Linux 4.16 cap_sys_module

[Dominick Grift]

Since Linux 4.16 (to atleast RC2) user space started to excessively trigger cap_sys_module

Here is one example of such and event:

type=SYSCALL msg=audit(02/27/2018 08:06:40.017:74) : arch=x86_64 syscall=ioctl success=no exit=ENOTTY(Inappropriate ioctl for device) a0=0x2 a1=TCGETS a2=0x7fff2d89f8f0 a3=0x55ba203a9010 items=0 ppid=1 pid=423 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=systemd-user-se exe=/usr/lib/systemd/systemd-user-sessions subj=sys.id:sys.role:user_sessions.subj:s0 key=(null)
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { sys_module } for pid=423 comm=systemd-user-se capability=sys_module scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:user_sessions.subj:s0 tclass=capability permissive=1
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { module_request } for pid=423 comm=systemd-user-se kmod=6E65746465762D80E72A05257F scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:sys.isid:s0 tclass=system permissive=1

Any idea what causes this and how to fix it?

[Dominick Grift]

Post by Dominick Grift
Since Linux 4.16 (to atleast RC2) user space started to excessively trigger cap_sys_module
type=SYSCALL msg=audit(02/27/2018 08:06:40.017:74) : arch=x86_64 syscall=ioctl success=no exit=ENOTTY(Inappropriate ioctl for device) a0=0x2 a1=TCGETS a2=0x7fff2d89f8f0 a3=0x55ba203a9010 items=0 ppid=1 pid=423 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=systemd-user-se exe=/usr/lib/systemd/systemd-user-sessions subj=sys.id:sys.role:user_sessions.subj:s0 key=(null)
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { sys_module } for pid=423 comm=systemd-user-se capability=sys_module scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:user_sessions.subj:s0 tclass=capability permissive=1
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { module_request } for pid=423 comm=systemd-user-se kmod=6E65746465762D80E72A05257F scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:sys.isid:s0 tclass=system permissive=1
Any idea what causes this and how to fix it?

For reference: https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments

Post by Dominick Grift
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Dominick Grift

[Stephen Smalley]

Post by Dominick Grift

Post by Dominick Grift
Since Linux 4.16 (to atleast RC2) user space started to excessively trigger cap_sys_module
type=SYSCALL msg=audit(02/27/2018 08:06:40.017:74) : arch=x86_64 syscall=ioctl success=no exit=ENOTTY(Inappropriate ioctl for device) a0=0x2 a1=TCGETS a2=0x7fff2d89f8f0 a3=0x55ba203a9010 items=0 ppid=1 pid=423 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=systemd-user-se exe=/usr/lib/systemd/systemd-user-sessions subj=sys.id:sys.role:user_sessions.subj:s0 key=(null)
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { sys_module } for pid=423 comm=systemd-user-se capability=sys_module scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:user_sessions.subj:s0 tclass=capability permissive=1
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { module_request } for pid=423 comm=systemd-user-se kmod=6E65746465762D80E72A05257F scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:sys.isid:s0 tclass=system permissive=1
Any idea what causes this and how to fix it?

For reference: https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments

Looks like this might be caused by:

commit 44c02a2c3dc55835e9f0d8ef73966406cd805001
Author: Al Viro <***@zeniv.linux.org.uk>
Date: Thu Oct 5 12:59:44 2017 -0400

dev_ioctl(): move copyin/copyout to callers

Signed-off-by: Al Viro <***@zeniv.linux.org.uk>


It moves the dev_load() call out of the switch statement, which was only
conditionally called in the default case if the cmd had certain values,
and unconditionally calls it. So we trigger module load denials on
simple TCGETS (isatty) probes on a socket. We need it moved back.

[Stephen Smalley]

Post by Stephen Smalley

Post by Dominick Grift

Post by Dominick Grift
Since Linux 4.16 (to atleast RC2) user space started to excessively trigger cap_sys_module
type=SYSCALL msg=audit(02/27/2018 08:06:40.017:74) : arch=x86_64 syscall=ioctl success=no exit=ENOTTY(Inappropriate ioctl for device) a0=0x2 a1=TCGETS a2=0x7fff2d89f8f0 a3=0x55ba203a9010 items=0 ppid=1 pid=423 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=systemd-user-se exe=/usr/lib/systemd/systemd-user-sessions subj=sys.id:sys.role:user_sessions.subj:s0 key=(null)
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { sys_module } for pid=423 comm=systemd-user-se capability=sys_module scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:user_sessions.subj:s0 tclass=capability permissive=1
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { module_request } for pid=423 comm=systemd-user-se kmod=6E65746465762D80E72A05257F scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:sys.isid:s0 tclass=system permissive=1
Any idea what causes this and how to fix it?

For reference: https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments

commit 44c02a2c3dc55835e9f0d8ef73966406cd805001
Date: Thu Oct 5 12:59:44 2017 -0400
dev_ioctl(): move copyin/copyout to callers
It moves the dev_load() call out of the switch statement, which was only
conditionally called in the default case if the cmd had certain values,
and unconditionally calls it. So we trigger module load denials on
simple TCGETS (isatty) probes on a socket. We need it moved back.

(expanded cc list since this affects more than just SELinux)

[Paul Moore]

Post by Stephen Smalley

Post by Stephen Smalley

Post by Dominick Grift

Post by Dominick Grift
Since Linux 4.16 (to atleast RC2) user space started to excessively trigger cap_sys_module
type=SYSCALL msg=audit(02/27/2018 08:06:40.017:74) : arch=x86_64 syscall=ioctl success=no exit=ENOTTY(Inappropriate ioctl for device) a0=0x2 a1=TCGETS a2=0x7fff2d89f8f0 a3=0x55ba203a9010 items=0 ppid=1 pid=423 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=systemd-user-se exe=/usr/lib/systemd/systemd-user-sessions subj=sys.id:sys.role:user_sessions.subj:s0 key=(null)
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { sys_module } for pid=423 comm=systemd-user-se capability=sys_module scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:user_sessions.subj:s0 tclass=capability permissive=1
type=AVC msg=audit(02/27/2018 08:06:40.017:74) : avc: denied { module_request } for pid=423 comm=systemd-user-se kmod=6E65746465762D80E72A05257F scontext=sys.id:sys.role:user_sessions.subj:s0 tcontext=sys.id:sys.role:sys.isid:s0 tclass=system permissive=1
Any idea what causes this and how to fix it?

For reference: https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments

commit 44c02a2c3dc55835e9f0d8ef73966406cd805001
Date: Thu Oct 5 12:59:44 2017 -0400
dev_ioctl(): move copyin/copyout to callers
It moves the dev_load() call out of the switch statement, which was only
conditionally called in the default case if the cmd had certain values,
and unconditionally calls it. So we trigger module load denials on
simple TCGETS (isatty) probes on a socket. We need it moved back.

(expanded cc list since this affects more than just SELinux)

Just in case any of you on the To/CC line missed the patch:

* https://marc.info/?l=linux-netdev&m=152037526927844&w=2