Re: Linux 4.16 cap_sys_module

[Paul Moore]

On Wed, Feb 28, 2018 at 9:18 AM, Stephen Smalley  wrote:
> On 02/28/2018 08:53 AM, Stephen Smalley wrote:
>> On 02/28/2018 04:53 AM, Dominick Grift wrote:
>>> On Wed, Feb 28, 2018 at 10:27:08AM +0100, Dominick Grift wrote:
 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?
>>>
>>> For reference: 
>>> https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments
>>
>> Looks like this might be caused by:
>>
>> commit 44c02a2c3dc55835e9f0d8ef73966406cd805001
>> Author: Al Viro 
>> Date:   Thu Oct 5 12:59:44 2017 -0400
>>
>> dev_ioctl(): move copyin/copyout to callers
>>
>> Signed-off-by: Al Viro 
>>
>>
>> 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=152037526927844=2

-- 
paul moore
www.paul-moore.com

Re: Linux 4.16 cap_sys_module

[Stephen Smalley]

On 02/28/2018 08:53 AM, Stephen Smalley wrote:
> On 02/28/2018 04:53 AM, Dominick Grift wrote:
>> On Wed, Feb 28, 2018 at 10:27:08AM +0100, Dominick Grift wrote:
>>> 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?
>>
>> For reference: 
>> https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments
> 
> Looks like this might be caused by:
> 
> commit 44c02a2c3dc55835e9f0d8ef73966406cd805001
> Author: Al Viro 
> Date:   Thu Oct 5 12:59:44 2017 -0400
> 
> dev_ioctl(): move copyin/copyout to callers
> 
> Signed-off-by: Al Viro 
> 
> 
> 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)

Re: Linux 4.16 cap_sys_module

[Stephen Smalley]

On 02/28/2018 04:53 AM, Dominick Grift wrote:
> On Wed, Feb 28, 2018 at 10:27:08AM +0100, Dominick Grift wrote:
>> 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?
> 
> For reference: 
> https://github.com/fedora-selinux/selinux-policy/commit/2c13be1fb543c51935785e7a43b798a9f35f5aa0#comments

Looks like this might be caused by:

commit 44c02a2c3dc55835e9f0d8ef73966406cd805001
Author: Al Viro 
Date:   Thu Oct 5 12:59:44 2017 -0400

dev_ioctl(): move copyin/copyout to callers

Signed-off-by: Al Viro 


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.

Re: Linux 4.16 cap_sys_module

[Dominick Grift]

On Wed, Feb 28, 2018 at 10:27:08AM +0100, Dominick Grift wrote:
> 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?

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

> 
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> Dominick Grift



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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?

-- 
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Dominick Grift


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