| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <tip-1ad83c858c7d4ea210429142c99a1548e6715a35@git.kernel.org>
Date: Mon, 3 Nov 2014 12:49:07 -0800
From: tip-bot for Andy Lutomirski <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: mingo@...nel.org, tglx@...utronix.de, luto@...capital.net,
hpa@...or.com, linux-kernel@...r.kernel.org, josh@...htriplett.org,
konrad.wilk@...cle.com
Subject: [tip:x86/vdso] x86_64,vsyscall:
Make vsyscall emulation configurable
Commit-ID: 1ad83c858c7d4ea210429142c99a1548e6715a35
Gitweb: http://git.kernel.org/tip/1ad83c858c7d4ea210429142c99a1548e6715a35
Author: Andy Lutomirski <luto@...capital.net>
AuthorDate: Wed, 29 Oct 2014 14:33:47 -0700
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 3 Nov 2014 21:44:57 +0100
x86_64,vsyscall: Make vsyscall emulation configurable
This adds CONFIG_X86_VSYSCALL_EMULATION, guarded by CONFIG_EXPERT.
Turning it off completely disables vsyscall emulation, saving ~3.5k
for vsyscall_64.c, 4k for vsyscall_emu_64.S (the fake vsyscall
page), some tiny amount of core mm code that supports a gate area,
and possibly 4k for a wasted pagetable. The latter is because the
vsyscall addresses are misaligned and fit poorly in the fixmap.
Signed-off-by: Andy Lutomirski <luto@...capital.net>
Reviewed-by: Josh Triplett <josh@...htriplett.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Link: http://lkml.kernel.org/r/406db88b8dd5f0cbbf38216d11be34bbb43c7eae.1414618407.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
arch/x86/Kconfig | 18 ++++++++++++++++++
arch/x86/include/asm/fixmap.h | 2 ++
arch/x86/include/asm/page_64.h | 4 +++-
arch/x86/include/asm/vsyscall.h | 8 ++++++++
arch/x86/kernel/Makefile | 3 +--
arch/x86/kernel/setup.c | 2 --
arch/x86/xen/mmu.c | 6 ++++--
7 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f2327e8..cd10436 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -984,6 +984,24 @@ config X86_ESPFIX64
def_bool y
depends on X86_16BIT && X86_64
+config X86_VSYSCALL_EMULATION
+ bool "Enable vsyscall emulation" if EXPERT
+ default y
+ depends on X86_64
+ ---help---
+ This enables emulation of the legacy vsyscall page. Disabling
+ it is roughly equivalent to booting with vsyscall=none, except
+ that it will also disable the helpful warning if a program
+ tries to use a vsyscall. With this option set to N, offending
+ programs will just segfault, citing addresses of the form
+ 0xffffffffff600?00.
+
+ This option is required by many programs built before 2013, and
+ care should be used even with newer programs if set to N.
+
+ Disabling this option saves about 7K of kernel size and
+ possibly 4K of additional runtime pagetable memory.
+
config TOSHIBA
tristate "Toshiba Laptop support"
depends on X86_32
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index ffb1733..d8d5bcb 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -69,7 +69,9 @@ enum fixed_addresses {
#ifdef CONFIG_X86_32
FIX_HOLE,
#else
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
VSYSCALL_PAGE = (FIXADDR_TOP - VSYSCALL_ADDR) >> PAGE_SHIFT,
+#endif
#ifdef CONFIG_PARAVIRT_CLOCK
PVCLOCK_FIXMAP_BEGIN,
PVCLOCK_FIXMAP_END = PVCLOCK_FIXMAP_BEGIN+PVCLOCK_VSYSCALL_NR_PAGES-1,
diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
index f408caf..b3bebf9 100644
--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -39,6 +39,8 @@ void copy_page(void *to, void *from);
#endif /* !__ASSEMBLY__ */
-#define __HAVE_ARCH_GATE_AREA 1
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+# define __HAVE_ARCH_GATE_AREA 1
+#endif
#endif /* _ASM_X86_PAGE_64_H */
diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h
index 34f7d88..6ba66ee 100644
--- a/arch/x86/include/asm/vsyscall.h
+++ b/arch/x86/include/asm/vsyscall.h
@@ -4,6 +4,7 @@
#include <linux/seqlock.h>
#include <uapi/asm/vsyscall.h>
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
extern void map_vsyscall(void);
/*
@@ -11,5 +12,12 @@ extern void map_vsyscall(void);
* Returns true if handled.
*/
extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address);
+#else
+static inline void map_vsyscall(void) {}
+static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
+{
+ return false;
+}
+#endif
#endif /* _ASM_X86_VSYSCALL_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8f1e774..5d4502c 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -28,8 +28,7 @@ obj-$(CONFIG_X86_32) += i386_ksyms_32.o
obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += mcount_64.o
obj-y += syscall_$(BITS).o vsyscall_gtod.o
-obj-$(CONFIG_X86_64) += vsyscall_64.o
-obj-$(CONFIG_X86_64) += vsyscall_emu_64.o
+obj-$(CONFIG_X86_VSYSCALL_EMULATION) += vsyscall_64.o vsyscall_emu_64.o
obj-$(CONFIG_X86_ESPFIX64) += espfix_64.o
obj-$(CONFIG_SYSFS) += ksysfs.o
obj-y += bootflag.o e820.o
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 235cfd3..59a6f884 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1190,9 +1190,7 @@ void __init setup_arch(char **cmdline_p)
tboot_probe();
-#ifdef CONFIG_X86_64
map_vsyscall();
-#endif
generic_apic_probe();
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index a8a1a3d..8906cf0 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1457,8 +1457,10 @@ static int xen_pgd_alloc(struct mm_struct *mm)
page->private = (unsigned long)user_pgd;
if (user_pgd != NULL) {
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
user_pgd[pgd_index(VSYSCALL_ADDR)] =
__pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE);
+#endif
ret = 0;
}
@@ -2021,7 +2023,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
# ifdef CONFIG_HIGHMEM
case FIX_KMAP_BEGIN ... FIX_KMAP_END:
# endif
-#else
+#elif defined(CONFIG_X86_VSYSCALL_EMULATION)
case VSYSCALL_PAGE:
#endif
case FIX_TEXT_POKE0:
@@ -2060,7 +2062,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
__native_set_fixmap(idx, pte);
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
/* Replicate changes to map the vsyscall page into the user
pagetable vsyscall mapping. */
if (idx == VSYSCALL_PAGE) {
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists