diff options
| -rw-r--r-- | .gitignore | 2 | ||||
| -rw-r--r-- | ks.c | 8 | ||||
| -rw-r--r-- | ks_flash.c | 18 | ||||
| -rw-r--r-- | ks_mmap.c | 42 | ||||
| -rw-r--r-- | ks_volatile.c | 36 |
5 files changed, 95 insertions, 11 deletions
@@ -11,6 +11,8 @@ tests/test-ecdsa tests/test-ecdsa-*.der tests/test-hash tests/test-pbkdf2 +tests/test-rpc_hash +tests/test-rpc_server tests/test-rsa tests/test-rsa-*.der tests/test-trng @@ -294,14 +294,6 @@ hal_error_t hal_ks_get_pin(const hal_user_t user, return HAL_OK; } -hal_error_t hal_ks_get_kek(uint8_t *kek, - size_t *kek_len, - const size_t kek_max) -{ -# warning Stub out hal_ks_get_kek() for now - return HAL_ERROR_IMPOSSIBLE; -} - /* * Local variables: * indent-tabs-mode: nil @@ -85,6 +85,24 @@ hal_error_t hal_ks_set_pin(const hal_user_t user, } +hal_error_t hal_ks_get_kek(uint8_t *kek, + size_t *kek_len, + const size_t kek_max) +{ + if (kek == NULL || kek_len == NULL || kek_max < bitsToBytes(128)) + return HAL_ERROR_BAD_ARGUMENTS; + + const size_t len = ((kek_max < bitsToBytes(192)) ? bitsToBytes(128) : + (kek_max < bitsToBytes(256)) ? bitsToBytes(192) : + bitsToBytes(256)); + +#error Or what goes here + + return HAL_OK; +} + + + /* * Local variables: * indent-tabs-mode: nil @@ -51,7 +51,15 @@ #define MAP_FILE 0 #endif +/* + * Storing the KEK in with the keys it's protecting is a bad idea, but we have no better + * place to put it (real protection requires dedicated hardware, which we don't have here). + */ + +#define KEKBUF_LEN (bitsToBytes(256)) + static hal_ks_keydb_t *db; +static uint8_t *kekbuf; const hal_ks_keydb_t *hal_ks_get_keydb(void) { @@ -62,7 +70,7 @@ const hal_ks_keydb_t *hal_ks_get_keydb(void) const char * const home = getenv("HOME"); const char * const base = HAL_KS_MMAP_FILE; const long pagemask = sysconf(_SC_PAGESIZE) - 1; - const size_t len = (sizeof(hal_ks_keydb_t) + pagemask) & ~pagemask; + const size_t len = (sizeof(hal_ks_keydb_t) + KEKBUF_LEN + pagemask) & ~pagemask; char fn_[strlen(base) + (home == NULL ? 0 : strlen(home)) + 2]; const char *fn = fn_; @@ -87,8 +95,8 @@ const hal_ks_keydb_t *hal_ks_get_keydb(void) fd = open(fn, O_RDWR | O_CREAT, 0600); } - if (fd >= 0) - db = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0); + if (fd >= 0 && (db = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0)) != NULL) + kekbuf = (uint8_t *) (db + 1); (void) close(fd); @@ -135,6 +143,34 @@ hal_error_t hal_ks_set_pin(const hal_user_t user, return HAL_OK; } +hal_error_t hal_ks_get_kek(uint8_t *kek, + size_t *kek_len, + const size_t kek_max) +{ + if (kek == NULL || kek_len == NULL || kek_max < bitsToBytes(128)) + return HAL_ERROR_BAD_ARGUMENTS; + + if (kekbuf == NULL) + return HAL_ERROR_IMPOSSIBLE; + + hal_error_t err; + + const size_t len = ((kek_max < bitsToBytes(192)) ? bitsToBytes(128) : + (kek_max < bitsToBytes(256)) ? bitsToBytes(192) : + bitsToBytes(256)); + + uint8_t t = 0; + + for (int i = 0; i < KEKBUF_LEN; i++) + t |= kekbuf[i]; + + if (t == 0 && (err = hal_rpc_get_random(kekbuf, sizeof(KEKBUF_LEN))) != HAL_OK) + return err; + + memcpy(kek, kekbuf, len); + return HAL_OK; +} + /* * Local variables: * indent-tabs-mode: nil diff --git a/ks_volatile.c b/ks_volatile.c index 2381f4c..b71e27e 100644 --- a/ks_volatile.c +++ b/ks_volatile.c @@ -55,6 +55,17 @@ static hal_ks_keydb_t db[1]; +/* + * There's no good place to store the master key (KEK) in this volatile memory implementation. + * We might be able to add a bit of protection doing things like using locked physical memory, + * as gpg does, or obfuscating the KEK a bit to make it harder to pull out of a crash dump, + * but, really, there's not a lot we can do against a determined opponant in this case. + * + * For now, we just go through the motions. + */ + +static uint8_t kekbuf[bitsToBytes(256)]; + const hal_ks_keydb_t *hal_ks_get_keydb(void) { return db; @@ -99,6 +110,31 @@ hal_error_t hal_ks_set_pin(const hal_user_t user, return HAL_OK; } +hal_error_t hal_ks_get_kek(uint8_t *kek, + size_t *kek_len, + const size_t kek_max) +{ + if (kek == NULL || kek_len == NULL || kek_max < bitsToBytes(128)) + return HAL_ERROR_BAD_ARGUMENTS; + + hal_error_t err; + + const size_t len = ((kek_max < bitsToBytes(192)) ? bitsToBytes(128) : + (kek_max < bitsToBytes(256)) ? bitsToBytes(192) : + bitsToBytes(256)); + + uint8_t t = 0; + + for (int i = 0; i < sizeof(kekbuf); i++) + t |= kekbuf[i]; + + if (t == 0 && (err = hal_rpc_get_random(kekbuf, sizeof(kekbuf))) != HAL_OK) + return err; + + memcpy(kek, kekbuf, len); + return HAL_OK; +} + /* * Local variables: * indent-tabs-mode: nil |