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From: Michael Ellerman <mpe@ellerman.id.au>
To: Ingo Molnar <mingo@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
	Hugh Dickins <hughd@google.com>, Kees Cook <keescook@google.com>,
	linux-mm <linux-mm@kvack.org>,
	michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at,
	richard.fellner@student.tugraz.at
Subject: Re: [PATCH] vfs: Add PERM_* symbolic helpers for common file mode/permissions
Date: Wed, 29 Nov 2017 19:52:56 +1100	[thread overview]
Message-ID: <87tvxda2l3.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20171128111214.42esi4igzgnldsx5@gmail.com>

Ingo Molnar <mingo@kernel.org> writes:
...
> Index: tip/include/linux/stat.h
> ===================================================================
> --- tip.orig/include/linux/stat.h
> +++ tip/include/linux/stat.h
> @@ -6,6 +6,34 @@
>  #include <asm/stat.h>
>  #include <uapi/linux/stat.h>
>  
> +/*
> + * Human readable symbolic definitions for common
> + * file permissions:
> + */
> +#define PERM_r________	0400
> +#define PERM_r__r_____	0440
> +#define PERM_r__r__r__	0444
> +
> +#define PERM_rw_______	0600
> +#define PERM_rw_r_____	0640
> +#define PERM_rw_r__r__	0644
> +#define PERM_rw_rw_r__	0664
> +#define PERM_rw_rw_rw_	0666
> +
> +#define PERM__w_______	0200
> +#define PERM__w__w____	0220
> +#define PERM__w__w__w_	0222
> +
> +#define PERM_r_x______	0500
> +#define PERM_r_xr_x___	0550
> +#define PERM_r_xr_xr_x	0555
> +
> +#define PERM_rwx______	0700
> +#define PERM_rwxr_x___	0750
> +#define PERM_rwxr_xr_x	0755
> +#define PERM_rwxrwxr_x	0775
> +#define PERM_rwxrwxrwx	0777

I see what you're trying to do with all the explicit underscores, but it
does make them look kinda ugly.

What if you just used underscores to separate the user/group/other, and
the unset permission bits are just omitted.

Then the two most common cases would be:

  PERM_rw_r_r
  PERM_r_r_r

Both of those read nicely I think. ie. the first is "perm read write,
read, read".

Full set would be:

#define PERM_r			0400
#define PERM_r_r		0440
#define PERM_r_r_r		0444

#define PERM_rw			0600
#define PERM_rw_r		0640
#define PERM_rw_r_r		0644
#define PERM_rw_rw_r		0664
#define PERM_rw_rw_rw		0666

#define PERM_w			0200
#define PERM_w_w		0220
#define PERM_w_w_w		0222

#define PERM_rx			0500
#define PERM_rx_rx		0550
#define PERM_rx_rx_rx		0555

#define PERM_rwx		0700
#define PERM_rwx_rx		0750
#define PERM_rwx_rx_rx		0755
#define PERM_rwx_rwx_rx		0775
#define PERM_rwx_rwx_rwx	0777


cheers

WARNING: multiple messages have this Message-ID
From: Michael Ellerman <mpe@ellerman.id.au>
To: Ingo Molnar <mingo@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
	Hugh Dickins <hughd@google.com>, Kees Cook <keescook@google.com>,
	linux-mm <linux-mm@kvack.org>,
	michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at,
	richard.fellner@student.tugraz.at
Subject: Re: [PATCH] vfs: Add PERM_* symbolic helpers for common file mode/permissions
Date: Wed, 29 Nov 2017 19:52:56 +1100	[thread overview]
Message-ID: <87tvxda2l3.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20171128111214.42esi4igzgnldsx5@gmail.com>

Ingo Molnar <mingo@kernel.org> writes:
...
> Index: tip/include/linux/stat.h
> ===================================================================
> --- tip.orig/include/linux/stat.h
> +++ tip/include/linux/stat.h
> @@ -6,6 +6,34 @@
>  #include <asm/stat.h>
>  #include <uapi/linux/stat.h>
>  
> +/*
> + * Human readable symbolic definitions for common
> + * file permissions:
> + */
> +#define PERM_r________	0400
> +#define PERM_r__r_____	0440
> +#define PERM_r__r__r__	0444
> +
> +#define PERM_rw_______	0600
> +#define PERM_rw_r_____	0640
> +#define PERM_rw_r__r__	0644
> +#define PERM_rw_rw_r__	0664
> +#define PERM_rw_rw_rw_	0666
> +
> +#define PERM__w_______	0200
> +#define PERM__w__w____	0220
> +#define PERM__w__w__w_	0222
> +
> +#define PERM_r_x______	0500
> +#define PERM_r_xr_x___	0550
> +#define PERM_r_xr_xr_x	0555
> +
> +#define PERM_rwx______	0700
> +#define PERM_rwxr_x___	0750
> +#define PERM_rwxr_xr_x	0755
> +#define PERM_rwxrwxr_x	0775
> +#define PERM_rwxrwxrwx	0777

I see what you're trying to do with all the explicit underscores, but it
does make them look kinda ugly.

What if you just used underscores to separate the user/group/other, and
the unset permission bits are just omitted.

Then the two most common cases would be:

  PERM_rw_r_r
  PERM_r_r_r

Both of those read nicely I think. ie. the first is "perm read write,
read, read".

Full set would be:

#define PERM_r			0400
#define PERM_r_r		0440
#define PERM_r_r_r		0444

#define PERM_rw			0600
#define PERM_rw_r		0640
#define PERM_rw_r_r		0644
#define PERM_rw_rw_r		0664
#define PERM_rw_rw_rw		0666

#define PERM_w			0200
#define PERM_w_w		0220
#define PERM_w_w_w		0222

#define PERM_rx			0500
#define PERM_rx_rx		0550
#define PERM_rx_rx_rx		0555

#define PERM_rwx		0700
#define PERM_rwx_rx		0750
#define PERM_rwx_rx_rx		0755
#define PERM_rwx_rwx_rx		0775
#define PERM_rwx_rwx_rwx	0777


cheers

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  reply	other threads:[~2017-11-29  8:52 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-26 23:14 [patch V2 0/5] x86/kaiser: Boot time disabling and debug support Thomas Gleixner
2017-11-26 23:14 ` Thomas Gleixner
2017-11-26 23:14 ` [patch V2 1/5] x86/kaiser: Respect disabled CPU features Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27  9:57   ` Peter Zijlstra
2017-11-27  9:57     ` Peter Zijlstra
2017-11-27 11:47     ` Thomas Gleixner
2017-11-27 11:47       ` Thomas Gleixner
2017-11-27 12:31       ` Brian Gerst
2017-11-27 12:31         ` Brian Gerst
2017-11-27 13:18         ` Thomas Gleixner
2017-11-27 13:18           ` Thomas Gleixner
2017-11-27 18:11   ` Dave Hansen
2017-11-27 18:11     ` Dave Hansen
2017-11-27 18:37     ` Kees Cook
2017-11-27 18:37       ` Kees Cook
2017-11-26 23:14 ` [patch V2 2/5] x86/kaiser: Simplify disabling of global pages Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27 11:49   ` Thomas Gleixner
2017-11-27 11:49     ` Thomas Gleixner
2017-11-27 18:15   ` Dave Hansen
2017-11-27 18:15     ` Dave Hansen
2017-11-27 20:28     ` Thomas Gleixner
2017-11-27 20:28       ` Thomas Gleixner
2017-11-26 23:14 ` [patch V2 3/5] x86/dump_pagetables: Check KAISER shadow page table for WX pages Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27 18:17   ` Dave Hansen
2017-11-27 18:17     ` Dave Hansen
2017-11-26 23:14 ` [patch V2 4/5] x86/mm/debug_pagetables: Allow dumping current pagetables Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27  9:41   ` Peter Zijlstra
2017-11-27  9:41     ` Peter Zijlstra
2017-11-27 10:06     ` [PATCH] vfs: Add PERM_* symbolic helpers for common file mode/permissions Ingo Molnar
2017-11-27 10:06       ` Ingo Molnar
2017-11-27 19:21       ` Linus Torvalds
2017-11-27 19:21         ` Linus Torvalds
2017-11-28 10:54         ` Ingo Molnar
2017-11-28 10:54           ` Ingo Molnar
2017-11-28 11:12         ` Ingo Molnar
2017-11-28 11:12           ` Ingo Molnar
2017-11-29  8:52           ` Michael Ellerman [this message]
2017-11-29  8:52             ` Michael Ellerman
2017-11-27 18:18   ` [patch V2 4/5] x86/mm/debug_pagetables: Allow dumping current pagetables Dave Hansen
2017-11-27 18:18     ` Dave Hansen
2017-11-26 23:14 ` [patch V2 5/5] x86/kaiser: Add boottime disable switch Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27  9:48   ` Peter Zijlstra
2017-11-27  9:48     ` Peter Zijlstra
2017-11-27 10:22     ` Peter Zijlstra
2017-11-27 10:22       ` Peter Zijlstra
2017-11-27 11:50       ` Thomas Gleixner
2017-11-27 11:50         ` Thomas Gleixner
2017-11-27 12:49         ` Peter Zijlstra
2017-11-27 12:49           ` Peter Zijlstra
2017-11-27 21:43       ` Peter Zijlstra
2017-11-27 21:43         ` Peter Zijlstra
2017-11-27 18:22   ` Dave Hansen
2017-11-27 18:22     ` Dave Hansen
2017-11-27 19:00     ` Thomas Gleixner
2017-11-27 19:00       ` Thomas Gleixner
2017-11-27 19:18       ` Josh Poimboeuf
2017-11-27 19:18         ` Josh Poimboeuf
2017-11-27 20:47         ` Thomas Gleixner
2017-11-27 20:47           ` Thomas Gleixner

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