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libnm/crypto: cleanup convert_iv() and handle more errors

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crypto_make_des_aes_key() asserts that iv-lenght is at least
8 characters. Whatever the reason. That means, decrypt_key()
must check for that condition first, and gracefully fail.

Also, don't use strtol() to convert a pair of hex digits to
integer.

Also, don't keep the IV in memory. Yes, it's not very critical,
but this is crypto code, we should not leave data behind.
This commit is contained in:
Thomas Haller 2018-08-29 13:49:37 +02:00
parent 9ca12145a3
commit 5ff12dc86d
1 changed files with 37 additions and 22 deletions
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59
libnm-core/crypto.c
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@ -313,20 +313,20 @@ file_to_g_byte_array (const char *filename, GError **error)
/*
* Convert a hex string into bytes.
*/
static char *
static guint8 *
convert_iv (const char *src,
gsize *out_len,
GError **error)
{
int num;
int i;
char conv[3];
gs_free char *c = NULL;
gsize i, num;
gs_free guint8 *c = NULL;
int c0, c1;
g_return_val_if_fail (src != NULL, NULL);
nm_assert (src);
num = strlen (src);
if (num % 2) {
if ( num == 0
|| (num % 2) != 0) {
g_set_error (error, NM_CRYPTO_ERROR,
NM_CRYPTO_ERROR_INVALID_DATA,
_("IV must be an even number of bytes in length."));
@ -334,20 +334,23 @@ convert_iv (const char *src,
}
num /= 2;
c = g_malloc0 (num + 1);
c = g_malloc (num + 1);
/* defensively add trailing NUL. This function returns binary data,
* do not assume it's NUL terminated. */
c[num] = '\0';
conv[2] = '\0';
for (i = 0; i < num; i++) {
conv[0] = src[(i * 2)];
conv[1] = src[(i * 2) + 1];
if (!g_ascii_isxdigit (conv[0]) || !g_ascii_isxdigit (conv[1])) {
if ( ((c0 = nm_utils_hexchar_to_int (*(src++))) < 0)
|| ((c1 = nm_utils_hexchar_to_int (*(src++))) < 0)) {
g_set_error (error, NM_CRYPTO_ERROR,
NM_CRYPTO_ERROR_INVALID_DATA,
_("IV contains non-hexadecimal digits."));
nm_explicit_bzero (c, i);
return FALSE;
}
c[i] = strtol(conv, NULL, 16);
c[i] = (c0 << 4) + c1;
}
*out_len = num;
return g_steal_pointer (&c);
@ -415,28 +418,40 @@ decrypt_key (const char *cipher,
const char *password,
GError **error)
{
gs_free char *bin_iv = NULL;
gsize bin_iv_len = 0;
nm_auto_clear_secret_ptr NMSecretPtr bin_iv = { 0 };
nm_auto_clear_secret_ptr NMSecretPtr key = { 0 };
gs_free char *output = NULL;
gsize decrypted_len = 0;
GByteArray *decrypted = NULL;
g_return_val_if_fail (password != NULL, NULL);
g_return_val_if_fail (iv, NULL);
bin_iv = convert_iv (iv, &bin_iv_len, error);
if (!bin_iv)
bin_iv.bin = convert_iv (iv, &bin_iv.len, error);
if (!bin_iv.bin)
return NULL;
if (bin_iv.len < 8) {
g_set_error (error,
NM_CRYPTO_ERROR,
NM_CRYPTO_ERROR_INVALID_DATA,
_("IV must contain at least 8 characters"));
return NULL;
}
/* Convert the password and IV into a DES or AES key */
key.str = crypto_make_des_aes_key (cipher, bin_iv, bin_iv_len, password, &key.len, error);
key.str = crypto_make_des_aes_key (cipher, bin_iv.str, bin_iv.len, password, &key.len, error);
if (!key.str || !key.len)
return NULL;
output = crypto_decrypt (cipher, key_type,
data, data_len,
bin_iv, bin_iv_len,
key.str, key.len,
output = crypto_decrypt (cipher,
key_type,
data,
data_len,
bin_iv.str,
bin_iv.len,
key.str,
key.len,
&decrypted_len,
error);
if (output && decrypted_len) {