For AEADs (our only EVP_CIPH_FLAG_CUSTOM_CIPHER is GCM), EVP_Cipher is
not a one-shot operation. It is a thin wrapper over the internal
cipher callback in the EVP_CIPHER, complete with treating in == NULL as
EVP_CipherFinal_ex. Also document that you should not do this.
Also document how you feed in the AAD for an AEAD EVP_CIPHER. (Although
callers really should use EVP_AEAD for a much less complex interface.)
Bug: 494
Change-Id: I0beb1c88cdf0406506af2772e53e9d3f8d07172a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52727
Commit-Queue: Bob Beck <bbe@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
If we're to have any hope of fixing EVP_CIPHER_CTX's calling convention, we
need to be able to change the shape of its method table.
Looking back, it looks like we exported this in
https://boringssl-review.googlesource.com/4330, for OpenSSH. I don't
remember exactly what OpenSSH was doing, but I see in this commit, they
removed a bunch of custom EVP_CIPHERs which would definitely have
required an exported EVP_CIPHER struct:
cdccebdf85
That's been gone for a while now, so hopefully we can hide it again. (If
a project needs a cipher not implemented by OpenSSL, it's not strictly
necessarily to make a custom EVP_CIPHER. It might be convenient to reuse
the abstraction, but you can always just call your own APIs directly.)
Update-Note: EVP_CIPHER is now opaque. Use accessors instead.
Bug: 494
Change-Id: I9344690c3cfe7d19d6ca12fb66484ced57dbe869
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52725
Reviewed-by: Bob Beck <bbe@google.com>
Commit-Queue: Bob Beck <bbe@google.com>
The non-_ex EVP_CIPHER_CTX Final functions are a bit interesting. Unlike
EVP_DigestFinal(_ex), where the non-_ex version calls EVP_MD_CTX_cleanup
for you, the EVP_CIPHER_CTX ones do not automatically cleanup.
EVP_CipherFinal and EVP_CipherFinal_ex are identical in all releases
where they exist.
This appears to date to OpenSSL 0.9.7:
Prior to OpenSSL 0.9.7, EVP_MD_CTX and EVP_CIPHER_CTX did not use void*
data fields. Instead, they just had a union of context structures for
every algorithm OpenSSL implemented.
EVP_MD_CTX was truly cleanup-less. There were no EVP_MD_CTX_init or
EVP_MD_CTX_cleanup functions at all. EVP_DigestInit filled things in
without reference to the previous state. EVP_DigestFinal didn't cleanup
because there was nothing to cleanup.
EVP_CIPHER_CTX was also a union, but for some reason did include
EVP_CIPHER_CTX_init and EVP_CIPHER_CTX_cleanup. EVP_CIPHER_CTX_init
seemed to be optional: EVP_CipherInit with non-NULL EVP_CIPHER similarly
didn't reference the previous state. EVP_CipherFinal did not call
EVP_CIPHER_CTX_cleanup, but EVP_CIPHER_CTX_cleanup didn't do anything.
It called an optional cleanup hook on the EVP_CIPHER, but as far as I
can tell, no EVP_CIPHER implemented it.
Then OpenSSL 0.9.7 introduced ENGINE. The union didn't work anymore, so
EVP_MD_CTX and EVP_CIPHER_CTX contained void* with allocated
type-specific data. The introduced EVP_MD_CTX_init and
EVP_MD_CTX_cleanup. For (imperfect!) backwards compatibility,
EVP_DigestInit and EVP_DigestFinal transparently called init/cleanup for
you. EVP_DigestInit_ex and EVP_DigestFinal_ex became the more flexible
versions that left init/cleanup to the caller.
EVP_CIPHER_CTX got the same treatment with
EVP_CipherInit/EVP_CipherInit_ex, but *not*
EVP_CipherFinal/EVP_CipherFinal_ex. The latter did the same thing. The
history seems to be that 581f1c84940d77451c2592e9fa470893f6c3c3eb
introduced the Final/Final_ex split, with the former doing an
auto-cleanup, then 544a2aea4ba1fad76f0802fb70d92a5a8e6ad85a undid it.
Looks like the motivation is that EVP_CIPHER_CTX objects are often
reused to do multiple operations with a single key. But they missed that
the split functions are now unnecessary.
Amusingly, OpenSSL's documentation incorrectly said that EVP_CipherFinal
cleaned up after the call until it was fixed in
538860a3ce0b9fd142a7f1a62e597cccb74475d3. The fix says that some
releases cleaned up, but there were, as far as I can tell, no actual
releases with that behavior.
I've put the new Final functions in the deprecated section, purely
because there is no sense in recommending two different versions of the
same function to users, and Final_ex seems to be more popular. But there
isn't actually anything wrong with plain Final.
Change-Id: Ic2bfda48fdcf30f292141add8c5f745348036852
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50485
Reviewed-by: Adam Langley <agl@google.com>
Node seems uncommonly sensitive to this, so let's write these functions
in a way that stays in sync and test this. See also
https://boringssl-review.googlesource.com/c/boringssl/+/49585
This does incur a cost across all BoringSSL consumers that use these
functions: as a result of Node indiscriminately exposing every cipher,
we end up pulling more and more ciphers into these getters. But that
ship sailed long ago, so, instead, document that EVP_get_cipherby*
should not be used by size-conscious callers.
EVP_get_digestby* probably should have the same warning, but I've left
it alone for now because we don't quite have the same proliferation of
digests as ciphers. (Though there are things in there, like MD4, that
ought to be better disconnected.)
Change-Id: I61ca406c146279bd05a52bed6c57200d1619c5da
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/49625
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
This may as well be computed from block_size. This reduces the
per-EVP_CIPHER_CTX memory usage slightly.
Update-Note: It doesn't look like anyone is reading into this field. If
they are, we can ideally fix it, or revert this if absolutely necessary.
Change-Id: Ieef9177bed1671efca23d4f94d3d528f82568fc6
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45884
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CVE-2021-23840
(Imported from upstream's 6a51b9e1d0cf0bf8515f7201b68fb0a3482b3dc1.)
This differs slightly from upstream's version:
- EVP_R_OUTPUT_WOULD_OVERFLOW didn't seem necessary when ERR_R_OVERFLOW
already exists. (Also since we use CIPHER_R_*, it wouldn't have helped
with compatibility anyway. Though there's probably something to be
said for us folding CIPHER_R_* back into EVP_R_*.)
- For simplicity, just check in_len + bl at the top, rather than trying
to predict the exact number of bytes written.
Update-Note: Passing extremely large input lengths into EVP_CipherUpdate
will now fail. Use EVP_AEAD instead, which is size_t-based and has more
explicit output bounds.
Change-Id: I31835c89dcdecb6b112828f57deb798dc7187db5
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45685
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Change-Id: I814f55742910c519e9b64aca1b15a4d754adc541
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/44944
Commit-Queue: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
David Benjamin
Adam Langley
Adam Langley