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![Linus Torvalds](/assets/img/avatar_default.png)
Pull force_sig() argument change from Eric Biederman: "A source of error over the years has been that force_sig has taken a task parameter when it is only safe to use force_sig with the current task. The force_sig function is built for delivering synchronous signals such as SIGSEGV where the userspace application caused a synchronous fault (such as a page fault) and the kernel responded with a signal. Because the name force_sig does not make this clear, and because the force_sig takes a task parameter the function force_sig has been abused for sending other kinds of signals over the years. Slowly those have been fixed when the oopses have been tracked down. This set of changes fixes the remaining abusers of force_sig and carefully rips out the task parameter from force_sig and friends making this kind of error almost impossible in the future" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits) signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus signal: Remove the signal number and task parameters from force_sig_info signal: Factor force_sig_info_to_task out of force_sig_info signal: Generate the siginfo in force_sig signal: Move the computation of force into send_signal and correct it. signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal signal: Remove the task parameter from force_sig_fault signal: Use force_sig_fault_to_task for the two calls that don't deliver to current signal: Explicitly call force_sig_fault on current signal/unicore32: Remove tsk parameter from __do_user_fault signal/arm: Remove tsk parameter from __do_user_fault signal/arm: Remove tsk parameter from ptrace_break signal/nds32: Remove tsk parameter from send_sigtrap signal/riscv: Remove tsk parameter from do_trap signal/sh: Remove tsk parameter from force_sig_info_fault signal/um: Remove task parameter from send_sigtrap signal/x86: Remove task parameter from send_sigtrap signal: Remove task parameter from force_sig_mceerr signal: Remove task parameter from force_sig signal: Remove task parameter from force_sigsegv ...
322 lines
8.3 KiB
C
322 lines
8.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* OpenRISC signal.c
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*
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* Linux architectural port borrowing liberally from similar works of
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* others. All original copyrights apply as per the original source
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* declaration.
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*
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* Modifications for the OpenRISC architecture:
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* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
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* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
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*/
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/wait.h>
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#include <linux/ptrace.h>
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#include <linux/unistd.h>
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#include <linux/stddef.h>
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#include <linux/tracehook.h>
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#include <asm/processor.h>
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#include <asm/syscall.h>
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#include <asm/ucontext.h>
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#include <linux/uaccess.h>
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#define DEBUG_SIG 0
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struct rt_sigframe {
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struct siginfo info;
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struct ucontext uc;
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unsigned char retcode[16]; /* trampoline code */
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};
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static int restore_sigcontext(struct pt_regs *regs,
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struct sigcontext __user *sc)
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{
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int err = 0;
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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/*
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* Restore the regs from &sc->regs.
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* (sc is already checked since the sigframe was
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* checked in sys_sigreturn previously)
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*/
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err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
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err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long));
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err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long));
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/* make sure the SM-bit is cleared so user-mode cannot fool us */
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regs->sr &= ~SPR_SR_SM;
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regs->orig_gpr11 = -1; /* Avoid syscall restart checks */
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/* TODO: the other ports use regs->orig_XX to disable syscall checks
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* after this completes, but we don't use that mechanism. maybe we can
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* use it now ?
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*/
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return err;
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}
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asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
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{
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struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
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sigset_t set;
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/*
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* Since we stacked the signal on a dword boundary,
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* then frame should be dword aligned here. If it's
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* not, then the user is trying to mess with us.
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*/
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if (((long)frame) & 3)
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goto badframe;
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if (!access_ok(frame, sizeof(*frame)))
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goto badframe;
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if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
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goto badframe;
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set_current_blocked(&set);
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if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
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goto badframe;
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if (restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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return regs->gpr[11];
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badframe:
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force_sig(SIGSEGV);
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return 0;
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}
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/*
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* Set up a signal frame.
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*/
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static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
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{
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int err = 0;
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/* copy the regs */
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/* There should be no need to save callee-saved registers here...
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* ...but we save them anyway. Revisit this
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*/
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err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
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err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long));
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err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long));
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return err;
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}
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static inline unsigned long align_sigframe(unsigned long sp)
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{
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return sp & ~3UL;
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}
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/*
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* Work out where the signal frame should go. It's either on the user stack
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* or the alternate stack.
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*/
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static inline void __user *get_sigframe(struct ksignal *ksig,
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struct pt_regs *regs, size_t frame_size)
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{
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unsigned long sp = regs->sp;
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/* redzone */
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sp -= STACK_FRAME_OVERHEAD;
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sp = sigsp(sp, ksig);
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sp = align_sigframe(sp - frame_size);
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return (void __user *)sp;
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}
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/* grab and setup a signal frame.
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*
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* basically we stack a lot of state info, and arrange for the
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* user-mode program to return to the kernel using either a
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* trampoline which performs the syscall sigreturn, or a provided
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* user-mode trampoline.
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*/
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static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
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struct pt_regs *regs)
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{
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struct rt_sigframe *frame;
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unsigned long return_ip;
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int err = 0;
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frame = get_sigframe(ksig, regs, sizeof(*frame));
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if (!access_ok(frame, sizeof(*frame)))
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return -EFAULT;
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/* Create siginfo. */
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if (ksig->ka.sa.sa_flags & SA_SIGINFO)
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err |= copy_siginfo_to_user(&frame->info, &ksig->info);
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(NULL, &frame->uc.uc_link);
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err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
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err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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return -EFAULT;
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/* trampoline - the desired return ip is the retcode itself */
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return_ip = (unsigned long)&frame->retcode;
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/* This is:
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l.ori r11,r0,__NR_sigreturn
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l.sys 1
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*/
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err |= __put_user(0xa960, (short *)(frame->retcode + 0));
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err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
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err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
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err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
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if (err)
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return -EFAULT;
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/* Set up registers for signal handler */
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regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
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regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
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regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */
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regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
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regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
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/* actually move the usp to reflect the stacked frame */
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regs->sp = (unsigned long)frame;
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return 0;
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}
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static inline void
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handle_signal(struct ksignal *ksig, struct pt_regs *regs)
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{
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int ret;
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ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
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signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
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}
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/*
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* Note that 'init' is a special process: it doesn't get signals it doesn't
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* want to handle. Thus you cannot kill init even with a SIGKILL even by
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* mistake.
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*
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* Also note that the regs structure given here as an argument, is the latest
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* pushed pt_regs. It may or may not be the same as the first pushed registers
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* when the initial usermode->kernelmode transition took place. Therefore
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* we can use user_mode(regs) to see if we came directly from kernel or user
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* mode below.
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*/
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int do_signal(struct pt_regs *regs, int syscall)
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{
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struct ksignal ksig;
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unsigned long continue_addr = 0;
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unsigned long restart_addr = 0;
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unsigned long retval = 0;
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int restart = 0;
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if (syscall) {
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continue_addr = regs->pc;
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restart_addr = continue_addr - 4;
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retval = regs->gpr[11];
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/*
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* Setup syscall restart here so that a debugger will
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* see the already changed PC.
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*/
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switch (retval) {
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case -ERESTART_RESTARTBLOCK:
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restart = -2;
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/* Fall through */
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case -ERESTARTNOHAND:
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case -ERESTARTSYS:
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case -ERESTARTNOINTR:
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restart++;
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regs->gpr[11] = regs->orig_gpr11;
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regs->pc = restart_addr;
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break;
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}
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}
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/*
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* Get the signal to deliver. During the call to get_signal the
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* debugger may change all our registers so we may need to revert
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* the decision to restart the syscall; specifically, if the PC is
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* changed, don't restart the syscall.
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*/
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if (get_signal(&ksig)) {
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if (unlikely(restart) && regs->pc == restart_addr) {
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if (retval == -ERESTARTNOHAND ||
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retval == -ERESTART_RESTARTBLOCK
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|| (retval == -ERESTARTSYS
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&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
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/* No automatic restart */
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regs->gpr[11] = -EINTR;
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regs->pc = continue_addr;
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}
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}
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handle_signal(&ksig, regs);
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} else {
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/* no handler */
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restore_saved_sigmask();
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/*
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* Restore pt_regs PC as syscall restart will be handled by
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* kernel without return to userspace
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*/
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if (unlikely(restart) && regs->pc == restart_addr) {
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regs->pc = continue_addr;
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return restart;
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}
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}
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return 0;
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}
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asmlinkage int
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do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
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{
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do {
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if (likely(thread_flags & _TIF_NEED_RESCHED)) {
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schedule();
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} else {
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if (unlikely(!user_mode(regs)))
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return 0;
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local_irq_enable();
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if (thread_flags & _TIF_SIGPENDING) {
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int restart = do_signal(regs, syscall);
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if (unlikely(restart)) {
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/*
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* Restart without handlers.
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* Deal with it without leaving
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* the kernel space.
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*/
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return restart;
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}
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syscall = 0;
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} else {
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clear_thread_flag(TIF_NOTIFY_RESUME);
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tracehook_notify_resume(regs);
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}
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}
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local_irq_disable();
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thread_flags = current_thread_info()->flags;
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} while (thread_flags & _TIF_WORK_MASK);
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return 0;
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}
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