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authorDavid Howells <dhowells@redhat.com>2008-04-29 01:01:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 08:06:17 -0700
commit0b77f5bfb45c13e1e5142374f9d6ca75292252a4 (patch)
treecf62055536d267e9a4abe6518e5d9f683a1ceb75
parent69664cf16af4f31cd54d77948a4baf9c7e0ca7b9 (diff)
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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: David Howells <dhowells@redhat.com> Cc: <kwc@citi.umich.edu> Cc: <arunsr@cse.iitk.ac.in> Cc: <dwalsh@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/keys.txt24
-rw-r--r--include/linux/key.h5
-rw-r--r--kernel/sysctl.c9
-rw-r--r--security/keys/Makefile1
-rw-r--r--security/keys/internal.h14
-rw-r--r--security/keys/key.c23
-rw-r--r--security/keys/keyctl.c12
-rw-r--r--security/keys/proc.c9
-rw-r--r--security/keys/sysctl.c50
9 files changed, 131 insertions, 16 deletions
diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index be424b02437..d5c7a57d170 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -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
===============================
diff --git a/include/linux/key.h b/include/linux/key.h
index 2effd031a81..ad02d9cfe17 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -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
*/
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index fd3364827cc..0a1d2733cf4 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -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
diff --git a/security/keys/Makefile b/security/keys/Makefile
index 5145adfb6a0..747a464943a 100644
--- a/security/keys/Makefile
+++ b/security/keys/Makefile
@@ -14,3 +14,4 @@ obj-y := \
obj-$(CONFIG_KEYS_COMPAT) += compat.o
obj-$(CONFIG_PROC_FS) += proc.o
+obj-$(CONFIG_SYSCTL) += sysctl.o
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 2ab38854c47..8c05587f501 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -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;
diff --git a/security/keys/key.c b/security/keys/key.c
index 46f125aa7fa..14948cf83ef 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -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 {
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 993be634a5e..acc9c89e40a 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -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++;
diff --git a/security/keys/proc.c b/security/keys/proc.c
index e54679b848c..f619170da76 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -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;
diff --git a/security/keys/sysctl.c b/security/keys/sysctl.c
new file mode 100644
index 00000000000..b611d493c2d
--- /dev/null
+++ b/security/keys/sysctl.c
@@ -0,0 +1,50 @@
+/* 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 }
+};