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-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 be424b0..d5c7a57d 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 2effd03..ad02d9c 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 fd33648..0a1d273 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 5145adf..747a464 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 2ab3885..8c05587 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 46f125a..14948cf 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 993be63..acc9c89 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 e54679b..f619170 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 0000000..b611d49
--- /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 }
+};
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