Commit 0b77f5bf authored by David Howells's avatar David Howells Committed by Linus Torvalds

keys: make the keyring quotas controllable through /proc/sys

Make the keyring quotas controllable through /proc/sys files:

 (*) /proc/sys/kernel/keys/root_maxkeys
     /proc/sys/kernel/keys/root_maxbytes

     Maximum number of keys that root may have and the maximum total number of
     bytes of data that root may have stored in those keys.

 (*) /proc/sys/kernel/keys/maxkeys
     /proc/sys/kernel/keys/maxbytes

     Maximum number of keys that each non-root user may have and the maximum
     total number of bytes of data that each of those users may have stored in
     their keys.

Also increase the quotas as a number of people have been complaining that it's
not big enough.  I'm not sure that it's big enough now either, but on the
other hand, it can now be set in /etc/sysctl.conf.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: <kwc@citi.umich.edu>
Cc: <arunsr@cse.iitk.ac.in>
Cc: <dwalsh@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 69664cf1
......@@ -170,7 +170,8 @@ The key service provides a number of features besides keys:
amount of description and payload space that can be consumed.
The user can view information on this and other statistics through procfs
files.
files. The root user may also alter the quota limits through sysctl files
(see the section "New procfs files").
Process-specific and thread-specific keyrings are not counted towards a
user's quota.
......@@ -329,6 +330,27 @@ about the status of the key service:
<bytes>/<max> Key size quota
Four new sysctl files have been added also for the purpose of controlling the
quota limits on keys:
(*) /proc/sys/kernel/keys/root_maxkeys
/proc/sys/kernel/keys/root_maxbytes
These files hold the maximum number of keys that root may have and the
maximum total number of bytes of data that root may have stored in those
keys.
(*) /proc/sys/kernel/keys/maxkeys
/proc/sys/kernel/keys/maxbytes
These files hold the maximum number of keys that each non-root user may
have and the maximum total number of bytes of data that each of those
users may have stored in their keys.
Root may alter these by writing each new limit as a decimal number string to
the appropriate file.
===============================
USERSPACE SYSTEM CALL INTERFACE
===============================
......
......@@ -19,6 +19,7 @@
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.h>
#include <linux/sysctl.h>
#include <asm/atomic.h>
#ifdef __KERNEL__
......@@ -265,6 +266,10 @@ extern struct key *key_lookup(key_serial_t id);
#define key_serial(key) ((key) ? (key)->serial : 0)
#ifdef CONFIG_SYSCTL
extern ctl_table key_sysctls[];
#endif
/*
* the userspace interface
*/
......
......@@ -38,6 +38,7 @@
#include <linux/writeback.h>
#include <linux/hugetlb.h>
#include <linux/initrd.h>
#include <linux/key.h>
#include <linux/times.h>
#include <linux/limits.h>
#include <linux/dcache.h>
......@@ -809,6 +810,14 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dostring,
.strategy = &sysctl_string,
},
#ifdef CONFIG_KEYS
{
.ctl_name = CTL_UNNUMBERED,
.procname = "keys",
.mode = 0555,
.child = key_sysctls,
},
#endif
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt
......
......@@ -14,3 +14,4 @@ obj-y := \
obj-$(CONFIG_KEYS_COMPAT) += compat.o
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SYSCTL) += sysctl.o
......@@ -57,10 +57,6 @@ struct key_user {
int qnbytes; /* number of bytes allocated to this user */
};
#define KEYQUOTA_MAX_KEYS 100
#define KEYQUOTA_MAX_BYTES 10000
#define KEYQUOTA_LINK_BYTES 4 /* a link in a keyring is worth 4 bytes */
extern struct rb_root key_user_tree;
extern spinlock_t key_user_lock;
extern struct key_user root_key_user;
......@@ -68,6 +64,16 @@ extern struct key_user root_key_user;
extern struct key_user *key_user_lookup(uid_t uid);
extern void key_user_put(struct key_user *user);
/*
* key quota limits
* - root has its own separate limits to everyone else
*/
extern unsigned key_quota_root_maxkeys;
extern unsigned key_quota_root_maxbytes;
extern unsigned key_quota_maxkeys;
extern unsigned key_quota_maxbytes;
#define KEYQUOTA_LINK_BYTES 4 /* a link in a keyring is worth 4 bytes */
extern struct rb_root key_serial_tree;
......
......@@ -27,6 +27,11 @@ DEFINE_SPINLOCK(key_serial_lock);
struct rb_root key_user_tree; /* tree of quota records indexed by UID */
DEFINE_SPINLOCK(key_user_lock);
unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */
unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */
unsigned int key_quota_maxkeys = 200; /* general key count quota */
unsigned int key_quota_maxbytes = 20000; /* general key space quota */
static LIST_HEAD(key_types_list);
static DECLARE_RWSEM(key_types_sem);
......@@ -236,11 +241,16 @@ struct key *key_alloc(struct key_type *type, const char *desc,
/* check that the user's quota permits allocation of another key and
* its description */
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
unsigned maxkeys = (uid == 0) ?
key_quota_root_maxkeys : key_quota_maxkeys;
unsigned maxbytes = (uid == 0) ?
key_quota_root_maxbytes : key_quota_maxbytes;
spin_lock(&user->lock);
if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
)
if (user->qnkeys + 1 >= maxkeys ||
user->qnbytes + quotalen >= maxbytes ||
user->qnbytes + quotalen < user->qnbytes)
goto no_quota;
}
......@@ -345,11 +355,14 @@ int key_payload_reserve(struct key *key, size_t datalen)
/* contemplate the quota adjustment */
if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
unsigned maxbytes = (key->user->uid == 0) ?
key_quota_root_maxbytes : key_quota_maxbytes;
spin_lock(&key->user->lock);
if (delta > 0 &&
key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES
) {
(key->user->qnbytes + delta >= maxbytes ||
key->user->qnbytes + delta < key->user->qnbytes)) {
ret = -EDQUOT;
}
else {
......
......@@ -731,10 +731,16 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
/* transfer the quota burden to the new user */
if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
unsigned maxkeys = (uid == 0) ?
key_quota_root_maxkeys : key_quota_maxkeys;
unsigned maxbytes = (uid == 0) ?
key_quota_root_maxbytes : key_quota_maxbytes;
spin_lock(&newowner->lock);
if (newowner->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
newowner->qnbytes + key->quotalen >=
KEYQUOTA_MAX_BYTES)
if (newowner->qnkeys + 1 >= maxkeys ||
newowner->qnbytes + key->quotalen >= maxbytes ||
newowner->qnbytes + key->quotalen <
newowner->qnbytes)
goto quota_overrun;
newowner->qnkeys++;
......
......@@ -242,6 +242,10 @@ 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,
......@@ -249,10 +253,9 @@ static int proc_key_users_show(struct seq_file *m, void *v)
atomic_read(&user->nkeys),
atomic_read(&user->nikeys),
user->qnkeys,
KEYQUOTA_MAX_KEYS,
maxkeys,
user->qnbytes,
KEYQUOTA_MAX_BYTES
);
maxbytes);
return 0;
......
/* Key management controls
*
* Copyright (C) 2008 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 Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/key.h>
#include <linux/sysctl.h>
#include "internal.h"
ctl_table key_sysctls[] = {
{
.ctl_name = CTL_UNNUMBERED,
.procname = "maxkeys",
.data = &key_quota_maxkeys,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "maxbytes",
.data = &key_quota_maxbytes,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "root_maxkeys",
.data = &key_quota_root_maxkeys,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "root_maxbytes",
.data = &key_quota_root_maxbytes,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{ .ctl_name = 0 }
};
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