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alistair23-linux/arch/alpha/kernel/signal.c
Linus Torvalds 96d4f267e4 Remove 'type' argument from access_ok() function 
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-03 18:57:57 -08:00

542 lines
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// SPDX-License-Identifier: GPL-2.0
/*
* linux/arch/alpha/kernel/signal.c
*
* Copyright (C) 1995 Linus Torvalds
*
* 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
*/
#include <linux/sched/signal.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/bitops.h>
#include <linux/syscalls.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include "proto.h"
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
asmlinkage void ret_from_sys_call(void);
/*
* The OSF/1 sigprocmask calling sequence is different from the
* C sigprocmask() sequence..
*/
SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
{
sigset_t oldmask;
sigset_t mask;
unsigned long res;
siginitset(&mask, newmask & _BLOCKABLE);
res = sigprocmask(how, &mask, &oldmask);
if (!res) {
force_successful_syscall_return();
res = oldmask.sig[0];
}
return res;
}
SYSCALL_DEFINE3(osf_sigaction, int, sig,
const struct osf_sigaction __user *, act,
struct osf_sigaction __user *, oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (!access_ok(act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
__get_user(mask, &act->sa_mask))
return -EFAULT;
siginitset(&new_ka.sa.sa_mask, mask);
new_ka.ka_restorer = NULL;
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (!access_ok(oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
return -EFAULT;
}
return ret;
}
SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
struct sigaction __user *, oact,
size_t, sigsetsize, void __user *, restorer)
{
struct k_sigaction new_ka, old_ka;
int ret;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (act) {
new_ka.ka_restorer = restorer;
if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
return -EFAULT;
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
return -EFAULT;
}
return ret;
}
/*
* Do a signal return; undo the signal stack.
*/
#if _NSIG_WORDS > 1
# error "Non SA_SIGINFO frame needs rearranging"
#endif
struct sigframe
{
struct sigcontext sc;
unsigned int retcode[3];
};
struct rt_sigframe
{
struct siginfo info;
struct ucontext uc;
unsigned int retcode[3];
};
/* If this changes, userland unwinders that Know Things about our signal
frame will break. Do not undertake lightly. It also implies an ABI
change wrt the size of siginfo_t, which may cause some pain. */
extern char compile_time_assert
[offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
#define INSN_MOV_R30_R16 0x47fe0410
#define INSN_LDI_R0 0x201f0000
#define INSN_CALLSYS 0x00000083
static long
restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
{
unsigned long usp;
struct switch_stack *sw = (struct switch_stack *)regs - 1;
long i, err = __get_user(regs->pc, &sc->sc_pc);
current->restart_block.fn = do_no_restart_syscall;
sw->r26 = (unsigned long) ret_from_sys_call;
err |= __get_user(regs->r0, sc->sc_regs+0);
err |= __get_user(regs->r1, sc->sc_regs+1);
err |= __get_user(regs->r2, sc->sc_regs+2);
err |= __get_user(regs->r3, sc->sc_regs+3);
err |= __get_user(regs->r4, sc->sc_regs+4);
err |= __get_user(regs->r5, sc->sc_regs+5);
err |= __get_user(regs->r6, sc->sc_regs+6);
err |= __get_user(regs->r7, sc->sc_regs+7);
err |= __get_user(regs->r8, sc->sc_regs+8);
err |= __get_user(sw->r9, sc->sc_regs+9);
err |= __get_user(sw->r10, sc->sc_regs+10);
err |= __get_user(sw->r11, sc->sc_regs+11);
err |= __get_user(sw->r12, sc->sc_regs+12);
err |= __get_user(sw->r13, sc->sc_regs+13);
err |= __get_user(sw->r14, sc->sc_regs+14);
err |= __get_user(sw->r15, sc->sc_regs+15);
err |= __get_user(regs->r16, sc->sc_regs+16);
err |= __get_user(regs->r17, sc->sc_regs+17);
err |= __get_user(regs->r18, sc->sc_regs+18);
err |= __get_user(regs->r19, sc->sc_regs+19);
err |= __get_user(regs->r20, sc->sc_regs+20);
err |= __get_user(regs->r21, sc->sc_regs+21);
err |= __get_user(regs->r22, sc->sc_regs+22);
err |= __get_user(regs->r23, sc->sc_regs+23);
err |= __get_user(regs->r24, sc->sc_regs+24);
err |= __get_user(regs->r25, sc->sc_regs+25);
err |= __get_user(regs->r26, sc->sc_regs+26);
err |= __get_user(regs->r27, sc->sc_regs+27);
err |= __get_user(regs->r28, sc->sc_regs+28);
err |= __get_user(regs->gp, sc->sc_regs+29);
err |= __get_user(usp, sc->sc_regs+30);
wrusp(usp);
for (i = 0; i < 31; i++)
err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
err |= __get_user(sw->fp[31], &sc->sc_fpcr);
return err;
}
/* Note that this syscall is also used by setcontext(3) to install
a given sigcontext. This because it's impossible to set *all*
registers and transfer control from userland. */
asmlinkage void
do_sigreturn(struct sigcontext __user *sc)
{
struct pt_regs *regs = current_pt_regs();
sigset_t set;
/* Verify that it's a good sigcontext before using it */
if (!access_ok(sc, sizeof(*sc)))
goto give_sigsegv;
if (__get_user(set.sig[0], &sc->sc_mask))
goto give_sigsegv;
set_current_blocked(&set);
if (restore_sigcontext(sc, regs))
goto give_sigsegv;
/* Send SIGTRAP if we're single-stepping: */
if (ptrace_cancel_bpt (current)) {
send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
current);
}
return;
give_sigsegv:
force_sig(SIGSEGV, current);
}
asmlinkage void
do_rt_sigreturn(struct rt_sigframe __user *frame)
{
struct pt_regs *regs = current_pt_regs();
sigset_t set;
/* Verify that it's a good ucontext_t before using it */
if (!access_ok(&frame->uc, sizeof(frame->uc)))
goto give_sigsegv;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto give_sigsegv;
set_current_blocked(&set);
if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
goto give_sigsegv;
/* Send SIGTRAP if we're single-stepping: */
if (ptrace_cancel_bpt (current)) {
send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
current);
}
return;
give_sigsegv:
force_sig(SIGSEGV, current);
}
/*
* Set up a signal frame.
*/
static inline void __user *
get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
{
return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
}
static long
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
unsigned long mask, unsigned long sp)
{
struct switch_stack *sw = (struct switch_stack *)regs - 1;
long i, err = 0;
err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
err |= __put_user(mask, &sc->sc_mask);
err |= __put_user(regs->pc, &sc->sc_pc);
err |= __put_user(8, &sc->sc_ps);
err |= __put_user(regs->r0 , sc->sc_regs+0);
err |= __put_user(regs->r1 , sc->sc_regs+1);
err |= __put_user(regs->r2 , sc->sc_regs+2);
err |= __put_user(regs->r3 , sc->sc_regs+3);
err |= __put_user(regs->r4 , sc->sc_regs+4);
err |= __put_user(regs->r5 , sc->sc_regs+5);
err |= __put_user(regs->r6 , sc->sc_regs+6);
err |= __put_user(regs->r7 , sc->sc_regs+7);
err |= __put_user(regs->r8 , sc->sc_regs+8);
err |= __put_user(sw->r9 , sc->sc_regs+9);
err |= __put_user(sw->r10 , sc->sc_regs+10);
err |= __put_user(sw->r11 , sc->sc_regs+11);
err |= __put_user(sw->r12 , sc->sc_regs+12);
err |= __put_user(sw->r13 , sc->sc_regs+13);
err |= __put_user(sw->r14 , sc->sc_regs+14);
err |= __put_user(sw->r15 , sc->sc_regs+15);
err |= __put_user(regs->r16, sc->sc_regs+16);
err |= __put_user(regs->r17, sc->sc_regs+17);
err |= __put_user(regs->r18, sc->sc_regs+18);
err |= __put_user(regs->r19, sc->sc_regs+19);
err |= __put_user(regs->r20, sc->sc_regs+20);
err |= __put_user(regs->r21, sc->sc_regs+21);
err |= __put_user(regs->r22, sc->sc_regs+22);
err |= __put_user(regs->r23, sc->sc_regs+23);
err |= __put_user(regs->r24, sc->sc_regs+24);
err |= __put_user(regs->r25, sc->sc_regs+25);
err |= __put_user(regs->r26, sc->sc_regs+26);
err |= __put_user(regs->r27, sc->sc_regs+27);
err |= __put_user(regs->r28, sc->sc_regs+28);
err |= __put_user(regs->gp , sc->sc_regs+29);
err |= __put_user(sp, sc->sc_regs+30);
err |= __put_user(0, sc->sc_regs+31);
for (i = 0; i < 31; i++)
err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
err |= __put_user(0, sc->sc_fpregs+31);
err |= __put_user(sw->fp[31], &sc->sc_fpcr);
err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
return err;
}
static int
setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
unsigned long oldsp, r26, err = 0;
struct sigframe __user *frame;
oldsp = rdusp();
frame = get_sigframe(ksig, oldsp, sizeof(*frame));
if (!access_ok(frame, sizeof(*frame)))
return -EFAULT;
err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
if (err)
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
r26 = (unsigned long) ksig->ka.ka_restorer;
if (!r26) {
err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
err |= __put_user(INSN_CALLSYS, frame->retcode+2);
imb();
r26 = (unsigned long) frame->retcode;
}
/* Check that everything was written properly. */
if (err)
return err;
/* "Return" to the handler */
regs->r26 = r26;
regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
regs->r16 = ksig->sig; /* a0: signal number */
regs->r17 = 0; /* a1: exception code */
regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
wrusp((unsigned long) frame);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->pc, regs->r26);
#endif
return 0;
}
static int
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
unsigned long oldsp, r26, err = 0;
struct rt_sigframe __user *frame;
oldsp = rdusp();
frame = get_sigframe(ksig, oldsp, sizeof(*frame));
if (!access_ok(frame, sizeof(*frame)))
return -EFAULT;
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
err |= __save_altstack(&frame->uc.uc_stack, oldsp);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
set->sig[0], oldsp);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
r26 = (unsigned long) ksig->ka.ka_restorer;
if (!r26) {
err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
frame->retcode+1);
err |= __put_user(INSN_CALLSYS, frame->retcode+2);
imb();
r26 = (unsigned long) frame->retcode;
}
if (err)
return -EFAULT;
/* "Return" to the handler */
regs->r26 = r26;
regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
regs->r16 = ksig->sig; /* a0: signal number */
regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */
wrusp((unsigned long) frame);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->pc, regs->r26);
#endif
return 0;
}
/*
* OK, we're invoking a handler.
*/
static inline void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
int ret;
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(ksig, oldset, regs);
else
ret = setup_frame(ksig, oldset, regs);
signal_setup_done(ret, ksig, 0);
}
static inline void
syscall_restart(unsigned long r0, unsigned long r19,
struct pt_regs *regs, struct k_sigaction *ka)
{
switch (regs->r0) {
case ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
case ERESTARTNOHAND:
regs->r0 = EINTR;
break;
}
/* fallthrough */
case ERESTARTNOINTR:
regs->r0 = r0; /* reset v0 and a3 and replay syscall */
regs->r19 = r19;
regs->pc -= 4;
break;
case ERESTART_RESTARTBLOCK:
regs->r0 = EINTR;
break;
}
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*
* "r0" and "r19" are the registers we need to restore for system call
* restart. "r0" is also used as an indicator whether we can restart at
* all (if we get here from anything but a syscall return, it will be 0)
*/
static void
do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
{
unsigned long single_stepping = ptrace_cancel_bpt(current);
struct ksignal ksig;
/* This lets the debugger run, ... */
if (get_signal(&ksig)) {
/* ... so re-check the single stepping. */
single_stepping |= ptrace_cancel_bpt(current);
/* Whee! Actually deliver the signal. */
if (r0)
syscall_restart(r0, r19, regs, &ksig.ka);
handle_signal(&ksig, regs);
} else {
single_stepping |= ptrace_cancel_bpt(current);
if (r0) {
switch (regs->r0) {
case ERESTARTNOHAND:
case ERESTARTSYS:
case ERESTARTNOINTR:
/* Reset v0 and a3 and replay syscall. */
regs->r0 = r0;
regs->r19 = r19;
regs->pc -= 4;
break;
case ERESTART_RESTARTBLOCK:
/* Set v0 to the restart_syscall and replay */
regs->r0 = __NR_restart_syscall;
regs->pc -= 4;
break;
}
}
restore_saved_sigmask();
}
if (single_stepping)
ptrace_set_bpt(current); /* re-set breakpoint */
}
void
do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
unsigned long r0, unsigned long r19)
{
do {
if (thread_flags & _TIF_NEED_RESCHED) {
schedule();
} else {
local_irq_enable();
if (thread_flags & _TIF_SIGPENDING) {
do_signal(regs, r0, r19);
r0 = 0;
} else {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
}
local_irq_disable();
thread_flags = current_thread_info()->flags;
} while (thread_flags & _TIF_WORK_MASK);
}
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