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From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: pageexec@freemail.hu, Andi Kleen <andi@firstfloor.org>,
	Andy Lutomirski <luto@mit.edu>,
	x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org, Jesper Juhl <jj@chaosbits.net>,
	Borislav Petkov <bp@alien8.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@infradead.org>,
	Jan Beulich <JBeulich@novell.com>,
	richard -rw- weinberger <richard.weinberger@gmail.com>,
	Mikael Pettersson <mikpe@it.uu.se>,
	Brian Gerst <brgerst@gmail.com>,
	Louis Rilling <Louis.Rilling@kerlabs.com>,
	Valdis.Kletnieks@vt.edu
Subject: Re: [PATCH v5 9/9] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule
Date: Mon, 6 Jun 2011 23:48:23 +0200
Message-ID: <20110606214823.GA11489@elte.hu> (raw)
In-Reply-To: <20110606214545.GA6492@elte.hu>


* Ingo Molnar <mingo@elte.hu> wrote:

> I was unsure how big of a problem the time() slowdown was and the 
> config option was easy enough to provide. My preference would be to 
> just remove the config option and simplify the code - complexity is 
> the #1 enemy of security.

The patch below is what the config removal brings us.

Thanks,

	Ingo

--
 Documentation/feature-removal-schedule.txt |   13 -------------
 arch/x86/Kconfig                           |   23 -----------------------
 arch/x86/kernel/vsyscall_64.c              |   26 --------------------------
 arch/x86/kernel/vsyscall_emu_64.S          |    2 --
 4 files changed, 0 insertions(+), 64 deletions(-)

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 7a7446b..1a9446b 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -600,16 +600,3 @@ Why:	Superseded by the UVCIOC_CTRL_QUERY ioctl.
 Who:	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 
 ----------------------------
-
-What:	CONFIG_LEGACY_VTIME (x86_64)
-When:	When glibc 2.14 or newer is ubiquitous.  Perhaps 2013.
-Why:	Having user-executable syscall invoking code at a fixed addresses makes
-	it easier for attackers to exploit security holes.  Turning off
-	CONFIG_LEGACY_VTIME reduces the risk without breaking binary
-	compatibility but will make the time() function slightly slower on
-	glibc versions 2.13 and below.
-
-	We may flip the default setting to N before 2013.
-Who:	Andy Lutomirski <luto@mit.edu>
-
-----------------------------
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6746d35..da34972 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1646,29 +1646,6 @@ config COMPAT_VDSO
 
 	  If unsure, say Y.
 
-config LEGACY_VTIME
-	def_bool y
-	prompt "Fast legacy sys_time() vsyscall"
-	depends on X86_64
-	---help---
-	  Glibc 2.13 and older, statically linked binaries, and a few
-	  other things use a legacy ABI to implement time().
-
-	  If you say N here, the kernel will emulate that interface in
-	  order to make certain types of userspace bugs more difficult
-	  to exploit.  This will cause some legacy software to run
-	  slightly more slowly.
-
-	  If you say Y here, then the kernel will provide native code to
-	  allow legacy programs to run without any performance impact.
-	  This could make it easier to exploit certain types of
-	  userspace bugs.
-
-	  If unsure, say Y.
-
-	  NOTE: disabling this option will not break any ABI; the kernel
-	        will be fully compatible with all binaries either way.
-
 config CMDLINE_BOOL
 	bool "Built-in kernel command line"
 	---help---
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index f56644e..41f6a98 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -102,30 +102,6 @@ static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
 	       regs->ip - 2, regs->sp, regs->ax, regs->si, regs->di);
 }
 
-#ifdef CONFIG_LEGACY_VTIME
-
-/* This will break when the xtime seconds get inaccurate, but that is
- * unlikely */
-time_t __attribute__ ((unused, __section__(".vsyscall_1"))) notrace
-vtime(time_t *t)
-{
-	unsigned seq;
-	time_t result;
-
-	do {
-		seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
-
-		result = VVAR(vsyscall_gtod_data).wall_time_sec;
-
-	} while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
-
-	if (t)
-		*t = result;
-	return result;
-}
-
-#endif /* CONFIG_LEGACY_VTIME */
-
 void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
 {
 	static DEFINE_RATELIMIT_STATE(rs, 3600 * HZ, 3);
@@ -169,12 +145,10 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
 			(struct timezone __user *)regs->si);
 		break;
 
-#ifndef CONFIG_LEGACY_VTIME
 	case 1:
 		vsyscall_name = "time";
 		ret = sys_time((time_t __user *)regs->di);
 		break;
-#endif
 
 	case 2:
 		vsyscall_name = "getcpu";
diff --git a/arch/x86/kernel/vsyscall_emu_64.S b/arch/x86/kernel/vsyscall_emu_64.S
index b192283..bc10dba 100644
--- a/arch/x86/kernel/vsyscall_emu_64.S
+++ b/arch/x86/kernel/vsyscall_emu_64.S
@@ -14,12 +14,10 @@ ENTRY(vsyscall_0)
 	int $VSYSCALL_EMU_VECTOR
 END(vsyscall_0)
 
-#ifndef CONFIG_LEGACY_VTIME
 .section .vsyscall_1, "a"
 ENTRY(vsyscall_1)
 	int $VSYSCALL_EMU_VECTOR
 END(vsyscall_1)
-#endif
 
 .section .vsyscall_2, "a"
 ENTRY(vsyscall_2)

  reply index

Thread overview: 112+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-05 17:50 [PATCH v5 0/9] Remove syscall instructions at fixed addresses Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 1/9] x86-64: Fix alignment of jiffies variable Andy Lutomirski
2011-06-06  8:31   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 2/9] x86-64: Document some of entry_64.S Andy Lutomirski
2011-06-06  8:31   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 3/9] x86-64: Give vvars their own page Andy Lutomirski
2011-06-06  8:32   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 4/9] x86-64: Remove kernel.vsyscall64 sysctl Andy Lutomirski
2011-06-06  8:32   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-12-05 18:27   ` [PATCH v5 4/9] " Matthew Maurer
2011-06-05 17:50 ` [PATCH v5 5/9] x86-64: Map the HPET NX Andy Lutomirski
2011-06-06  8:33   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 6/9] x86-64: Remove vsyscall number 3 (venosys) Andy Lutomirski
2011-06-06  8:33   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 7/9] x86-64: Fill unused parts of the vsyscall page with 0xcc Andy Lutomirski
2011-06-06  8:34   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 8/9] x86-64: Emulate legacy vsyscalls Andy Lutomirski
2011-06-05 19:30   ` Ingo Molnar
2011-06-05 20:01     ` Andrew Lutomirski
2011-06-06  7:39       ` Ingo Molnar
2011-06-06  9:42       ` pageexec
2011-06-06 11:19         ` Andrew Lutomirski
2011-06-06 11:56           ` pageexec
2011-06-06 12:43             ` Andrew Lutomirski
2011-06-06 13:58               ` pageexec
2011-06-06 14:07                 ` Brian Gerst
2011-06-07 23:32                   ` pageexec
2011-06-07 23:49                     ` Andrew Lutomirski
2011-06-08  6:32                       ` pageexec
2011-06-06 15:26                 ` Ingo Molnar
2011-06-06 15:48                   ` pageexec
2011-06-06 15:59                     ` Ingo Molnar
2011-06-06 16:19                       ` pageexec
2011-06-06 16:47                         ` Ingo Molnar
2011-06-06 22:49                           ` pageexec
2011-06-06 22:57                             ` david
2011-06-07  9:07                               ` Ingo Molnar
2011-06-07  6:59                             ` Pekka Enberg
2011-06-07  8:30                             ` Ingo Molnar
2011-06-07 23:24                               ` pageexec
2011-06-08  5:55                                 ` Pekka Enberg
2011-06-08  6:19                                   ` pageexec
2011-06-08  6:48                                 ` Ingo Molnar
2011-06-08  9:02                                   ` pageexec
2011-06-08  9:11                                     ` Andi Kleen
2011-06-08  9:35                                       ` pageexec
2011-06-08 10:06                                         ` Andi Kleen
2011-06-08 10:26                                           ` pageexec
2011-06-08 10:39                                             ` Ingo Molnar
2011-06-08 10:35                                           ` Ingo Molnar
2011-06-08  9:15                                     ` Ingo Molnar
2011-06-08  7:16                                 ` Ingo Molnar
2011-06-08  9:29                                   ` pageexec
2011-06-06 14:01             ` Linus Torvalds
2011-06-06 14:55               ` pageexec
2011-06-06 15:33                 ` Ingo Molnar
2011-06-06 15:58                   ` pageexec
2011-06-06 15:41         ` Ingo Molnar
2011-06-06  8:34   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-06  8:35   ` [tip:x86/vdso] x86-64, vdso, seccomp: Fix !CONFIG_SECCOMP build tip-bot for Ingo Molnar
2011-06-07  7:49   ` [tip:x86/vdso] x86-64: Emulate legacy vsyscalls tip-bot for Andy Lutomirski
2011-06-07  8:03   ` tip-bot for Andy Lutomirski
2011-06-05 17:50 ` [PATCH v5 9/9] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule Andy Lutomirski
2011-06-06  8:34   ` [tip:x86/vdso] " tip-bot for Andy Lutomirski
2011-06-06  8:46   ` [PATCH v5 9/9] " Linus Torvalds
2011-06-06  9:31     ` Andi Kleen
2011-06-06 10:39       ` pageexec
2011-06-06 13:56         ` Linus Torvalds
2011-06-06 18:46           ` pageexec
2011-06-06 20:40             ` Linus Torvalds
2011-06-06 20:51               ` Andrew Lutomirski
2011-06-06 21:54                 ` Ingo Molnar
2011-06-06 21:45               ` Ingo Molnar
2011-06-06 21:48                 ` Ingo Molnar [this message]
     [not found]                 ` <BANLkTi==uw_h78oaep1cCOCzwY0edLUU_Q@mail.gmail.com>
2011-06-07  8:03                   ` [PATCH, v6] x86-64: Emulate legacy vsyscalls Ingo Molnar
2011-06-06 21:53               ` [PATCH v5 9/9] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule pageexec
2011-06-06 14:44         ` Ingo Molnar
2011-06-06 15:01           ` pageexec
2011-06-06 15:15             ` Ingo Molnar
2011-06-06 15:29               ` pageexec
2011-06-06 16:54                 ` Ingo Molnar
2011-06-06 18:59           ` pageexec
2011-06-06 19:25             ` Ingo Molnar
2011-06-07  0:34               ` pageexec
2011-06-07  9:51                 ` Ingo Molnar
2011-06-07 23:24                   ` pageexec
2011-06-10 11:19                     ` Ingo Molnar
2011-06-14  0:48                       ` pageexec
2011-06-15 19:42                         ` Valdis.Kletnieks
2011-06-06 14:52         ` Ingo Molnar
2011-06-06 10:24     ` [PATCH] x86-64, vsyscalls: Rename UNSAFE_VSYSCALLS to COMPAT_VSYSCALLS Ingo Molnar
2011-06-06 11:20       ` pageexec
2011-06-06 12:47         ` Ingo Molnar
2011-06-06 12:48           ` Ingo Molnar
2011-06-06 18:04           ` pageexec
2011-06-06 19:12             ` Ingo Molnar
2011-06-07  0:02               ` pageexec
2011-06-07  9:56                 ` Ingo Molnar
2011-06-07 23:24                   ` pageexec
2011-06-09  6:48                     ` Ingo Molnar
2011-06-09 23:33                       ` pageexec
2011-06-07 10:05                 ` Ingo Molnar
2011-06-07 23:24                   ` pageexec
2011-06-09  7:02                     ` Ingo Molnar
2011-06-09 23:33                       ` pageexec
2011-06-07 10:13                 ` Ingo Molnar
2011-06-07 23:24                   ` pageexec
2011-06-06 12:19       ` Ted Ts'o
2011-06-06 12:33         ` Andrew Lutomirski
2011-06-06 12:37         ` Ingo Molnar
2011-06-06 14:34     ` [tip:x86/vdso] " tip-bot for Ingo Molnar
2011-06-05 20:05 ` [PATCH v5 0/9] Remove syscall instructions at fixed addresses Andrew Lutomirski

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