CBS_asn1_ber_to_der currently uses heuristics because implicitly-tagged
constructed strings in BER are ambiguous with implicitly-tagged sequences. It's
not possible to convert BER to DER without knowing the schema.
Fortunately, implicitly tagged strings don't appear often so instead split the
job up: CBS_asn1_ber_to_der fixes indefinite-length elements and constructed
strings it can see. Implicitly-tagged strings it leaves uncoverted, but they
will only nest one level down (because BER kindly allows one to nest
constructed strings arbitrarily!).
CBS_get_asn1_implicit_string then performs the final concatenation at parse
time. This isn't much more complex and lets us parse BER more accurately and
also reject a number of mis-encoded values (e.g. constructed INTEGERs are not a
thing) we'd previously let through. The downside is the post-conversion parsing
code must be aware of this limitation of CBS_asn1_ber_to_der. Fortunately,
there's only one implicitly-tagged string in our PKCS#12 code.
(In the category of things that really really don't matter, but I had spare
cycles and the old BER converter is weird.)
Change-Id: Iebdd13b08559fa158b308ef83a5bb07bfdf80ae8
Reviewed-on: https://boringssl-review.googlesource.com/7052
Reviewed-by: Adam Langley <agl@google.com>
These will be needed when we start writing variable-length things to a
CBB.
Change-Id: Ie7b9b140f5f875b43adedc8203ce9d3f4068dfea
Reviewed-on: https://boringssl-review.googlesource.com/6764
Reviewed-by: Adam Langley <agl@google.com>
Rather than the length of the top-level CBB, which is kind of odd when ASN.1
length prefixes are not yet determined, return the number of bytes written to
the CBB so far. This can be computed without increasing the size of CBB at all.
Have offset and pending_*.
This means functions which take in a CBB as argument will not be sensitive to
whether the CBB is a top-level or child CBB. The extensions logic had to be
careful to only ever compare differences of lengths, which was awkward.
The reversal will also allow for the following pattern in the future, once
CBB_add_space is split into, say, CBB_reserve and CBB_did_write and we add a
CBB_data:
uint8_t *signature;
size_t signature_len = 0;
if (!CBB_add_asn1(out, &cert, CBB_ASN1_SEQUENCE) ||
/* Emit the TBSCertificate. */
!CBB_add_asn1(&cert, &tbs_cert, CBS_ASN1_SEQUENCE) ||
!CBB_add_tbs_cert_stuff(&tbs_cert, stuff) ||
!CBB_flush(&cert) ||
/* Feed it into md_ctx. */
!EVP_DigestSignInit(&md_ctx, NULL, EVP_sha256(), NULL, pkey) ||
!EVP_DigestSignUpdate(&md_ctx, CBB_data(&cert), CBB_len(&cert)) ||
/* Emit the signature algorithm. */
!CBB_add_asn1(&cert, &sig_alg, CBS_ASN1_SEQUENCE) ||
!CBB_add_sigalg_stuff(&sig_alg, other_stuff) ||
/* Emit the signature. */
!EVP_DigestSignFinal(&md_ctx, NULL, &signature_len) ||
!CBB_reserve(&cert, &signature, signature_len) ||
!EVP_DigestSignFinal(&md_ctx, signature, &signature_len) ||
!CBB_did_write(&cert, signature_len)) {
goto err;
}
(Were TBSCertificate not the first field, we'd still have to sample
CBB_len(&cert), but at least that's reasonable straight-forward. The
alternative would be if CBB_data and CBB_len somehow worked on
recently-invalidated CBBs, but that would go wrong once the invalidated CBB's
parent flushed and possibly shifts everything.)
And similar for signing ServerKeyExchange.
Change-Id: I7761e492ae472d7632875b5666b6088970261b14
Reviewed-on: https://boringssl-review.googlesource.com/6681
Reviewed-by: Adam Langley <agl@google.com>
stdint.h already has macros for this. The spec says that, in C++,
__STDC_CONSTANT_MACROS is needed, so define it for bytestring_test.cc.
Chromium seems to use these macros without trouble, so I'm assuming we
can rely on them.
Change-Id: I56d178689b44d22c6379911bbb93d3b01dd832a3
Reviewed-on: https://boringssl-review.googlesource.com/6510
Reviewed-by: Adam Langley <agl@google.com>
To no great surprise, ASAN didn't like this test and I suspect that
Chromium, with its crashing allocator, won't like it either. Oh well.
Change-Id: I235dbb965dbba186f8f37d7df45f8eac9addc7eb
Reviewed-on: https://boringssl-review.googlesource.com/6496
Reviewed-by: Adam Langley <agl@google.com>
People expect to do:
CBB foo;
if (!CBB_init(&foo, 100) ||
…
…) {
CBB_cleanup(&foo);
return 0;
}
However, currently, if the allocation of |initial_capacity| fails in
|CBB_init| then |CBB_cleanup| will operate on uninitialised values. This
change makes the above pattern safe.
Change-Id: I3e002fda8f0a3ac18650b504e7e84a842d4165ca
Reviewed-on: https://boringssl-review.googlesource.com/6495
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
Chromium's toolchains may now assume C++11 library support, so we may freely
use C++11 features. (Chromium's still in the process of deciding what to allow,
but we use Google's style guide directly, toolchain limitations aside.)
Change-Id: I1c7feb92b7f5f51d9091a4c686649fb574ac138d
Reviewed-on: https://boringssl-review.googlesource.com/6465
Reviewed-by: Adam Langley <agl@google.com>
Start converting the ones we can right now. Some of the messier ones
resize init_buf rather than assume the initial size is sufficient, so
those will probably wait until init_buf is gone and the handshake's
undergone some more invasive surgery. The async ones will also require
some thought. But some can be incrementally converted now.
BUG=468889
Change-Id: I0bc22e4dca37d9d671a488c42eba864c51933638
Reviewed-on: https://boringssl-review.googlesource.com/6190
Reviewed-by: Adam Langley <alangley@gmail.com>
One tedious thing about using CBB is that you can't safely CBB_cleanup
until CBB_init is successful, which breaks the general 'goto err' style
of cleanup. This makes it possible:
CBB_zero ~ EVP_MD_CTX_init
CBB_init ~ EVP_DigestInit
CBB_cleanup ~ EVP_MD_CTX_cleanup
Change-Id: I085ecc4405715368886dc4de02285a47e7fc4c52
Reviewed-on: https://boringssl-review.googlesource.com/5267
Reviewed-by: Adam Langley <agl@google.com>
kData5 was meant to test lengths that are too long, but the input
gets rejected earlier for not using short-form encoding. Switch it to
testing a badly encoded element of length 128, the shortest element that
uses long-form encoding.
Change-Id: I35f4df89bfa7a681698eda569c525b5871288487
Reviewed-on: https://boringssl-review.googlesource.com/5264
Reviewed-by: Adam Langley <agl@google.com>
The encoding of an INTEGER should not have leading zeros, except to pad for the
sign bit.
Change-Id: I80d22818cf1d2ca9d27e215620392e1725372aa5
Reviewed-on: https://boringssl-review.googlesource.com/4218
Reviewed-by: Adam Langley <agl@google.com>
