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linux/arch/arm64/kernel/signal32.c

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/*
* Based on arch/arm/kernel/signal.c
*
* Copyright (C) 1995-2009 Russell King
* Copyright (C) 2012 ARM Ltd.
* Modified by Will Deacon <will.deacon@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/ratelimit.h>
#include <asm/fpsimd.h>
#include <asm/signal32.h>
#include <asm/uaccess.h>
#include <asm/unistd32.h>
struct compat_sigcontext {
/* We always set these two fields to 0 */
compat_ulong_t trap_no;
compat_ulong_t error_code;
compat_ulong_t oldmask;
compat_ulong_t arm_r0;
compat_ulong_t arm_r1;
compat_ulong_t arm_r2;
compat_ulong_t arm_r3;
compat_ulong_t arm_r4;
compat_ulong_t arm_r5;
compat_ulong_t arm_r6;
compat_ulong_t arm_r7;
compat_ulong_t arm_r8;
compat_ulong_t arm_r9;
compat_ulong_t arm_r10;
compat_ulong_t arm_fp;
compat_ulong_t arm_ip;
compat_ulong_t arm_sp;
compat_ulong_t arm_lr;
compat_ulong_t arm_pc;
compat_ulong_t arm_cpsr;
compat_ulong_t fault_address;
};
struct compat_ucontext {
compat_ulong_t uc_flags;
compat_uptr_t uc_link;
compat_stack_t uc_stack;
struct compat_sigcontext uc_mcontext;
compat_sigset_t uc_sigmask;
int __unused[32 - (sizeof (compat_sigset_t) / sizeof (int))];
compat_ulong_t uc_regspace[128] __attribute__((__aligned__(8)));
};
struct compat_vfp_sigframe {
compat_ulong_t magic;
compat_ulong_t size;
struct compat_user_vfp {
compat_u64 fpregs[32];
compat_ulong_t fpscr;
} ufp;
struct compat_user_vfp_exc {
compat_ulong_t fpexc;
compat_ulong_t fpinst;
compat_ulong_t fpinst2;
} ufp_exc;
} __attribute__((__aligned__(8)));
#define VFP_MAGIC 0x56465001
#define VFP_STORAGE_SIZE sizeof(struct compat_vfp_sigframe)
struct compat_aux_sigframe {
struct compat_vfp_sigframe vfp;
/* Something that isn't a valid magic number for any coprocessor. */
unsigned long end_magic;
} __attribute__((__aligned__(8)));
struct compat_sigframe {
struct compat_ucontext uc;
compat_ulong_t retcode[2];
};
struct compat_rt_sigframe {
struct compat_siginfo info;
struct compat_sigframe sig;
};
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
/*
* For ARM syscalls, the syscall number has to be loaded into r7.
* We do not support an OABI userspace.
*/
#define MOV_R7_NR_SIGRETURN (0xe3a07000 | __NR_compat_sigreturn)
#define SVC_SYS_SIGRETURN (0xef000000 | __NR_compat_sigreturn)
#define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | __NR_compat_rt_sigreturn)
#define SVC_SYS_RT_SIGRETURN (0xef000000 | __NR_compat_rt_sigreturn)
/*
* For Thumb syscalls, we also pass the syscall number via r7. We therefore
* need two 16-bit instructions.
*/
#define SVC_THUMB_SIGRETURN (((0xdf00 | __NR_compat_sigreturn) << 16) | \
0x2700 | __NR_compat_sigreturn)
#define SVC_THUMB_RT_SIGRETURN (((0xdf00 | __NR_compat_rt_sigreturn) << 16) | \
0x2700 | __NR_compat_rt_sigreturn)
const compat_ulong_t aarch32_sigret_code[6] = {
/*
* AArch32 sigreturn code.
* We don't construct an OABI SWI - instead we just set the imm24 field
* to the EABI syscall number so that we create a sane disassembly.
*/
MOV_R7_NR_SIGRETURN, SVC_SYS_SIGRETURN, SVC_THUMB_SIGRETURN,
MOV_R7_NR_RT_SIGRETURN, SVC_SYS_RT_SIGRETURN, SVC_THUMB_RT_SIGRETURN,
};
static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
{
compat_sigset_t cset;
cset.sig[0] = set->sig[0] & 0xffffffffull;
cset.sig[1] = set->sig[0] >> 32;
return copy_to_user(uset, &cset, sizeof(*uset));
}
static inline int get_sigset_t(sigset_t *set,
const compat_sigset_t __user *uset)
{
compat_sigset_t s32;
if (copy_from_user(&s32, uset, sizeof(*uset)))
return -EFAULT;
set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
return 0;
}
int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
{
int err;
if (!access_ok(VERIFY_WRITE, to, sizeof(*to)))
return -EFAULT;
/* If you change siginfo_t structure, please be sure
* this code is fixed accordingly.
* It should never copy any pad contained in the structure
* to avoid security leaks, but must copy the generic
* 3 ints plus the relevant union member.
* This routine must convert siginfo from 64bit to 32bit as well
* at the same time.
*/
err = __put_user(from->si_signo, &to->si_signo);
err |= __put_user(from->si_errno, &to->si_errno);
err |= __put_user((short)from->si_code, &to->si_code);
if (from->si_code < 0)
err |= __copy_to_user(&to->_sifields._pad, &from->_sifields._pad,
SI_PAD_SIZE);
else switch (from->si_code & __SI_MASK) {
case __SI_KILL:
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
break;
case __SI_TIMER:
err |= __put_user(from->si_tid, &to->si_tid);
err |= __put_user(from->si_overrun, &to->si_overrun);
err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr,
&to->si_ptr);
break;
case __SI_POLL:
err |= __put_user(from->si_band, &to->si_band);
err |= __put_user(from->si_fd, &to->si_fd);
break;
case __SI_FAULT:
err |= __put_user((compat_uptr_t)(unsigned long)from->si_addr,
&to->si_addr);
#ifdef BUS_MCEERR_AO
/*
* Other callers might not initialize the si_lsb field,
* so check explicitely for the right codes here.
*/
if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
#endif
break;
case __SI_CHLD:
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user(from->si_status, &to->si_status);
err |= __put_user(from->si_utime, &to->si_utime);
err |= __put_user(from->si_stime, &to->si_stime);
break;
case __SI_RT: /* This is not generated by the kernel as of now. */
case __SI_MESGQ: /* But this is */
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr, &to->si_ptr);
break;
default: /* this is just in case for now ... */
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
break;
}
return err;
}
int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
memset(to, 0, sizeof *to);
if (copy_from_user(to, from, __ARCH_SI_PREAMBLE_SIZE) ||
copy_from_user(to->_sifields._pad,
from->_sifields._pad, SI_PAD_SIZE))
return -EFAULT;
return 0;
}
/*
* VFP save/restore code.
*/
static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
{
struct fpsimd_state *fpsimd = &current->thread.fpsimd_state;
compat_ulong_t magic = VFP_MAGIC;
compat_ulong_t size = VFP_STORAGE_SIZE;
compat_ulong_t fpscr, fpexc;
int err = 0;
/*
* Save the hardware registers to the fpsimd_state structure.
* Note that this also saves V16-31, which aren't visible
* in AArch32.
*/
fpsimd_save_state(fpsimd);
/* Place structure header on the stack */
__put_user_error(magic, &frame->magic, err);
__put_user_error(size, &frame->size, err);
/*
* Now copy the FP registers. Since the registers are packed,
* we can copy the prefix we want (V0-V15) as it is.
* FIXME: Won't work if big endian.
*/
err |= __copy_to_user(&frame->ufp.fpregs, fpsimd->vregs,
sizeof(frame->ufp.fpregs));
/* Create an AArch32 fpscr from the fpsr and the fpcr. */
fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
(fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
__put_user_error(fpscr, &frame->ufp.fpscr, err);
/*
* The exception register aren't available so we fake up a
* basic FPEXC and zero everything else.
*/
fpexc = (1 << 30);
__put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
__put_user_error(0, &frame->ufp_exc.fpinst, err);
__put_user_error(0, &frame->ufp_exc.fpinst2, err);
return err ? -EFAULT : 0;
}
static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
{
struct fpsimd_state fpsimd;
compat_ulong_t magic = VFP_MAGIC;
compat_ulong_t size = VFP_STORAGE_SIZE;
compat_ulong_t fpscr;
int err = 0;
__get_user_error(magic, &frame->magic, err);
__get_user_error(size, &frame->size, err);
if (err)
return -EFAULT;
if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
return -EINVAL;
/*
* Copy the FP registers into the start of the fpsimd_state.
* FIXME: Won't work if big endian.
*/
err |= __copy_from_user(fpsimd.vregs, frame->ufp.fpregs,
sizeof(frame->ufp.fpregs));
/* Extract the fpsr and the fpcr from the fpscr */
__get_user_error(fpscr, &frame->ufp.fpscr, err);
fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
/*
* We don't need to touch the exception register, so
* reload the hardware state.
*/
if (!err) {
preempt_disable();
fpsimd_load_state(&fpsimd);
preempt_enable();
}
return err ? -EFAULT : 0;
}
static int compat_restore_sigframe(struct pt_regs *regs,
struct compat_sigframe __user *sf)
{
int err;
sigset_t set;
struct compat_aux_sigframe __user *aux;
err = get_sigset_t(&set, &sf->uc.uc_sigmask);
if (err == 0) {
sigdelsetmask(&set, ~_BLOCKABLE);
set_current_blocked(&set);
}
__get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
__get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
__get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
__get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
__get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
__get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
__get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
__get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
__get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
__get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
__get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
__get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
__get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
__get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
__get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
__get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
__get_user_error(regs->pstate, &sf->uc.uc_mcontext.arm_cpsr, err);
/*
* Avoid compat_sys_sigreturn() restarting.
*/
regs->syscallno = ~0UL;
err |= !valid_user_regs(&regs->user_regs);
aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
if (err == 0)
err |= compat_restore_vfp_context(&aux->vfp);
return err;
}
asmlinkage int compat_sys_sigreturn(struct pt_regs *regs)
{
struct compat_sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (regs->compat_sp & 7)
goto badframe;
frame = (struct compat_sigframe __user *)regs->compat_sp;
if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
goto badframe;
if (compat_restore_sigframe(regs, frame))
goto badframe;
return regs->regs[0];
badframe:
if (show_unhandled_signals)
pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
current->comm, task_pid_nr(current), __func__,
regs->pc, regs->sp);
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int compat_sys_rt_sigreturn(struct pt_regs *regs)
{
struct compat_rt_sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (regs->compat_sp & 7)
goto badframe;
frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
goto badframe;
if (compat_restore_sigframe(regs, &frame->sig))
goto badframe;
if (compat_restore_altstack(&frame->sig.uc.uc_stack))
goto badframe;
return regs->regs[0];
badframe:
if (show_unhandled_signals)
pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
current->comm, task_pid_nr(current), __func__,
regs->pc, regs->sp);
force_sig(SIGSEGV, current);
return 0;
}
static void __user *compat_get_sigframe(struct k_sigaction *ka,
struct pt_regs *regs,
int framesize)
{
compat_ulong_t sp = regs->compat_sp;
void __user *frame;
/*
* This is the X/Open sanctioned signal stack switching.
*/
if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
/*
* ATPCS B01 mandates 8-byte alignment
*/
frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));
/*
* Check that we can actually write to the signal frame.
*/
if (!access_ok(VERIFY_WRITE, frame, framesize))
frame = NULL;
return frame;
}
static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
compat_ulong_t __user *rc, void __user *frame,
int usig)
{
compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
compat_ulong_t retcode;
compat_ulong_t spsr = regs->pstate & ~PSR_f;
int thumb;
/* Check if the handler is written for ARM or Thumb */
thumb = handler & 1;
if (thumb) {
spsr |= COMPAT_PSR_T_BIT;
spsr &= ~COMPAT_PSR_IT_MASK;
} else {
spsr &= ~COMPAT_PSR_T_BIT;
}
if (ka->sa.sa_flags & SA_RESTORER) {
retcode = ptr_to_compat(ka->sa.sa_restorer);
} else {
/* Set up sigreturn pointer */
unsigned int idx = thumb << 1;
if (ka->sa.sa_flags & SA_SIGINFO)
idx += 3;
retcode = AARCH32_VECTORS_BASE +
AARCH32_KERN_SIGRET_CODE_OFFSET +
(idx << 2) + thumb;
}
regs->regs[0] = usig;
regs->compat_sp = ptr_to_compat(frame);
regs->compat_lr = retcode;
regs->pc = handler;
regs->pstate = spsr;
}
static int compat_setup_sigframe(struct compat_sigframe __user *sf,
struct pt_regs *regs, sigset_t *set)
{
struct compat_aux_sigframe __user *aux;
int err = 0;
__put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
__put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
__put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
__put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
__put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
__put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
__put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
__put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
__put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
__put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
__put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
__put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
__put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
__put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
__put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
__put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
__put_user_error(regs->pstate, &sf->uc.uc_mcontext.arm_cpsr, err);
__put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
__put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.error_code, err);
__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
__put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
err |= put_sigset_t(&sf->uc.uc_sigmask, set);
aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
if (err == 0)
err |= compat_preserve_vfp_context(&aux->vfp);
__put_user_error(0, &aux->end_magic, err);
return err;
}
/*
* 32-bit signal handling routines called from signal.c
*/
int compat_setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct compat_rt_sigframe __user *frame;
int err = 0;
frame = compat_get_sigframe(ka, regs, sizeof(*frame));
if (!frame)
return 1;
err |= copy_siginfo_to_user32(&frame->info, info);
__put_user_error(0, &frame->sig.uc.uc_flags, err);
__put_user_error(0, &frame->sig.uc.uc_link, err);
err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
err |= compat_setup_sigframe(&frame->sig, regs, set);
if (err == 0) {
compat_setup_return(regs, ka, frame->sig.retcode, frame, usig);
regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
}
return err;
}
int compat_setup_frame(int usig, struct k_sigaction *ka, sigset_t *set,
struct pt_regs *regs)
{
struct compat_sigframe __user *frame;
int err = 0;
frame = compat_get_sigframe(ka, regs, sizeof(*frame));
if (!frame)
return 1;
__put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
err |= compat_setup_sigframe(frame, regs, set);
if (err == 0)
compat_setup_return(regs, ka, frame->retcode, frame, usig);
return err;
}
void compat_setup_restart_syscall(struct pt_regs *regs)
{
regs->regs[7] = __NR_compat_restart_syscall;
}
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