diff options
Diffstat (limited to 'security/selinux/ss/avtab.c')
| -rw-r--r-- | security/selinux/ss/avtab.c | 41 |
1 files changed, 37 insertions, 4 deletions
diff --git a/security/selinux/ss/avtab.c b/security/selinux/ss/avtab.c index 3ea0198fc964..b64f2772b030 100644 --- a/security/selinux/ss/avtab.c +++ b/security/selinux/ss/avtab.c @@ -25,10 +25,43 @@ static struct kmem_cache *avtab_node_cachep; -static inline int avtab_hash(struct avtab_key *keyp, u16 mask) +/* Based on MurmurHash3, written by Austin Appleby and placed in the + * public domain. + */ +static inline int avtab_hash(struct avtab_key *keyp, u32 mask) { - return ((keyp->target_class + (keyp->target_type << 2) + - (keyp->source_type << 9)) & mask); + static const u32 c1 = 0xcc9e2d51; + static const u32 c2 = 0x1b873593; + static const u32 r1 = 15; + static const u32 r2 = 13; + static const u32 m = 5; + static const u32 n = 0xe6546b64; + + u32 hash = 0; + +#define mix(input) { \ + u32 v = input; \ + v *= c1; \ + v = (v << r1) | (v >> (32 - r1)); \ + v *= c2; \ + hash ^= v; \ + hash = (hash << r2) | (hash >> (32 - r2)); \ + hash = hash * m + n; \ +} + + mix(keyp->target_class); + mix(keyp->target_type); + mix(keyp->source_type); + +#undef mix + + hash ^= hash >> 16; + hash *= 0x85ebca6b; + hash ^= hash >> 13; + hash *= 0xc2b2ae35; + hash ^= hash >> 16; + + return hash & mask; } static struct avtab_node* @@ -256,7 +289,7 @@ int avtab_init(struct avtab *h) int avtab_alloc(struct avtab *h, u32 nrules) { - u16 mask = 0; + u32 mask = 0; u32 shift = 0; u32 work = nrules; u32 nslot = 0; |