* log_msg : New log_set_verbosity(): It sets the default verbosity for the
log module according to the verbose option set by the user through the command
line.
* Remove useless checks of the verbose option when log_msg() is invoked.
This commit is a follow up to Ryman's report (#85) of a potential timing attack
that could be leveraged against fwknop when strncmp() is used to compare HMAC
digests. All strncmp() calls that do similar things have been replaced with a
new constant_runtime_cmp() function that mitigates this problem.
Lots of places in the code were already using {0} to initialize stack char
arrays, but memset() was being used as well. This commit removes all
unnecessary memset() calls against char arrays that are already initialized
via {0} (which sets all members to zero for such arrays).
Within the access loop always call fko_destroy() right up front whenever
ctx != NULL to ensure a clean slate each time through the loop regardless of
what state may have been reached the previous time through the loop.
These are simple logic fixes that would not have impacted run time to address
the following warnings generated by the CLANG static analyzer:
incoming_spa.c:433:17: warning: Value stored to 'attempted_decrypt' is never read
attempted_decrypt = 1;
^ ~
incoming_spa.c:647:13: warning: Value stored to 'acc' is never read
acc = acc->next;
^ ~~~~~~~~~
This change allows SPA clients to include long messages in command mode and
generally allows decryption operations to dictate success/failure instead of
SPA packet length to gate decryption attempts. Closes#40.
This is a fairly significant commit that lays the groundwork for getting
selectable HMAC modes working for both the client and server. One libfko API
change was required so that the hmac_type is passed into fko_new_with_data().
This allows the server to set the hmac_type via access.conf stanzas. The
effort in this commit will be extended to allow HMAC MD5, SHA1, and SHA512
also function properly.
This commit completes the conversion to the strtol() wrapper function in order
to remove all atoi() calls. In addition, variable max values are enforced
using more broadly defined RCHK_* values.
This commit replaces most atoi() calls (which don't report errors) with a strtol()
wrapper function for stronger string -> integer conversion validation.
Added a new '--pcap-file <file>' option to allow pcap files to
be processed directly by fwknopd instead of sniffing an interface. This
feature is mostly intended for debugging purposes.
For GPG mode, added a new access.conf variable "GPG_ALLOW_NO_PW" to make it
possible to leverage a server-side GPG key pair that has no associated
password. This comes in handy when a system requires the user to leverage
gpg-agent / pinentry which can present a problem in automated environments as
required by the fwknopd server. Now, it might seem like a problem to remove
the passphrase from a GPG key pair, but it's important to note that simply
doing this is little worse than storing the passphrase in the clear on disk
anyway in the access.conf file. Further, this link help provides additional
detail:
http://www.gnupg.org/faq/GnuPG-FAQ.html#how-can-i-use-gnupg-in-an-automated-environment
Ensure that an attacker cannot force a replay attack by intercepting an
SPA packet and the replaying it with the base64 version of "Salted__"
(for Rindael) or the "hQ" prefix (for GnuPG). This is an important fix.
The following comment was added into the fwknopd code:
/* Ignore any SPA packets that contain the Rijndael or GnuPG prefixes
* since an attacker might have tacked them on to a previously seen
* SPA packet in an attempt to get past the replay check. And, we're
* no worse off since a legitimate SPA packet that happens to include
* a prefix after the outer one is stripped off won't decrypt properly
* anyway because libfko would not add a new one.
*/
Conflicts:
lib/cipher_funcs.h
This commit fixes the following memory leak found with valgrind:
44 bytes in 1 blocks are definitely lost in loss record 2 of 2
at 0x482BE68: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
by 0x490EA50: strdup (strdup.c:43)
by 0x10CD69: incoming_spa (incoming_spa.c:162)
by 0x10E000: process_packet (process_packet.c:200)
by 0x4862E63: ??? (in /usr/lib/i386-linux-gnu/libpcap.so.1.1.1)
by 0x4865667: pcap_dispatch (in /usr/lib/i386-linux-gnu/libpcap.so.1.1.1)
by 0x10DABF: pcap_capture (pcap_capture.c:226)
by 0x10A798: main (fwknopd.c:299)
Ensure that an attacker cannot force a replay attack by intercepting an
SPA packet and the replaying it with the base64 version of "Salted__"
(for Rindael) or the "hQ" prefix (for GnuPG). This is an important fix.
The following comment was added into the fwknopd code:
/* Ignore any SPA packets that contain the Rijndael or GnuPG prefixes
* since an attacker might have tacked them on to a previously seen
* SPA packet in an attempt to get past the replay check. And, we're
* no worse off since a legitimate SPA packet that happens to include
* a prefix after the outer one is stripped off won't decrypt properly
* anyway because libfko would not add a new one.
*/
This commit fixes the following memory leak found with valgrind:
44 bytes in 1 blocks are definitely lost in loss record 2 of 2
at 0x482BE68: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
by 0x490EA50: strdup (strdup.c:43)
by 0x10CD69: incoming_spa (incoming_spa.c:162)
by 0x10E000: process_packet (process_packet.c:200)
by 0x4862E63: ??? (in /usr/lib/i386-linux-gnu/libpcap.so.1.1.1)
by 0x4865667: pcap_dispatch (in /usr/lib/i386-linux-gnu/libpcap.so.1.1.1)
by 0x10DABF: pcap_capture (pcap_capture.c:226)
by 0x10A798: main (fwknopd.c:299)
Now that encryptions keys and hmac keys may be acquired from /dev/random with
--key-gen (and base64 encoded), they may contain NULL bytes. This emphasizes
the need to not leverage code that assumes C-style strings when making use of
key information.
This change ensures that we only cache replay digests for those SPA packets
that actually decrypt. Not doing this would have allowed an attacker to
potentially fill up digest cache space with digests for garbage packets.
This commit fixes a bug where the same encryption key used for two stanzas in
the access.conf file would result in access requests that matched the second
stanza to always be treated as a replay attack. This has been fixed for
the fwknop-2.0.1 release, and was reported by Andy Rowland. Now the fwknopd
server computes the SHA256 digest of raw incoming payload data before
decryption, and compares this against all previous hashes. Previous to this
commit, fwknopd would add a new hash to the replay digest list right after
the first access.conf stanza match, so when SPA packet data matched the
second access.conf stanza a matching replay digest would already be there.
Added --key-gen to allow KEY_BASE64 and HMAC_KEY_BASE64 keys to be created from
reading random data from /dev/random. These keys can be placed within server
access.conf files and corresponding client .fwknoprc files for SPA
communications. The HMAC key is not used yet with this commit, but that is
coming.
fwknopd access stanzas can have both Rijndael and GnuPG keys, so this
commit fixes a bug where any gpg info would force only gpg decryption
attempts even if a Rijndael key is provided in the stanza.
This is a significant update to allow AES encryption modes to be selected on a
per-key basis. For now, only ECB and CBC (recommended) modes are supported.
The default is ECB modes in order to maintain backwards compatibility with the
older perl version of fwknop and the Crypt::CBC CPAN module. This will likely
be changed to use CBC mode by default because of its better security
properties.
In the access.conf file on the server side, there is a new configuration
variable "ENCRYPTION_MODE" that controls the mode for the corresponding AES
key. On the client side, a new command line argument "--encryption-mode"
controls how the client encrypts SPA packets.
