** Description changed: - As reported in https://discourse.ubuntu.com/t/private-home-directories- - for-ubuntu-21-04-onwards/19533/13: + [Impact] A common situation is to have a central set of users (e.g. in LDAP) and use pam_mkhomedir.so to create the home directory when the user first logs in. These changes do not cover this situation. The default configuration of pam_mkhomedir.so will result in a home directory created with 0755 permissions. To make pam_mkhomedir.so create a home directory by default with permissions consistent with the other tools then a umask argument can be added to the pam_mkhomedir.so module in the file /usr/share/pam- configs/mkhomedir. I believe this would have to be done before enabling the module. The file is part of the libpam-modules package. + + [Test plan] + + 1. Test with current defaults and confirm the permission is 0755 for home directory. + # enable pam_mkhomedir.so configuration + pam-auth-update --enable mkhomedir + # create a user with adduser that creates the home directory + adduser --disabled-password --gecos adduser homemadebyadduser + # create a user with useradd that creates the home directory + useradd --create-home homemadebyuseradd + # create a user with useradd that does *not* create the home directory so that pam_mkhomedir.so can create it + useradd --no-create-home homemadebymkhomedir + # trigger pam_mkhomedir.so to create the home directory + su - homemadebymkhomedir -c exit + # verify the permissions are 0755 for the one created by pam and 0750 for the one by adduser' + root@ubuntu:~# ls -al /home + + 2. Install the package with the fix + # enable mkhomedir again + pam-auth-update --enable mkhomedir + # create a user with useradd that does *not* create the home directory so that pam_mkhomedir.so can create it + useradd --no-create-home homemadebymkhomedirpatch + # trigger pam_mkhomedir.so to create the home directory + su - homemadebymkhomedirpatch -c exit + # verify that the home dir created by pam has 0750 as well + + [ Where problems could occur ] + + This could result in inconsistent permissions between existing home directories created by pam (before the fix) and the ones created with this fix. While there's no reason to believe it could result in any actual issues, this can + be mitigated by changing the existing home directories to have 0750 for consistency. + + Anyone in the 'others' group will lose access to the home directories of the + rest of the users whose $HOME was created by pam. That behaviour should be + treated as unexpected as that's how $HOME adduser will behave. In general, + one's not expected to have access to $HOME of others. + + In the absolute pathological cases, where it's desired to give to $HOME to + everyone, the permissions can be adjusted manually. But this should be + treated as 'workaround' and non-standard behaviour. + + [other info] + + This has been at https://discourse.ubuntu.com/t/private-home- + directories-for-ubuntu-21-04-onwards/19533/13: + + And agreed that (1) having $HOME consistent across tools is the right + behaviour and (2) 0750 is the desired permission for $HOME. + + This has been merged into Plucky already: + https://git.launchpad.net/ubuntu/+source/pam/commit/?id=c576b5c19abb383ce53dfc10a986d7cf164eaeaf
** Tags added: sts ** Description changed: [Impact] A common situation is to have a central set of users (e.g. in LDAP) and use pam_mkhomedir.so to create the home directory when the user first logs in. These changes do not cover this situation. The default configuration of pam_mkhomedir.so will result in a home directory created with 0755 permissions. To make pam_mkhomedir.so create a home directory by default with permissions consistent with the other tools then a umask argument can be added to the pam_mkhomedir.so module in the file /usr/share/pam- configs/mkhomedir. I believe this would have to be done before enabling the module. The file is part of the libpam-modules package. [Test plan] 1. Test with current defaults and confirm the permission is 0755 for home directory. # enable pam_mkhomedir.so configuration pam-auth-update --enable mkhomedir # create a user with adduser that creates the home directory adduser --disabled-password --gecos adduser homemadebyadduser # create a user with useradd that creates the home directory useradd --create-home homemadebyuseradd # create a user with useradd that does *not* create the home directory so that pam_mkhomedir.so can create it useradd --no-create-home homemadebymkhomedir # trigger pam_mkhomedir.so to create the home directory su - homemadebymkhomedir -c exit - # verify the permissions are 0755 for the one created by pam and 0750 for the one by adduser' + # verify the permissions are 0755 for the one created by pam and 0750 for the one by adduser' root@ubuntu:~# ls -al /home 2. Install the package with the fix # enable mkhomedir again pam-auth-update --enable mkhomedir # create a user with useradd that does *not* create the home directory so that pam_mkhomedir.so can create it useradd --no-create-home homemadebymkhomedirpatch # trigger pam_mkhomedir.so to create the home directory su - homemadebymkhomedirpatch -c exit # verify that the home dir created by pam has 0750 as well [ Where problems could occur ] This could result in inconsistent permissions between existing home directories created by pam (before the fix) and the ones created with this fix. While there's no reason to believe it could result in any actual issues, this can be mitigated by changing the existing home directories to have 0750 for consistency. - Anyone in the 'others' group will lose access to the home directories of the + Anyone in the 'others' group will lose access to the home directories of the rest of the users whose $HOME was created by pam. That behaviour should be treated as unexpected as that's how $HOME adduser will behave. In general, one's not expected to have access to $HOME of others. In the absolute pathological cases, where it's desired to give to $HOME to - everyone, the permissions can be adjusted manually. But this should be - treated as 'workaround' and non-standard behaviour. + everyone, the permissions can be adjusted manually and the umask can be changed + in the conf file on those systems. But this should be treated as 'workaround' and non-standard behaviour. [other info] This has been at https://discourse.ubuntu.com/t/private-home- directories-for-ubuntu-21-04-onwards/19533/13: And agreed that (1) having $HOME consistent across tools is the right behaviour and (2) 0750 is the desired permission for $HOME. This has been merged into Plucky already: https://git.launchpad.net/ubuntu/+source/pam/commit/?id=c576b5c19abb383ce53dfc10a986d7cf164eaeaf -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1957024 Title: pam-mkhomedir does not honor private home directories To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pam/+bug/1957024/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
