linux/security/keys/proc.c
David Howells fd75815f72 KEYS: Add invalidation support
Add support for invalidating a key - which renders it immediately invisible to
further searches and causes the garbage collector to immediately wake up,
remove it from keyrings and then destroy it when it's no longer referenced.

It's better not to do this with keyctl_revoke() as that marks the key to start
returning -EKEYREVOKED to searches when what is actually desired is to have the
key refetched.

To invalidate a key the caller must be granted SEARCH permission by the key.
This may be too strict.  It may be better to also permit invalidation if the
caller has any of READ, WRITE or SETATTR permission.

The primary use for this is to evict keys that are cached in special keyrings,
such as the DNS resolver or an ID mapper.

Signed-off-by: David Howells <dhowells@redhat.com>
2012-05-11 10:56:56 +01:00

354 lines
8.3 KiB
C

/* procfs files for key database enumeration
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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 rb_node *n)
{
struct user_namespace *user_ns = current_user_ns();
n = rb_next(n);
while (n) {
struct key *key = rb_entry(n, struct key, serial_node);
if (key->user->user_ns == user_ns)
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(key_serial_t id)
{
struct user_namespace *user_ns = current_user_ns();
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 (minkey->user->user_ns == user_ns)
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(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(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,
key->uid,
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 rb_node *n)
{
while (n) {
struct key_user *user = rb_entry(n, struct key_user, node);
if (user->user_ns == current_user_ns())
break;
n = rb_next(n);
}
return n;
}
static struct rb_node *key_user_next(struct rb_node *n)
{
return __key_user_next(rb_next(n));
}
static struct rb_node *key_user_first(struct rb_root *r)
{
struct rb_node *n = rb_first(r);
return __key_user_next(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(&key_user_tree);
while (pos > 0 && _p) {
pos--;
_p = key_user_next(_p);
}
return _p;
}
static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
{
(*_pos)++;
return key_user_next((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 = (user->uid == 0) ?
key_quota_root_maxkeys : key_quota_maxkeys;
unsigned maxbytes = (user->uid == 0) ?
key_quota_root_maxbytes : key_quota_maxbytes;
seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
user->uid,
atomic_read(&user->usage),
atomic_read(&user->nkeys),
atomic_read(&user->nikeys),
user->qnkeys,
maxkeys,
user->qnbytes,
maxbytes);
return 0;
}