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Subject[PATCH 03/11] keys: Simplify key description management
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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>
---

include/linux/key.h | 14 ++++++++-
security/keys/internal.h | 6 ++++
security/keys/key.c | 2 +
security/keys/keyring.c | 70 +++++++++++++-------------------------------
security/keys/persistent.c | 1 +
5 files changed, 43 insertions(+), 50 deletions(-)

diff --git a/include/linux/key.h b/include/linux/key.h
index aaa93fe3f587..33d87cb2d469 100644
--- 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 8f533c81aa8d..02592d24f13a 100644
--- 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 d705b950ce2a..1d0250a8990e 100644
--- 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);
@@ -859,6 +860,7 @@ 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_begin(keyring, &index_key, &edit);
if (ret < 0) {
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index e14f09e3a4b0..7bb1f499996c 100644
--- 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 d0cb5b32eff7..fc29ec59efa7 100644
--- 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);
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