* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip:
x86-64: Rework vsyscall emulation and add vsyscall= parameter
x86-64: Wire up getcpu syscall
x86: Remove unnecessary compile flag tweaks for vsyscall code
x86-64: Add vsyscall:emulate_vsyscall trace event
x86-64: Add user_64bit_mode paravirt op
x86-64, xen: Enable the vvar mapping
x86-64: Work around gold bug 13023
x86-64: Move the "user" vsyscall segment out of the data segment.
x86-64: Pad vDSO to a page boundary
vmpoff= [KNL,S390] Perform z/VM CP command after power off.
Format: <command>
+ vsyscall= [X86-64]
+ Controls the behavior of vsyscalls (i.e. calls to
+ fixed addresses of 0xffffffffff600x00 from legacy
+ code). Most statically-linked binaries and older
+ versions of glibc use these calls. Because these
+ functions are at fixed addresses, they make nice
+ targets for exploits that can control RIP.
+
+ emulate [default] Vsyscalls turn into traps and are
+ emulated reasonably safely.
+
+ native Vsyscalls are native syscall instructions.
+ This is a little bit faster than trapping
+ and makes a few dynamic recompilers work
+ better than they would in emulation mode.
+ It also makes exploits much easier to write.
+
+ none Vsyscalls don't work at all. This makes
+ them quite hard to use for exploits but
+ might break your system.
+
vt.cur_default= [VT] Default cursor shape.
Format: 0xCCBBAA, where AA, BB, and CC are the same as
the parameters of the <Esc>[?A;B;Cc escape sequence;
desc->base2 = (info->base_addr & 0xff000000) >> 24;
/*
- * Don't allow setting of the lm bit. It is useless anyway
- * because 64bit system calls require __USER_CS:
+ * Don't allow setting of the lm bit. It would confuse
+ * user_64bit_mode and would get overridden by sysret anyway.
*/
desc->l = 0;
}
* Vectors 0 ... 31 : system traps and exceptions - hardcoded events
* Vectors 32 ... 127 : device interrupts
* Vector 128 : legacy int80 syscall interface
- * Vector 204 : legacy x86_64 vsyscall emulation
* Vectors 129 ... INVALIDATE_TLB_VECTOR_START-1 except 204 : device interrupts
* Vectors INVALIDATE_TLB_VECTOR_START ... 255 : special interrupts
*
#ifdef CONFIG_X86_32
# define SYSCALL_VECTOR 0x80
#endif
-#ifdef CONFIG_X86_64
-# define VSYSCALL_EMU_VECTOR 0xcc
-#endif
/*
* Vectors 0x30-0x3f are used for ISA interrupts.
#include <asm/desc_defs.h>
#include <asm/kmap_types.h>
+#include <asm/pgtable_types.h>
struct page;
struct thread_struct;
struct pv_info {
unsigned int kernel_rpl;
int shared_kernel_pmd;
+
+#ifdef CONFIG_X86_64
+ u16 extra_user_64bit_cs; /* __USER_CS if none */
+#endif
+
int paravirt_enabled;
const char *name;
};
#ifdef __KERNEL__
#include <linux/init.h>
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt_types.h>
+#endif
struct cpuinfo_x86;
struct task_struct;
#endif
}
+#ifdef CONFIG_X86_64
+static inline bool user_64bit_mode(struct pt_regs *regs)
+{
+#ifndef CONFIG_PARAVIRT
+ /*
+ * On non-paravirt systems, this is the only long mode CPL 3
+ * selector. We do not allow long mode selectors in the LDT.
+ */
+ return regs->cs == __USER_CS;
+#else
+ /* Headers are too twisted for this to go in paravirt.h. */
+ return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
+#endif
+}
+#endif
+
/*
* X86_32 CPUs don't save ss and esp if the CPU is already in kernel mode
* when it traps. The previous stack will be directly underneath the saved
asmlinkage void machine_check(void);
#endif /* CONFIG_X86_MCE */
asmlinkage void simd_coprocessor_error(void);
-asmlinkage void emulate_vsyscall(void);
dotraplinkage void do_divide_error(struct pt_regs *, long);
dotraplinkage void do_debug(struct pt_regs *, long);
dotraplinkage void do_machine_check(struct pt_regs *, long);
#endif
dotraplinkage void do_simd_coprocessor_error(struct pt_regs *, long);
-dotraplinkage void do_emulate_vsyscall(struct pt_regs *, long);
#ifdef CONFIG_X86_32
dotraplinkage void do_iret_error(struct pt_regs *, long);
#endif
__SYSCALL(__NR_sendmmsg, sys_sendmmsg)
#define __NR_setns 308
__SYSCALL(__NR_setns, sys_setns)
+#define __NR_getcpu 309
+__SYSCALL(__NR_getcpu, sys_getcpu)
#ifndef __NO_STUBS
#define __ARCH_WANT_OLD_READDIR
extern void map_vsyscall(void);
+/*
+ * Called on instruction fetch fault in vsyscall page.
+ * Returns true if handled.
+ */
+extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address);
+
#endif /* __KERNEL__ */
#endif /* _ASM_X86_VSYSCALL_H */
CFLAGS_REMOVE_early_printk.o = -pg
endif
-#
-# vsyscalls (which work on the user stack) should have
-# no stack-protector checks:
-#
-nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp)
-CFLAGS_hpet.o := $(nostackp)
-CFLAGS_paravirt.o := $(nostackp)
-GCOV_PROFILE_vsyscall_64.o := n
-GCOV_PROFILE_hpet.o := n
-GCOV_PROFILE_tsc.o := n
-GCOV_PROFILE_paravirt.o := n
-
obj-y := process_$(BITS).o signal.o entry_$(BITS).o
obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
obj-y += time.o ioport.o ldt.o dumpstack.o
zeroentry coprocessor_error do_coprocessor_error
errorentry alignment_check do_alignment_check
zeroentry simd_coprocessor_error do_simd_coprocessor_error
-zeroentry emulate_vsyscall do_emulate_vsyscall
/* Reload gs selector with exception handling */
.paravirt_enabled = 0,
.kernel_rpl = 0,
.shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
+
+#ifdef CONFIG_X86_64
+ .extra_user_64bit_cs = __USER_CS,
+#endif
};
struct pv_init_ops pv_init_ops = {
#ifdef CONFIG_X86_64
case 0x40 ... 0x4f:
- if (regs->cs != __USER_CS)
+ if (!user_64bit_mode(regs))
/* 32-bit mode: register increment */
return 0;
/* 64-bit mode: REX prefix */
set_bit(SYSCALL_VECTOR, used_vectors);
#endif
-#ifdef CONFIG_X86_64
- BUG_ON(test_bit(VSYSCALL_EMU_VECTOR, used_vectors));
- set_system_intr_gate(VSYSCALL_EMU_VECTOR, &emulate_vsyscall);
- set_bit(VSYSCALL_EMU_VECTOR, used_vectors);
-#endif
-
/*
* Should be a barrier for any external CPU state:
*/
text PT_LOAD FLAGS(5); /* R_E */
data PT_LOAD FLAGS(6); /* RW_ */
#ifdef CONFIG_X86_64
- user PT_LOAD FLAGS(5); /* R_E */
#ifdef CONFIG_SMP
percpu PT_LOAD FLAGS(6); /* RW_ */
#endif
#ifdef CONFIG_X86_64
-#define VSYSCALL_ADDR (-10*1024*1024)
-
-#define VLOAD_OFFSET (VSYSCALL_ADDR - __vsyscall_0 + LOAD_OFFSET)
-#define VLOAD(x) (ADDR(x) - VLOAD_OFFSET)
-
-#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0)
-#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
-
- . = ALIGN(4096);
- __vsyscall_0 = .;
-
- . = VSYSCALL_ADDR;
- .vsyscall : AT(VLOAD(.vsyscall)) {
- *(.vsyscall_0)
-
- . = 1024;
- *(.vsyscall_1)
-
- . = 2048;
- *(.vsyscall_2)
-
- . = 4096; /* Pad the whole page. */
- } :user =0xcc
- . = ALIGN(__vsyscall_0 + PAGE_SIZE, PAGE_SIZE);
-
-#undef VSYSCALL_ADDR
-#undef VLOAD_OFFSET
-#undef VLOAD
-#undef VVIRT_OFFSET
-#undef VVIRT
-
+ . = ALIGN(PAGE_SIZE);
__vvar_page = .;
.vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
+ /* work around gold bug 13023 */
+ __vvar_beginning_hack = .;
- /* Place all vvars at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) \
- . = offset; \
+ /* Place all vvars at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) \
+ . = __vvar_beginning_hack + offset; \
*(.vvar_ ## name)
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
* use the vDSO.
*/
-/* Disable profiling for userspace code: */
-#define DISABLE_BRANCH_PROFILING
-
#include <linux/time.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <asm/vgtod.h>
#include <asm/traps.h>
+#define CREATE_TRACE_POINTS
+#include "vsyscall_trace.h"
+
DEFINE_VVAR(int, vgetcpu_mode);
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
{
.lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
};
+static enum { EMULATE, NATIVE, NONE } vsyscall_mode = EMULATE;
+
+static int __init vsyscall_setup(char *str)
+{
+ if (str) {
+ if (!strcmp("emulate", str))
+ vsyscall_mode = EMULATE;
+ else if (!strcmp("native", str))
+ vsyscall_mode = NATIVE;
+ else if (!strcmp("none", str))
+ vsyscall_mode = NONE;
+ else
+ return -EINVAL;
+
+ return 0;
+ }
+
+ return -EINVAL;
+}
+early_param("vsyscall", vsyscall_setup);
+
void update_vsyscall_tz(void)
{
unsigned long flags;
printk("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
level, tsk->comm, task_pid_nr(tsk),
- message, regs->ip - 2, regs->cs,
+ message, regs->ip, regs->cs,
regs->sp, regs->ax, regs->si, regs->di);
}
return nr;
}
-void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
+bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
{
struct task_struct *tsk;
unsigned long caller;
int vsyscall_nr;
long ret;
- local_irq_enable();
-
/*
- * Real 64-bit user mode code has cs == __USER_CS. Anything else
- * is bogus.
+ * No point in checking CS -- the only way to get here is a user mode
+ * trap to a high address, which means that we're in 64-bit user code.
*/
- if (regs->cs != __USER_CS) {
- /*
- * If we trapped from kernel mode, we might as well OOPS now
- * instead of returning to some random address and OOPSing
- * then.
- */
- BUG_ON(!user_mode(regs));
- /* Compat mode and non-compat 32-bit CS should both segfault. */
- warn_bad_vsyscall(KERN_WARNING, regs,
- "illegal int 0xcc from 32-bit mode");
- goto sigsegv;
+ WARN_ON_ONCE(address != regs->ip);
+
+ if (vsyscall_mode == NONE) {
+ warn_bad_vsyscall(KERN_INFO, regs,
+ "vsyscall attempted with vsyscall=none");
+ return false;
}
- /*
- * x86-ism here: regs->ip points to the instruction after the int 0xcc,
- * and int 0xcc is two bytes long.
- */
- vsyscall_nr = addr_to_vsyscall_nr(regs->ip - 2);
+ vsyscall_nr = addr_to_vsyscall_nr(address);
+
+ trace_emulate_vsyscall(vsyscall_nr);
+
if (vsyscall_nr < 0) {
warn_bad_vsyscall(KERN_WARNING, regs,
- "illegal int 0xcc (exploit attempt?)");
+ "misaligned vsyscall (exploit attempt or buggy program) -- look up the vsyscall kernel parameter if you need a workaround");
goto sigsegv;
}
if (get_user(caller, (unsigned long __user *)regs->sp) != 0) {
- warn_bad_vsyscall(KERN_WARNING, regs, "int 0xcc with bad stack (exploit attempt?)");
+ warn_bad_vsyscall(KERN_WARNING, regs,
+ "vsyscall with bad stack (exploit attempt?)");
goto sigsegv;
}
regs->ip = caller;
regs->sp += 8;
- local_irq_disable();
- return;
+ return true;
sigsegv:
- regs->ip -= 2; /* The faulting instruction should be the int 0xcc. */
force_sig(SIGSEGV, current);
- local_irq_disable();
+ return true;
}
/*
void __init map_vsyscall(void)
{
- extern char __vsyscall_0;
- unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+ extern char __vsyscall_page;
+ unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page);
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(VSYSCALL_FIRST_PAGE, physaddr_vsyscall,
+ vsyscall_mode == NATIVE
+ ? PAGE_KERNEL_VSYSCALL
+ : PAGE_KERNEL_VVAR);
+ BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_FIRST_PAGE) !=
+ (unsigned long)VSYSCALL_START);
+
__set_fixmap(VVAR_PAGE, physaddr_vvar_page, PAGE_KERNEL_VVAR);
- BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) != (unsigned long)VVAR_ADDRESS);
+ BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) !=
+ (unsigned long)VVAR_ADDRESS);
}
static int __init vsyscall_init(void)
*/
#include <linux/linkage.h>
+
#include <asm/irq_vectors.h>
+#include <asm/page_types.h>
+#include <asm/unistd_64.h>
+
+__PAGE_ALIGNED_DATA
+ .globl __vsyscall_page
+ .balign PAGE_SIZE, 0xcc
+ .type __vsyscall_page, @object
+__vsyscall_page:
+
+ mov $__NR_gettimeofday, %rax
+ syscall
+ ret
-/* The unused parts of the page are filled with 0xcc by the linker script. */
+ .balign 1024, 0xcc
+ mov $__NR_time, %rax
+ syscall
+ ret
-.section .vsyscall_0, "a"
-ENTRY(vsyscall_0)
- int $VSYSCALL_EMU_VECTOR
-END(vsyscall_0)
+ .balign 1024, 0xcc
+ mov $__NR_getcpu, %rax
+ syscall
+ ret
-.section .vsyscall_1, "a"
-ENTRY(vsyscall_1)
- int $VSYSCALL_EMU_VECTOR
-END(vsyscall_1)
+ .balign 4096, 0xcc
-.section .vsyscall_2, "a"
-ENTRY(vsyscall_2)
- int $VSYSCALL_EMU_VECTOR
-END(vsyscall_2)
+ .size __vsyscall_page, 4096
--- /dev/null
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vsyscall
+
+#if !defined(__VSYSCALL_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __VSYSCALL_TRACE_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(emulate_vsyscall,
+
+ TP_PROTO(int nr),
+
+ TP_ARGS(nr),
+
+ TP_STRUCT__entry(__field(int, nr)),
+
+ TP_fast_assign(
+ __entry->nr = nr;
+ ),
+
+ TP_printk("nr = %d", __entry->nr)
+);
+
+#endif
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ../../arch/x86/kernel
+#define TRACE_INCLUDE_FILE vsyscall_trace
+#include <trace/define_trace.h>
* but for now it's good enough to assume that long
* mode only uses well known segments or kernel.
*/
- return (!user_mode(regs)) || (regs->cs == __USER_CS);
+ return (!user_mode(regs) || user_64bit_mode(regs));
#endif
case 0x60:
/* 0x64 thru 0x67 are valid prefixes in all modes. */
if (is_errata100(regs, address))
return;
+#ifdef CONFIG_X86_64
+ /*
+ * Instruction fetch faults in the vsyscall page might need
+ * emulation.
+ */
+ if (unlikely((error_code & PF_INSTR) &&
+ ((address & ~0xfff) == VSYSCALL_START))) {
+ if (emulate_vsyscall(regs, address))
+ return;
+ }
+#endif
+
if (unlikely(show_unhandled_signals))
show_signal_msg(regs, error_code, address, tsk);
vdso_start:
.incbin "arch/x86/vdso/vdso.so"
vdso_end:
+ .align PAGE_SIZE /* extra data here leaks to userspace. */
.previous
.paravirt_enabled = 1,
.shared_kernel_pmd = 0,
+#ifdef CONFIG_X86_64
+ .extra_user_64bit_cs = FLAT_USER_CS64,
+#endif
+
.name = "Xen",
};
# endif
#else
case VSYSCALL_LAST_PAGE ... VSYSCALL_FIRST_PAGE:
+ case VVAR_PAGE:
#endif
case FIX_TEXT_POKE0:
case FIX_TEXT_POKE1:
#ifdef CONFIG_X86_64
/* Replicate changes to map the vsyscall page into the user
pagetable vsyscall mapping. */
- if (idx >= VSYSCALL_LAST_PAGE && idx <= VSYSCALL_FIRST_PAGE) {
+ if ((idx >= VSYSCALL_LAST_PAGE && idx <= VSYSCALL_FIRST_PAGE) ||
+ idx == VVAR_PAGE) {
unsigned long vaddr = __fix_to_virt(idx);
set_pte_vaddr_pud(level3_user_vsyscall, vaddr, pte);
}
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