ns = task_active_pid_ns(current);
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options = data;
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if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
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return ERR_PTR(-EPERM);
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/* Does the mounter have privilege over the pid namespace? */
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if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
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return ERR_PTR(-EPERM);
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}
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sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns);
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if (IS_ERR(sb))
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return ERR_CAST(sb);
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if (!proc_parse_options(options, ns)) {
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deactivate_locked_super(sb);
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return ERR_PTR(-EINVAL);
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}
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if (!sb->s_root) {
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err = proc_fill_super(sb);
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if (err) {
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deactivate_locked_super(sb);
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return ERR_PTR(err);
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}
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sb->s_flags |= MS_ACTIVE;
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}
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return dget(sb->s_root);
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}
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static void proc_kill_sb(struct super_block *sb)
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{
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struct pid_namespace *ns;
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ns = (struct pid_namespace *)sb->s_fs_info;
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if (ns->proc_self)
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dput(ns->proc_self);
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kill_anon_super(sb);
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put_pid_ns(ns);
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}
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static struct file_system_type proc_fs_type = {
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.name = "proc",
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.mount = proc_mount,
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.kill_sb = proc_kill_sb,
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.fs_flags = FS_USERNS_MOUNT,
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};
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void __init proc_root_init(void)
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{
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int err;
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proc_init_inodecache();
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err = register_filesystem(&proc_fs_type);
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if (err)
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return;
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proc_self_init();
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proc_symlink("mounts", NULL, "self/mounts");
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proc_net_init();
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#ifdef CONFIG_SYSVIPC
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proc_mkdir("sysvipc", NULL);
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#endif
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proc_mkdir("fs", NULL);
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proc_mkdir("driver", NULL);
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proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
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#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
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/* just give it a mountpoint */
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proc_mkdir("openprom", NULL);
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#endif
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proc_tty_init();
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proc_mkdir("bus", NULL);
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proc_sys_init();
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}
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static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
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)
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{
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generic_fillattr(dentry->d_inode, stat);
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stat->nlink = proc_root.nlink + nr_processes();
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return 0;
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}
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static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
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{
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if (!proc_pid_lookup(dir, dentry, flags))
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return NULL;
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return proc_lookup(dir, dentry, flags);
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}
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static int proc_root_readdir(struct file *file, struct dir_context *ctx)
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{
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if (ctx->pos < FIRST_PROCESS_ENTRY) {
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int error = proc_readdir(file, ctx);
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if (unlikely(error <= 0))
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return error;
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ctx->pos = FIRST_PROCESS_ENTRY;
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}
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return proc_pid_readdir(file, ctx);
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}
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/*
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* The root /proc directory is special, as it has the
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* <pid> directories. Thus we don't use the generic
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* directory handling functions for that..
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*/
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static const struct file_operations proc_root_operations = {
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.read = generic_read_dir,
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.iterate = proc_root_readdir,
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.llseek = default_llseek,
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};
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/*
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* proc root can do almost nothing..
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*/
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static const struct inode_operations proc_root_inode_operations = {
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.lookup = proc_root_lookup,
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.getattr = proc_root_getattr,
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};
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/*
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* This is the root "inode" in the /proc tree..
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*/
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struct proc_dir_entry proc_root = {
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.low_ino = PROC_ROOT_INO,
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.namelen = 5,
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.mode = S_IFDIR | S_IRUGO | S_IXUGO,
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.nlink = 2,
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.count = ATOMIC_INIT(1),
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.proc_iops = &proc_root_inode_operations,
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.proc_fops = &proc_root_operations,
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.parent = &proc_root,
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.name = "/proc",
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};
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int pid_ns_prepare_proc(struct pid_namespace *ns)
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{
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struct vfsmount *mnt;
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mnt = kern_mount_data(&proc_fs_type, ns);
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if (IS_ERR(mnt))
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return PTR_ERR(mnt);
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ns->proc_mnt = mnt;
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return 0;
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}
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void pid_ns_release_proc(struct pid_namespace *ns)
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{
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kern_unmount(ns->proc_mnt);
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}
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