diff options
Diffstat (limited to 'src/basic/random-util.c')
| -rw-r--r-- | src/basic/random-util.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/src/basic/random-util.c b/src/basic/random-util.c index 205d5501e5..40f1928936 100644 --- a/src/basic/random-util.c +++ b/src/basic/random-util.c @@ -28,6 +28,7 @@ #include "io-util.h" #include "missing.h" #include "random-util.h" +#include "siphash24.h" #include "time-util.h" int rdrand(unsigned long *ret) { @@ -203,14 +204,19 @@ void initialize_srand(void) { return; #if HAVE_SYS_AUXV_H - /* The kernel provides us with 16 bytes of entropy in auxv, so let's - * try to make use of that to seed the pseudo-random generator. It's - * better than nothing... */ + /* The kernel provides us with 16 bytes of entropy in auxv, so let's try to make use of that to seed + * the pseudo-random generator. It's better than nothing... But let's first hash it to make it harder + * to recover the original value by watching any pseudo-random bits we generate. After all the + * AT_RANDOM data might be used by other stuff too (in particular: ASLR), and we probably shouldn't + * leak the seed for that. */ - auxv = (const void*) getauxval(AT_RANDOM); + auxv = ULONG_TO_PTR(getauxval(AT_RANDOM)); if (auxv) { - assert_cc(sizeof(x) <= 16); - memcpy(&x, auxv, sizeof(x)); + static const uint8_t auxval_hash_key[16] = { + 0x92, 0x6e, 0xfe, 0x1b, 0xcf, 0x00, 0x52, 0x9c, 0xcc, 0x42, 0xcf, 0xdc, 0x94, 0x1f, 0x81, 0x0f + }; + + x = (unsigned) siphash24(auxv, 16, auxval_hash_key); } else #endif x = 0; |