Messages in this thread |  | | | Date | Thu, 13 Mar 2008 15:28:50 -0700 | | From | Andrew Morton <> | | Subject | Re: [PATCH 3/3] KEYS: Make the keyring quotas controllable through /proc/sys |
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On Thu, 13 Mar 2008 19:14:42 +0000 David Howells <dhowells@redhat.com> wrote: > 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. > > ... > > --- 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)
err, why was that a macro? It could have been implemented as an inline. One which doesn't evaluate its argument twice (or once if it was -1).
> +#ifdef CONFIG_SYSCTL > +extern ctl_table key_sysctls[]; > +#endif
I've been going around telling people to not bother with the ifdefs here. Upside: looks nicer. Downside: defers the build error from compile-time to link-time.
> > +/* > + * 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;
open-coded knowledge of uid==0 might be problematic for containerisation. Maybe it's on the containers team's radar, maybe it's actually not a problem, don't know. (adds cc).
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