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bpo-32329: Fix -R option for hash randomization (#4873)

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bpo-32329, bpo-32030:

* The -R option now turns on hash randomization when the
  PYTHONHASHSEED environment variable is set to 0 Previously, the
  option was ignored.
* sys.flags.hash_randomization is now properly set to 0 when hash
  randomization is turned off by PYTHONHASHSEED=0.
* _PyCoreConfig_ReadEnv() now reads the PYTHONHASHSEED environment
  variable. _Py_HashRandomization_Init() now only apply the
  configuration, it doesn't read PYTHONHASHSEED anymore.
This commit is contained in:
Victor Stinner 2017-12-15 00:51:22 +01:00 • committed by GitHub
parent 96a5e50a5d
commit 358e5e17a5
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GPG key ID: 4AEE18F83AFDEB23
6 changed files with 63 additions and 39 deletions
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37
Python/bootstrap_hash.c
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@ -533,9 +533,10 @@ _PyOS_URandomNonblock(void *buffer, Py_ssize_t size)
return pyurandom(buffer, size, 0, 1);
}
int Py_ReadHashSeed(const char *seed_text,
int *use_hash_seed,
unsigned long *hash_seed)
int
_Py_ReadHashSeed(const char *seed_text,
int *use_hash_seed,
unsigned long *hash_seed)
{
Py_BUILD_ASSERT(sizeof(_Py_HashSecret_t) == sizeof(_Py_HashSecret.uc));
/* Convert a text seed to a numeric one */
@ -561,9 +562,9 @@ int Py_ReadHashSeed(const char *seed_text,
return 0;
}
static _PyInitError
init_hash_secret(int use_hash_seed,
unsigned long hash_seed)
_PyInitError
_Py_HashRandomization_Init(const _PyCoreConfig *config)
{
void *secret = &_Py_HashSecret;
Py_ssize_t secret_size = sizeof(_Py_HashSecret_t);
@ -573,14 +574,14 @@ init_hash_secret(int use_hash_seed,
}
_Py_HashSecret_Initialized = 1;
if (use_hash_seed) {
if (hash_seed == 0) {
if (config->use_hash_seed) {
if (config->hash_seed == 0) {
/* disable the randomized hash */
memset(secret, 0, secret_size);
}
else {
/* use the specified hash seed */
lcg_urandom(hash_seed, secret, secret_size);
lcg_urandom(config->hash_seed, secret, secret_size);
}
}
else {
@ -601,24 +602,6 @@ init_hash_secret(int use_hash_seed,
return _Py_INIT_OK();
}
_PyInitError
_Py_HashRandomization_Init(_PyCoreConfig *core_config)
{
const char *seed_text;
int use_hash_seed = core_config->use_hash_seed;
unsigned long hash_seed = core_config->hash_seed;
if (use_hash_seed < 0) {
seed_text = Py_GETENV("PYTHONHASHSEED");
if (Py_ReadHashSeed(seed_text, &use_hash_seed, &hash_seed) < 0) {
return _Py_INIT_USER_ERR("PYTHONHASHSEED must be \"random\" "
"or an integer in range [0; 4294967295]");
}
core_config->use_hash_seed = use_hash_seed;
core_config->hash_seed = hash_seed;
}
return init_hash_secret(use_hash_seed, hash_seed);
}
void
_Py_HashRandomization_Fini(void)