Daniel J Walsh wrote:
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Manuel Wolfshant wrote:
Daniel J Walsh wrote:
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Manuel Wolfshant wrote:
hello
I have migrated a working mailserver from Centos 4.7 to Centos 5.2.
The system uses postfix to receive messages from a mail relay and is
supposed to deliver them to folders named after the users, following
the /home/firstname.lastname@domain template. Authentication is done via
mysql against a db running on another system.
New accounts are created automatically when a mail has to be
delivered to an user which has never been seen before.
For the users which existed before migration, everything is fine.
However, for non-existing (i.e. to be created) users the homedir is
created with wrong contexts, which prohibit postfix to finalize the
delivery. Once a message is received for a new user, the following is
created:
[root@imap2 ~]# ll -Zl /home/gigi.test\@nobugconsulting.ro/ -R
/home/gigi.test@xxxxxxxxxxxxxxxxxx/: total
8 drwx------ 2
root:object_r:home_root_t postfix postfix 4096 Feb 17 01:05 tmp
/home/gigi.test@xxxxxxxxxxxxxxxxxx/tmp:
total 4 -rw------- 1
root:object_r:home_root_t postfix postfix 0 Feb 17 01:05
1234825528.P26797.imap2
After that postfix tries to do stuff on the newly created file and
selinux kicks in and denies access.
Running restorecon at this point fixes things:
[root@imap2 ~]# restorecon -v -R
/home/gigi.test@xxxxxxxxxxxxxxxxxx
restorecon reset /home/gigi.test@xxxxxxxxxxxxxxxxxx context
root:object_r:home_root_t:s0->user_u:object_r:user_home_dir_t:s0
restorecon reset /home/gigi.test@xxxxxxxxxxxxxxxxxx/tmp context
root:object_r:home_root_t:s0->user_u:object_r:user_home_t:s0
restorecon reset
/home/gigi.test@xxxxxxxxxxxxxxxxxx/tmp/1234825528.P26797.imap2 context
root:object_r:home_root_t:s0->user_u:object_r:user_home_t:s0
I am running the following versions of packages:
[root@imap2 ~]# rpm -qa kernel\* \*selinux\* postfix\*
kernel-xen-2.6.18-92.1.22.el5
libselinux-utils-1.33.4-5.1.el5
selinux-policy-targeted-2.4.6-203.el5
libselinux-1.33.4-5.1.el5
libselinux-python-1.33.4-5.1.el5
selinux-policy-2.4.6-203.el5
postfix-2.3.3-2.1.centos.mysql_pgsql
Selinux related packages have been upgraded last night in the hope to
fix the problem, postfix is almost stock centosplus 5.2, recompiled with
support for mysql but without postgresql- support.
Obviously I no not want to follow the result of audit2allow,
home_root_t:dir should not be there in the first place:
[root@imap2 ~]# grep avc /var/log/audit/audit.log|audit2allow
#============= postfix_virtual_t ==============
allow postfix_virtual_t home_root_t:dir { write remove_name create
add_name };
allow postfix_virtual_t home_root_t:file { write create unlink link
getattr };
allow postfix_virtual_t postfix_private_t:dir search;
allow postfix_virtual_t postfix_private_t:sock_file write;
allow postfix_virtual_t usr_t:file { read getattr };
Correct access rights and contexts seem to be:
[root@imap2 ~]# ls -l /home/ -dZ
drwxr-xr-x+ postfix postfix system_u:object_r:home_root_t /home/
[root@imap2 ~]# ls -l /home/gigi.test\@nobugconsulting.ro/ -dZ
drwx------ postfix postfix user_u:object_r:user_home_dir_t
/home/gigi.test@xxxxxxxxxxxxxxxxxx/
The only user on the system (beside root) is postfix:
[root@imap2 ~]# getent passwd postfix
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
raw content of audit log after a failed delivery for a never-seen
before user:
type=AVC msg=audit(1234873447.682:45616): avc: denied { write } for
pid=2958 comm="virtual"
path="/home/gigi.test@xxxxxxxxxxxxxxxxxx/tmp/1234873447.P2958.imap2"
dev=hda1 ino=2736137 scontext=root:system_r:postfix_virtual_t:s0
tcontext=root:object_r:home_root_t:s0 tclass=file
type=SYSCALL msg=audit(1234873447.682:45616): arch=c000003e syscall=1
success=no exit=-13 a0=c a1=2b96176fe510 a2=1b5 a3=7228206f722e676e
items=0 ppid=26787 pid=2958 auid=0 uid=0 gid=0 euid=89 suid=0 fsuid=89
egid=89 sgid=0 fsgid=89 tty=(none) ses=7290 comm="virtual"
exe="/usr/libexec/postfix/virtual"
subj=root:system_r:postfix_virtual_t:s0 key=(null)
type=AVC msg=audit(1234873447.710:45617): avc: denied { write } for
pid=2958 comm="virtual" name="1234873447.P2958.imap2" dev=hda1
ino=2736137 scontext=root:system_r:postfix_virtual_t:s0
tcontext=root:object_r:home_root_t:s0 tclass=file
type=SYSCALL msg=audit(1234873447.710:45617): arch=c000003e syscall=77
success=no exit=-13 a0=c a1=0 a2=2 a3=0 items=0 ppid=26787 pid=2958
auid=0 uid=0 gid=0 euid=89 suid=0 fsuid=89 egid=89 sgid=0 fsgid=89
tty=(none) ses=7290 comm="virtual" exe="/usr/libexec/postfix/virtual"
subj=root:system_r:postfix_virtual_t:s0 key=(null)
type=AVC msg=audit(1234873447.710:45618): avc: denied { remove_name }
for pid=2958 comm="virtual" name="1234873447.P2958.imap2"
dev=hda1ino=2736137 scontext=root:system_r:postfix_virtual_t:s0
tcontext=root:object_r:home_root_t:s0 tclass=dir
type=SYSCALL msg=audit(1234873447.710:45618): arch=c000003e syscall=87
success=no exit=-13 a0=2b96176fdb80 a1=64 a2=4 a3=2b95fb0340ec items=0
ppid=26787 pid=2958 auid=0 uid=0 gid=0 euid=89 suid=0 fsuid=89 egid=89
sgid=0 fsgid=89 tty=(none) ses=7290 comm="virtual"
exe="/usr/libexec/postfix/virtual"
subj=root:system_r:postfix_virtual_t:s0 key=(null)
My questions are
a) why does postfix create the initial home directories with a wrong
context ? Note this only happens for NEW users, messages for the users
which already existed [and have correct context] on the old system are
perfectly fine.
Does postfix actually create the homedir or was the homedir created by
an init script? postfix does not know anything about SELinux but there
are rules about processes running as postfix_t creating files in
user_home_dir_t directories. In your case it seems that the directory
was labeled home_root_t, which is where the problem is.
/home exists; everything below it is created (and should be created
with correct contexts) by postfix in real time
Why is postfix creating a homedir?
Because that's where all the virtual users have their mails.
I have never seen this before.
That is where the problem is, selinux policy does not allow postfix to
create directories under /home (home_root_t), so it is being blocked.
I am sorry, I do not remember from which site was the setup taken. 4
years or so since I installed it the first time in Centos 4.2, but if I
am not mistaken it's an almost exact replica of the setup suggested by
postfixadmin
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