Any timing variance dependant on the output of this function enables a
Bleichenbacher attack. It is extremely difficult to use safely.
In the Marvin attack paper
(https://people.redhat.com/~hkario/marvin/marvin-attack-paper.pdf) the
author suggests that implementations of PKCS 1.5 decryption that don't
include a countermeasure should be considered inherently dangerous.
They suggest that all libraries implement the same countermeasure, as
implementing different countermeasures across libraries enables the
Bleichenbacher attack as well.
This is extremely fragile and therefore we don't implement it. The use
of PKCS 1.5 in Mbed TLS implements the countermeasures recommended in
the TLS standard (7.4.7.1 of RFC 5246) and is not vulnerable.
Add a warning to PKCS 1.5 decryption to warn users about this.
Signed-off-by: Janos Follath <janos.follath@arm.com>
mbedtls_ssl_cache_get() and mbedtls_ssl_cache_set() returned 1 on many error
conditions. Change this to returning a negative MBEDTLS_ERR_xxx error code.
Completeness: after this commit, there are no longer any occurrences of
`return 1` or `ret = 1`.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
- the \internal note said that calling cipher_init() first would be made
mandatory later, but the documention of the ctx parameter already said
the context had to be initialized...
- the documentation was using the word initialize for two different
meanings (calling setup() vs calling init()), making the documentation
of the ctx parameter quite confusing (you must initialize before you can
initialize...)
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Add new mbedtls_pkcs12_pbe_ext function to replace
old mbedtls_pkcs12_pbe function that have security
issues.
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
The official spelling of the trade mark changed from all-lowercase "mbed"
to normal proper noun capitalization "Mbed" a few years ago. We've been
using the new spelling in new text but still have the old spelling in a
lot of text. This commit updates most occurrences of "mbed TLS":
```
sed -i -e 's/mbed TLS/Mbed TLS/g' $(git ls-files ':!ChangeLog' ':!tests/data_files/**' ':!tests/suites/*.data' ':!programs/x509/*' ':!configs/tfm*')
```
Justification for the omissions:
* `ChangeLog`: historical text.
* `test/data_files/**`, `tests/suites/*.data`, `programs/x509/*`: many
occurrences are significant names in certificates and such. Changing
the spelling would invalidate many signatures and tests.
* `configs/tfm*`: this is an imported file. We'll follow the upstream
updates.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
* Prevent pkcs12_pbe encryption when PKCS7 padding has been
disabled since this not part of the specs.
* Allow decryption when PKCS7 padding is disabled for legacy
reasons, However, invalid padding is not checked.
* Document new behaviour, known limitations and possible
security concerns.
* Add tests to check these scenarios. Test data has been
generated by the below code using OpenSSL as a reference:
int main()
{
char pass[] = "\xBB\xBB\xBB\xBB\xBB\xBB\xBB\xBB\xBB";
unsigned char salt[] = "\xCC\xCC\xCC\xCC\xCC\xCC\xCC\xCC\xCC";
unsigned char plaintext[] = "\xAA\xAA\xAA\xAA\xAA\xAA\xAA\xAA";
unsigned char *ciphertext = NULL;
int iter = 10;
X509_ALGOR *alg = X509_ALGOR_new();
int ciphertext_len = 0;
int alg_nid = NID_pbe_WithSHA1And3_Key_TripleDES_CBC;
alg->parameter = ASN1_TYPE_new();
struct asn1_object_st * aobj;
PKCS5_pbe_set0_algor(alg, alg_nid, iter,
salt, sizeof(salt)-1);
aobj = alg->algorithm;
printf("\"30%.2X", 2 + aobj->length + alg->parameter->value.asn1_string->length);
printf("06%.2X", aobj->length);
for (int i = 0; i < aobj->length; i++) {
printf("%.2X", aobj->data[i]);
}
for (int i = 0; i < alg->parameter->value.asn1_string->length; i++) {
printf("%.2X", alg->parameter->value.asn1_string->data[i]);
}
printf("\":\"");
for (int i = 0; i < sizeof(pass)-1; i++) {
printf("%.2X", pass[i] & 0xFF);
}
printf("\":\"");
for (int i = 0; i < sizeof(plaintext)-1; i++) {
printf("%.2X", plaintext[i]);
}
printf("\":");
printf("0");
printf(":\"");
unsigned char * res = PKCS12_pbe_crypt(alg, pass, sizeof(pass)-1, plaintext, sizeof(plaintext)-1, &ciphertext, &ciphertext_len, 1);
if (res == NULL)
printf("Encryption failed!\n");
for (int i = 0; i < ciphertext_len; i++) {
printf("%.2X", res[i]);
}
printf("\"\n");
return 0;
}
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
Boolean options that modify the behavior of a module are supposed to be in
the "feature support" section, not in the "configuration options" support:
that section is documented to contain commented-out definitions with a
value, for which the comment contains the default version. In particular,
merely uncommenting a definition in the "configuration options" section is
not supposed to change anything.
Move the offending boolean options to the proper section.
This causes those options to be enabled by `config.py full` unless
explicitly excluded. For the moved options:
* Everest is already explicitly excluded.
* The ALT options need to link against a custom function, so exclude them.
* `MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE` is ok for testing, and is
currently never tested in `all.sh`. With this commit, we will now test the
library with it enabled in configurations based on `full`.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add new mbedtls_pkcs5_pbe2_ext function to replace old
function with possible security issues.
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
* Prevent pkcs5_pbe2 encryption when PKCS7 padding has been
disabled since this not part of the specs.
* Allow decryption when PKCS7 padding is disabled for legacy
reasons, However, invalid padding is not checked.
* Add tests to check these scenarios. Test data has been
reused but with changing padding data in last block to
check for valid/invalid padding.
* Document new behaviour, known limitations and possible
security concerns.
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
When all TLS 1.2 support is disabled, union mbedtls_ssl_premaster_secret was
empty, which is not valid C even if the union is never used. Fixes#6628.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
