summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/vsyscall_64.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/vsyscall_64.c')
-rw-r--r--arch/x86/kernel/vsyscall_64.c90
1 files changed, 54 insertions, 36 deletions
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index dda7dff9cef7..b56c65de384d 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -18,9 +18,6 @@
* use the vDSO.
*/
-/* Disable profiling for userspace code: */
-#define DISABLE_BRANCH_PROFILING
-
#include <linux/time.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -50,12 +47,36 @@
#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 = NATIVE;
+
+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;
@@ -100,7 +121,7 @@ static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
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);
}
@@ -118,46 +139,39 @@ static int addr_to_vsyscall_nr(unsigned long addr)
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;
}
@@ -202,13 +216,11 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
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;
}
/*
@@ -256,15 +268,21 @@ cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
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)