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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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1deb9c5dfb
The kernel was allowing any component of the pt_regs to be updated either by signal handlers writing to the stack, or by processes writing via PTRACE_POKEUSR or PTRACE_SETREGS, which meant they could set their PL up from 0 to 1 and get access to kernel code and data (or, in practice, cause a kernel panic). We now always reset the ex1 field, allowing the user to set their ICS bit only. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
205 lines
5.1 KiB
C
205 lines
5.1 KiB
C
/*
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* Copyright 2010 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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*
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* Copied from i386: Ross Biro 1/23/92
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*/
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#include <linux/kernel.h>
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#include <linux/ptrace.h>
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#include <linux/kprobes.h>
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#include <linux/compat.h>
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#include <linux/uaccess.h>
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#include <asm/traps.h>
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void user_enable_single_step(struct task_struct *child)
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{
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set_tsk_thread_flag(child, TIF_SINGLESTEP);
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}
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void user_disable_single_step(struct task_struct *child)
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{
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clear_tsk_thread_flag(child, TIF_SINGLESTEP);
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}
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/*
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* Called by kernel/ptrace.c when detaching..
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*/
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void ptrace_disable(struct task_struct *child)
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{
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clear_tsk_thread_flag(child, TIF_SINGLESTEP);
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/*
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* These two are currently unused, but will be set by arch_ptrace()
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* and used in the syscall assembly when we do support them.
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*/
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clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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}
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long arch_ptrace(struct task_struct *child, long request,
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unsigned long addr, unsigned long data)
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{
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unsigned long __user *datap = (long __user __force *)data;
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unsigned long tmp;
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long ret = -EIO;
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char *childreg;
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struct pt_regs copyregs;
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int ex1_offset;
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switch (request) {
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case PTRACE_PEEKUSR: /* Read register from pt_regs. */
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if (addr >= PTREGS_SIZE)
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break;
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childreg = (char *)task_pt_regs(child) + addr;
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#ifdef CONFIG_COMPAT
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if (is_compat_task()) {
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if (addr & (sizeof(compat_long_t)-1))
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break;
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ret = put_user(*(compat_long_t *)childreg,
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(compat_long_t __user *)datap);
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} else
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#endif
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{
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if (addr & (sizeof(long)-1))
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break;
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ret = put_user(*(long *)childreg, datap);
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}
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break;
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case PTRACE_POKEUSR: /* Write register in pt_regs. */
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if (addr >= PTREGS_SIZE)
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break;
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childreg = (char *)task_pt_regs(child) + addr;
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/* Guard against overwrites of the privilege level. */
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ex1_offset = PTREGS_OFFSET_EX1;
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#if defined(CONFIG_COMPAT) && defined(__BIG_ENDIAN)
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if (is_compat_task()) /* point at low word */
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ex1_offset += sizeof(compat_long_t);
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#endif
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if (addr == ex1_offset)
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data = PL_ICS_EX1(USER_PL, EX1_ICS(data));
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#ifdef CONFIG_COMPAT
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if (is_compat_task()) {
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if (addr & (sizeof(compat_long_t)-1))
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break;
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*(compat_long_t *)childreg = data;
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} else
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#endif
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{
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if (addr & (sizeof(long)-1))
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break;
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*(long *)childreg = data;
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}
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ret = 0;
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break;
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case PTRACE_GETREGS: /* Get all registers from the child. */
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if (copy_to_user(datap, task_pt_regs(child),
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sizeof(struct pt_regs)) == 0) {
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ret = 0;
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}
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break;
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case PTRACE_SETREGS: /* Set all registers in the child. */
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if (copy_from_user(©regs, datap,
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sizeof(struct pt_regs)) == 0) {
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copyregs.ex1 =
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PL_ICS_EX1(USER_PL, EX1_ICS(copyregs.ex1));
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*task_pt_regs(child) = copyregs;
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ret = 0;
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}
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break;
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case PTRACE_GETFPREGS: /* Get the child FPU state. */
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case PTRACE_SETFPREGS: /* Set the child FPU state. */
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break;
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case PTRACE_SETOPTIONS:
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/* Support TILE-specific ptrace options. */
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child->ptrace &= ~PT_TRACE_MASK_TILE;
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tmp = data & PTRACE_O_MASK_TILE;
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data &= ~PTRACE_O_MASK_TILE;
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ret = ptrace_request(child, request, addr, data);
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if (tmp & PTRACE_O_TRACEMIGRATE)
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child->ptrace |= PT_TRACE_MIGRATE;
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break;
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default:
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#ifdef CONFIG_COMPAT
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if (task_thread_info(current)->status & TS_COMPAT) {
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ret = compat_ptrace_request(child, request,
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addr, data);
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break;
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}
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#endif
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ret = ptrace_request(child, request, addr, data);
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break;
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}
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return ret;
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}
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#ifdef CONFIG_COMPAT
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/* Not used; we handle compat issues in arch_ptrace() directly. */
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long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
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compat_ulong_t addr, compat_ulong_t data)
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{
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BUG();
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}
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#endif
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void do_syscall_trace(void)
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{
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if (!test_thread_flag(TIF_SYSCALL_TRACE))
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return;
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if (!(current->ptrace & PT_PTRACED))
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return;
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/*
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* The 0x80 provides a way for the tracing parent to distinguish
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* between a syscall stop and SIGTRAP delivery
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*/
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ptrace_notify(SIGTRAP|((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
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/*
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* this isn't the same as continuing with a signal, but it will do
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* for normal use. strace only continues with a signal if the
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* stopping signal is not SIGTRAP. -brl
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*/
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if (current->exit_code) {
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send_sig(current->exit_code, current, 1);
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current->exit_code = 0;
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}
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}
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void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
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{
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struct siginfo info;
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memset(&info, 0, sizeof(info));
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info.si_signo = SIGTRAP;
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info.si_code = TRAP_BRKPT;
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info.si_addr = (void __user *) regs->pc;
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/* Send us the fakey SIGTRAP */
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force_sig_info(SIGTRAP, &info, tsk);
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}
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/* Handle synthetic interrupt delivered only by the simulator. */
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void __kprobes do_breakpoint(struct pt_regs* regs, int fault_num)
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{
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send_sigtrap(current, regs, fault_num);
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}
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