This patch changes our bits-to-bytes conversion logic in the NSS
implementation of `tor_tls_cert_matches_key()` from using (x >> 3) to
((x + 7) >> 3) since DER bit-strings are allowed to contain a number of
bits that is not a multiple of 8.
Additionally, we add a comment on why we cannot use the
`DER_ConvertBitString()` macro from NSS, as we would potentially apply
the bits-to-bytes conversion logic twice, which would lead to an
insignificant amount of bytes being compared in
`SECITEM_ItemsAreEqual()` and thus turn the logic into being a
prefix match instead of a full match.
The `DER_ConvertBitString()` macro is defined in NSS as:
/*
** Macro to convert der decoded bit string into a decoded octet
** string. All it needs to do is fiddle with the length code.
*/
#define DER_ConvertBitString(item) \
{ \
(item)->len = ((item)->len + 7) >> 3; \
}
Thanks to Taylor Yu for spotting this problem.
This patch is part of the fix for TROVE-2020-001.
See: https://bugs.torproject.org/33119
We add constness to `peer_info_orig_len` and `cert_info_orig_len` in
`tor_tls_cert_matches_key` to ensure that we don't accidentally alter
the variables.
This patch is part of the fix for TROVE-2020-001.
See: https://bugs.torproject.org/33119
This patch fixes an out-of-bound memory read in
`tor_tls_cert_matches_key()` when Tor is compiled to use Mozilla's NSS
instead of OpenSSL.
The NSS library stores some length fields in bits instead of bytes, but
the comparison function found in `SECITEM_ItemsAreEqual()` needs the
length to be encoded in bytes. This means that for a 140-byte,
DER-encoded, SubjectPublicKeyInfo struct (with a 1024-bit RSA public key
in it), we would ask `SECITEM_ItemsAreEqual()` to compare the first 1120
bytes instead of 140 (140bytes * 8bits = 1120bits).
This patch fixes the issue by converting from bits to bytes before
calling `SECITEM_ItemsAreEqual()` and convert the `len`-fields back to
bits before we leave the function.
This patch is part of the fix for TROVE-2020-001.
See: https://bugs.torproject.org/33119
Now instead of saying "DONE, DONE" or "MISC, MISC" or "TLS_ERROR,
TLS_ERROR", we can finally give a nice sensible "TLS_ERROR,
wrong version number" which should help debug a great deal.
Closes ticket 32622.
The buf_read_from_tls() function was designed to read up to a certain number
of bytes a TLS socket using read_to_chunk_tls() which boils down to SSL_read()
(with OpenSSL, common case).
However, at the end of the loop, the returned number of bytes from
read_to_chunk_tls() was treated like the syscall read() for which if less
bytes than the total asked are returned, it signals EOF.
But, with SSL_read(), it returns up to a TLS record which can be less than
what was asked. The assumption that it was EOF was wrong which made the while
loop exiting before it was able to consume all requested bytes (at_most
parameter).
The general use case that Tor sees is that it will ask the network layer to
give it at most 16KB (that is roughly 32 cells) but because of KIST scheduler,
the highest possible TLS record we currently observe is 4096 bytes (4KB or 8
cells). Thus the loop would at best always return 8 cells even though much
more could be on the TLS socket. See ticket #40006 for more details.
Fixes#40006
Signed-off-by: David Goulet <dgoulet@torproject.org>
M_SYSCALL is used to report information about a sandbox violation,
but when we don't have a definition for it, it still makes sense to
compile.
Closes ticket 34382.
Nick Mathewson
Alexander Færøy
David Goulet
George Kadianakis
rl1987
c
rl1987
Daniel Pinto