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Padding bug mismatch #144

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merged 2 commits into from
Jan 21, 2025
Merged

Padding bug mismatch #144

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692b3a4
Add test to show a bug in AES CBC
simo5 Jan 20, 2025
eeae3d6
Ensure padding is off for ECB and CBC modes
simo5 Jan 20, 2025
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42 changes: 29 additions & 13 deletions src/ossl/aes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -749,12 +749,20 @@ impl AesOperation {
if res != 1 {
return Err(self.op_err(CKR_DEVICE_ERROR))?;
}
if self.mech == CKM_AES_CBC_PAD {
let res =
unsafe { EVP_CIPHER_CTX_set_padding(self.ctx.as_mut_ptr(), 1) };
if res != 1 {
return Err(self.op_err(CKR_DEVICE_ERROR));
}
/* OpenSSL defaults to padding on, so we need to turn it explicitly
* off for mechanisms that do not use it because PKCS#11 does not
* implicitly provide padding. */
let res = match self.mech {
CKM_AES_ECB | CKM_AES_CBC => unsafe {
EVP_CIPHER_CTX_set_padding(self.ctx.as_mut_ptr(), 0)
},
CKM_AES_CBC_PAD => unsafe {
EVP_CIPHER_CTX_set_padding(self.ctx.as_mut_ptr(), 1)
},
_ => 1,
};
if res != 1 {
return Err(self.op_err(CKR_DEVICE_ERROR));
}

if self.mech == CKM_AES_CCM {
Expand Down Expand Up @@ -850,11 +858,14 @@ impl AesOperation {
if res != 1 {
return Err(self.op_err(CKR_DEVICE_ERROR))?;
}
let res = unsafe {
EVP_CIPHER_CTX_set_padding(
self.ctx.as_mut_ptr(),
if self.mech == CKM_AES_CBC_PAD { 1 } else { 0 },
)
let res = match self.mech {
CKM_AES_ECB | CKM_AES_CBC => unsafe {
EVP_CIPHER_CTX_set_padding(self.ctx.as_mut_ptr(), 0)
},
CKM_AES_CBC_PAD => unsafe {
EVP_CIPHER_CTX_set_padding(self.ctx.as_mut_ptr(), 1)
},
_ => 1,
};
if res != 1 {
return Err(self.op_err(CKR_DEVICE_ERROR));
Expand Down Expand Up @@ -1594,10 +1605,10 @@ impl Encryption for AesOperation {
}
}
}
CKM_AES_CTS | CKM_AES_CBC | CKM_AES_ECB => (),
CKM_AES_CTS => (),
#[cfg(not(feature = "fips"))]
CKM_AES_CFB8 | CKM_AES_CFB1 | CKM_AES_CFB128 | CKM_AES_OFB => (),
CKM_AES_CBC_PAD => {
CKM_AES_ECB | CKM_AES_CBC | CKM_AES_CBC_PAD => {
/* check if this is a second call after
* we saved the final buffer */
if self.finalbuf.len() > 0 {
Expand Down Expand Up @@ -1628,6 +1639,11 @@ impl Encryption for AesOperation {
)
};
if res != 1 {
if self.mech != CKM_AES_CBC_PAD {
/* For raw ECB and CBC mode this most likely means there
* was data left in the internal OpenSSL buffer */
return Err(self.op_err(CKR_DATA_LEN_RANGE));
}
return Err(self.op_err(CKR_DEVICE_ERROR));
}
outlen = usize::try_from(outl)?;
Expand Down
17 changes: 17 additions & 0 deletions src/tests/aes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,23 @@ fn test_aes_operations() {
));
assert_eq!(dec.len(), data.len());
assert_eq!(data.as_bytes(), dec.as_slice());

/* AES CBC negative test */
let data = "short";
let iv = "FEDCBA0987654321";
err_or_panic!(
encrypt(
session,
handle,
data.as_bytes(),
&CK_MECHANISM {
mechanism: CKM_AES_CBC,
pParameter: void_ptr!(iv.as_bytes()),
ulParameterLen: iv.len() as CK_ULONG,
}
),
CKR_DATA_LEN_RANGE
);
}

{
Expand Down