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-rw-r--r--src/shared/hashmap.c104
-rw-r--r--src/shared/util.c19
-rw-r--r--src/shared/util.h1
3 files changed, 84 insertions, 40 deletions
diff --git a/src/shared/hashmap.c b/src/shared/hashmap.c
index 633079277d..f06fce6ef3 100644
--- a/src/shared/hashmap.c
+++ b/src/shared/hashmap.c
@@ -24,6 +24,10 @@
#include <string.h>
#include <errno.h>
+#ifdef HAVE_SYS_AUXV_H
+#include <sys/auxv.h>
+#endif
+
#include "util.h"
#include "hashmap.h"
#include "macro.h"
@@ -46,6 +50,7 @@ struct Hashmap {
struct hashmap_entry ** buckets;
unsigned n_buckets, n_entries;
+ unsigned random_xor;
bool from_pool;
};
@@ -171,10 +176,15 @@ int uint64_compare_func(const void *_a, const void *_b) {
return a < b ? -1 : (a > b ? 1 : 0);
}
+static unsigned bucket_hash(Hashmap *h, const void *p) {
+ return (h->hash_func(p) ^ h->random_xor) % h->n_buckets;
+}
+
Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func) {
bool b;
Hashmap *h;
size_t size;
+ void *auxv;
b = is_main_thread();
@@ -204,6 +214,19 @@ Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func) {
h->from_pool = b;
+ /* Let's randomize our hash functions a bit so that they are
+ * harder to guess for clients. For this, start out by cheaply
+ * using some bits the kernel passed into the process using
+ * the auxiliary vector. If the hashmap grows later on we will
+ * rehash everything using a new random XOR mask from
+ * /dev/random. */
+#ifdef HAVE_SYS_AUXV_H
+ auxv = (void*) getauxval(AT_RANDOM);
+ h->random_xor = auxv ? *(unsigned*) auxv : random_u();
+#else
+ h->random_xor = random_u();
+#endif
+
return h;
}
@@ -284,8 +307,7 @@ static void remove_entry(Hashmap *h, struct hashmap_entry *e) {
assert(h);
assert(e);
- hash = h->hash_func(e->key) % h->n_buckets;
-
+ hash = bucket_hash(h, e->key);
unlink_entry(h, e, hash);
if (h->from_pool)
@@ -368,7 +390,6 @@ void hashmap_clear_free_free(Hashmap *h) {
}
}
-
static struct hashmap_entry *hash_scan(Hashmap *h, unsigned hash, const void *key) {
struct hashmap_entry *e;
assert(h);
@@ -382,8 +403,8 @@ static struct hashmap_entry *hash_scan(Hashmap *h, unsigned hash, const void *ke
}
static bool resize_buckets(Hashmap *h) {
- unsigned m;
struct hashmap_entry **n, *i;
+ unsigned m, nxor;
assert(h);
@@ -398,6 +419,11 @@ static bool resize_buckets(Hashmap *h) {
if (!n)
return false;
+ /* Let's use a different randomized xor value for the
+ * extension, so that people cannot guess what we are using
+ * here forever */
+ nxor = random_u();
+
for (i = h->iterate_list_head; i; i = i->iterate_next) {
unsigned hash, x;
@@ -410,10 +436,10 @@ static bool resize_buckets(Hashmap *h) {
if (i->bucket_previous)
i->bucket_previous->bucket_next = i->bucket_next;
else
- h->buckets[hash % h->n_buckets] = i->bucket_next;
+ h->buckets[(hash ^ h->random_xor) % h->n_buckets] = i->bucket_next;
/* Then, add to new backet table */
- x = hash % m;
+ x = (hash ^ nxor) % m;
i->bucket_next = n[x];
i->bucket_previous = NULL;
@@ -427,6 +453,7 @@ static bool resize_buckets(Hashmap *h) {
h->buckets = n;
h->n_buckets = m;
+ h->random_xor = nxor;
return true;
}
@@ -437,7 +464,7 @@ int hashmap_put(Hashmap *h, const void *key, void *value) {
assert(h);
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (e) {
if (e->value == value)
@@ -446,7 +473,7 @@ int hashmap_put(Hashmap *h, const void *key, void *value) {
}
if (resize_buckets(h))
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
if (h->from_pool)
e = allocate_tile(&first_entry_pool, &first_entry_tile, sizeof(struct hashmap_entry));
@@ -470,7 +497,7 @@ int hashmap_replace(Hashmap *h, const void *key, void *value) {
assert(h);
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (e) {
e->key = key;
@@ -487,7 +514,7 @@ int hashmap_update(Hashmap *h, const void *key, void *value) {
assert(h);
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (!e)
return -ENOENT;
@@ -503,7 +530,7 @@ void* hashmap_get(Hashmap *h, const void *key) {
if (!h)
return NULL;
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (!e)
return NULL;
@@ -518,7 +545,7 @@ void* hashmap_get2(Hashmap *h, const void *key, void **key2) {
if (!h)
return NULL;
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (!e)
return NULL;
@@ -535,12 +562,8 @@ bool hashmap_contains(Hashmap *h, const void *key) {
if (!h)
return false;
- hash = h->hash_func(key) % h->n_buckets;
-
- if (!hash_scan(h, hash, key))
- return false;
-
- return true;
+ hash = bucket_hash(h, key);
+ return !!hash_scan(h, hash, key);
}
void* hashmap_remove(Hashmap *h, const void *key) {
@@ -551,9 +574,9 @@ void* hashmap_remove(Hashmap *h, const void *key) {
if (!h)
return NULL;
- hash = h->hash_func(key) % h->n_buckets;
-
- if (!(e = hash_scan(h, hash, key)))
+ hash = bucket_hash(h, key);
+ e = hash_scan(h, hash, key);
+ if (!e)
return NULL;
data = e->value;
@@ -569,11 +592,12 @@ int hashmap_remove_and_put(Hashmap *h, const void *old_key, const void *new_key,
if (!h)
return -ENOENT;
- old_hash = h->hash_func(old_key) % h->n_buckets;
- if (!(e = hash_scan(h, old_hash, old_key)))
+ old_hash = bucket_hash(h, old_key);
+ e = hash_scan(h, old_hash, old_key);
+ if (!e)
return -ENOENT;
- new_hash = h->hash_func(new_key) % h->n_buckets;
+ new_hash = bucket_hash(h, new_key);
if (hash_scan(h, new_hash, new_key))
return -EEXIST;
@@ -594,12 +618,14 @@ int hashmap_remove_and_replace(Hashmap *h, const void *old_key, const void *new_
if (!h)
return -ENOENT;
- old_hash = h->hash_func(old_key) % h->n_buckets;
- if (!(e = hash_scan(h, old_hash, old_key)))
+ old_hash = bucket_hash(h, old_key);
+ e = hash_scan(h, old_hash, old_key);
+ if (!e)
return -ENOENT;
- new_hash = h->hash_func(new_key) % h->n_buckets;
- if ((k = hash_scan(h, new_hash, new_key)))
+ new_hash = bucket_hash(h, new_key);
+ k = hash_scan(h, new_hash, new_key);
+ if (k)
if (e != k)
remove_entry(h, k);
@@ -620,7 +646,7 @@ void* hashmap_remove_value(Hashmap *h, const void *key, void *value) {
if (!h)
return NULL;
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (!e)
@@ -711,7 +737,7 @@ void *hashmap_iterate_skip(Hashmap *h, const void *key, Iterator *i) {
if (!h)
return NULL;
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (!e)
@@ -820,9 +846,9 @@ int hashmap_merge(Hashmap *h, Hashmap *other) {
for (e = other->iterate_list_head; e; e = e->iterate_next) {
int r;
- if ((r = hashmap_put(h, e->key, e->value)) < 0)
- if (r != -EEXIST)
- return r;
+ r = hashmap_put(h, e->key, e->value);
+ if (r < 0 && r != -EEXIST)
+ return r;
}
return 0;
@@ -844,13 +870,11 @@ void hashmap_move(Hashmap *h, Hashmap *other) {
n = e->iterate_next;
- h_hash = h->hash_func(e->key) % h->n_buckets;
-
+ h_hash = bucket_hash(h, e->key);
if (hash_scan(h, h_hash, e->key))
continue;
- other_hash = other->hash_func(e->key) % other->n_buckets;
-
+ other_hash = bucket_hash(other, e->key);
unlink_entry(other, e, other_hash);
link_entry(h, e, h_hash);
}
@@ -865,11 +889,11 @@ int hashmap_move_one(Hashmap *h, Hashmap *other, const void *key) {
assert(h);
- h_hash = h->hash_func(key) % h->n_buckets;
+ h_hash = bucket_hash(h, key);
if (hash_scan(h, h_hash, key))
return -EEXIST;
- other_hash = other->hash_func(key) % other->n_buckets;
+ other_hash = bucket_hash(other, key);
e = hash_scan(other, other_hash, key);
if (!e)
return -ENOENT;
@@ -925,7 +949,7 @@ void *hashmap_next(Hashmap *h, const void *key) {
if (!h)
return NULL;
- hash = h->hash_func(key) % h->n_buckets;
+ hash = bucket_hash(h, key);
e = hash_scan(h, hash, key);
if (!e)
return NULL;
diff --git a/src/shared/util.c b/src/shared/util.c
index 5dc605eb8d..9be6acfc8f 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2424,6 +2424,25 @@ fallback:
return random() * RAND_MAX + random();
}
+unsigned random_u(void) {
+ _cleanup_close_ int fd;
+ unsigned u;
+ ssize_t r;
+
+ fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (fd < 0)
+ goto fallback;
+
+ r = loop_read(fd, &u, sizeof(u), true);
+ if (r != sizeof(u))
+ goto fallback;
+
+ return u;
+
+fallback:
+ return random() * RAND_MAX + random();
+}
+
void rename_process(const char name[8]) {
assert(name);
diff --git a/src/shared/util.h b/src/shared/util.h
index 63f4e3dff2..1b845b3803 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -253,6 +253,7 @@ int make_null_stdio(void);
int make_console_stdio(void);
unsigned long long random_ull(void);
+unsigned random_u(void);
/* For basic lookup tables with strictly enumerated entries */
#define __DEFINE_STRING_TABLE_LOOKUP(name,type,scope) \
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-12-18 04:03:12 +0000