diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/vsyscall.h | 12 | ||||
| -rw-r--r-- | arch/x86/kernel/vsyscall_64.c | 61 |
2 files changed, 41 insertions, 32 deletions
diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h index bb710cb0cdc1..d55597351f6a 100644 --- a/arch/x86/include/asm/vsyscall.h +++ b/arch/x86/include/asm/vsyscall.h @@ -31,18 +31,6 @@ extern struct timezone sys_tz; extern void map_vsyscall(void); -/* Emulation */ - -static inline bool is_vsyscall_entry(unsigned long addr) -{ - return (addr & ~0xC00UL) == VSYSCALL_START; -} - -static inline int vsyscall_entry_nr(unsigned long addr) -{ - return (addr & 0xC00UL) >> 10; -} - #endif /* __KERNEL__ */ #endif /* _ASM_X86_VSYSCALL_H */ diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c index 10cd8ac3395a..a262400c3479 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -38,6 +38,7 @@ #include <asm/vsyscall.h> #include <asm/pgtable.h> +#include <asm/compat.h> #include <asm/page.h> #include <asm/unistd.h> #include <asm/fixmap.h> @@ -97,33 +98,63 @@ static void warn_bad_vsyscall(const char *level, struct pt_regs *regs, tsk = current; - printk("%s%s[%d] %s ip:%lx sp:%lx ax:%lx si:%lx di:%lx\n", + 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->sp, regs->ax, regs->si, regs->di); + message, regs->ip - 2, regs->cs, + regs->sp, regs->ax, regs->si, regs->di); +} + +static int addr_to_vsyscall_nr(unsigned long addr) +{ + int nr; + + if ((addr & ~0xC00UL) != VSYSCALL_START) + return -EINVAL; + + nr = (addr & 0xC00UL) >> 10; + if (nr >= 3) + return -EINVAL; + + return nr; } void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code) { - 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(); /* + * Real 64-bit user mode code has cs == __USER_CS. Anything else + * is bogus. + */ + 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; + } + + /* * 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?)"); + vsyscall_nr = addr_to_vsyscall_nr(regs->ip - 2); + if (vsyscall_nr < 0) { + warn_bad_vsyscall(KERN_WARNING, regs, + "illegal int 0xcc (exploit attempt?)"); goto sigsegv; } - vsyscall_nr = vsyscall_entry_nr(regs->ip - 2); if (get_user(caller, (unsigned long __user *)regs->sp) != 0) { warn_bad_vsyscall(KERN_WARNING, regs, "int 0xcc with bad stack (exploit attempt?)"); @@ -136,31 +167,20 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code) 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(); } if (ret == -EFAULT) { @@ -188,6 +208,7 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code) sigsegv: regs->ip -= 2; /* The faulting instruction should be the int 0xcc. */ force_sig(SIGSEGV, current); + local_irq_disable(); } /* |