This includes two new kinds of postmaster processes, walsenders and
walreceiver. Walreceiver is responsible for connecting to the primary server
and streaming WAL to disk, while walsender runs in the primary server and
streams WAL from disk to the client.
Documentation still needs work, but the basics are there. We will probably
pull the replication section to a new chapter later on, as well as the
sections describing file-based replication. But let's do that as a separate
patch, so that it's easier to see what has been added/changed. This patch
also adds a new section to the chapter about FE/BE protocol, documenting the
protocol used by walsender/walreceivxer.
Bump catalog version because of two new functions,
pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), for
monitoring the progress of replication.
Fujii Masao, with additional hacking by me
at least in some Windows versions, these functions are capable of returning
a failure indication without setting errno. That puts us into an infinite
loop if the previous value happened to be EINTR. Per report from Brendan
Hill.
Back-patch to 8.2. We could take it further back, but since this is only
known to be an issue on Windows and we don't support Windows before 8.2,
it does not seem worth the trouble.
attacks where an attacker would put <attack>\0<propername> in the field and
trick the validation code that the certificate was for <attack>.
This is a very low risk attack since it reuqires the attacker to trick the
CA into issuing a certificate with an incorrect field, and the common
PostgreSQL deployments are with private CAs, and not external ones. Also,
default mode in 8.4 does not do any name validation, and is thus also not
vulnerable - but the higher security modes are.
Backpatch all the way. Even though versions 8.3.x and before didn't have
certificate name validation support, they still exposed this field for
the user to perform the validation in the application code, and there
is no way to detect this problem through that API.
Security: CVE-2009-4034
to the documented API value. The previous code got it right as
it's implemented, but accepted too much/too little compared to
the API documentation.
Per comment from Zdenek Kotala.
it's connection. This is required for applications that unload
the libpq library (such as PHP) in which case we'd otherwise
have pointers to these functions when they no longer exist.
This needs a bit more testing before we can consider a backpatch,
so not doing that yet.
In passing, remove unused functions in backend/libpq.
Bruce Momjian and Magnus Hagander, per report and analysis
by Russell Smith.
key files that are similar to the one for the postmaster's data directory
permissions check. (I chose to standardize on that one since it's the most
heavily used and presumably best-wordsmithed by now.) Also eliminate explicit
tests on file ownership in these places, since the ensuing read attempt must
fail anyway if it's wrong, and there seems no value in issuing the same error
message for distinct problems. (But I left in the explicit ownership test in
postmaster.c, since it had its own error message anyway.) Also be more
specific in the documentation's descriptions of these checks. Per a gripe
from Kevin Hunter.
had been taught not to do that ages ago, the SSL code was helpfully bleating
anyway. Resolves some recent reports such as bug #3266; however the
underlying cause of the related bug #2829 is still unclear.
o read global SSL configuration file
o add GUC "ssl_ciphers" to control allowed ciphers
o add libpq environment variable PGSSLKEY to control SSL hardware keys
Victor B. Wagner
input in the stats collector. Our select() emulation is apparently buggy
for UDP sockets :-(. This should resolve problems with stats collection
(and hence autovacuum) failing under more than minimal load. Diagnosis
and patch by Magnus Hagander.
Patch probably needs to be back-ported to 8.1 and 8.0, but first let's
see if it makes the buildfarm happy...
rather than "return expr;" -- the latter style is used in most of the
tree. I kept the parentheses when they were necessary or useful because
the return expression was complex.
comment line where output as too long, and update typedefs for /lib
directory. Also fix case where identifiers were used as variable names
in the backend, but as typedefs in ecpg (favor the backend for
indenting).
Backpatch to 8.1.X.
chdir into PGDATA and subsequently use relative paths instead of absolute
paths to access all files under PGDATA. This seems to give a small
performance improvement, and it should make the system more robust
against naive DBAs doing things like moving a database directory that
has a live postmaster in it. Per recent discussion.
to just around the bare recv() call that gets a command from the client.
The former placement in PostgresMain was unsafe because the intermediate
processing layers (especially SSL) use facilities such as malloc that are
not necessarily re-entrant. Per report from counterstorm.com.
Also performed an initial run through of upgrading our Copyright date to
extend to 2005 ... first run here was very simple ... change everything
where: grep 1996-2004 && the word 'Copyright' ... scanned through the
generated list with 'less' first, and after, to make sure that I only
picked up the right entries ...
* Links with -leay32 and -lssleay32 instead of crypto and ssl. On win32,
"crypto and ssl" is only used for static linking.
* Initializes SSL in the backend and not just in the postmaster. We
cannot pass the SSL context from the postmaster through the parameter
file, because it contains function pointers.
* Split one error check in be-secure.c. Previously we could not tell
which of three calls actually failed. The previous code also returned
incorrect error messages if SSL_accept() failed - that function needs to
use SSL_get_error() on the return value, can't just use the error queue.
* Since the win32 implementation uses non-blocking sockets "behind the
scenes" in order to deliver signals correctly, implements a version of
SSL_accept() that can handle this. Also, add a wait function in case
SSL_read or SSL_write() needs more data.
Magnus Hagander
and send() very well at all; and in any case we can't use retval==0
for EOF due to race conditions. Make the same fixes in the backend as
are required in libpq.
some reading on the subject.
1) PostgreSQL uses ephemeral keying, for its connections (good thing)
2) PostgreSQL doesn't set the cipher list that it allows (bad thing,
fixed)
3) PostgreSQL's renegotiation code wasn't text book correct (could be
bad, fixed)
4) The rate of renegotiating was insanely low (as Tom pointed out, set
to a more reasonable level)
I haven't checked around much to see if there are any other SSL bits
that need some review, but I'm doing some OpenSSL work right now
and'll send patches for improvements along the way (if I find them).
At the very least, the changes in this patch will make security folks
happier for sure. The constant renegotiation of sessions was likely a
boon to systems that had bad entropy gathering means (read: Slowaris
/dev/rand|/dev/urand != ANDIrand). The new limit for renegotiations
is 512MB which should be much more reasonable.
Sean Chittenden
Win32 port is now called 'win32' rather than 'win'
add -lwsock32 on Win32
make gethostname() be only used when kerberos4 is enabled
use /port/getopt.c
new /port/opendir.c routines
disable GUC unix_socket_group on Win32
convert some keywords.c symbols to KEYWORD_P to prevent conflict
create new FCNTL_NONBLOCK macro to turn off socket blocking
create new /include/port.h file that has /port prototypes, move
out of c.h
new /include/port/win32_include dir to hold missing include files
work around ERROR being defined in Win32 includes
typing error in src/backend/libpq/be-secure.c ???
Long Description
In src/backend/libpq/be-secure.c: secure_write
on SSL_ERROR_WANT_WRITE call secure_read instead
secure_write again. May be is this a typing error?
Sergey N. Yatskevich (syatskevich@n21lab.gosniias.msk.ru)
believe I didn't notice this before -- once 64k was sent to/from the
server the client would crash. Basicly, in 7.3 the server SSL code set
the initial state to "about to renegotiate" without actually starting
the renegotiation. In addition, the server and client didn't properly
handle the SSL_ERROR_WANT_(READ|WRITE) error. This is fixed in the
second patch.
Nathan Mueller
first, that I missed when checking over 7.3.1, was that the client
method was switched to SSLv23 along with the server. The SSLv23 client
method does SSLv2 by default, but can also understand SSLv3. In our
situation the SSLv2 backwords compatibility is really only needed on the
server. This is the first patch.
The last thing is that I found a way for the server to understand SSLv2
HELLO messages (sent by pre-7.3 clients) but then get them to talk
SSLv3. This is the last one.
Nathan Mueller
"SSLv23_method(void), SSLv23_server_method(void), SSLv23_client_method(void)
A TLS/SSL connection established with these methods will understand the SSLv2,
SSLv3, and TLSv1 protocol. A client will send out SSLv2 client hello messages
and will indicate that it also understands SSLv3 and TLSv1. A server will
understand SSLv2, SSLv3, and TLSv1 client hello messages. This is the best
choice when compatibility is a concern."
This will maintain backwards compatibility for those us that don't use
TLS connections ...
on the server, if DebugLvl >= 2.
The patch also includes a late addition to the last patch
(X509_check_private_key()). I'm not sure why it the currect
revision wasn't tagged.
Bear Giles
If the user has certificates in $HOME/.postgresql/postgresql.crt
and $HOME/.postgresql/postgresql.key exist, they are provided
to the server. The certificate used to sign this cert must be
known to the server, in $DataDir/root.crt. If successful, the
cert's "common name" is logged.
Client certs are not used for authentication, but they could be
via the port->peer (X509 *), port->peer_dn (char *) or
port->peer_cn (char *) fields. Or any other function could be
used, e.g., many sites like the issuer + serial number hash.
Bear Giles
In order to reduce the risk of cryptanalysis during extended
sessions (or brief ones involving a substantial amount of data),
this patch renegotiates the session key after 64kib has been
transferred.
Bear Giles
As the comment headers in be-secure.c discusses, EPH preserves
confidentiality even if the static private key (which is usually
kept unencrypted) is compromised.
Because of the value of this, common default values are hard-coded
to protect the confidentiality of the data even if an attacker
successfully deletes or modifies the external file.
Bear Giles
Attached are a revised set of SSL patches. Many of these patches
are motivated by security concerns, it's not just bug fixes. The key
differences (from stock 7.2.1) are:
*) almost all code that directly uses the OpenSSL library is in two
new files,
src/interfaces/libpq/fe-ssl.c
src/backend/postmaster/be-ssl.c
in the long run, it would be nice to merge these two files.
*) the legacy code to read and write network data have been
encapsulated into read_SSL() and write_SSL(). These functions
should probably be renamed - they handle both SSL and non-SSL
cases.
the remaining code should eliminate the problems identified
earlier, albeit not very cleanly.
*) both front- and back-ends will send a SSL shutdown via the
new close_SSL() function. This is necessary for sessions to
work properly.
(Sessions are not yet fully supported, but by cleanly closing
the SSL connection instead of just sending a TCP FIN packet
other SSL tools will be much happier.)
*) The client certificate and key are now expected in a subdirectory
of the user's home directory. Specifically,
- the directory .postgresql must be owned by the user, and
allow no access by 'group' or 'other.'
- the file .postgresql/postgresql.crt must be a regular file
owned by the user.
- the file .postgresql/postgresql.key must be a regular file
owned by the user, and allow no access by 'group' or 'other'.
At the current time encrypted private keys are not supported.
There should also be a way to support multiple client certs/keys.
*) the front-end performs minimal validation of the back-end cert.
Self-signed certs are permitted, but the common name *must*
match the hostname used by the front-end. (The cert itself
should always use a fully qualified domain name (FDQN) in its
common name field.)
This means that
psql -h eris db
will fail, but
psql -h eris.example.com db
will succeed. At the current time this must be an exact match;
future patches may support any FQDN that resolves to the address
returned by getpeername(2).
Another common "problem" is expiring certs. For now, it may be
a good idea to use a very-long-lived self-signed cert.
As a compile-time option, the front-end can specify a file
containing valid root certificates, but it is not yet required.
*) the back-end performs minimal validation of the client cert.
It allows self-signed certs. It checks for expiration. It
supports a compile-time option specifying a file containing
valid root certificates.
*) both front- and back-ends default to TLSv1, not SSLv3/SSLv2.
*) both front- and back-ends support DSA keys. DSA keys are
moderately more expensive on startup, but many people consider
them preferable than RSA keys. (E.g., SSH2 prefers DSA keys.)
*) if /dev/urandom exists, both client and server will read 16k
of randomization data from it.
*) the server can read empheral DH parameters from the files
$DataDir/dh512.pem
$DataDir/dh1024.pem
$DataDir/dh2048.pem
$DataDir/dh4096.pem
if none are provided, the server will default to hardcoded
parameter files provided by the OpenSSL project.
Remaining tasks:
*) the select() clauses need to be revisited - the SSL abstraction
layer may need to absorb more of the current code to avoid rare
deadlock conditions. This also touches on a true solution to
the pg_eof() problem.
*) the SIGPIPE signal handler may need to be revisited.
*) support encrypted private keys.
*) sessions are not yet fully supported. (SSL sessions can span
multiple "connections," and allow the client and server to avoid
costly renegotiations.)
*) makecert - a script that creates back-end certs.
*) pgkeygen - a tool that creates front-end certs.
*) the whole protocol issue, SASL, etc.
*) certs are fully validated - valid root certs must be available.
This is a hassle, but it means that you *can* trust the identity
of the server.
*) the client library can handle hardcoded root certificates, to
avoid the need to copy these files.
*) host name of server cert must resolve to IP address, or be a
recognized alias. This is more liberal than the previous
iteration.
*) the number of bytes transferred is tracked, and the session
key is periodically renegotiated.
*) basic cert generation scripts (mkcert.sh, pgkeygen.sh). The
configuration files have reasonable defaults for each type
of use.
Bear Giles
Heikki Linnakangas
Bruce Momjian
Tom Lane
Magnus Hagander
Peter Eisentraut
Neil Conway
PostgreSQL Daemon