On 03/23/2018 05:40 AM, Paul Howarth wrote: > On Thu, 22 Mar 2018 13:04:28 -0400 > Stephen Smalley <sds@xxxxxxxxxxxxx> wrote: > >> On 03/22/2018 07:55 AM, Paul Howarth wrote: >>> I've seen a few reports that proftpd's sftp support isn't working >>> with SELinux in enforcing mode: >>> >>> https://bugzilla.redhat.com/show_bug.cgi?id=1529576 >>> https://github.com/proftpd/proftpd/issues/659 >>> >>> Using strace, it appears that proftpd is rejecting logins after >>> failing to access /etc/shadow, but why would it be doing that at >>> all, rather than using the unix_chkpwd helper? >>> >>> Googling this, the only similar issue I saw was this: >>> http://blog.siphos.be/2014/12/why-does-it-access-etcshadow/ >>> but this seems to be different because ftpd policy does include >>> auth_use_pam. >>> >>> Any thoughts on this? I did try this locally and couldn't reproduce >>> it, so it seems to be configuration/environment-specific rather than >>> something being fundamentally wrong. >> >> Is it possible that proftpd is running in a chroot environment with a >> read-only or non-exisitent selinuxfs mount, faking libselinux into >> believing that SELinux is disabled (and thus pam doesn't bother >> trying to run unix_chkpwd when it runs with uid 0)? > > Not sure about the vagrant example in github, but the example from > bz.redhat.com is a regular install, and the reporter says he says the > same behaviour on both machines he's tried. > > The strace logs from bz.redhat.com don't contain the string "selinux"; > shouldn't there be an access to something under /sys/fs/selinux to > check if SELinux is enabled? Yes, anything that links with libselinux will probe for that, e.g. $ strace ls |& grep selinux openat(AT_FDCWD, "/lib64/libselinux.so.1", O_RDONLY|O_CLOEXEC) = 3 statfs("/sys/fs/selinux", {f_type=SELINUX_MAGIC, f_bsize=4096, f_blocks=0, f_bfree=0, f_bavail=0, f_files=0, f_ffree=0, f_fsid={val=[0, 0]}, f_namelen=255, f_frsize=4096, f_flags=ST_VALID|ST_RELATIME}) = 0 statfs("/sys/fs/selinux", {f_type=SELINUX_MAGIC, f_bsize=4096, f_blocks=0, f_bfree=0, f_bavail=0, f_files=0, f_ffree=0, f_fsid={val=[0, 0]}, f_namelen=255, f_frsize=4096, f_flags=ST_VALID|ST_RELATIME}) = 0 access("/etc/selinux/config", F_OK) = 0 _______________________________________________ selinux mailing list -- selinux@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to selinux-leave@xxxxxxxxxxxxxxxxxxxxxxx
