patch initially by Jack Stone <jwjstone@fastmail.fm>,
cleaned up by Jan Synacek <jsynacek@redhat.com>,
... and then almost completely rewritten by me. ^^
RequireCRAM (another fairly stupid "use if available" option) is now
deprecated. instead, the AuthMech option can be used to give a precise
list of acceptable authentication mechanisms (which is currently "a bit"
short). in particular, this allows *not* using CRAM-MD5 even if it's
available.
the combinations of the various options made quite a mess. additionally,
'RequireSSL no' is inherently insecure - "use SSL if available" is plain
stupid.
the old options are still accepted, but will elicit a warning.
it doesn't belong there - it's a property of imap_server_conf_t.
the port setup is now done while reading the config.
this makes socket.[hc] imap-agnostic.
memcmp() is unfortunately not guaranteed to read forward byte-by-byte,
which means that the clever use as a strncmp() without the pointless
strlen()s is not permitted, and can actually misbehave with
SSE-optimized string functions.
so implement proper equals() and starts_with() functions. as a bonus,
the calls are less cryptic.
such connections don't support STARTTLS. that is reasonable, as whatever
makes the connection preauthenticated (typically a Tunnel used to launch
imapd via a shell login) must already rely on the connection's security.
consequently, we would not try to use STARTTLS with such connections.
unfortunately, we'd also skip the RequireSSL check as a side effect.
this means that a rogue server (via a MITM attack) could simply offer a
preauthenticated connection to make us not use SSL, and thus bypass
server authentication. as a result, we could send potentially sensitive
data to the attacker:
- with Patterns used, we would send a LIST command which reveals the
remote Path setting. this isn't very useful to an attacker. also, IMAP
Accounts usually rely on the server-provided NAMESPACE to start with.
- with Create enabled for the remote Store, we would upload messages
from newly appeared local folders. this isn't a very likely situation,
unless the attacker manages to convince the victim to move/copy
interesting mails to a new folder right before the attack.
- with Expunge enabled for the local Store, previously synchronized
folders would be wiped. however, this would require the attacker to
know the correct UIDVALIDITY of each remote folder, which would
require incredible luck or convincing the victim to disclose them.
the first mismatch would likely tip off the victim.
in practice, someone with the level of technical and social engineering
skills required for this attack would very likely find more attractive
attack vectors. therefore, i don't consider this a particularly serious
issue.
configurations with UseIMAPS enabled or using a secure Tunnel were not
affected to start with.
a side effect of this fix is that most users of Tunnel will now need to
explicitly set RequireSSL to false.
an alternative approach would be defaulting all SSL-related settings to
off when Tunnel is used. this would be too invasive for a patch release,
but i'll consider it for 1.2.
see also CVE-2014-2567 for the Trojita MUA.
this would happen in the absurd corner case that the response code is
properly terminated with a closing bracket, but the atom itself is an
unterminated double-quoted string.
NOT found by coverity.
the BODY[] item in the FETCH response corresponds to what we requested,
and its presence doesn't imply that it actually contains anything useful
- new messages may appear in the mailbox in addition to those we stored
ourselves, and these will obviously have no TUID.
the global timezone variable is glibc-specific.
so use timegm() instead of mktime() for the conversion.
as that is specific to the BSDs and glibc, provide a fallback.
amends 62a6099.
the warning suppression pragma within function scope is apparently a new
thing.
as i don't want to disable the check for the entire function (even if
this currently would make no difference), just use a wrapper function
to suppress the format string check.
this would happen if we were trying to find newly pushed messages, but
none actually arrived.
as imap's ranges are not ordered, this would actually fetch one message.
Oswald Buddenhagen