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LibCrypto: Remove all uses of VLAs

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This removes all uses of VLAs with either Vectors with inline capacity
for the expected soft upper bound, or the occasional heap allocation.
This commit is contained in:
Ali Mohammad Pur 2021-05-13 12:13:11 +04:30 • committed by Andreas Kling
parent 0d50d3ed1e
commit b05beb79d4
7 changed files with 41 additions and 36 deletions
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26
Userland/Libraries/LibCrypto/PK/Code/EMSA_PSS.h
View file

@ -33,7 +33,7 @@ public:
auto& hash_fn = this->hasher();
hash_fn.update(in);
auto message_hash = hash_fn.digest();
auto hash_length = hash_fn.DigestSize;
constexpr auto hash_length = hash_fn.DigestSize;
auto em_length = (em_bits + 7) / 8;
u8 salt[SaltLength];
@ -51,8 +51,9 @@ public:
hash_fn.update(m_buffer);
auto hash = hash_fn.digest();
u8 DB_data[em_length - HashFunction::DigestSize - 1];
auto DB = Bytes { DB_data, em_length - HashFunction::DigestSize - 1 };
Vector<u8, 256> DB_data;
DB_data.resize(em_length - HashFunction::DigestSize - 1);
Bytes DB = DB_data;
auto DB_offset = 0;
for (size_t i = 0; i < em_length - SaltLength - HashFunction::DigestSize - 2; ++i)
@ -64,8 +65,9 @@ public:
auto mask_length = em_length - HashFunction::DigestSize - 1;
u8 DB_mask[mask_length];
auto DB_mask_buffer = Bytes { DB_mask, mask_length };
Vector<u8, 256> DB_mask;
DB_mask.resize(mask_length);
Bytes DB_mask_buffer { DB_mask };
// FIXME: we should probably allow reading from u8*
MGF1(ReadonlyBytes { hash.data, HashFunction::DigestSize }, mask_length, DB_mask_buffer);
@ -102,11 +104,13 @@ public:
if ((octet >> (8 - i)) & 0x01)
return VerificationConsistency::Inconsistent;
u8 DB_mask[mask_length];
auto DB_mask_buffer = Bytes { DB_mask, mask_length };
Vector<u8, 256> DB_mask;
DB_mask.resize(mask_length);
Bytes DB_mask_buffer { DB_mask };
MGF1(H, mask_length, DB_mask_buffer);
u8 DB[mask_length];
Vector<u8, 256> DB;
DB.resize(mask_length);
for (size_t i = 0; i < mask_length; ++i)
DB[i] = masked_DB[i] ^ DB_mask[i];
@ -122,8 +126,8 @@ public:
if (DB[check_octets + 1] != 0x01)
return VerificationConsistency::Inconsistent;
auto* salt = DB + mask_length - SaltLength;
u8 m_prime[8 + HashFunction::DigestSize + SaltLength] { 0, 0, 0, 0, 0, 0, 0, 0 };
auto* salt = DB.span().offset(mask_length - SaltLength);
u8 m_prime[8 + HashFunction::DigestSize + SaltLength] { 0 };
auto m_prime_buffer = Bytes { m_prime, sizeof(m_prime) };
@ -133,7 +137,7 @@ public:
hash_fn.update(m_prime_buffer);
auto H_prime = hash_fn.digest();
if (__builtin_memcmp(message_hash.data, H_prime.data, HashFunction::DigestSize))
if (__builtin_memcmp(message_hash.data, H_prime.data, HashFunction::DigestSize) != 0)
return VerificationConsistency::Inconsistent;
return VerificationConsistency::Consistent;

22
Userland/Libraries/LibCrypto/PK/RSA.cpp
View file

@ -293,8 +293,9 @@ void RSA_EMSA_PSS<HashFunction>::sign(ReadonlyBytes in, Bytes& out)
// -- encode via EMSA_PSS
auto mod_bits = m_rsa.private_key().modulus().trimmed_length() * sizeof(u32) * 8;
u8 EM[mod_bits];
auto EM_buf = Bytes { EM, mod_bits };
Vector<u8, 2048> EM;
EM.resize(mod_bits);
auto EM_buf = Bytes { EM };
m_emsa_pss.encode(in, EM_buf, mod_bits - 1);
// -- sign via RSA
@ -308,8 +309,9 @@ VerificationConsistency RSA_EMSA_PSS<HashFunction>::verify(ReadonlyBytes in)
if (in.size() != mod_bytes)
return VerificationConsistency::Inconsistent;
u8 EM[mod_bytes];
auto EM_buf = Bytes { EM, mod_bytes };
Vector<u8, 256> EM;
EM.resize(mod_bytes);
auto EM_buf = Bytes { EM };
// -- verify via RSA
m_rsa.verify(in, EM_buf);
@ -333,22 +335,20 @@ void RSA_PKCS1_EME::encrypt(ReadonlyBytes in, Bytes& out)
}
auto ps_length = mod_len - in.size() - 3;
u8 ps[ps_length];
Vector<u8, 8096> ps;
ps.resize(ps_length);
// FIXME: Without this assertion, GCC refuses to compile due to a memcpy overflow(!?)
VERIFY(ps_length < 16384);
fill_with_random(ps, ps_length);
fill_with_random(ps.data(), ps_length);
// since arc4random can create zeros (shocking!)
// we have to go through and un-zero the zeros
for (size_t i = 0; i < ps_length; ++i)
while (!ps[i])
fill_with_random(ps + i, 1);
fill_with_random(ps.span().offset(i), 1);
u8 paddings[] { 0x00, 0x02 };
out.overwrite(0, paddings, 2);
out.overwrite(2, ps, ps_length);
out.overwrite(2, ps.data(), ps_length);
out.overwrite(2 + ps_length, paddings, 1);
out.overwrite(3 + ps_length, in.data(), in.size());
out = out.trim(3 + ps_length + in.size()); // should be a single block