Bug 866714

Also in dhcp-4.2.4-16.P2.fc17.x86_64.

This bug is a duplicate of Bug #837474.

(In reply to comment #2)
> This bug is a duplicate of Bug #837474.

Well, that bug was closed without the real fix.

Yes and as I already mentioned twice in that bug report, I've had no idea how to better fix this.

dhcpd first starts as root, then writes (as root:root) leases file and then it de-roots itself. After that it finally runs as user:group set with -user and -group parameters.

When I had changed the sequence and had made dhcpd write leases file after de-rooting itself (so the leases file had correct ownership) it resulted in bug #765967 which was quite a serious problem.

This is a duplicate of bug #837474 indeed, but we can leave it open until we have some better solution.

OK, I'll have a look at the source. No promises though...

Great. I actually already have one idea.

From time to time dhcpd makes (server/db.c::new_lease_file() I think) a backup leases~ file and creates new leases file (this time with correct user:group being dhcpd:dhcpd).
If we could do this directly after the de-rooting (server/dhcpd.c line 816) then the time of leases file having wrong ownership would be minimal.

I'm thinking, maybe db_startup() needs to get set_uid and set_gid arguments, pass them to new_lease_file() which then fchown()'s after open()?

The snippet below is junk, but you'll get what I mean:
--------------------------------
diff -ruN dhcp-4.2.4-P2-vanilla/server/db.c dhcp-4.2.4-P2/server/db.c
--- dhcp-4.2.4-P2-vanilla/server/db.c	2012-08-28 12:13:03.000000000 +1000
+++ dhcp-4.2.4-P2/server/db.c	2012-10-16 21:49:26.036638351 +1100
@@ -36,6 +36,11 @@
 #include <ctype.h>
 #include <errno.h>
 
+#if defined (PARANOIA)
+#  include <sys/types.h>
+#  include <unistd.h>
+#endif /* PARANOIA */
+
 #define LEASE_REWRITE_PERIOD 3600
 
 static isc_result_t write_binding_scope(FILE *db_file, struct binding *bnd,
@@ -1027,8 +1032,11 @@
 	return (1);
 }
 
-void db_startup (testp)
-	int testp;
+#if defined (PARANOIA)
+void db_startup (int testp, uid_t set_user, gid_t set_group)
+#else
+void db_startup (int testp)
+#endif /* PARANOIA */
 {
 	isc_result_t status;
 
@@ -1052,7 +1060,11 @@
 	   append it, so we create one immediately (maybe this isn't
 	   the best solution... */
 	if (trace_playback ()) {
+#if defined (PARANOIA)
+		new_lease_file (set_uid, set_gid);
+#else
 		new_lease_file ();
+#endif /* PARANOIA */
 	}
 #endif
 	if (!testp) {
@@ -1066,7 +1078,11 @@
 		else
 #endif
 			time(&write_time);
+#if defined (PARANOIA)
+		new_lease_file (set_uid, set_gid);
+#else
 		new_lease_file ();
+#endif /* PARANOIA */
 	}
 
 #if defined(REPORT_HASH_PERFORMANCE)
@@ -1080,7 +1096,11 @@
 #endif
 }
 
+#if defined (PARANOIA)
+int new_lease_file (uid_t set_uid, gid_t set_gid)
+#else
 int new_lease_file ()
+#endif /* PARANOIA */
 {
 	char newfname [512];
 	char backfname [512];
@@ -1109,6 +1129,14 @@
 		log_error ("Can't create new lease file: %m");
 		return 0;
 	}
+#if defined (PARANOIA)
+	if (fchown(db_fd, set_uid, set_gid)) {
+		log_fatal ("Can't chown new lease file: %m");
+		close(db_fd);
+		goto fdfail;
+	}
+#endif /* PARANOIA */
+
 	if ((new_db_file = fdopen(db_fd, "w")) == NULL) {
 		log_error("Can't fdopen new lease file: %m");
 		close(db_fd);
--------------------------------

The function new_lease_file() gets called quite a bit, so all invocations would have to have all that changed, including the functions that calls that call new_lease_file() etc. I didn't even bother compiling this - just tossing ideas around...

Yes, that's even better, great.
Can you test this scratch-build ?
http://koji.fedoraproject.org/koji/taskinfo?taskID=4595257

You need to 'setenforce 0', because we need to tweak selinux-policy - I'll fill a bug.

(In reply to comment #9)
> Yes, that's even better, great.
> Can you test this scratch-build ?
> http://koji.fedoraproject.org/koji/taskinfo?taskID=4595257
> 
> You need to 'setenforce 0', because we need to tweak selinux-policy - I'll
> fill a bug.

Hmm, missing dependencies:
--------------------
# yum --nogpgcheck --enablerepo=updates-testing localinstall dhcp-4.2.4-17.P2.fc17.x86_64.rpm dhcp-libs-4.2.4-17.P2.fc17.x86_64.rpm dhcp-common-4.2.4-17.P2.fc17.x86_64.rpm 
Loaded plugins: fastestmirror, langpacks, presto, refresh-packagekit
Examining dhcp-4.2.4-17.P2.fc17.x86_64.rpm: 12:dhcp-4.2.4-17.P2.fc17.x86_64
Marking dhcp-4.2.4-17.P2.fc17.x86_64.rpm as an update to 12:dhcp-4.2.4-16.P2.fc17.x86_64
Examining dhcp-libs-4.2.4-17.P2.fc17.x86_64.rpm: 12:dhcp-libs-4.2.4-17.P2.fc17.x86_64
Marking dhcp-libs-4.2.4-17.P2.fc17.x86_64.rpm as an update to 12:dhcp-libs-4.2.4-16.P2.fc17.x86_64
Examining dhcp-common-4.2.4-17.P2.fc17.x86_64.rpm: 12:dhcp-common-4.2.4-17.P2.fc17.x86_64
Marking dhcp-common-4.2.4-17.P2.fc17.x86_64.rpm as an update to 12:dhcp-common-4.2.4-16.P2.fc17.x86_64
Resolving Dependencies
--> Running transaction check
---> Package dhcp.x86_64 12:4.2.4-16.P2.fc17 will be updated
---> Package dhcp.x86_64 12:4.2.4-17.P2.fc17 will be an update
--> Processing Dependency: libdns-export.so.93()(64bit) for package: 12:dhcp-4.2.4-17.P2.fc17.x86_64
Loading mirror speeds from cached hostfile
 * fedora: mirror.optus.net
 * updates: mirror.optus.net
 * updates-testing: mirror.optus.net
--> Processing Dependency: libisc-export.so.90()(64bit) for package: 12:dhcp-4.2.4-17.P2.fc17.x86_64
---> Package dhcp-common.x86_64 12:4.2.4-16.P2.fc17 will be updated
--> Processing Dependency: dhcp-common = 12:4.2.4-16.P2.fc17 for package: 12:dhclient-4.2.4-16.P2.fc17.x86_64
---> Package dhcp-common.x86_64 12:4.2.4-17.P2.fc17 will be an update
---> Package dhcp-libs.x86_64 12:4.2.4-16.P2.fc17 will be updated
--> Processing Dependency: dhcp-libs(x86-64) = 12:4.2.4-16.P2.fc17 for package: 12:dhclient-4.2.4-16.P2.fc17.x86_64
---> Package dhcp-libs.x86_64 12:4.2.4-17.P2.fc17 will be an update
--> Finished Dependency Resolution
Error: Package: 12:dhcp-4.2.4-17.P2.fc17.x86_64 (/dhcp-4.2.4-17.P2.fc17.x86_64)
           Requires: libdns-export.so.93()(64bit)
           Available: 32:bind-libs-lite-9.9.0-4.fc17.x86_64 (InstallMedia)
               libdns-export.so.93()(64bit)
           Available: 32:bind-libs-lite-9.9.1-9.P3.fc17.x86_64 (updates)
               libdns-export.so.93()(64bit)
           Installed: 32:bind-libs-lite-9.9.2-2.fc17.x86_64 (@updates-testing)
               Not found
Error: Package: 12:dhclient-4.2.4-16.P2.fc17.x86_64 (@updates-testing)
           Requires: dhcp-common = 12:4.2.4-16.P2.fc17
           Removing: 12:dhcp-common-4.2.4-16.P2.fc17.x86_64 (@updates-testing)
               dhcp-common = 12:4.2.4-16.P2.fc17
           Updated By: 12:dhcp-common-4.2.4-17.P2.fc17.x86_64 (/dhcp-common-4.2.4-17.P2.fc17.x86_64)
               dhcp-common = 12:4.2.4-17.P2.fc17
           Available: 12:dhcp-common-4.2.4-0.4.rc1.fc17.x86_64 (InstallMedia)
               dhcp-common = 12:4.2.4-0.4.rc1.fc17
           Available: 12:dhcp-common-4.2.4-13.P2.fc17.x86_64 (updates)
               dhcp-common = 12:4.2.4-13.P2.fc17
Error: Package: 12:dhcp-4.2.4-17.P2.fc17.x86_64 (/dhcp-4.2.4-17.P2.fc17.x86_64)
           Requires: libisc-export.so.90()(64bit)
           Available: 32:bind-libs-lite-9.9.0-4.fc17.x86_64 (InstallMedia)
               libisc-export.so.90()(64bit)
           Available: 32:bind-libs-lite-9.9.1-9.P3.fc17.x86_64 (updates)
               libisc-export.so.90()(64bit)
           Installed: 32:bind-libs-lite-9.9.2-2.fc17.x86_64 (@updates-testing)
               Not found
Error: Package: 12:dhclient-4.2.4-16.P2.fc17.x86_64 (@updates-testing)
           Requires: dhcp-libs(x86-64) = 12:4.2.4-16.P2.fc17
           Removing: 12:dhcp-libs-4.2.4-16.P2.fc17.x86_64 (@updates-testing)
               dhcp-libs(x86-64) = 12:4.2.4-16.P2.fc17
           Updated By: 12:dhcp-libs-4.2.4-17.P2.fc17.x86_64 (/dhcp-libs-4.2.4-17.P2.fc17.x86_64)
               dhcp-libs(x86-64) = 12:4.2.4-17.P2.fc17
           Available: 12:dhcp-libs-4.2.4-0.4.rc1.fc17.x86_64 (InstallMedia)
               dhcp-libs(x86-64) = 12:4.2.4-0.4.rc1.fc17
           Available: 12:dhcp-libs-4.2.4-13.P2.fc17.x86_64 (updates)
               dhcp-libs(x86-64) = 12:4.2.4-13.P2.fc17
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest
--------------------

I see this:
--------------------
# rpm -q --provides bind-libs-lite
bind-libbind-devel = 31:9.3.3-4.fc7
libdns-export.so.95()(64bit)  
libirs-export.so.90()(64bit)  
libisc-export.so.92()(64bit)  
libisccfg-export.so.90()(64bit)  
bind-libs-lite = 32:9.9.2-2.fc17
bind-libs-lite(x86-64) = 32:9.9.2-2.fc17
--------------------

Did you build this against some other version of bind?

Ah, I see what's going on - this was built against current stable bind.

Yep, I can confirm that after using the RPMs from the scratch build, the leases file indeed stays owned by dhcpd:dhcpd.

This is the SELinux policy requirement:
-------------------
require {
	type dhcpd_t;
	class capability chown;
}

#============= dhcpd_t ==============
allow dhcpd_t self:capability chown;
-------------------

Could you place an official build in F-17 testing repo? Give it super high karma requirement, if you wish, so it cannot be pushed into stable by accident.

In most cases karma comes from people having only dhclient installed so I usually can't rely on somebody testing dhcpd. But I'll do it (if Miroslav changes the selinux-policy for F17) because you provided the original idea & patch ;-)

I am encountering this issue, and I am happy to test any fix and give karma to it if it works and doesn't seem to cause any other issues.

dhcp-4.2.4-23.P2.fc18 has been submitted as an update for Fedora 18.
https://admin.fedoraproject.org/updates/dhcp-4.2.4-23.P2.fc18

Package dhcp-4.2.4-23.P2.fc18:
* should fix your issue,
* was pushed to the Fedora 18 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing dhcp-4.2.4-23.P2.fc18'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2012-19436/dhcp-4.2.4-23.P2.fc18
then log in and leave karma (feedback).

dhcp-4.2.4-23.P2.fc18 has been pushed to the Fedora 18 stable repository.  If problems still persist, please make note of it in this bug report.