__nss_database_lookup2's extra arguments were left unused in the
nsswitch reloading patch set; this broke compat (default config
ignored) and shadow files (secondary name ignored) which relies on
these fallbacks.
This patch adds in the previous behavior by correcting the
initialization of the database list to reflect the fallbacks. This
means that the nss_database_lookup2 interface no longer needs to be
passed the fallback info, so API and callers were adjusted.
Since all callers needed to be edited anyway, the calls were changed
from __nss_database_lookup2 to the faster __nss_database_get. This
was an intended optimization which was deferred during the initial
lookup changes to avoid touching so many files.
The test case verifies that compat targets work (passwd) and that the
default configuration works (group). Tested on x86-64.
The glibc 2.33 release enabled /etc/nsswitch.conf reloading,
and to prevent potential security issues like CVE-2019-14271
the re-loading of nsswitch.conf and all mdoules was disabled
when the root filesystem changes (see bug 27077).
Unfortunately php-lpfm and openldap both require the ability
to continue to load NSS modules after chroot. The packages
do not exec after the chroot, and so do not cause the
protections to be reset. The only solution is to re-enable
only NSS module loading (not nsswitch.conf reloading) and so
get back the previous glibc behaviour.
In the future we may introduce a way to harden applications
so they do not reload NSS modules once the root filesystem
changes, or that only files/dns are available pre-loaded
(or builtin).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Before the change nss_database_check_reload_and_get() did not populate
the '*result' value when it returned success in a case of chroot
detection. This caused initgroups() to use garage pointer in the
following test (extracted from unbound):
```
int main() {
// load some NSS modules
struct passwd * pw = getpwnam("root");
chdir("/tmp");
chroot("/tmp");
chdir("/");
// access nsswitch.conf in a chroot
initgroups("root", 0);
}
```
Reviewed-by: DJ Delorie <dj@redhat.com>
https://sourceware.org/bugzilla/show_bug.cgi?id=27077
Before reloading nsswitch.conf, verify that the root directory
hasn't changed - if it has, it's likely that we've entered a
container and should not trust the nsswitch inside the container
nor load any shared objects therein.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
Some internal functions need to know if a database has a nonzero
list of actions; success getting the database does not guarantee
that. Add checks for such as needed.
Skip the ":" in each nsswitch.conf line so as not to add a dummy
action libnss_:.so
See also https://bugzilla.redhat.com/show_bug.cgi?id=1906066
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Starting with recent commits, I get 43 conform/.../linknamespace FAILs:
- nss: Introduce <nss_module.h>
- <nss_action.h>: New abstraction for combining NSS modules and NSS actions
- nss: Implement <nss_database.h> (see nss/nss_database.c)
- nsswitch: use new internal API (core)
- nsswitch: user new internal API (tests)
- nsswitch: use new internal API (callers)
e.g. conform/XPG42/wordexp.h/linknamespace.out
[initial] wordexp -> [libc.a(wordexp.o)] __getpwnam_r -> [libc.a(getpwnam_r.o)] __nss_database_custom -> [libc.a(nsswitch.o)] __nss_database_get -> [libc.a(nss_database.o)] feof_unlocked
[initial] wordexp -> [libc.a(wordexp.o)] __getpwnam_r -> [libc.a(getpwnam_r.o)] __nss_database_custom -> [libc.a(nsswitch.o)] __nss_database_get -> [libc.a(nss_database.o)] ferror_unlocked
This patch is just using __ferror_unlocked and __feof_unlocked instead of the
non "__" prefixed ones.
Reviewed-by: DJ Delorie <dj@redhat.com>
This code manages the mappings of the available databases in NSS
(i.e. passwd, hosts, netgroup, etc) with the actions that should
be taken to do a query on those databases.
This is the main API between query functions scattered throughout
glibc and the underlying code (actions, modules, etc).
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
