From: Andy Lutomirski <luto@MIT.EDU>
To: Ingo Molnar <mingo@elte.hu>, x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Jesper Juhl <jj@chaosbits.net>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
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>,
Andi Kleen <andi@firstfloor.org>, Brian Gerst <brgerst@gmail.com>,
Louis Rilling <Louis.Rilling@kerlabs.com>,
Valdis.Kletnieks@vt.edu, pageexec@freemail.hu,
Andy Lutomirski <luto@MIT.EDU>
Subject: [PATCH v5 3/9] x86-64: Give vvars their own page
Date: Sun, 5 Jun 2011 13:50:19 -0400 [thread overview]
Message-ID: <b1460f81dc4463d66ea3f2b5ce240f58d48effec.1307292171.git.luto@mit.edu> (raw)
In-Reply-To: <cover.1307292171.git.luto@mit.edu>
In-Reply-To: <cover.1307292171.git.luto@mit.edu>
Move vvars out of the vsyscall page into their own page and mark it
NX.
Without this patch, an attacker who can force a daemon to call some
fixed address could wait until the time contains, say, 0xCD80, and
then execute the current time.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
---
arch/x86/include/asm/fixmap.h | 1 +
arch/x86/include/asm/pgtable_types.h | 2 ++
arch/x86/include/asm/vvar.h | 22 ++++++++++------------
arch/x86/kernel/vmlinux.lds.S | 28 +++++++++++++++++-----------
arch/x86/kernel/vsyscall_64.c | 5 +++++
5 files changed, 35 insertions(+), 23 deletions(-)
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 4729b2b..460c74e 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -78,6 +78,7 @@ enum fixed_addresses {
VSYSCALL_LAST_PAGE,
VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
+ ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
+ VVAR_PAGE,
VSYSCALL_HPET,
#endif
FIX_DBGP_BASE,
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index d56187c..6a29aed6 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -108,6 +108,7 @@
#define __PAGE_KERNEL_UC_MINUS (__PAGE_KERNEL | _PAGE_PCD)
#define __PAGE_KERNEL_VSYSCALL (__PAGE_KERNEL_RX | _PAGE_USER)
#define __PAGE_KERNEL_VSYSCALL_NOCACHE (__PAGE_KERNEL_VSYSCALL | _PAGE_PCD | _PAGE_PWT)
+#define __PAGE_KERNEL_VVAR (__PAGE_KERNEL_RO | _PAGE_USER)
#define __PAGE_KERNEL_LARGE (__PAGE_KERNEL | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_NOCACHE (__PAGE_KERNEL | _PAGE_CACHE_UC | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE)
@@ -130,6 +131,7 @@
#define PAGE_KERNEL_LARGE_EXEC __pgprot(__PAGE_KERNEL_LARGE_EXEC)
#define PAGE_KERNEL_VSYSCALL __pgprot(__PAGE_KERNEL_VSYSCALL)
#define PAGE_KERNEL_VSYSCALL_NOCACHE __pgprot(__PAGE_KERNEL_VSYSCALL_NOCACHE)
+#define PAGE_KERNEL_VVAR __pgprot(__PAGE_KERNEL_VVAR)
#define PAGE_KERNEL_IO __pgprot(__PAGE_KERNEL_IO)
#define PAGE_KERNEL_IO_NOCACHE __pgprot(__PAGE_KERNEL_IO_NOCACHE)
diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h
index a4eaca4..de656ac 100644
--- a/arch/x86/include/asm/vvar.h
+++ b/arch/x86/include/asm/vvar.h
@@ -10,15 +10,14 @@
* In normal kernel code, they are used like any other variable.
* In user code, they are accessed through the VVAR macro.
*
- * Each of these variables lives in the vsyscall page, and each
- * one needs a unique offset within the little piece of the page
- * reserved for vvars. Specify that offset in DECLARE_VVAR.
- * (There are 896 bytes available. If you mess up, the linker will
- * catch it.)
+ * These variables live in a page of kernel data that has an extra RO
+ * mapping for userspace. Each variable needs a unique offset within
+ * that page; specify that offset with the DECLARE_VVAR macro. (If
+ * you mess up, the linker will catch it.)
*/
-/* Offset of vars within vsyscall page */
-#define VSYSCALL_VARS_OFFSET (3072 + 128)
+/* Base address of vvars. This is not ABI. */
+#define VVAR_ADDRESS (-10*1024*1024 - 4096)
#if defined(__VVAR_KERNEL_LDS)
@@ -26,17 +25,17 @@
* right place.
*/
#define DECLARE_VVAR(offset, type, name) \
- EMIT_VVAR(name, VSYSCALL_VARS_OFFSET + offset)
+ EMIT_VVAR(name, offset)
#else
#define DECLARE_VVAR(offset, type, name) \
static type const * const vvaraddr_ ## name = \
- (void *)(VSYSCALL_START + VSYSCALL_VARS_OFFSET + (offset));
+ (void *)(VVAR_ADDRESS + (offset));
#define DEFINE_VVAR(type, name) \
- type __vvar_ ## name \
- __attribute__((section(".vsyscall_var_" #name), aligned(16)))
+ type name \
+ __attribute__((section(".vvar_" #name), aligned(16)))
#define VVAR(name) (*vvaraddr_ ## name)
@@ -49,4 +48,3 @@ DECLARE_VVAR(16, int, vgetcpu_mode)
DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
#undef DECLARE_VVAR
-#undef VSYSCALL_VARS_OFFSET
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 89aed99..98b378d 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -161,12 +161,6 @@ SECTIONS
#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0)
#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
-#define EMIT_VVAR(x, offset) .vsyscall_var_ ## x \
- ADDR(.vsyscall_0) + offset \
- : AT(VLOAD(.vsyscall_var_ ## x)) { \
- *(.vsyscall_var_ ## x) \
- } \
- x = VVIRT(.vsyscall_var_ ## x);
. = ALIGN(4096);
__vsyscall_0 = .;
@@ -192,19 +186,31 @@ SECTIONS
*(.vsyscall_3)
}
-#define __VVAR_KERNEL_LDS
-#include <asm/vvar.h>
-#undef __VVAR_KERNEL_LDS
-
- . = __vsyscall_0 + PAGE_SIZE;
+ . = ALIGN(__vsyscall_0 + PAGE_SIZE, PAGE_SIZE);
#undef VSYSCALL_ADDR
#undef VLOAD_OFFSET
#undef VLOAD
#undef VVIRT_OFFSET
#undef VVIRT
+
+ __vvar_page = .;
+
+ .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
+
+ /* Place all vvars at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) \
+ . = offset; \
+ *(.vvar_ ## name)
+#define __VVAR_KERNEL_LDS
+#include <asm/vvar.h>
+#undef __VVAR_KERNEL_LDS
#undef EMIT_VVAR
+ } :data
+
+ . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
+
#endif /* CONFIG_X86_64 */
/* Init code and data - will be freed after init */
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 3e68218..3cf1cef 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -284,9 +284,14 @@ void __init map_vsyscall(void)
{
extern char __vsyscall_0;
unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+ extern char __vvar_page;
+ unsigned long physaddr_vvar_page = __pa_symbol(&__vvar_page);
/* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
+ __set_fixmap(VVAR_PAGE, physaddr_vvar_page, PAGE_KERNEL_VVAR);
+ BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) !=
+ (unsigned long)VVAR_ADDRESS);
}
static int __init vsyscall_init(void)
--
1.7.5.2
next prev parent reply other threads:[~2011-06-05 18:02 UTC|newest]
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 ` Andy Lutomirski [this message]
2011-06-06 8:32 ` [tip:x86/vdso] x86-64: Give vvars their own page 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
[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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