replace the dozen other various hacks in the code that do all sorts
of crude things including spamming the envrionment strings with the new
argv string.
This version is mainly inspired by the sendmail version, with a couple of
ideas taken from the NetBSD implementation as well.
- Fix buffer overflow problem once and for all: do away with the buffer
copies to 'user' prior to calling _scancaches() and just pass a pointer
to the buffer returned by yp_match()/yp_first()/yp_next()/whatever.
(We turn the first ':' to a NUL first so strcmp() works, then change it
back later. Submitted by Bill Fenner <fenner@parc.xerox.com> and
tweaked slightly by me.
- Give _pw_breakout_yp() the 'more elegant solution' I promised way back when.
Eliminate several copies to static buffers and replace them with just
one copy. (The buffer returned by the NIS functions is at most
YPMAXRECORD bytes long, so we should only need one static buffer of
the same length (plus 2 for paranoia's sake).)
- Also in _pw_breakout_yp(): always set pw.pw_passwd to the username
obtained via NIS regardless of what pw_fields says: usernames cannot
be overridden so we have no choice but to use the name returned by
NIS.
- _Again_ in _pw_breakout_yp(): before doing anything else, check that
the first character of the NIS-returned buffer is not a '+' or '-'.
If it is, drop the entry. (#define EXTRA_PARANOIA 1 :)
- Probe for the master.passwd.* maps once during __initdb() instead
of doing it each time _getyppass() or _nextyppass() is called.
- Don't copy the NIS data buffers to static memory in _getyppass()
and _nextyppass(): this is done in _pw_breakout_yp() now.
- Test against phkmalloc and phkmalloc/2 (TNG!) to make sure we're
free()ing the yp buffers sanely.
- Put _havemaster(), _getyppass() and nextyppass() prototypes under
#ifdef YP. (Somehow they ended up on the wrong side of the #endif.)
- Remove unused variable ___yp_only.
- In some cases, we don't properly resolve _all_ possible group memberships.
If a user is a member of both local and NIS groups, we sometimes lose some
of the membership info from NIS. (Reported by: Thorsten Kukuk
<kukuk@uni-paderborn.de>)
- Make NIS +groupname overrides actually work the way the SunOS group(5)
man page says they should (make them work for all cases: getgrent(),
getgrnam() and getgrgid()).
- When not compiled with -DYP, grscan() should ignore entries that
begin with a '+'. When compiled _with_ -DYP, grscan() should ignore
+groupname entries that don't refer to real NIS groups.
- Remove redundant redeclaration of fgets(), strsep() and index() inside
grscan(). We already #include all the right header files for these.
Note: -groupname exclusion as specified in the Sun documentation still
isn't supported. This'll be a 2.2 addition. Right now I just want this
stuff to work.
What was happening, is if syslogd was not running, syslog() would do
a strcat("\r\n") on a non-null-terminated buffer, and write it to the console.
This meant that sometimes extra characters could be written to the console
during boot, depending on the stack contents.
This totally avoids the potential problem by using writev() like the rest
of the does, and avoid modifying the buffer after the trouble we've gone to
to carefully protect it.
This is actually a trivial fix, in spite of the long commit message.. :-)
It only appeared during boot and shutdown with syslogd stopped.
running on a tty. (Same as isatty()) The old-style TIOCGETP ioctl
wouldn't fly if the kernel didn't have COMPAT_43.
Submitted by: Carl Fongheiser <cmf@netins.net>
control hooks.
It is similar to an unrolled multi-part snprintf(), in that a "FILE *" is
attached to a string buffer. There is also an optimisation for the case
where the syslog format string does not contain %m, which should improve
performance of "informational" logging, like from ftpd.
the group map after encountering a badly formatted entry.
getpwent.c: same as above for _nextyppass(), and also turn a couple of
sprintf()s into snprintf()s to avoid potential buffer overruns. (The
other day I nearly went mad because of a username in my NIS database
that's actually 9 characters long instead of 8. Stuffing a 9-character
username into an 8-character buffer can do some strange things.)
(This reminds me: I hope somebody's planning to fix the buffer overrun
security hole in syslog(3) before 2.1 ships.)
seperate function to avoid duplication. Also fix getpwent() a
small bit to properly handle the case where the magic NIS '+'
entry appears before the end of the password file.
getgrent.c: be a little more SunOS-ish. Make it look like the NIS
group map is 'inserted' at the the point(s) where the magic NIS '+'
entry/entries appear.
getgrent: fix a file descriptor leak: remember to close the netgroup
file after we determine that we're using NIS-only innetgr() lookups.
- getnetgrent.c: address some NIS compatibility problems. We really need
to use the netgroup.byuser and netgroup.byhost maps to speed up innetgr()
when using NIS. Also, change the NIS interaction in the following way:
If /etc/netgroup does not exist or is empty (or contains only the
NIS '+' token), we now use NIS exclusively. This lets us use the
'reverse netgroup' maps and is more or less the behavior of other
platforms.
If /etc/netgroup exists and contains local netgroup data (but no '+').
we use only lthe local stuff and ignore NIS.
If /etc/netgroup exists and contains both local data and the '+',
we use the local data nd the netgroup map as a single combined
database (which, unfortunately, can be slow when the netgroup
database is large). This is what we have been doing up until now.
Head off a potential NULL pointer dereference in the old innetgr()
matching code.
Also fix the way the NIS netgroup map is incorporated into things:
adding the '+' is supposed to make it seem as though the netgroup
database is 'inserted' wherever the '+' is placed. We didn't quite
do it that way before.
(The NetBSD people apparently use a real, honest-to-gosh, netgroup.db
database that works just like the password database. This is
actually a neat idea since netgroups is the sort of thing that
can really benefit from having multi-key search capability,
particularly since reverse lookups require more than a trivial
amount of processing. Should we do something like this too?)
- netgroup.5: document all this stuff.
- rcmd.c: some sleuthing with some test programs linked with my own
version of innetgr() has revealed that SunOS always passes the NIS
domain name to innetgr() in the 'domain' argument. We might as well
do the same (if YP is defined).
- ether_addr.c: also fix the NIS interaction so that placing the
'+' token in the /etc/ethers file makes it seem like the NIS
ethers data is 'inserted' at that point. (Chances are nobody will
notice the effect of this change, which is just te way I like it. :)
_gr_breakout_yp(): if we encounter a NULL pointer generated as the
result of a badly formatted NIS passwd entry (e.g. missing fields),
we punt and return an error code, thereby silently skipping the
bad entry.
last night:
_gr_breakout_yp() doesn't check for badly formatted NIS group entries.
For example, a bogus entry like this:
bootp::user1,user2,user3
will lead to a null pointer dereference and a SEGV (note that the GID
field is missing -- this results in one of the strsep(&result, ":")
returning NULL). The symtpom of this problem is programs dumping
core left and right the moment you add a + entry to /etc/group.
Note that while this is similar to an earlier bug, it's caused by a
different set of circumstances.
The fix is to check for the NULL pointers and have _gr_breakout_yp()
punt and return a failure code if it catches one. This is more or
less the behavior of SunOS: if a bad NIS group entry is encountered,
it's silently ignored. I don't think our standard (non-NIS) group
parsing code behaves the same way. It doesn't crash though, so I'm
citing the 'it ain't broken, don't fix it' rule and leaving it alone.
I'll probably have to add similar checks to _pw_breakout_yp() in
getpwent.c to ward off the same problems. It's rare that bad NIS
map entries like this occur, but we should handle them gracefully
when they do.
'cycle in netgroup check too greedy').
PR #508 is apparently due to an inconsistency in the way the 4.4BSD
netgroup code deals with bad netgroups. When 4.4BSD code encounters
a badly formed netgroup entry (e.g. (somehost,-somedomain), which,
because of the missing comma between the '-' and 'somedomain,' has
only 2 fields instead of 3), it generates an error message and
then bails out without doing any more processing on the netgroup
containing the bad entry. Conversely, every other *NIX in the world
that usees netgroups just tries to parse the entry as best it can
and then silently continues on its way.
The result is that two bad things happen: 1) we ignore other valid entries
within the netgroup containing the bogus entry, which prevents
us from interoperating with other systems that don't behave this way,
and 2) by printing an error to stderr from inside libc, we hose certain
programs, in this case rlogind. In the problem report, Bill Fenner
noted that the 'B' from 'Bad' was missing, and that rlogind exited
immediately after generating the error. The missing 'B' is apparently
not caused by any problem in getnetgrent.c; more likely it's getting
swallowed up by rlogind somehow, and the error message itself causes
rlogind to become confused. I was able to duplicate this problem and
discovered that running a simple test program on my FreeBSD system
resulted in a properly formatted (if confusing) error, whereas triggering
the error by trying to rlogin to the machine yielded the missing 'B'
problem.
Anyway, the fixes for this are as follows:
- The error message has been reformatted so that it prints out more useful
information (e.g. Bad entry (somehost,-somedomain) in netgroup "foo").
We check for NULL entries so that we don't print '(null)' anymore too. :)
- Rearranged things in parse_netgrp() so that we make a best guess at
what bad entries are supposed to look like and then continue processing
instead of bailing out.
- Even though the error message has been cleaned up, it's wrapped inside
a #ifdef DEBUG. This way we match the behavior of other systems. Since we
now handle the error condition better anyway, this error message becomes
less important.
PR #507 is another case of inconsistency. The code that handles
duplicate/circular netgroup entries isn't really 'too greedy; -- it's
just too noisy. If you have a netgroup containing duplicate entries,
the code actually does the right thing, but it also generates an error
message. As with the 'Bad netgroup' message, spewing this out from
inside libc can also hose certain programs (like rlogind). Again, no
other system generates an error message in this case.
The only change here is to hide the error message inside an #ifdef DEBUG.
Like the other message, it's largely superfluous since the code handles
the condition correctly.
Note that PR #510 (+@netgroup host matching in /etc/hosts.equiv) is still
being investigated. I haven't been able to duplicate it myself, and I
strongly suspect it to be a configuration problem of some kind. However,
I'm leaving all three PRs open until I get 510 resolved just for the
sake of paranoia.
- If you take the wheel entry out of /etc/group and turn on NIS,
the '+:*::' line is incorrectly flagged as the entry for wheel (the
empty gid section is translated to 0), hence getgrgid() returns '+'
as the name of the group instead of 'wheel.'
- Using just '+:' as the 'turn on NIS' switch in /etc/group makes
getgrgid() dump core because of a null pointer dereference. (Last
time I was in here, I foolishly assumed that fixing the core dump
problems with getgrnam() and getgrent() would fix getgrgid() too.
Silly me.)
- it succeeded on non-directories (see POSIX 5.1.2.4).
- it hung on (non-open) named pipes.
- it leaked memory if the second malloc() failed.
- it didn't preserve errno across errors in close().
of the plus or minus lists at all, reject him. This lets you create
a +@netgroup list of users that you want to admit and reject everybody
else. If you end your +@netgroup list with the wildcard line
(+:::::::::) then you'll have a +@netgroup list that remaps the
specified people but leaves people not in any netgroup unaffected.
add #includes for YP headers when compiling with -DYP to avoid some implicit
declarations.
getgrent.c & getnetgrent.c: add some #includes to avoid implicit declarations
of YP functions.
remapping mechanism in the following manner: if given an entry +@foo
and there is no netgroup named 'foo,' try searching for a regular
user group called 'foo' and build the cache using the members of
group 'foo' instead. If both a netgroup 'foo' and a user group 'foo'
exist, the 'foo' netgroup takes precedence, since we're primarily
interested in netgroup matching anyway.
This allows access control schemes based on ordinary user groups
(which are also available via NIS) rather than netgroups, since
netgroups on some systems are limited in really brain-damaged ways.
my network because setnetgrent() was trying to do a lookup on group "".
It seems that an attempt to do a yp_match() (and possible yp_next())
on a null or empty key causes Sun's ypserv in SunOS 4.1.3 to exit
suddenly (and without warning). Our ypserv behaves badly in this
situation too, thoush it doesn't appear to crash. In any event, getpwent,
getnetgrent and yp_match() and yp_next() are now extra careful not to
accidentally pass on null or empty arguments.
Also made a small change to getpwent.c to allow +::::::::: wildcarding,
which I had disabled previously.
- Have the +@netgroup/-@netgroup caches handle the +user/-user cases too.
- Clean up getpwent() to take advantage of the improved +user/-user handling.
work because parse_netgrp() doesn't recurse properly. Fixed by
changing
if (parse_netgrp(spos))
return(1);
to
if (parse_netgrp(spos))
continue;
inside parse_netgrp(). (Lucky for me I happen to have a fairly complex
'live' netgroup database to test this stuff with.)
- Added support for reading netgroups from NIS/YP in addition to the
local /etc/netgroups file. (Note that SunOS and many other systems only
support reading netgroups via NIS, which is a bit odd.)
- Fix Evil Null Pointer Dereferences From Hell (tm) that caused
parse_netgrp() to SEGV when expanding netgroups that include
references to other netgroups. Funny how nobody else noticed this.
This is the first step in implimenting +@netgroup substitution in
getpwent.c and any other places that could use it and don't already
support it (which is probably everywhere).
by heading off possible null pointer dereferences in grscan(). Also
change getgrnam() slightly to properly handle the change: if grscan()
returns an rval of 1 and leaves a '+' in the gr_name field and YP is
enabled, poll the YP group.byname map before giving up. This should
insure that we make every effort to find a match in the local and
YP group databases before bailing out.
in an (unlikely) border case (maxgroups==1 and the user is on
an /etc/group line for the same group and that group only ...).
Now this case is dealt with as before ...
Add a missing apostrophe that suggests inverting the frequency to get
tick size. It read better before because `CLK_TCK' suggests a tick
size although it is actually a frequency.
as an NIS client. The pw_breakout_yp routines that are used to populate the
_pw_passwd structire only do anything if the bits in the pw_fields member
_pw_passwd are cleared. Unfortunately, we can get into a state where
pw_fields has garbage in it right before the YP lookup functions are
called, which causes the breakout functions to screw up in a big way.
Here's how to duplicate the problem:
- Configure FreeBSD as an NIS client
- Log in as a user who's password database records reside only in
the NIS passwd maps.
- Type ps -aux
Result: your processes appear to be owned by 'root' or 'deamon.'
/bin/ls can exhibit the same problem.
The reason this happens:
- When ps(1) needs to match a username to a UID, it calls getpwuid().
- root is in the local password file, so getpwuid() calls __hashpw()
and __hashpw() populates the _pw_passwd struct, including the pw_fields
member. This happens before NIS lookups take place because, by coincidence,
ps(1) tends to display processes owned by root before it happens upon
a proccess owned by you.
- When your UID comes up, __hashpw() fails to find your entry in the
local password database, so it bails out, BUT THE BITS IN THE pw_fields
STRUCTURE OF _pw_passwd ARE NEVER CLEARED AND STILL CONTAIN INFORMATION
FROM THE PREVIOUS CALL TO __hash_pw()!!
- If we have NIS enabled, the NIS lookup functions are called.
- The pw_breakout_yp routines see that the pw_fields bits are set and
decline to place the data retrieved from the NIS passwd maps into the
_pw_passwd structure.
- getpwuid() returns the results of the last __hashpw() lookup instead
of the valid NIS data.
- Hijinxs ensue when user_from_uid() caches this bogus information and
starts handing out the wrong usernames.
AAAARRRRRRRRRGGGGGGHHHHHHHHHH!!!
*Please* don't tell me I'm the only person to have noticed this.
Fixed by having __hashpw() check the state of pw_fields just before
bailing out on a failed lookup and clearing away any leftover garbage.
What a fun way to spend an afternoon.
- FreeBSD's NIS server can supply a master.passwd map, which has
more fields in it than a standard passwd map, so we need a
_master_pw_breakout() fuction.
- When doing passwd map lookups, look for master.passwd.* by attempting
a _yp_first() on master.passwd.byname. If it exists, we're being served
by a FreeBSD NIS server and we should use this map.
- If we aren't the superuser, retrieve only the standard passwd maps.
If we're being served by a FreeBSD system, then the passwd map has
no passwords in it, and it won't serve us the master.passwd map unless
we're superuser anyway.
There's a small speed hit for the superuser inherent in the check for
the master.passwd map, but this lets us dynamically decide what to do
rather than rely on a non-standard config file somewhere. Since all
of this is bypassed for normal users, they shouldn't notice the
difference.
YP by disallowing `+' entries as logins in all cases. (This handles the
case of a `+' entry in the password file but YP not running, which should
never happen but is easy enough to check for so we'll apply some
prophylaxis.)
getcwd() has two off-by-one bugs in FreeBSD-2.0:
1. getcwd(buf, size) fails when the size is just large enough.
2. getcwd(buf + 1, 1) incorrectly succeeds when the current directory
is "/". buf[0] and buf[2] are clobbered.
(I modified Bruce's original patch to return the proper error code
[ERANGE] in the case of #2, but otherwise... -DG)
This program demonstrates the bug:
---
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
int main(void)
{
char buf[5];
int errors;
errors = 0;
if (chdir("/tmp") != 0) {
perror("chdir");
abort();
}
if (getcwd(buf, 5) == NULL) {
perror("oops, getcwd failed for buffer size = size required");
++errors;
}
if (chdir("/") != 0) {
perror("chdir");
abort();
}
buf[0] = 0;
buf[2] = 1;
if (getcwd(buf + 1, 1) != NULL) {
fprintf(stderr,
"oops, getcwd succeeded for buffer size = one too small\n");
++errors;
}
if (buf[0] != 0) {
fprintf(stderr,
"oops, getcwd scribbled on memory before start of buffer\n");
++errors;
}
if (buf[2] != 1) {
fprintf(stderr,
"oops, getcwd scribbled on memory after end of buffer\n");
++errors;
}
exit(errors == 0 ? 0 : 1);
}
pointer returned by realloc(). All callers free the pointer if the
execve fails. Nuke the caching. This essentially restores buildargv()
to the 1.1.5 version. Also fix a memory leak if realloc() fails. Also
nuke similar but non-broken caching in execvp(). malloc() should be
efficient enough.
later be applied to a number of programs (inetd for instance) to clean
out the bogus code doing the same thing, modulus all the bugs.
If you need to read a '#'-is-a-comment-file, please use these routines.
I realize that the shlib# should be bumped (for the non-US world:
increased by something), but will defer this until something significant
happens.
!!!!!!!!
NB
!!!!!!!!
You MUST pwd_mkdb /etc/master.passwd before attempting to use the new
libc, or things may go wrong. (I doubt anything actually /will/ go
wrong, but the actual behavior is undefined. YOU HAVE BEEN WARNED.)
The database format is, however, backwards-compatible, so old executables
will still work.
are running under. Here's how to bootstrap (order is important):
1) Re-compile gcc (just the driver is all you need).
2) Re-compile libc.
3) Re-compile your kernel. Reboot.
4) cd /usr/src/include; make install
You can now detect the compilation environment with the following code:
#if !defined(__FreeBSD__)
#define __FreeBSD_version 199401
#elif __FreeBSD__ == 1
#define __FreeBSD_version 199405
#else
#include <osreldate.h>
#endif
You can determine the run-time environment by calling the new C library
function getosreldate(), or by examining the MIB variable kern.osreldate.
For the time being, the release date is defined as 199409, which we have
already established as our target.
