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

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

Documentation/keys.txt

+23 −1
Original line number Diff line number Diff line
@@ -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

===============================

include/linux/key.h

+5 −0
Original line number Diff line number Diff line
@@ -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

 */

kernel/sysctl.c

+9 −0
Original line number Diff line number Diff line
@@ -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

security/keys/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -14,3 +14,4 @@ obj-y := \ 


obj-$(CONFIG_KEYS_COMPAT) += compat.o

obj-$(CONFIG_PROC_FS) += proc.o

obj-$(CONFIG_SYSCTL) += sysctl.o

security/keys/internal.h

+10 −4
Original line number Diff line number Diff line
@@ -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;