The implementation for NETLINK_FIREWALL and NETLINK_IP6_FW protocols
was removed from the kernel in commit
d16cf20e2f2f13411eece7f7fb72c17d141c4a84 ("netfilter: remove ip_queue
support") circa Linux 3.5. Consequently, kernels >= 3.5 should never
perform permission checks on these classes although they remained
defined in the SELinux kernel classmap until the netlink classes
were updated by
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6c6d2e9bde1c1c87a7ead806f8f5e2181d41a652
circa Linux v4.2.
Removing these class definitions would break legacy userspace that relies
upon stable values for the userspace security class definitions since it
will perturb those values by removing classes that preceded them. dbus-daemon
in particular is known to break if its dbus class changes at runtime,
which could occur upon a policy reload that removes these classes.
Fixing this requires ensuring that dbus-daemon looks up the appropriate
class value on each use or upon policy reload, via userspace interfaces
such as selinux_check_access(), string_to_security_class(), and/or
selinux_set_callback(SELINUX_CB_POLICYLOAD, ...) with a callback function
that remaps the class value if needed. Other userspace policy enforcers
are believed to have been updated in recent versions but older versions
may break upon such a change.
Hence, this change renames these classes with obsolete_ prefixes and
removes all rules referencing them from refpolicy, thereby preserving
the class numbering for subsequent classes while making it clear that
these classses are no longer meaningful for modern kernels.
This change does however create a potential compatibility break for
kernels < 3.5, since the policy will cease to define the kernel class
names and therefore the kernel will handle permission checks on the
class based on the handle_unknown setting in policy. For most
Linux distributions, this will default to allow and therefore avoid
breaking userspace but will fail open. For kernels < 2.6.33 (i.e.
the dynamic class/perm discovery support), the presence of a class
in policy with the same number but a different name than the kernel
class will cause the policy load to fail entirely.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
entrypoint and execute_no_trans permissions are only ever checked by the
kernel to regular files. They were added to the chr_file class when
execmod was added (which can be checked on chr_file) to ensure that it
was assigned the same value as for the file class, since the kernel code
always checked FILE__EXECMOD. However, the policy definitions are not
necessary since the kernel and policy values have been decoupled ever
since dynamic class/perm support was introduced and further with the
move of execmod to the common definitions, they were not even needed
in the kernel.
These were removed from the kernel's classmap by
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b424485abe2b16580a178b469917a7b6ee0c152a
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Remove unused permission definitions from SELinux.
Many of these were only ever used in pre-mainline
versions of SELinux, prior to Linux 2.6.0. Some of them
were used in the legacy network or compat_net=1 checks
that were disabled by default in Linux 2.6.18 and
fully removed in Linux 2.6.30.
The corresponding classmap declarations were removed from the
mainline kernel in:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=42a9699a9fa179c0054ea3cf5ad3cc67104a6162
Permissions never used in mainline Linux:
file swapon
filesystem transition
tcp_socket { connectto newconn acceptfrom }
node enforce_dest
unix_stream_socket { newconn acceptfrom }
Legacy network checks, removed in 2.6.30:
socket { recv_msg send_msg }
node { tcp_recv tcp_send udp_recv udp_send rawip_recv rawip_send dccp_recv dccp_send }
netif { tcp_recv tcp_send udp_recv udp_send rawip_recv rawip_send dccp_recv dccp_send }
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
When provisioning a Debian test virtual machine with VirtualBox (using
the main Vagrantfile), vagrant runs commands dhclient and ip from a ssh
session because of this directive:
debian.vm.network "private_network", type: "dhcp"
This triggers:
type=AVC msg=audit(1578749426.820:68): avc: denied { write } for
pid=541 comm="dhclient" path="pipe:[14006]" dev="pipefs" ino=14006
scontext=unconfined_u:unconfined_r:dhcpc_t
tcontext=system_u:system_r:sshd_t tclass=fifo_file permissive=1
type=PROCTITLE msg=audit(1578749426.820:68):
proctitle=2F7362696E2F6468636C69656E74002D34002D76002D69002D72002D
7066002F72756E2F6468636C69656E742E657468312E706964002D6C66002F7661
722F6C69622F646863702F6468636C69656E742E657468312E6C6561736573002D
49002D6466002F7661722F6C69622F646863702F6468636C69656E74362E657468
31
type=AVC msg=audit(1578749427.868:69): avc: denied { read } for
pid=544 comm="ip" path="pipe:[14005]" dev="pipefs" ino=14005
scontext=unconfined_u:unconfined_r:ifconfig_t
tcontext=system_u:system_r:sshd_t tclass=fifo_file permissive=1
type=AVC msg=audit(1578749427.868:69): avc: denied { write } for
pid=544 comm="ip" path="pipe:[14006]" dev="pipefs" ino=14006
scontext=unconfined_u:unconfined_r:ifconfig_t
tcontext=system_u:system_r:sshd_t tclass=fifo_file permissive=1
type=PROCTITLE msg=audit(1578749427.868:69):
proctitle=6970002D34006164647200666C757368006465760065746831006C61
62656C0065746831
Handle this by adding attribute vagrant_provisioning_cmd_type to the
relevant domains, in the policy module specific to the Vagrant test
environments.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Since commit 210b64f10a ("Remove shell automatic domain transitions to
unconfined_t from various pam login programs"), setting ssh_sysadm_login
is mandatory in order to allow vagrant user to use SSH while using
unconfined_u or sysadm_u.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
As adding attribute fixed_disk_raw_read to a type cannot occur in a
conditional statement, create a new interface that takes a tunable as
parameter to allow a dangerous access conditionally.
Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
When using libvirt to manage virtual machines, libvirt_leaseshelper
wants to:
* read /etc/libnl/classid
* list the content of /sys/devices/system/node/ in order to read files
such as /sys/devices/system/node/node0/meminfo
* use getsched
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Since systemd 244, systemd can parse EFI variable
SystemdOptions-8cf2644b-4b0b-428f-9387-6d876050dc67 like /proc/cmdline
in order to find options. systemd's NEWS file [1] states:
systemd will also read configuration options from the EFI variable
SystemdOptions. This may be used to configure systemd behaviour when
modifying the kernel command line is inconvenient, but configuration
on disk is read too late, for example for the options related to
cgroup hierarchy setup. 'bootctl systemd-efi-options' may be used to
set the EFI variable.
In practice, all callers of log_parse_environment() read this EFI
variable, because:
* log_parse_environment() is a macro which is expanded to
log_parse_environment_realm(LOG_REALM) [2].
* log_parse_environment_realm() calls proc_cmdline_parse() when being
use in system daemons [3].
* proc_cmdline_parse() always calls systemd_efi_options_variable() [4].
* systemd_efi_options_variable() reads SystemdOptions variable [5].
For SELinux, this means that every domain with attribute
systemd_log_parse_env_type wants to read an EFI variable. Allow this
access.
[1] https://github.com/systemd/systemd/blob/v244/NEWS#L18-L23
[2] https://github.com/systemd/systemd/blob/v244/src/basic/log.h#L84
[3] https://github.com/systemd/systemd/blob/v244/src/basic/log.c#L1116
[4] https://github.com/systemd/systemd/blob/v244/src/basic/proc-cmdline.c#L122
[5] https://github.com/systemd/systemd/blob/v244/src/basic/efivars.c#L242
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
dirmngr needs to listen and accept on /run/user/1000/gnupg/S.dirmngr
type=AVC msg=audit(1554175286.968:2720907): avc: denied { accept } for pid=15692 comm="dirmngr" path="/run/user/1000/gnupg/S.dirmngr" scontext=staff_u:staff_r:dirmngr_t:s0-s0:c0.c1023 tcontext=staff_u:staff_r:dirmngr_t:s0-s0:c0.c1023 tclass=unix_stream_socket permissive=0
Signed-off-by: Jason Zaman <jason@perfinion.com>
When using Vagrant to run virtual machines with SELinux enabled, several
specific accesses need to be allowed. It does not make much sense to add
the needed rules to the refpolicy, as they are very specific to the use
of Vagrant to provision a virtual machine to test a policy. Therefore,
create a dedicated module to allow the required accesses.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
CryFS (https://www.cryfs.org/) is a software that can be run by non-root
users that have access to /dev/fuse. Its command is directly used to
mount a directory ("/usr/bin/cryfs basedir mountpoint"), like command
"mount". Unmounting a mountpoint is done with "fusermount -u
mountpoint", /usr/bin/fusermount being a setuid-root program labeled
mount_exec_t.
EncFS (https://www.arg0.net/encfs) is a similar software that has been
considered insecure since a security audit in 2014 found vulnerabilities
that are not yet fixed (like https://github.com/vgough/encfs/issues/9).
gocryptfs (https://nuetzlich.net/gocryptfs/) is a similar software that
has been inspired by EncFS.
Allow users with role sysadm to use all these projects.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
