Previously, we were checking if the last padding byte was in the range
1-16 and returning early if not. This was to prevent an integer overflow
in the output length.
Instead, do the checks in constant-time and conditionally set the output
length based on whether the padding is correct or not, preventing both
the side-channel and the integer overflow.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
When trying to decrypt data with an invalid key, we found that `mbedtls`
returned `0x6200` (`-25088`), which means "_CIPHER - Input data contains
invalid padding and is rejected_" from `mbedtls_cipher_finish`, but it also
set the output len as `18446744073709551516`.
In case we detect an error with padding, we leave the output len zero'ed
and return `MBEDTLS_ERR_CIPHER_INVALID_PADDING`.
Here's a reference for the way `openssl` checks the padding length:
- 1848c561ec/crypto/evp/evp_enc.c (L1023)
- b554eef43b
So add a check ensuring output is set to the least-harmful value in the
error cases.
With the robustness fix:
`PASSED (125 suites, 26644 tests run)`
Without the robustness fix:
`FAILED (125 suites, 26644 tests run)`
Signed-off-by: Andre Goddard Rosa <andre.goddard@gmail.com>
Signed-off-by: Andre Goddard Rosa <agoddardrosa@roku.com>
We have checks for CBC, XTS and KW modes in check_config.h. This
means we should never get a successful build with above three modes.
Therefore, the checks in cipher_setkey is not necessary as other
error will be emitted if asking for those modes in the cipher.
Additionally, removing the checks can save extra code size.
Signed-off-by: Yanray Wang <yanray.wang@arm.com>
If MBEDTLS_BLOCK_CIPHER_NO_DECRYPT is enabled, but decryption is
still requested in some incompatible modes, we return an error of
FEATURE_UNAVAILABLE as additional indication.
Signed-off-by: Yanray Wang <yanray.wang@arm.com>
Conflicts:
* `include/mbedtls/build_info.h`: a new fragment to auto-enable
`MBEDTLS_CIPHER_PADDING_PKCS7` was added in
c9f4040f7f3356293e90c58d11f6567def641e08 in `development-restricted`.
In `development`, this section of the file has moved to
`include/mbedtls/config_adjust_legacy_crypto.h`.
* `library/bignum.c`: function name change in `development-restricted` vs
comment change in development. The comment change in `development` is not
really relevant, so just take the line from `development-restricted`.
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>
There is no need to set decrypt key under CIPHER_ENCRYPT_ONLY,
so we can remove *setkey_dec_func from ctx to save extra code size.
Signed-off-by: Yanray Wang <yanray.wang@arm.com>
Fixes an "unused static function" warning in builds with
DEPRECATED_REMOVED.
While at it, remove an include that's now useless.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Most functions in psa_util.h are going to end up there (except those
that can be static in one file), but I wanted to have separate commits
for file creation and moving code around, so for now the new file's
pretty empty but that will change in the next few commits.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
