If passt or pasta are started as root, we need to read the passwd file (be it /etc/passwd or whatever sssd provides) to find out UID and GID of 'nobody' so that we can switch to it. Instead of a bunch of allow rules for passwd_file_t and sssd macros, use the more convenient auth_read_passwd() interface which should cover our usage of getpwnam(). The existing rules weren't actually enough: # strace -e openat passt -f [...] Started as root, will change to nobody. openat(AT_FDCWD, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 4 openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 4 openat(AT_FDCWD, "/lib64/libnss_sss.so.2", O_RDONLY|O_CLOEXEC) = 4 openat(AT_FDCWD, "/var/lib/sss/mc/passwd", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied) openat(AT_FDCWD, "/var/lib/sss/mc/passwd", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied) openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 4 with corresponding SELinux warnings logged in audit.log. Reported-by: Minxi Hou Analysed-by: Miloš Malik Signed-off-by: Stefano Brivio --- contrib/selinux/passt.te | 5 +---- contrib/selinux/pasta.te | 9 +-------- 2 files changed, 2 insertions(+), 12 deletions(-) diff --git a/contrib/selinux/passt.te b/contrib/selinux/passt.te index 80bf780..c6cea34 100644 --- a/contrib/selinux/passt.te +++ b/contrib/selinux/passt.te @@ -47,8 +47,6 @@ require { type port_t; type http_port_t; - type passwd_file_t; - class netlink_route_socket { bind create nlmsg_read }; type sysctl_net_t; @@ -96,8 +94,7 @@ allow passt_t self:capability { sys_tty_config setpcap net_bind_service setuid s allow passt_t self:cap_userns { setpcap sys_admin sys_ptrace }; allow passt_t self:user_namespace create; -allow passt_t passwd_file_t:file read_file_perms; -sssd_search_lib(passt_t) +auth_read_passwd(passt_t) allow passt_t proc_net_t:file read; allow passt_t net_conf_t:file { open read }; diff --git a/contrib/selinux/pasta.te b/contrib/selinux/pasta.te index 310383c..69be081 100644 --- a/contrib/selinux/pasta.te +++ b/contrib/selinux/pasta.te @@ -68,9 +68,6 @@ require { type system_dbusd_t; type systemd_hostnamed_t; type systemd_systemctl_exec_t; - type passwd_file_t; - type sssd_public_t; - type sssd_var_lib_t; class dbus send_msg; class system module_request; class system status; @@ -115,8 +112,7 @@ allow pasta_t self:capability { setpcap net_bind_service sys_tty_config dac_read allow pasta_t self:cap_userns { setpcap sys_admin sys_ptrace net_admin net_bind_service }; allow pasta_t self:user_namespace create; -allow pasta_t passwd_file_t:file read_file_perms; -sssd_search_lib(pasta_t) +auth_read_passwd(pasta_t) domain_auto_trans(pasta_t, bin_t, unconfined_t); domain_auto_trans(pasta_t, shell_exec_t, unconfined_t); @@ -178,12 +174,9 @@ allow pasta_t init_t:system status; allow pasta_t unconfined_t:dir search; allow pasta_t unconfined_t:file read; allow pasta_t unconfined_t:lnk_file read; -allow pasta_t passwd_file_t:file { getattr open read }; allow pasta_t self:process { setpgid setcap }; allow pasta_t shell_exec_t:file { execute execute_no_trans map }; -allow pasta_t sssd_var_lib_t:dir search; -allow pasta_t sssd_public_t:dir search; allow pasta_t hostname_exec_t:file { execute execute_no_trans getattr open read map }; allow pasta_t system_dbusd_t:unix_stream_socket connectto; allow pasta_t system_dbusd_t:dbus send_msg; -- 2.43.0