all: merge branch 'th/nm-hash-seed'

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1783

src/core/devices/wifi/nm-device-wifi.c

@@ -3191,7 +3191,11 @@ ensure_hotspot_frequency(NMDeviceWifi *self, NMSettingWireless *s_wifi, NMWifiAP
         GBytes       *ssid;
         gsize         ssid_len;
         const guint8 *ssid_data;
-        const guint8  random_seed[16] = {0x9a,
+
+        /* Calculate a stable "random" number based on the SSID. */
+        ssid      = nm_setting_wireless_get_ssid(s_wifi);
+        ssid_data = g_bytes_get_data(ssid, &ssid_len);
+        rnd       = c_siphash_hash(NM_HASH_SEED_16(0x9a,
                                              0xdc,
                                              0x86,
                                              0x9a,
@@ -3206,12 +3210,9 @@ ensure_hotspot_frequency(NMDeviceWifi *self, NMSettingWireless *s_wifi, NMWifiAP
                                              0x9f,
                                              0xa8,
                                              0x09,
-                                         0x2b};
+                                             0x2b),
-
+                             ssid_data,
-        /* Calculate a stable "random" number based on the SSID. */
+                             ssid_len);
-        ssid      = nm_setting_wireless_get_ssid(s_wifi);
-        ssid_data = g_bytes_get_data(ssid, &ssid_len);
-        rnd       = c_siphash_hash(random_seed, ssid_data, ssid_len);
     }
 
     if (nm_streq0(band, "a")) {

src/core/nm-core-utils.c

@@ -2711,7 +2711,7 @@ _host_id_read_timestamp(gboolean      use_secret_key_file,
 
 #define EPOCH_TWO_YEARS (G_GINT64_CONSTANT(2 * 365 * 24 * 3600) * NM_UTILS_NSEC_PER_SEC)
 
-    v = nm_hash_siphash42(1156657133u, host_id, host_id_len);
+    v = c_siphash_hash(NM_HASH_SEED_16_U64(1156657133u), host_id, host_id_len);
 
     now = time(NULL);
     *out_timestamp_ns =
@@ -3820,7 +3820,7 @@ nm_utils_dhcp_client_id_mac(int arp_type, const guint8 *hwaddr, gsize hwaddr_len
 }
 
 #define HASH_KEY          \
-    ((const guint8[16]){0x80, \
+    NM_HASH_SEED_16(0x80, \
                     0x11, \
                     0x8c, \
                     0xc2, \
@@ -3835,7 +3835,7 @@ nm_utils_dhcp_client_id_mac(int arp_type, const guint8 *hwaddr, gsize hwaddr_len
                     0x36, \
                     0x39, \
                     0x14, \
-                        0x09})
+                    0x09)
 
 /**
  * nm_utils_create_dhcp_iaid:

src/core/nm-l3-ipv4ll.c

@@ -391,7 +391,7 @@ _ipv4ll_addrgen(NML3IPv4LL *self, gboolean generate_new_addr)
 
     /* MAC_HASH_KEY is the same as used by systemd. */
 #define MAC_HASH_KEY      \
-    ((const guint8[16]){0xdf, \
+    NM_HASH_SEED_16(0xdf, \
                     0x04, \
                     0x22, \
                     0x98, \
@@ -406,7 +406,7 @@ _ipv4ll_addrgen(NML3IPv4LL *self, gboolean generate_new_addr)
                     0x9c, \
                     0x70, \
                     0xe2, \
-                        0xf2})
+                    0xf2)
 
     if (self->mac_set && (!self->seed_set || !nm_ether_addr_equal(&self->mac, &self->seed_mac))) {
         /* systemd's ipv4ll library by default only hashes the MAC address (as we do here).
@@ -466,7 +466,7 @@ _ipv4ll_addrgen(NML3IPv4LL *self, gboolean generate_new_addr)
 gen_addr:
 
 #define PICK_HASH_KEY     \
-    ((const guint8[16]){0x15, \
+    NM_HASH_SEED_16(0x15, \
                     0xac, \
                     0x82, \
                     0xa6, \
@@ -481,7 +481,7 @@ gen_addr:
                     0x69, \
                     0x02, \
                     0x94, \
-                        0x0b})
+                    0x0b)
 
     h = c_siphash_hash(PICK_HASH_KEY, (const guint8 *) &self->seed, sizeof(self->seed));
 

src/libnm-core-impl/tests/test-general.c

@@ -557,6 +557,21 @@ test_nm_hash(void)
 #endif
 
     NM_STATIC_ASSERT_EXPR_VOID(NM_HASH_COMBINE_BOOLS(int, 1, 0, 1) == 5);
+
+    g_assert_cmpmem(NM_HASH_SEED_16(55, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15),
+                    16,
+                    ((guint8[16]){55, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}),
+                    16);
+
+    g_assert_cmpmem(NM_HASH_SEED_16_U64(1), 16, ((guint8[16]){0, 0, 0, 0, 0, 0, 0, 1, 0}), 16);
+    g_assert_cmpmem(NM_HASH_SEED_16_U64(0x1234567890ABCDEFu),
+                    16,
+                    ((guint8[16]){0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF, 0}),
+                    16);
+
+    g_assert_cmpint(c_siphash_hash(NM_HASH_SEED_16_U64(0x780E21E45489CC6Fu), (guint8 *) "foo", 3),
+                    ==,
+                    0XA5A41E5C1B4153BFu);
 }
 
 /*****************************************************************************/

src/libnm-glib-aux/nm-hash-utils.h

@@ -14,6 +14,30 @@
 #define NM_HASH_SEED_16(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, aa, ab, ac, ad, ae, af) \
     ((const guint8[16]){a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, aa, ab, ac, ad, ae, af})
 
+struct _nm_packed _nm_hash_seed_16_u64_data {
+    guint64 s1;
+    guint64 s2;
+};
+
+G_STATIC_ASSERT(sizeof(struct _nm_hash_seed_16_u64_data) == 16);
+G_STATIC_ASSERT(sizeof(struct _nm_hash_seed_16_u64_data) == sizeof(guint64) * 2);
+
+/* c_siphash_init() has a seed of 16 bytes (NM_HASH_SEED_16()). That is
+ * cumbersome to use, because we usually just hardcode an arbitrarily chosen,
+ * fixed number.
+ *
+ * This macro takes a u64 (in host-endianness) and returns a 16 byte seed
+ * buffer. The number will be big endian encoded, to be architecture
+ * independent. */
+#define NM_HASH_SEED_16_U64(u64)                              \
+    ((const guint8 *) ((gpointer)                             \
+                       & ((struct _nm_hash_seed_16_u64_data){ \
+                           .s1 = htobe64((u64)),              \
+                           .s2 = 0,                           \
+                       })))
+
+/*****************************************************************************/
+
 void nm_hash_siphash42_init(CSipHash *h, guint static_seed);
 
 /* Siphash24 of binary buffer @arr and @len, using the randomized seed from
@@ -22,7 +46,7 @@ void nm_hash_siphash42_init(CSipHash *h, guint static_seed);
  * Note, that this is guaranteed to use siphash42 under the hood (contrary to
  * all other NMHash API, which leave this undefined). That matters at the point,
  * where the caller needs to be sure that a reasonably strong hashing algorithm
- * is used.  (Yes, NMHash is all about siphash24, but otherwise that is not promised
+ * is used.  (Yes, NMHash is all about siphash42, but otherwise that is not promised
  * anywhere).
  *
  * Another difference is, that this returns guint64 (not guint like other NMHash functions).
@@ -32,6 +56,9 @@ void nm_hash_siphash42_init(CSipHash *h, guint static_seed);
  * Then, why not use c_siphash_hash() directly? Because this also uses the randomized,
  * per-run hash-seed like nm_hash_init(). So, you get siphash24 with a random
  * seed (which is cached for the current run of the program).
+ *
+ * WARNING: the static_seed gets randomized like with nm_hash*(). If you want a reproducible
+ *   siphash42, use instead `c_siphash_hash(NM_HASH_SEED_16_U64(number), ptr, len)`.
  */
 static inline guint64
 nm_hash_siphash42(guint static_seed, const void *ptr, gsize n)