proc.c

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/* procfs files for key database enumeration
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/errno.h>
#include "internal.h"

#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
static int proc_keys_open(struct inode *inode, struct file *file);
static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
static void proc_keys_stop(struct seq_file *p, void *v);
static int proc_keys_show(struct seq_file *m, void *v);

static const struct seq_operations proc_keys_ops = {
    .start  = proc_keys_start,
    .next   = proc_keys_next,
    .stop   = proc_keys_stop,
    .show   = proc_keys_show,
};

static const struct file_operations proc_keys_fops = {
    .open       = proc_keys_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
};
#endif

static int proc_key_users_open(struct inode *inode, struct file *file);
static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
static void proc_key_users_stop(struct seq_file *p, void *v);
static int proc_key_users_show(struct seq_file *m, void *v);

static const struct seq_operations proc_key_users_ops = {
    .start  = proc_key_users_start,
    .next   = proc_key_users_next,
    .stop   = proc_key_users_stop,
    .show   = proc_key_users_show,
};

static const struct file_operations proc_key_users_fops = {
    .open       = proc_key_users_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
};

/*
 * Declare the /proc files.
 */
static int __init key_proc_init(void)
{
    struct proc_dir_entry *p;

#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
    p = proc_create("keys", 0, NULL, &proc_keys_fops);
    if (!p)
        panic("Cannot create /proc/keys\n");
#endif

    p = proc_create("key-users", 0, NULL, &proc_key_users_fops);
    if (!p)
        panic("Cannot create /proc/key-users\n");

    return 0;
}

__initcall(key_proc_init);

/*
 * Implement "/proc/keys" to provide a list of the keys on the system that
 * grant View permission to the caller.
 */
#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS

static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
{
    struct user_namespace *user_ns = seq_user_ns(p);

    n = rb_next(n);
    while (n) {
        struct key *key = rb_entry(n, struct key, serial_node);
        if (kuid_has_mapping(user_ns, key->user->uid))
            break;
        n = rb_next(n);
    }
    return n;
}

static int proc_keys_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &proc_keys_ops);
}

static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
{
    struct user_namespace *user_ns = seq_user_ns(p);
    struct rb_node *n = key_serial_tree.rb_node;
    struct key *minkey = NULL;

    while (n) {
        struct key *key = rb_entry(n, struct key, serial_node);
        if (id < key->serial) {
            if (!minkey || minkey->serial > key->serial)
                minkey = key;
            n = n->rb_left;
        } else if (id > key->serial) {
            n = n->rb_right;
        } else {
            minkey = key;
            break;
        }
        key = NULL;
    }

    if (!minkey)
        return NULL;

    for (;;) {
        if (kuid_has_mapping(user_ns, minkey->user->uid))
            return minkey;
        n = rb_next(&minkey->serial_node);
        if (!n)
            return NULL;
        minkey = rb_entry(n, struct key, serial_node);
    }
}

static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
    __acquires(key_serial_lock)
{
    key_serial_t pos = *_pos;
    struct key *key;

    spin_lock(&key_serial_lock);

    if (*_pos > INT_MAX)
        return NULL;
    key = find_ge_key(p, pos);
    if (!key)
        return NULL;
    *_pos = key->serial;
    return &key->serial_node;
}

static inline key_serial_t key_node_serial(struct rb_node *n)
{
    struct key *key = rb_entry(n, struct key, serial_node);
    return key->serial;
}

static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
{
    struct rb_node *n;

    n = key_serial_next(p, v);
    if (n)
        *_pos = key_node_serial(n);
    return n;
}

static void proc_keys_stop(struct seq_file *p, void *v)
    __releases(key_serial_lock)
{
    spin_unlock(&key_serial_lock);
}

static int proc_keys_show(struct seq_file *m, void *v)
{
    const struct cred *cred = current_cred();
    struct rb_node *_p = v;
    struct key *key = rb_entry(_p, struct key, serial_node);
    struct timespec now;
    unsigned long timo;
    key_ref_t key_ref, skey_ref;
    char xbuf[12];
    int rc;

    key_ref = make_key_ref(key, 0);

    /* determine if the key is possessed by this process (a test we can
     * skip if the key does not indicate the possessor can view it
     */
    if (key->perm & KEY_POS_VIEW) {
        skey_ref = search_my_process_keyrings(key->type, key,
                              lookup_user_key_possessed,
                              true, cred);
        if (!IS_ERR(skey_ref)) {
            key_ref_put(skey_ref);
            key_ref = make_key_ref(key, 1);
        }
    }

    /* check whether the current task is allowed to view the key (assuming
     * non-possession)
     * - the caller holds a spinlock, and thus the RCU read lock, making our
     *   access to __current_cred() safe
     */
    rc = key_task_permission(key_ref, cred, KEY_VIEW);
    if (rc < 0)
        return 0;

    now = current_kernel_time();

    rcu_read_lock();

    /* come up with a suitable timeout value */
    if (key->expiry == 0) {
        memcpy(xbuf, "perm", 5);
    } else if (now.tv_sec >= key->expiry) {
        memcpy(xbuf, "expd", 5);
    } else {
        timo = key->expiry - now.tv_sec;

        if (timo < 60)
            sprintf(xbuf, "%lus", timo);
        else if (timo < 60*60)
            sprintf(xbuf, "%lum", timo / 60);
        else if (timo < 60*60*24)
            sprintf(xbuf, "%luh", timo / (60*60));
        else if (timo < 60*60*24*7)
            sprintf(xbuf, "%lud", timo / (60*60*24));
        else
            sprintf(xbuf, "%luw", timo / (60*60*24*7));
    }

#define showflag(KEY, LETTER, FLAG) \
    (test_bit(FLAG, &(KEY)->flags) ? LETTER : '-')

    seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
           key->serial,
           showflag(key, 'I', KEY_FLAG_INSTANTIATED),
           showflag(key, 'R', KEY_FLAG_REVOKED),
           showflag(key, 'D', KEY_FLAG_DEAD),
           showflag(key, 'Q', KEY_FLAG_IN_QUOTA),
           showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT),
           showflag(key, 'N', KEY_FLAG_NEGATIVE),
           showflag(key, 'i', KEY_FLAG_INVALIDATED),
           atomic_read(&key->usage),
           xbuf,
           key->perm,
           from_kuid_munged(seq_user_ns(m), key->uid),
           from_kgid_munged(seq_user_ns(m), key->gid),
           key->type->name);

#undef showflag

    if (key->type->describe)
        key->type->describe(key, m);
    seq_putc(m, '\n');

    rcu_read_unlock();
    return 0;
}

#endif /* CONFIG_KEYS_DEBUG_PROC_KEYS */

static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
{
    while (n) {
        struct key_user *user = rb_entry(n, struct key_user, node);
        if (kuid_has_mapping(user_ns, user->uid))
            break;
        n = rb_next(n);
    }
    return n;
}

static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
{
    return __key_user_next(user_ns, rb_next(n));
}

static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
{
    struct rb_node *n = rb_first(r);
    return __key_user_next(user_ns, n);
}

/*
 * Implement "/proc/key-users" to provides a list of the key users and their
 * quotas.
 */
static int proc_key_users_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &proc_key_users_ops);
}

static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
    __acquires(key_user_lock)
{
    struct rb_node *_p;
    loff_t pos = *_pos;

    spin_lock(&key_user_lock);

    _p = key_user_first(seq_user_ns(p), &key_user_tree);
    while (pos > 0 && _p) {
        pos--;
        _p = key_user_next(seq_user_ns(p), _p);
    }

    return _p;
}

static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
{
    (*_pos)++;
    return key_user_next(seq_user_ns(p), (struct rb_node *)v);
}

static void proc_key_users_stop(struct seq_file *p, void *v)
    __releases(key_user_lock)
{
    spin_unlock(&key_user_lock);
}

static int proc_key_users_show(struct seq_file *m, void *v)
{
    struct rb_node *_p = v;
    struct key_user *user = rb_entry(_p, struct key_user, node);
    unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
        key_quota_root_maxkeys : key_quota_maxkeys;
    unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
        key_quota_root_maxbytes : key_quota_maxbytes;

    seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
           from_kuid_munged(seq_user_ns(m), user->uid),
           atomic_read(&user->usage),
           atomic_read(&user->nkeys),
           atomic_read(&user->nikeys),
           user->qnkeys,
           maxkeys,
           user->qnbytes,
           maxbytes);

    return 0;
}