* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright 2003 Andi Kleen, SuSE Labs.
*
+ * [ NOTE: this mechanism is now deprecated in favor of the vDSO. ]
+ *
* Thanks to hpa@transmeta.com for some useful hint.
* Special thanks to Ingo Molnar for his early experience with
* a different vsyscall implementation for Linux/IA32 and for the name.
* vsyscalls. One vsyscall can reserve more than 1 slot to avoid
* jumping out of line if necessary. We cannot add more with this
* mechanism because older kernels won't return -ENOSYS.
- * If we want more than four we need a vDSO.
*
- * Note: the concept clashes with user mode linux. If you use UML and
- * want per guest time just set the kernel.vsyscall64 sysctl to 0.
+ * Note: the concept clashes with user mode linux. UML users should
+ * use the vDSO.
*/
/* Disable profiling for userspace code: */
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/notifier.h>
+#include <linux/syscalls.h>
+#include <linux/ratelimit.h>
#include <asm/vsyscall.h>
#include <asm/pgtable.h>
#include <asm/desc.h>
#include <asm/topology.h>
#include <asm/vgtod.h>
-
-#define __vsyscall(nr) \
- __attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace
-#define __syscall_clobber "r11","cx","memory"
+#include <asm/traps.h>
DEFINE_VVAR(int, vgetcpu_mode);
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
unsigned long flags;
write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
+
/* copy vsyscall data */
- vsyscall_gtod_data.clock.vread = clock->vread;
- vsyscall_gtod_data.clock.cycle_last = clock->cycle_last;
- vsyscall_gtod_data.clock.mask = clock->mask;
- vsyscall_gtod_data.clock.mult = mult;
- vsyscall_gtod_data.clock.shift = clock->shift;
- vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;
- vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;
- vsyscall_gtod_data.wall_to_monotonic = *wtm;
- vsyscall_gtod_data.wall_time_coarse = __current_kernel_time();
+ vsyscall_gtod_data.clock.vread = clock->vread;
+ vsyscall_gtod_data.clock.cycle_last = clock->cycle_last;
+ vsyscall_gtod_data.clock.mask = clock->mask;
+ vsyscall_gtod_data.clock.mult = mult;
+ vsyscall_gtod_data.clock.shift = clock->shift;
+ vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;
+ vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;
+ vsyscall_gtod_data.wall_to_monotonic = *wtm;
+ vsyscall_gtod_data.wall_time_coarse = __current_kernel_time();
+
write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
}
-/* RED-PEN may want to readd seq locking, but then the variable should be
- * write-once.
- */
-static __always_inline void do_get_tz(struct timezone * tz)
+static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
+ const char *message)
{
- *tz = VVAR(vsyscall_gtod_data).sys_tz;
-}
+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
+ struct task_struct *tsk;
-static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
-{
- int ret;
- asm volatile("syscall"
- : "=a" (ret)
- : "0" (__NR_gettimeofday),"D" (tv),"S" (tz)
- : __syscall_clobber );
- return ret;
-}
+ if (!show_unhandled_signals || !__ratelimit(&rs))
+ return;
-static __always_inline void do_vgettimeofday(struct timeval * tv)
-{
- cycle_t now, base, mask, cycle_delta;
- unsigned seq;
- unsigned long mult, shift, nsec;
- cycle_t (*vread)(void);
- do {
- seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
-
- vread = VVAR(vsyscall_gtod_data).clock.vread;
- if (unlikely(!vread)) {
- gettimeofday(tv,NULL);
- return;
- }
-
- now = vread();
- base = VVAR(vsyscall_gtod_data).clock.cycle_last;
- mask = VVAR(vsyscall_gtod_data).clock.mask;
- mult = VVAR(vsyscall_gtod_data).clock.mult;
- shift = VVAR(vsyscall_gtod_data).clock.shift;
-
- tv->tv_sec = VVAR(vsyscall_gtod_data).wall_time_sec;
- nsec = VVAR(vsyscall_gtod_data).wall_time_nsec;
- } while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
-
- /* calculate interval: */
- cycle_delta = (now - base) & mask;
- /* convert to nsecs: */
- nsec += (cycle_delta * mult) >> shift;
-
- while (nsec >= NSEC_PER_SEC) {
- tv->tv_sec += 1;
- nsec -= NSEC_PER_SEC;
- }
- tv->tv_usec = nsec / NSEC_PER_USEC;
-}
+ tsk = current;
-int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
-{
- if (tv)
- do_vgettimeofday(tv);
- if (tz)
- do_get_tz(tz);
- return 0;
+ printk("%s%s[%d] %s ip:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
+ level, tsk->comm, task_pid_nr(tsk),
+ message, regs->ip - 2, regs->sp, regs->ax, regs->si, regs->di);
}
-/* This will break when the xtime seconds get inaccurate, but that is
- * unlikely */
-time_t __vsyscall(1) vtime(time_t *t)
+void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
{
- unsigned seq;
- time_t result;
+ const char *vsyscall_name;
+ struct task_struct *tsk;
+ unsigned long caller;
+ int vsyscall_nr;
+ long ret;
+
+ /* Kernel code must never get here. */
+ BUG_ON(!user_mode(regs));
+
+ local_irq_enable();
+
+ /*
+ * x86-ism here: regs->ip points to the instruction after the int 0xcc,
+ * and int 0xcc is two bytes long.
+ */
+ if (!is_vsyscall_entry(regs->ip - 2)) {
+ warn_bad_vsyscall(KERN_WARNING, regs, "illegal int 0xcc (exploit attempt?)");
+ goto sigsegv;
+ }
+ vsyscall_nr = vsyscall_entry_nr(regs->ip - 2);
- do {
- seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
+ if (get_user(caller, (unsigned long __user *)regs->sp) != 0) {
+ warn_bad_vsyscall(KERN_WARNING, regs, "int 0xcc with bad stack (exploit attempt?)");
+ goto sigsegv;
+ }
- result = VVAR(vsyscall_gtod_data).wall_time_sec;
+ tsk = current;
+ if (seccomp_mode(&tsk->seccomp))
+ do_exit(SIGKILL);
+
+ switch (vsyscall_nr) {
+ case 0:
+ vsyscall_name = "gettimeofday";
+ ret = sys_gettimeofday(
+ (struct timeval __user *)regs->di,
+ (struct timezone __user *)regs->si);
+ break;
+
+ case 1:
+ vsyscall_name = "time";
+ ret = sys_time((time_t __user *)regs->di);
+ break;
+
+ case 2:
+ vsyscall_name = "getcpu";
+ ret = sys_getcpu((unsigned __user *)regs->di,
+ (unsigned __user *)regs->si,
+ 0);
+ break;
+
+ default:
+ /*
+ * If we get here, then vsyscall_nr indicates that int 0xcc
+ * happened at an address in the vsyscall page that doesn't
+ * contain int 0xcc. That can't happen.
+ */
+ BUG();
+ }
- } while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
+ if (ret == -EFAULT) {
+ /*
+ * Bad news -- userspace fed a bad pointer to a vsyscall.
+ *
+ * With a real vsyscall, that would have caused SIGSEGV.
+ * To make writing reliable exploits using the emulated
+ * vsyscalls harder, generate SIGSEGV here as well.
+ */
+ warn_bad_vsyscall(KERN_INFO, regs,
+ "vsyscall fault (exploit attempt?)");
+ goto sigsegv;
+ }
- if (t)
- *t = result;
- return result;
-}
+ regs->ax = ret;
-/* Fast way to get current CPU and node.
- This helps to do per node and per CPU caches in user space.
- The result is not guaranteed without CPU affinity, but usually
- works out because the scheduler tries to keep a thread on the same
- CPU.
+ /* Emulate a ret instruction. */
+ regs->ip = caller;
+ regs->sp += 8;
- tcache must point to a two element sized long array.
- All arguments can be NULL. */
-long __vsyscall(2)
-vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
-{
- unsigned int p;
- unsigned long j = 0;
-
- /* Fast cache - only recompute value once per jiffies and avoid
- relatively costly rdtscp/cpuid otherwise.
- This works because the scheduler usually keeps the process
- on the same CPU and this syscall doesn't guarantee its
- results anyways.
- We do this here because otherwise user space would do it on
- its own in a likely inferior way (no access to jiffies).
- If you don't like it pass NULL. */
- if (tcache && tcache->blob[0] == (j = VVAR(jiffies))) {
- p = tcache->blob[1];
- } else if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
- /* Load per CPU data from RDTSCP */
- native_read_tscp(&p);
- } else {
- /* Load per CPU data from GDT */
- asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
- }
- if (tcache) {
- tcache->blob[0] = j;
- tcache->blob[1] = p;
- }
- if (cpu)
- *cpu = p & 0xfff;
- if (node)
- *node = p >> 12;
- return 0;
+ local_irq_disable();
+ return;
+
+sigsegv:
+ regs->ip -= 2; /* The faulting instruction should be the int 0xcc. */
+ force_sig(SIGSEGV, current);
}
-/* Assume __initcall executes before all user space. Hopefully kmod
- doesn't violate that. We'll find out if it does. */
+/*
+ * Assume __initcall executes before all user space. Hopefully kmod
+ * doesn't violate that. We'll find out if it does.
+ */
static void __cpuinit vsyscall_set_cpu(int cpu)
{
unsigned long d;
if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP))
write_rdtscp_aux((node << 12) | cpu);
- /* Store cpu number in limit so that it can be loaded quickly
- in user space in vgetcpu.
- 12 bits for the CPU and 8 bits for the node. */
+ /*
+ * Store cpu number in limit so that it can be loaded quickly
+ * in user space in vgetcpu. (12 bits for the CPU and 8 bits for the node)
+ */
d = 0x0f40000000000ULL;
d |= cpu;
d |= (node & 0xf) << 12;
d |= (node >> 4) << 48;
+
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
}
cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
{
long cpu = (long)arg;
+
if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 1);
+
return NOTIFY_DONE;
}
/* 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);
+ BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) != (unsigned long)VVAR_ADDRESS);
}
static int __init vsyscall_init(void)
{
- BUG_ON(((unsigned long) &vgettimeofday !=
- VSYSCALL_ADDR(__NR_vgettimeofday)));
- BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
- BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
- BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu));
+ BUG_ON(VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE));
+
on_each_cpu(cpu_vsyscall_init, NULL, 1);
/* notifier priority > KVM */
hotcpu_notifier(cpu_vsyscall_notifier, 30);
+
return 0;
}
-
__initcall(vsyscall_init);
projects / kernel / kernel-generic.git / commitdiff