keys: Simplify key description management

Simplify key description management by cramming the word containing the
length with the first few chars of the description also.  This simplifies
the code that generates the index-key used by assoc_array.  It should speed
up key searching a bit too.

Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/include/linux/key.h b/include/linux/key.h
index 4cd5669..86ccc2d 100644 (file)
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -86,9 +86,20 @@ struct keyring_list;
 struct keyring_name;
 
 struct keyring_index_key {
+       union {
+               struct {
+#ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
+                       u8      desc_len;
+                       char    desc[sizeof(long) - 1]; /* First few chars of description */
+#else
+                       char    desc[sizeof(long) - 1]; /* First few chars of description */
+                       u8      desc_len;
+#endif
+               };
+               unsigned long x;
+       };
        struct key_type         *type;
        const char              *description;
-       size_t                  desc_len;
 };
 
 union key_payload {
@@ -202,6 +213,7 @@ struct key {
        union {
                struct keyring_index_key index_key;
                struct {
+                       unsigned long   len_desc;
                        struct key_type *type;          /* type of key */
                        char            *description;
                };

diff --git a/security/keys/internal.h b/security/keys/internal.h
index 3d5c08d..ee71c72 100644 (file)
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -90,6 +90,12 @@ extern struct mutex key_construction_mutex;
 extern wait_queue_head_t request_key_conswq;
 
 
+static inline void key_set_index_key(struct keyring_index_key *index_key)
+{
+       size_t n = min_t(size_t, index_key->desc_len, sizeof(index_key->desc));
+       memcpy(index_key->desc, index_key->description, n);
+}
+
 extern struct key_type *key_type_lookup(const char *type);
 extern void key_type_put(struct key_type *ktype);
 

diff --git a/security/keys/key.c b/security/keys/key.c
index e792d65..0a3828f 100644 (file)
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -285,6 +285,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
        key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
        if (!key->index_key.description)
                goto no_memory_3;
+       key_set_index_key(&key->index_key);
 
        refcount_set(&key->usage, 1);
        init_rwsem(&key->sem);
@@ -868,6 +869,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
                        goto error_free_prep;
        }
        index_key.desc_len = strlen(index_key.description);
+       key_set_index_key(&index_key);
 
        ret = __key_link_lock(keyring, &index_key);
        if (ret < 0) {

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index afa6d40..ebf5207 100644 (file)
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -179,9 +179,9 @@ static unsigned long hash_key_type_and_desc(const struct keyring_index_key *inde
        int n, desc_len = index_key->desc_len;
 
        type = (unsigned long)index_key->type;
-
        acc = mult_64x32_and_fold(type, desc_len + 13);
        acc = mult_64x32_and_fold(acc, 9207);
+
        for (;;) {
                n = desc_len;
                if (n <= 0)
@@ -215,23 +215,13 @@ static unsigned long hash_key_type_and_desc(const struct keyring_index_key *inde
 /*
  * Build the next index key chunk.
  *
- * On 32-bit systems the index key is laid out as:
- *
- *     0       4       5       9...
- *     hash    desclen typeptr desc[]
- *
- * On 64-bit systems:
- *
- *     0       8       9       17...
- *     hash    desclen typeptr desc[]
- *
  * We return it one word-sized chunk at a time.
  */
 static unsigned long keyring_get_key_chunk(const void *data, int level)
 {
        const struct keyring_index_key *index_key = data;
        unsigned long chunk = 0;
-       long offset = 0;
+       const u8 *d;
        int desc_len = index_key->desc_len, n = sizeof(chunk);
 
        level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
@@ -239,33 +229,23 @@ static unsigned long keyring_get_key_chunk(const void *data, int level)
        case 0:
                return hash_key_type_and_desc(index_key);
        case 1:
-               return ((unsigned long)index_key->type << 8) | desc_len;
+               return index_key->x;
        case 2:
-               if (desc_len == 0)
-                       return (u8)((unsigned long)index_key->type >>
-                                   (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
-               n--;
-               offset = 1;
-               /* fall through */
+               return (unsigned long)index_key->type;
        default:
-               offset += sizeof(chunk) - 1;
-               offset += (level - 3) * sizeof(chunk);
-               if (offset >= desc_len)
+               level -= 3;
+               if (desc_len <= sizeof(index_key->desc))
                        return 0;
-               desc_len -= offset;
+
+               d = index_key->description + sizeof(index_key->desc);
+               d += level * sizeof(long);
+               desc_len -= sizeof(index_key->desc);
                if (desc_len > n)
                        desc_len = n;
-               offset += desc_len;
                do {
                        chunk <<= 8;
-                       chunk |= ((u8*)index_key->description)[--offset];
+                       chunk |= *d++;
                } while (--desc_len > 0);
-
-               if (level == 2) {
-                       chunk <<= 8;
-                       chunk |= (u8)((unsigned long)index_key->type >>
-                                     (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
-               }
                return chunk;
        }
 }
@@ -304,39 +284,28 @@ static int keyring_diff_objects(const void *object, const void *data)
        seg_b = hash_key_type_and_desc(b);
        if ((seg_a ^ seg_b) != 0)
                goto differ;
+       level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
 
        /* The number of bits contributed by the hash is controlled by a
         * constant in the assoc_array headers.  Everything else thereafter we
         * can deal with as being machine word-size dependent.
         */
-       level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
-       seg_a = a->desc_len;
-       seg_b = b->desc_len;
+       seg_a = a->x;
+       seg_b = b->x;
        if ((seg_a ^ seg_b) != 0)
                goto differ;
+       level += sizeof(unsigned long);
 
        /* The next bit may not work on big endian */
-       level++;
        seg_a = (unsigned long)a->type;
        seg_b = (unsigned long)b->type;
        if ((seg_a ^ seg_b) != 0)
                goto differ;
-
        level += sizeof(unsigned long);
-       if (a->desc_len == 0)
-               goto same;
 
-       i = 0;
-       if (((unsigned long)a->description | (unsigned long)b->description) &
-           (sizeof(unsigned long) - 1)) {
-               do {
-                       seg_a = *(unsigned long *)(a->description + i);
-                       seg_b = *(unsigned long *)(b->description + i);
-                       if ((seg_a ^ seg_b) != 0)
-                               goto differ_plus_i;
-                       i += sizeof(unsigned long);
-               } while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
-       }
+       i = sizeof(a->desc);
+       if (a->desc_len <= i)
+               goto same;
 
        for (; i < a->desc_len; i++) {
                seg_a = *(unsigned char *)(a->description + i);
@@ -662,6 +631,9 @@ static bool search_nested_keyrings(struct key *keyring,
        BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
               (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
 
+       if (ctx->index_key.description)
+               key_set_index_key(&ctx->index_key);
+
        /* Check to see if this top-level keyring is what we are looking for
         * and whether it is valid or not.
         */

diff --git a/security/keys/persistent.c b/security/keys/persistent.c
index d0cb5b3..fc29ec5 100644 (file)
--- a/security/keys/persistent.c
+++ b/security/keys/persistent.c
@@ -87,6 +87,7 @@ static long key_get_persistent(struct user_namespace *ns, kuid_t uid,
        index_key.type = &key_type_keyring;
        index_key.description = buf;
        index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid));
+       key_set_index_key(&index_key);
 
        if (ns->persistent_keyring_register) {
                reg_ref = make_key_ref(ns->persistent_keyring_register, true);