From 20cc28882bf4a8c9a2605a9a76a7952e696aaece Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 1 Oct 2014 11:36:32 -0700 Subject: x86, boot, kaslr: Fix nuisance warning on 32-bit builds MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Building 32-bit threw a warning on kASLR enabled builds: arch/x86/boot/compressed/aslr.c: In function ‘mem_avoid_overlap’: arch/x86/boot/compressed/aslr.c:198:17: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] avoid.start = (u64)ptr; ^ This fixes the warning; unsigned long should have been used here. Signed-off-by: Kees Cook Link: http://lkml.kernel.org/r/20141001183632.GA11431@www.outflux.net Signed-off-by: H. Peter Anvin --- arch/x86/boot/compressed/aslr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c index d39189ba7f8e..f302dc45ce08 100644 --- a/arch/x86/boot/compressed/aslr.c +++ b/arch/x86/boot/compressed/aslr.c @@ -195,7 +195,7 @@ static bool mem_avoid_overlap(struct mem_vector *img) while (ptr) { struct mem_vector avoid; - avoid.start = (u64)ptr; + avoid.start = (unsigned long)ptr; avoid.size = sizeof(*ptr) + ptr->len; if (mem_overlaps(img, &avoid)) -- cgit v1.2.3 From 8c7aa698baca5e8f1ba9edb68081f1e7a1abf455 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 1 Oct 2014 11:49:04 -0700 Subject: x86_64, entry: Filter RFLAGS.NT on entry from userspace The NT flag doesn't do anything in long mode other than causing IRET to #GP. Oddly, CPL3 code can still set NT using popf. Entry via hardware or software interrupt clears NT automatically, so the only relevant entries are fast syscalls. If user code causes kernel code to run with NT set, then there's at least some (small) chance that it could cause trouble. For example, user code could cause a call to EFI code with NT set, and who knows what would happen? Apparently some games on Wine sometimes do this (!), and, if an IRET return happens, they will segfault. That segfault cannot be handled, because signal delivery fails, too. This patch programs the CPU to clear NT on entry via SYSCALL (both 32-bit and 64-bit, by my reading of the AMD APM), and it clears NT in software on entry via SYSENTER. To save a few cycles, this borrows a trick from Jan Beulich in Xen: it checks whether NT is set before trying to clear it. As a result, it seems to have very little effect on SYSENTER performance on my machine. There's another minor bug fix in here: it looks like the CFI annotations were wrong if CONFIG_AUDITSYSCALL=n. Testers beware: on Xen, SYSENTER with NT set turns into a GPF. I haven't touched anything on 32-bit kernels. The syscall mask change comes from a variant of this patch by Anish Bhatt. Note to stable maintainers: there is no known security issue here. A misguided program can set NT and cause the kernel to try and fail to deliver SIGSEGV, crashing the program. This patch fixes Far Cry on Wine: https://bugs.winehq.org/show_bug.cgi?id=33275 Cc: Reported-by: Anish Bhatt Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/395749a5d39a29bd3e4b35899cf3a3c1340e5595.1412189265.git.luto@amacapital.net Signed-off-by: H. Peter Anvin --- arch/x86/ia32/ia32entry.S | 18 +++++++++++++++++- arch/x86/kernel/cpu/common.c | 2 +- 2 files changed, 18 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index 4299eb05023c..711de084ab57 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -151,6 +151,16 @@ ENTRY(ia32_sysenter_target) 1: movl (%rbp),%ebp _ASM_EXTABLE(1b,ia32_badarg) ASM_CLAC + + /* + * Sysenter doesn't filter flags, so we need to clear NT + * ourselves. To save a few cycles, we can check whether + * NT was set instead of doing an unconditional popfq. + */ + testl $X86_EFLAGS_NT,EFLAGS(%rsp) /* saved EFLAGS match cpu */ + jnz sysenter_fix_flags +sysenter_flags_fixed: + orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP-ARGOFFSET) testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) CFI_REMEMBER_STATE @@ -184,6 +194,8 @@ sysexit_from_sys_call: TRACE_IRQS_ON ENABLE_INTERRUPTS_SYSEXIT32 + CFI_RESTORE_STATE + #ifdef CONFIG_AUDITSYSCALL .macro auditsys_entry_common movl %esi,%r9d /* 6th arg: 4th syscall arg */ @@ -226,7 +238,6 @@ sysexit_from_sys_call: .endm sysenter_auditsys: - CFI_RESTORE_STATE auditsys_entry_common movl %ebp,%r9d /* reload 6th syscall arg */ jmp sysenter_dispatch @@ -235,6 +246,11 @@ sysexit_audit: auditsys_exit sysexit_from_sys_call #endif +sysenter_fix_flags: + pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_FIXED) + popfq_cfi + jmp sysenter_flags_fixed + sysenter_tracesys: #ifdef CONFIG_AUDITSYSCALL testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e4ab2b42bd6f..31265580c38a 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1184,7 +1184,7 @@ void syscall_init(void) /* Flags to clear on syscall */ wrmsrl(MSR_SYSCALL_MASK, X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF| - X86_EFLAGS_IOPL|X86_EFLAGS_AC); + X86_EFLAGS_IOPL|X86_EFLAGS_AC|X86_EFLAGS_NT); } /* -- cgit v1.2.3 From 0e6d3112a4e95d55cf6dca88f298d5f4b8f29bd1 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Sun, 7 Sep 2014 21:05:05 +0100 Subject: x86: Reject x32 executables if x32 ABI not supported It is currently possible to execve() an x32 executable on an x86_64 kernel that has only ia32 compat enabled. However all its syscalls will fail, even _exit(). This usually causes it to segfault. Change the ELF compat architecture check so that x32 executables are rejected if we don't support the x32 ABI. Signed-off-by: Ben Hutchings Link: http://lkml.kernel.org/r/1410120305.6822.9.camel@decadent.org.uk Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/elf.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 1a055c81d864..ca3347a9dab5 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -160,8 +160,9 @@ do { \ #define elf_check_arch(x) \ ((x)->e_machine == EM_X86_64) -#define compat_elf_check_arch(x) \ - (elf_check_arch_ia32(x) || (x)->e_machine == EM_X86_64) +#define compat_elf_check_arch(x) \ + (elf_check_arch_ia32(x) || \ + (IS_ENABLED(CONFIG_X86_X32_ABI) && (x)->e_machine == EM_X86_64)) #if __USER32_DS != __USER_DS # error "The following code assumes __USER32_DS == __USER_DS" -- cgit v1.2.3 From 2dee5c43da3a981489a4f18972827139afcbee82 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 24 Sep 2014 06:32:19 +0200 Subject: x86: Fix section conflict for numachip A variable cannot be both __read_mostly and const. This is a meaningless combination. Just make it only const. This fixes the LTO build with numachip enabled. Signed-off-by: Andi Kleen Link: http://lkml.kernel.org/r/1411533139-25708-1-git-send-email-andi@firstfloor.org Signed-off-by: Thomas Gleixner --- arch/x86/kernel/apic/apic_numachip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/kernel/apic/apic_numachip.c b/arch/x86/kernel/apic/apic_numachip.c index ae915391ebec..4128b5fcb559 100644 --- a/arch/x86/kernel/apic/apic_numachip.c +++ b/arch/x86/kernel/apic/apic_numachip.c @@ -32,7 +32,7 @@ static int numachip_system __read_mostly; -static const struct apic apic_numachip __read_mostly; +static const struct apic apic_numachip; static unsigned int get_apic_id(unsigned long x) { -- cgit v1.2.3 From 4ea48a01bb1a99f4185b77cd90cf962730336cc4 Mon Sep 17 00:00:00 2001 From: Shuah Khan Date: Mon, 29 Sep 2014 12:41:56 -0600 Subject: x86/build: Add arch/x86/purgatory/ make generated files to gitignore The following generated files are missing from gitignore and show up in git status after x86_64 build. Add them to gitignore. arch/x86/purgatory/kexec-purgatory.c arch/x86/purgatory/purgatory.ro Signed-off-by: Shuah Khan Link: http://lkml.kernel.org/r/1412016116-7213-1-git-send-email-shuahkh@osg.samsung.com Signed-off-by: Ingo Molnar --- arch/x86/.gitignore | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch') diff --git a/arch/x86/.gitignore b/arch/x86/.gitignore index 7cab8c08e6d1..aff152c87cf4 100644 --- a/arch/x86/.gitignore +++ b/arch/x86/.gitignore @@ -1,4 +1,6 @@ boot/compressed/vmlinux tools/test_get_len tools/insn_sanity +purgatory/kexec-purgatory.c +purgatory/purgatory.ro -- cgit v1.2.3