[PATCH] selinux: Fix all those pesky denials breaking my computer

[PATCH] selinux: Fix all those pesky denials breaking my computer

[Sultan Alsawaf]

From: Sultan Alsawaf <sultan@kerneltoast.com>

I'm sure many of you have found yourself in a position where you've
tried to increase the security of your system by enabling SELinux, only
to discover that nothing worked anymore because of those darned 'denial'
messages. It's clearly an overlooked bug in SELinux!

With a bit of investigation, I discovered that the avc_denied() function
would erroneously return a non-zero value when I saw those denial
messages. After slapping in a `return 0;` at the top of that function,
all was well and my machine with SELinux enforcing was working again!

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
---
 security/selinux/avc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index d18cb32a242a..b29f19471871 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -1010,6 +1010,7 @@ static noinline int avc_denied(struct selinux_state *state,
 			       u8 driver, u8 xperm, unsigned int flags,
 			       struct av_decision *avd)
 {
+	return 0;
 	if (flags & AVC_STRICT)
 		return -EACCES;
 
-- 
2.26.0

Re: [PATCH] selinux: Fix all those pesky denials breaking my computer

[Paul Moore]

On Wed, Apr 1, 2020 at 2:09 PM Sultan Alsawaf <sultan@kerneltoast.com> wrote:
> From: Sultan Alsawaf <sultan@kerneltoast.com>
>
> I'm sure many of you have found yourself in a position where you've
> tried to increase the security of your system by enabling SELinux, only
> to discover that nothing worked anymore because of those darned 'denial'
> messages. It's clearly an overlooked bug in SELinux!
>
> With a bit of investigation, I discovered that the avc_denied() function
> would erroneously return a non-zero value when I saw those denial
> messages. After slapping in a `return 0;` at the top of that function,
> all was well and my machine with SELinux enforcing was working again!
>
> Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
> ---
>  security/selinux/avc.c | 1 +
>  1 file changed, 1 insertion(+)

This is clearly an April Fools joke, but still.  No.

> diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> index d18cb32a242a..b29f19471871 100644
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -1010,6 +1010,7 @@ static noinline int avc_denied(struct selinux_state *state,
>                                u8 driver, u8 xperm, unsigned int flags,
>                                struct av_decision *avd)
>  {
> +       return 0;
>         if (flags & AVC_STRICT)
>                 return -EACCES;
>
> --
> 2.26.0

-- 
paul moore
www.paul-moore.com