diff options
| -rw-r--r-- | security/keys/key.c | 28 |
1 files changed, 14 insertions, 14 deletions
diff --git a/security/keys/key.c b/security/keys/key.c index 3601fddca9f2..43295ca37b5d 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -15,11 +15,11 @@ #include <linux/slab.h> #include <linux/security.h> #include <linux/workqueue.h> +#include <linux/random.h> #include <linux/err.h> #include "internal.h" static kmem_cache_t *key_jar; -static key_serial_t key_serial_next = 3; struct rb_root key_serial_tree; /* tree of keys indexed by serial */ DEFINE_SPINLOCK(key_serial_lock); @@ -169,22 +169,23 @@ static void __init __key_insert_serial(struct key *key) /*****************************************************************************/ /* * assign a key the next unique serial number - * - we work through all the serial numbers between 2 and 2^31-1 in turn and - * then wrap + * - these are assigned randomly to avoid security issues through covert + * channel problems */ static inline void key_alloc_serial(struct key *key) { struct rb_node *parent, **p; struct key *xkey; - spin_lock(&key_serial_lock); - - /* propose a likely serial number and look for a hole for it in the + /* propose a random serial number and look for a hole for it in the * serial number tree */ - key->serial = key_serial_next; - if (key->serial < 3) - key->serial = 3; - key_serial_next = key->serial + 1; + do { + get_random_bytes(&key->serial, sizeof(key->serial)); + + key->serial >>= 1; /* negative numbers are not permitted */ + } while (key->serial < 3); + + spin_lock(&key_serial_lock); parent = NULL; p = &key_serial_tree.rb_node; @@ -204,12 +205,11 @@ static inline void key_alloc_serial(struct key *key) /* we found a key with the proposed serial number - walk the tree from * that point looking for the next unused serial number */ - serial_exists: +serial_exists: for (;;) { - key->serial = key_serial_next; + key->serial++; if (key->serial < 2) key->serial = 2; - key_serial_next = key->serial + 1; if (!rb_parent(parent)) p = &key_serial_tree.rb_node; @@ -228,7 +228,7 @@ static inline void key_alloc_serial(struct key *key) } /* we've found a suitable hole - arrange for this key to occupy it */ - insert_here: +insert_here: rb_link_node(&key->serial_node, parent, p); rb_insert_color(&key->serial_node, &key_serial_tree); |