Bug#702448: nfs-common: UID's do not get properly mapped
Package: nfs-common
Version: 1:1.2.6-3
Severity: grave
Tags: security
Justification: user security hole
Dear Maintainers,
I've recetly set up an NFSv4 server and I found that ID mapping does
always work as expected, allowing a user to read files they should not
have access to (and preventing them to access files they should have
access to). To demonstrate, I have set up a test NFS client and server
pair, both running wheezy. I've created users test1 and test2 in
/etc/passwd, but with swapped UID's:
SERVER
----------------------------------------
test1:x:5000:5000::/home/test1:/bin/bash
test2:x:5001:5001::/home/test2:/bin/bash
----------------------------------------
CLIENT
----------------------------------------
test2:x:5000:5000::/home/test2:/bin/bash
test1:x:5001:5001::/home/test1:/bin/bash
----------------------------------------
On the server, I have /srv/nfs exported; the output of "exportfs -a" is:
----------------------------------------
/srv/nfs <world>
----------------------------------------
To demonstrate the problem, I've crafted a script, which does the following:
* creates a file on the client as user test1 (a);
* created two files on the server, one as user test1 (b), one as user
test2 (c);
* runs "ls -l" on the files, both on the server and the client, to check
the ownerships/permissions reported;
* tries to read the files, both as user test1 and test2, both on the
server and the client.
What I've found is that
* the file created on the client by user1 (a) shows up owned by user2
both on the server and the client --> BUG
* the files created on the server (b and c) appear as expected both on
the client and the server --> OK
* on the client, user1
- can open the file created by user1 on the client (a) --> OK
- cannot open the file created by user1 on the server (b) --> BUG
- can open the file created by user2 on the server (c) --> SECURITY
* on the client, user2
- cannot open the file created by user1 on client (a) --> OK
- can open the file created by user1 on the server (b) --> SECURITY
- cannot open the file created by user2 on the server (c) --> BUG
* on the server, user1
- cannot open the file created by user1 on client (a) --> BUG
- can open the file created by user1 on the server (b) --> OK
- cannot open the file created by user2 on the server (c) --> OK
* on the server, user2
- can open the file created by user1 on client (a) --> SECURITY
- cannot open the file created by user1 on the server (b) --> OK
- cannot open the file created by user2 on the server (c) --> OK
The transscript and the debug output of rpc.idmapd on both the server
and the client is attached.
While my understanding of ID mapping is limited, I found it strange
that according to the debug log, nfs4_name_to_uid doesn't get called on
the client for user1 when creating the file.
The transcript is the following:
(NB: the script started on the client, and before it started, nfs-common
was stopped on both client and server, there were no nfs mounts on the
client, and the test directory was empty)
----------------------------------------
# date
Wed Mar 6 17:15:57 CET 2013
# SRV=192.168.56.102
# /etc/init.d/nfs-common start
Starting NFS common utilities: statd idmapd.
rpc.idmapd: libnfsidmap: using domain: localdomain
rpc.idmapd: libnfsidmap: Realms list: 'LOCALDOMAIN'
rpc.idmapd: libnfsidmap: loaded plugin /lib/i386-linux-gnu/libnfsidmap/nsswitch.so for method nsswitch
# ssh $SRV /etc/init.d/nfs-common start
Starting NFS common utilities: statd idmapd.
rpc.idmapd: libnfsidmap: using domain: localdomain
rpc.idmapd: libnfsidmap: Realms list: 'LOCALDOMAIN'
rpc.idmapd: libnfsidmap: loaded plugin /lib/i386-linux-gnu/libnfsidmap/nsswitch.so for method nsswitch
# mount $SRV:/ /mnt; mount -t nfs,nfs4
192.168.56.102:/ on /mnt type nfs4 (rw,relatime,vers=4,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=192.168.56.101,minorversion=0,local_lock=none,addr=192.168.56.102)
# sudo -u test1 sh -c "touch /mnt/srv/nfs/test/a; chmod 600 /mnt/srv/nfs/test/a"
# ssh $SRV sudo -u test1 "touch /srv/nfs/test/b; chmod 600 /srv/nfs/test/b"
# ssh $SRV sudo -u test2 "touch /srv/nfs/test/c; chmod 600 /srv/nfs/test/c"
# sleep 3; date
Wed Mar 6 17:16:01 CET 2013
# ls --full-time /mnt/srv/nfs/test
total 0
-rw------- 1 test2 test2 0 2013-03-06 17:15:58.000000000 +0100 a
-rw------- 1 test1 test1 0 2013-03-06 17:15:58.000000000 +0100 b
-rw------- 1 test2 test2 0 2013-03-06 17:15:58.000000000 +0100 c
# ssh $SRV ls --full-time /srv/nfs/test
total 0
-rw------- 1 test2 test2 0 2013-03-06 17:15:58.000000000 +0100 a
-rw------- 1 test1 test1 0 2013-03-06 17:15:58.000000000 +0100 b
-rw------- 1 test2 test2 0 2013-03-06 17:15:58.000000000 +0100 c
# sudo -u test1 cat /mnt/srv/nfs/test/*
cat: /mnt/srv/nfs/test/b: Permission denied
# sudo -u test2 cat /mnt/srv/nfs/test/*
cat: /mnt/srv/nfs/test/a: Permission denied
cat: /mnt/srv/nfs/test/c: Permission denied
# ssh $SRV sudo -u test1 cat /srv/nfs/test/*
cat: /srv/nfs/test/a: Permission denied
cat: /srv/nfs/test/c: Permission denied
# ssh $SRV sudo -u test2 cat /srv/nfs/test/*
cat: /srv/nfs/test/b: Permission denied
----------------------------------------
The log on the client shows the following:
----------------------------------------
Mar 6 17:15:57 adeb rpc.idmapd[11306]: libnfsidmap: using domain: localdomain
Mar 6 17:15:57 adeb rpc.idmapd[11306]: libnfsidmap: Realms list: 'LOCALDOMAIN'
Mar 6 17:15:57 adeb rpc.idmapd[11306]: libnfsidmap: loaded plugin /lib/i386-linux-gnu/libnfsidmap/nsswitch.so for method nsswitch
Mar 6 17:15:57 adeb rpc.idmapd[11307]: Expiration time is 600 seconds.
Mar 6 17:15:57 adeb rpc.idmapd[11307]: Opened /proc/net/rpc/nfs4.nametoid/channel
Mar 6 17:15:57 adeb rpc.idmapd[11307]: Opened /proc/net/rpc/nfs4.idtoname/channel
Mar 6 17:15:58 adeb rpc.idmapd[11307]: New client: 65
Mar 6 17:15:58 adeb rpc.idmapd[11307]: Opened /var/lib/nfs/rpc_pipefs/nfs/clnt65/idmap
Mar 6 17:15:58 adeb rpc.idmapd[11307]: New client: 66
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_uid: calling nsswitch->name_to_uid
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nss_getpwnam: name 'root@localdomain' domain 'localdomain': resulting localname 'root'
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_uid: nsswitch->name_to_uid returned 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_uid: final return value is 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: Client 65: (user) name "root@localdomain" -> id "0"
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_gid: calling nsswitch->name_to_gid
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_gid: nsswitch->name_to_gid returned 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_gid: final return value is 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: Client 65: (group) name "root@localdomain" -> id "0"
Mar 6 17:15:58 adeb rpc.idmapd[11307]: New client: 67
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_uid: calling nsswitch->name_to_uid
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nss_getpwnam: name 'test2@localdomain' domain 'localdomain': resulting localname 'test2'
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_uid: nsswitch->name_to_uid returned 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_uid: final return value is 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: Client 65: (user) name "test2@localdomain" -> id "5000"
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_gid: calling nsswitch->name_to_gid
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_gid: nsswitch->name_to_gid returned 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: nfs4_name_to_gid: final return value is 0
Mar 6 17:15:58 adeb rpc.idmapd[11307]: Client 65: (group) name "test2@localdomain" -> id "5000"
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nfs4_name_to_uid: calling nsswitch->name_to_uid
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nss_getpwnam: name 'test1@localdomain' domain 'localdomain': resulting localname 'test1'
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nfs4_name_to_uid: nsswitch->name_to_uid returned 0
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nfs4_name_to_uid: final return value is 0
Mar 6 17:16:01 adeb rpc.idmapd[11307]: Client 65: (user) name "test1@localdomain" -> id "5001"
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nfs4_name_to_gid: calling nsswitch->name_to_gid
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nfs4_name_to_gid: nsswitch->name_to_gid returned 0
Mar 6 17:16:01 adeb rpc.idmapd[11307]: nfs4_name_to_gid: final return value is 0
Mar 6 17:16:01 adeb rpc.idmapd[11307]: Client 65: (group) name "test1@localdomain" -> id "5001"
----------------------------------------
The log on the server is as follows:
----------------------------------------
Mar 6 17:15:58 adeb-srv rpc.idmapd[31323]: libnfsidmap: using domain: localdomain
Mar 6 17:15:58 adeb-srv rpc.idmapd[31323]: libnfsidmap: Realms list: 'LOCALDOMAIN'
Mar 6 17:15:58 adeb-srv rpc.idmapd[31323]: libnfsidmap: loaded plugin /lib/i386-linux-gnu/libnfsidmap/nsswitch.so for method nsswitch
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Expiration time is 600 seconds.
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Opened /proc/net/rpc/nfs4.nametoid/channel
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Opened /proc/net/rpc/nfs4.idtoname/channel
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfsdcb: authbuf=* authtype=user
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: calling nsswitch->uid_to_name
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: nsswitch->uid_to_name returned 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: final return value is 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Server : (user) id "0" -> name "root@localdomain"
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfsdcb: authbuf=* authtype=group
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: calling nsswitch->gid_to_name
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: nsswitch->gid_to_name returned 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: final return value is 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Server : (group) id "0" -> name "root@localdomain"
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfsdcb: authbuf=* authtype=user
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: calling nsswitch->uid_to_name
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: nsswitch->uid_to_name returned 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: final return value is 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Server : (user) id "5001" -> name "test2@localdomain"
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfsdcb: authbuf=* authtype=group
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: calling nsswitch->gid_to_name
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: nsswitch->gid_to_name returned 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: final return value is 0
Mar 6 17:15:58 adeb-srv rpc.idmapd[31324]: Server : (group) id "5001" -> name "test2@localdomain"
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfsdcb: authbuf=* authtype=user
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: calling nsswitch->uid_to_name
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: nsswitch->uid_to_name returned 0
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfs4_uid_to_name: final return value is 0
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: Server : (user) id "5000" -> name "test1@localdomain"
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfsdcb: authbuf=* authtype=group
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: calling nsswitch->gid_to_name
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: nsswitch->gid_to_name returned 0
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: nfs4_gid_to_name: final return value is 0
Mar 6 17:16:01 adeb-srv rpc.idmapd[31324]: Server : (group) id "5000" -> name "test1@localdomain"
----------------------------------------
-- Package-specific info (client):
-- rpcinfo --
program vers proto port service
100000 4 tcp 111 portmapper
100000 3 tcp 111 portmapper
100000 2 tcp 111 portmapper
100000 4 udp 111 portmapper
100000 3 udp 111 portmapper
100000 2 udp 111 portmapper
100024 1 udp 54629 status
100024 1 tcp 53767 status
-- /etc/default/nfs-common --
NEED_STATD=
STATDOPTS=
NEED_IDMAPD=
NEED_GSSD=
-- /etc/idmapd.conf --
[General]
Verbosity = 5
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = localdomain
[Mapping]
Nobody-User = nobody
Nobody-Group = nogroup
-- /etc/fstab --
-- System Information (client):
Debian Release: 7.0
APT prefers testing-updates
APT policy: (500, 'testing-updates'), (500, 'testing')
Architecture: i386 (i686)
Kernel: Linux 3.2.0-4-686-pae (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages nfs-common depends on:
ii adduser 3.113+nmu3
ii initscripts 2.88dsf-41
ii libc6 2.13-38
ii libcap2 1:2.22-1.2
ii libcomerr2 1.42.5-1
ii libdevmapper1.02.1 2:1.02.74-6
ii libevent-2.0-5 2.0.19-stable-3
ii libgssglue1 0.4-2
ii libk5crypto3 1.10.1+dfsg-4
ii libkeyutils1 1.5.5-3
ii libkrb5-3 1.10.1+dfsg-4
ii libmount1 2.20.1-5.3
ii libnfsidmap2 0.25-4
ii libtirpc1 0.2.2-5
ii libwrap0 7.6.q-24
ii lsb-base 4.1+Debian8
ii rpcbind 0.2.0-8
ii ucf 3.0025+nmu3
Versions of packages nfs-common recommends:
ii python 2.7.3-4
Versions of packages nfs-common suggests:
pn open-iscsi <none>
pn watchdog <none>
-- Package-specific info (server):
-- rpcinfo --
program vers proto port service
100000 4 tcp 111 portmapper
100000 3 tcp 111 portmapper
100000 2 tcp 111 portmapper
100000 4 udp 111 portmapper
100000 3 udp 111 portmapper
100000 2 udp 111 portmapper
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100227 2 tcp 2049
100227 3 tcp 2049
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100227 2 udp 2049
100227 3 udp 2049
100021 1 udp 46234 nlockmgr
100021 3 udp 46234 nlockmgr
100021 4 udp 46234 nlockmgr
100021 1 tcp 33838 nlockmgr
100021 3 tcp 33838 nlockmgr
100021 4 tcp 33838 nlockmgr
100005 1 udp 34897 mountd
100005 1 tcp 44933 mountd
100005 2 udp 36170 mountd
100005 2 tcp 43139 mountd
100005 3 udp 48328 mountd
100005 3 tcp 39413 mountd
100024 1 udp 42556 status
100024 1 tcp 45143 status
-- /etc/default/nfs-common --
NEED_STATD=
STATDOPTS=
NEED_IDMAPD=
NEED_GSSD=
-- /etc/idmapd.conf --
[General]
Verbosity = 5
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = localdomain
[Mapping]
Nobody-User = nobody
Nobody-Group = nogroup
-- System Information (server):
Debian Release: 7.0
APT prefers testing-updates
APT policy: (500, 'testing-updates'), (500, 'testing')
Architecture: i386 (i686)
Kernel: Linux 3.2.0-4-686-pae (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages nfs-common depends on:
ii adduser 3.113+nmu3
ii initscripts 2.88dsf-41
ii libc6 2.13-38
ii libcap2 1:2.22-1.2
ii libcomerr2 1.42.5-1
ii libdevmapper1.02.1 2:1.02.74-6
ii libevent-2.0-5 2.0.19-stable-3
ii libgssglue1 0.4-2
ii libk5crypto3 1.10.1+dfsg-4
ii libkeyutils1 1.5.5-3
ii libkrb5-3 1.10.1+dfsg-4
ii libmount1 2.20.1-5.3
ii libnfsidmap2 0.25-4
ii libtirpc1 0.2.2-5
ii libwrap0 7.6.q-24
ii lsb-base 4.1+Debian8
ii rpcbind 0.2.0-8
ii ucf 3.0025+nmu3
Versions of packages nfs-common recommends:
ii python 2.7.3-4
Versions of packages nfs-common suggests:
pn open-iscsi <none>
pn watchdog <none>
Versions of packages nfs-kernel-server depends on:
ii libblkid1 2.20.1-5.3
ii libc6 2.13-38
ii libtirpc1 0.2.2-5
ii libwrap0 7.6.q-24
ii lsb-base 4.1+Debian8
ii ucf 3.0025+nmu3
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