This bug goes back to the original Postgres95 sources. Its significance
to modern PG versions is marginal, since we have not used PQprintTuples()
internally in a very long time, and it doesn't seem to have ever been
documented either. Still, it *is* exposed to client apps, so somebody
out there might possibly be using it.
Xi Wang
The length of a socket path name is constrained by the size of struct
sockaddr_un, and there's not a lot we can do about it since that is a
kernel API. However, it would be a good thing if we produced an
intelligible error message when the user specifies a socket path that's too
long --- and getaddrinfo's standard API is too impoverished to do this in
the natural way. So insert explicit tests at the places where we construct
a socket path name. Now you'll get an error that makes sense and even
tells you what the limit is, rather than something generic like
"Non-recoverable failure in name resolution".
Per trouble report from Jeremy Drake and a fix idea from Andrew Dunstan.
I found that these functions tend to return -1 while leaving an empty error
message string in the PGconn, if they suffer some kind of I/O error on the
file. The reason is that lo_close, which thinks it's executed a perfectly
fine SQL command, clears the errorMessage. The minimum-change workaround
is to reorder operations here so that we don't fill the errorMessage until
after lo_close.
Both libpq and the backend would truncate a common name extracted from a
certificate at 32 bytes. Replace that fixed-size buffer with dynamically
allocated string so that there is no hard limit. While at it, remove the
code for extracting peer_dn, which we weren't using for anything; and
don't bother to store peer_cn longer than we need it in libpq.
This limit was not so terribly unreasonable when the code was written,
because we weren't using the result for anything critical, just logging it.
But now that there are options for checking the common name against the
server host name (in libpq) or using it as the user's name (in the server),
this could result in undesirable failures. In the worst case it even seems
possible to spoof a server name or user name, if the correct name is
exactly 32 bytes and the attacker can persuade a trusted CA to issue a
certificate in which that string is a prefix of the certificate's common
name. (To exploit this for a server name, he'd also have to send the
connection astray via phony DNS data or some such.) The case that this is
a realistic security threat is a bit thin, but nonetheless we'll treat it
as one.
Back-patch to 8.4. Older releases contain the faulty code, but it's not
a security problem because the common name wasn't used for anything
interesting.
Reported and patched by Heikki Linnakangas
Security: CVE-2012-0867
This makes it possible to use a libpq app with home directory set
to /dev/null, for example - treating it the same as if the file
doesn't exist (which it doesn't).
Per bug #6302, reported by Diego Elio Petteno
These days, such a response is far more likely to signify a server-side
problem, such as fork failure. Reporting "server does not support SSL"
(in sslmode=require) could be quite misleading. But the results could
be even worse in sslmode=prefer: if the problem was transient and the
next connection attempt succeeds, we'll have silently fallen back to
protocol version 2.0, possibly disabling features the user needs.
Hence, it seems best to just eliminate the assumption that backing off
to non-SSL/2.0 protocol is the way to recover from an "E" response, and
instead treat the server error the same as we would in non-SSL cases.
I tested this change against a pre-7.0 server, and found that there
was a second logic bug in the "prefer" path: the test to decide whether
to make a fallback connection attempt assumed that we must have opened
conn->ssl, which in fact does not happen given an "E" response. After
fixing that, the code does indeed connect successfully to pre-7.0,
as long as you didn't set sslmode=require. (If you did, you get
"Unsupported frontend protocol", which isn't completely off base
given the server certainly doesn't support SSL.)
Since there seems no reason to believe that pre-7.0 servers exist anymore
in the wild, back-patch to all supported branches.
There are assorted situations wherein PQconnectPoll() will abandon a
connection attempt and try again with different parameters (eg, SSL versus
not SSL). However, the code forgot to discard any pending data in libpq's
I/O buffers when doing this. In at least one case (server returns E
message during SSL negotiation), there is unread input data which bollixes
the next connection attempt. I have not checked to see whether this is
possible in the other cases where we close the socket and retry, but it
seems like a matter of good defensive programming to add explicit
buffer-flushing code to all of them.
This is one of several issues exposed by Daniel Farina's report of
misbehavior after a server-side fork failure.
This has been wrong since forever, so back-patch to all supported branches.
On balance, the need to cover this case changes my mind in favor of pushing
all error-message generation duties into the two fe-secure.c routines.
So do it that way.
In many cases, pqsecure_read/pqsecure_write set up useful error messages,
which were then overwritten with useless ones by their callers. Fix this
by defining the responsibility to set an error message to be entirely that
of the lower-level function when using SSL.
Back-patch to 8.3; the code is too different in 8.2 to be worth the
trouble.
This disables an entirely unnecessary "sanity check" that causes failures
in nonblocking mode, because OpenSSL complains if we move or compact the
write buffer. The only actual requirement is that we not modify pending
data once we've attempted to send it, which we don't. Per testing and
research by Martin Pihlak, though this fix is a lot simpler than his patch.
I put the same change into the backend, although it's less clear whether
it's necessary there. We do use nonblock mode in some situations in
streaming replication, so seems best to keep the same behavior in the
backend as in libpq.
Back-patch to all supported releases.
PQsetvalue unnecessarily duplicated the logic in pqAddTuple, and didn't
duplicate it exactly either --- pqAddTuple does not care what is in the
tuple-pointer array positions beyond the last valid entry, whereas the
code in PQsetvalue assumed such positions would contain NULL. This led
to possible crashes if PQsetvalue was applied to a PGresult that had
previously been enlarged with pqAddTuple, for instance one built from a
server query. Fix by relying on pqAddTuple instead of duplicating logic,
and not assuming anything about the contents of res->tuples[res->ntups].
Back-patch to 8.4, where PQsetvalue was introduced.
Andrew Chernow
This unifies a bunch of ugly #ifdef's in one place. Per discussion,
we only need this where HAVE_UNIX_SOCKETS, so no need to cover Windows.
Marko Kreen, some adjustment by Tom Lane
It turns out the reason we hadn't found out about the portability issues
with our credential-control-message code is that almost no modern platforms
use that code at all; the ones that used to need it now offer getpeereid(),
which we choose first. The last holdout was NetBSD, and they added
getpeereid() as of 5.0. So far as I can tell, the only live platform on
which that code was being exercised was Debian/kFreeBSD, ie, FreeBSD kernel
with Linux userland --- since glibc doesn't provide getpeereid(), we fell
back to the control message code. However, the FreeBSD kernel provides a
LOCAL_PEERCRED socket parameter that's functionally equivalent to Linux's
SO_PEERCRED. That is both much simpler to use than control messages, and
superior because it doesn't require receiving a message from the other end
at just the right time.
Therefore, add code to use LOCAL_PEERCRED when necessary, and rip out all
the credential-control-message code in the backend. (libpq still has such
code so that it can still talk to pre-9.1 servers ... but eventually we can
get rid of it there too.) Clean up related autoconf probes, too.
This means that libpq's requirepeer parameter now works on exactly the same
platforms where the backend supports peer authentication, so adjust the
documentation accordingly.
Even though our existing code for handling credentials control messages has
been basically unchanged since 2001, it was fundamentally wrong: it did not
ensure proper alignment of the supplied buffer, and it was calculating
buffer sizes and message sizes incorrectly. This led to failures on
platforms where alignment padding is relevant, for instance FreeBSD on
64-bit platforms, as seen in a recent Debian bug report passed on by
Martin Pitt (http://bugs.debian.org//cgi-bin/bugreport.cgi?bug=612888).
Rewrite to do the message-whacking using the macros specified in RFC 2292,
following a suggestion from Theo de Raadt in that thread. Tested by me
on Debian/kFreeBSD-amd64; since OpenBSD and NetBSD document the identical
CMSG API, it should work there too.
Back-patch to all supported branches.
Even though this only affects the insertion of a parenthesized word,
it's unwise to assume that parentheses can pass through untranslated.
And in any case, the new version is clearer in the code and for
translators.
The code to assemble ldap_get_values_len's output into a single string
wrote the terminating null one byte past where it should. Fix that,
and make some other cosmetic adjustments to make the code a trifle more
readable and more in line with usual Postgres coding style.
Also, free the "result" string when done with it, to avoid a permanent
memory leak.
Bug report and patch by Albe Laurenz, cosmetic adjustments by me.
The style is set to "printf" for backwards compatibility everywhere except
on Windows, where it is set to "gnu_printf", which eliminates hundreds of
false error messages from modern versions of gcc arising from %m and %ll{d,u}
formats.
This warning is new in gcc 4.6 and part of -Wall. This patch cleans
up most of the noise, but there are some still warnings that are
trickier to remove.
This would lead to leaking the PGconn structure after an error detected by
conninfo_array_parse(), as well as failing to return a useful error message
in such cases. Backpatch to 9.0 where the error was introduced.
Joseph Adams
