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linux/arch/s390/kernel/compat_signal.c
Eric W. Biederman ea64d5acc8 signal: Unify and correct copy_siginfo_to_user32 
Among the existing architecture specific versions of
copy_siginfo_to_user32 there are several different implementation
problems.  Some architectures fail to handle all of the cases in in
the siginfo union.  Some architectures perform a blind copy of the
siginfo union when the si_code is negative.  A blind copy suggests the
data is expected to be in 32bit siginfo format, which means that
receiving such a signal via signalfd won't work, or that the data is
in 64bit siginfo and the code is copying nonsense to userspace.

Create a single instance of copy_siginfo_to_user32 that all of the
architectures can share, and teach it to handle all of the cases in
the siginfo union correctly, with the assumption that siginfo is
stored internally to the kernel is 64bit siginfo format.

A special case is made for x86 x32 format.  This is needed as presence
of both x32 and ia32 on x86_64 results in two different 32bit signal
formats.  By allowing this small special case there winds up being
exactly one code base that needs to be maintained between all of the
architectures.  Vastly increasing the testing base and the chances of
finding bugs.

As the x86 copy of copy_siginfo_to_user32 the call of the x86
signal_compat_build_tests were moved into sigaction_compat_abi, so
that they will keep running.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-01-15 19:56:20 -06:00

429 lines
12 KiB
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2000, 2006
* Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
* Gerhard Tonn (ton@de.ibm.com)
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
*/
#include <linux/compat.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.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/stddef.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/lowcore.h>
#include <asm/switch_to.h>
#include "compat_linux.h"
#include "compat_ptrace.h"
#include "entry.h"
typedef struct
{
__u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
struct sigcontext32 sc;
_sigregs32 sregs;
int signo;
_sigregs_ext32 sregs_ext;
__u16 svc_insn; /* Offset of svc_insn is NOT fixed! */
} sigframe32;
typedef struct
{
__u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
__u16 svc_insn;
compat_siginfo_t info;
struct ucontext32 uc;
} rt_sigframe32;
/* Store registers needed to create the signal frame */
static void store_sigregs(void)
{
save_access_regs(current->thread.acrs);
save_fpu_regs();
}
/* Load registers after signal return */
static void load_sigregs(void)
{
restore_access_regs(current->thread.acrs);
}
static int save_sigregs32(struct pt_regs *regs, _sigregs32 __user *sregs)
{
_sigregs32 user_sregs;
int i;
user_sregs.regs.psw.mask = (__u32)(regs->psw.mask >> 32);
user_sregs.regs.psw.mask &= PSW32_MASK_USER | PSW32_MASK_RI;
user_sregs.regs.psw.mask |= PSW32_USER_BITS;
user_sregs.regs.psw.addr = (__u32) regs->psw.addr |
(__u32)(regs->psw.mask & PSW_MASK_BA);
for (i = 0; i < NUM_GPRS; i++)
user_sregs.regs.gprs[i] = (__u32) regs->gprs[i];
memcpy(&user_sregs.regs.acrs, current->thread.acrs,
sizeof(user_sregs.regs.acrs));
fpregs_store((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs32)))
return -EFAULT;
return 0;
}
static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
{
_sigregs32 user_sregs;
int i;
/* Alwys make any pending restarted system call return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
if (__copy_from_user(&user_sregs, &sregs->regs, sizeof(user_sregs)))
return -EFAULT;
if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW32_MASK_RI))
return -EINVAL;
/* Test the floating-point-control word. */
if (test_fp_ctl(user_sregs.fpregs.fpc))
return -EINVAL;
/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
(__u64)(user_sregs.regs.psw.mask & PSW32_MASK_USER) << 32 |
(__u64)(user_sregs.regs.psw.mask & PSW32_MASK_RI) << 32 |
(__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_AMODE);
/* Check for invalid user address space control. */
if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
regs->psw.mask = PSW_ASC_PRIMARY |
(regs->psw.mask & ~PSW_MASK_ASC);
regs->psw.addr = (__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_INSN);
for (i = 0; i < NUM_GPRS; i++)
regs->gprs[i] = (__u64) user_sregs.regs.gprs[i];
memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
sizeof(current->thread.acrs));
fpregs_load((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
return 0;
}
static int save_sigregs_ext32(struct pt_regs *regs,
_sigregs_ext32 __user *sregs_ext)
{
__u32 gprs_high[NUM_GPRS];
__u64 vxrs[__NUM_VXRS_LOW];
int i;
/* Save high gprs to signal stack */
for (i = 0; i < NUM_GPRS; i++)
gprs_high[i] = regs->gprs[i] >> 32;
if (__copy_to_user(&sregs_ext->gprs_high, &gprs_high,
sizeof(sregs_ext->gprs_high)))
return -EFAULT;
/* Save vector registers to signal stack */
if (MACHINE_HAS_VX) {
for (i = 0; i < __NUM_VXRS_LOW; i++)
vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1);
if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
sizeof(sregs_ext->vxrs_low)) ||
__copy_to_user(&sregs_ext->vxrs_high,
current->thread.fpu.vxrs + __NUM_VXRS_LOW,
sizeof(sregs_ext->vxrs_high)))
return -EFAULT;
}
return 0;
}
static int restore_sigregs_ext32(struct pt_regs *regs,
_sigregs_ext32 __user *sregs_ext)
{
__u32 gprs_high[NUM_GPRS];
__u64 vxrs[__NUM_VXRS_LOW];
int i;
/* Restore high gprs from signal stack */
if (__copy_from_user(&gprs_high, &sregs_ext->gprs_high,
sizeof(sregs_ext->gprs_high)))
return -EFAULT;
for (i = 0; i < NUM_GPRS; i++)
*(__u32 *)&regs->gprs[i] = gprs_high[i];
/* Restore vector registers from signal stack */
if (MACHINE_HAS_VX) {
if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
sizeof(sregs_ext->vxrs_low)) ||
__copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
&sregs_ext->vxrs_high,
sizeof(sregs_ext->vxrs_high)))
return -EFAULT;
for (i = 0; i < __NUM_VXRS_LOW; i++)
*((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i];
}
return 0;
}
COMPAT_SYSCALL_DEFINE0(sigreturn)
{
struct pt_regs *regs = task_pt_regs(current);
sigframe32 __user *frame = (sigframe32 __user *)regs->gprs[15];
sigset_t set;
if (get_compat_sigset(&set, (compat_sigset_t __user *)frame->sc.oldmask))
goto badframe;
set_current_blocked(&set);
save_fpu_regs();
if (restore_sigregs32(regs, &frame->sregs))
goto badframe;
if (restore_sigregs_ext32(regs, &frame->sregs_ext))
goto badframe;
load_sigregs();
return regs->gprs[2];
badframe:
force_sig(SIGSEGV, current);
return 0;
}
COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
{
struct pt_regs *regs = task_pt_regs(current);
rt_sigframe32 __user *frame = (rt_sigframe32 __user *)regs->gprs[15];
sigset_t set;
if (get_compat_sigset(&set, &frame->uc.uc_sigmask))
goto badframe;
set_current_blocked(&set);
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;
save_fpu_regs();
if (restore_sigregs32(regs, &frame->uc.uc_mcontext))
goto badframe;
if (restore_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
goto badframe;
load_sigregs();
return regs->gprs[2];
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
/*
* Determine which stack to use..
*/
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
unsigned long sp;
/* Default to using normal stack */
sp = (unsigned long) A(regs->gprs[15]);
/* Overflow on alternate signal stack gives SIGSEGV. */
if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
return (void __user *) -1UL;
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (! sas_ss_flags(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
}
return (void __user *)((sp - frame_size) & -8ul);
}
static int setup_frame32(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
int sig = ksig->sig;
sigframe32 __user *frame;
unsigned long restorer;
size_t frame_size;
/*
* gprs_high are always present for 31-bit compat tasks.
* The space for vector registers is only allocated if
* the machine supports it
*/
frame_size = sizeof(*frame) - sizeof(frame->sregs_ext.__reserved);
if (!MACHINE_HAS_VX)
frame_size -= sizeof(frame->sregs_ext.vxrs_low) +
sizeof(frame->sregs_ext.vxrs_high);
frame = get_sigframe(&ksig->ka, regs, frame_size);
if (frame == (void __user *) -1UL)
return -EFAULT;
/* Set up backchain. */
if (__put_user(regs->gprs[15], (unsigned int __user *) frame))
return -EFAULT;
/* Create struct sigcontext32 on the signal stack */
if (put_compat_sigset((compat_sigset_t __user *)frame->sc.oldmask,
set, sizeof(compat_sigset_t)))
return -EFAULT;
if (__put_user(ptr_to_compat(&frame->sc), &frame->sc.sregs))
return -EFAULT;
/* Store registers needed to create the signal frame */
store_sigregs();
/* Create _sigregs32 on the signal stack */
if (save_sigregs32(regs, &frame->sregs))
return -EFAULT;
/* Place signal number on stack to allow backtrace from handler. */
if (__put_user(regs->gprs[2], (int __force __user *) &frame->signo))
return -EFAULT;
/* Create _sigregs_ext32 on the signal stack */
if (save_sigregs_ext32(regs, &frame->sregs_ext))
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
restorer = (unsigned long __force)
ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
} else {
/* Signal frames without vectors registers are short ! */
__u16 __user *svc = (void __user *) frame + frame_size - 2;
if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
return -EFAULT;
restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
}
/* Set up registers for signal handler */
regs->gprs[14] = restorer;
regs->gprs[15] = (__force __u64) frame;
/* Force 31 bit amode and default user address space control. */
regs->psw.mask = PSW_MASK_BA |
(PSW_USER_BITS & PSW_MASK_ASC) |
(regs->psw.mask & ~PSW_MASK_ASC);
regs->psw.addr = (__force __u64) ksig->ka.sa.sa_handler;
regs->gprs[2] = sig;
regs->gprs[3] = (__force __u64) &frame->sc;
/* We forgot to include these in the sigcontext.
To avoid breaking binary compatibility, they are passed as args. */
if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
sig == SIGTRAP || sig == SIGFPE) {
/* set extra registers only for synchronous signals */
regs->gprs[4] = regs->int_code & 127;
regs->gprs[5] = regs->int_parm_long;
regs->gprs[6] = current->thread.last_break;
}
return 0;
}
static int setup_rt_frame32(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
rt_sigframe32 __user *frame;
unsigned long restorer;
size_t frame_size;
u32 uc_flags;
frame_size = sizeof(*frame) -
sizeof(frame->uc.uc_mcontext_ext.__reserved);
/*
* gprs_high are always present for 31-bit compat tasks.
* The space for vector registers is only allocated if
* the machine supports it
*/
uc_flags = UC_GPRS_HIGH;
if (MACHINE_HAS_VX) {
uc_flags |= UC_VXRS;
} else
frame_size -= sizeof(frame->uc.uc_mcontext_ext.vxrs_low) +
sizeof(frame->uc.uc_mcontext_ext.vxrs_high);
frame = get_sigframe(&ksig->ka, regs, frame_size);
if (frame == (void __user *) -1UL)
return -EFAULT;
/* Set up backchain. */
if (__put_user(regs->gprs[15], (unsigned int __force __user *) frame))
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
restorer = (unsigned long __force)
ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
} else {
__u16 __user *svc = &frame->svc_insn;
if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
return -EFAULT;
restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
}
/* Create siginfo on the signal stack */
if (copy_siginfo_to_user32(&frame->info, &ksig->info))
return -EFAULT;
/* Store registers needed to create the signal frame */
store_sigregs();
/* Create ucontext on the signal stack. */
if (__put_user(uc_flags, &frame->uc.uc_flags) ||
__put_user(0, &frame->uc.uc_link) ||
__compat_save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
save_sigregs32(regs, &frame->uc.uc_mcontext) ||
put_compat_sigset(&frame->uc.uc_sigmask, set, sizeof(compat_sigset_t)) ||
save_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
return -EFAULT;
/* Set up registers for signal handler */
regs->gprs[14] = restorer;
regs->gprs[15] = (__force __u64) frame;
/* Force 31 bit amode and default user address space control. */
regs->psw.mask = PSW_MASK_BA |
(PSW_USER_BITS & PSW_MASK_ASC) |
(regs->psw.mask & ~PSW_MASK_ASC);
regs->psw.addr = (__u64 __force) ksig->ka.sa.sa_handler;
regs->gprs[2] = ksig->sig;
regs->gprs[3] = (__force __u64) &frame->info;
regs->gprs[4] = (__force __u64) &frame->uc;
regs->gprs[5] = current->thread.last_break;
return 0;
}
/*
* OK, we're invoking a handler
*/
void handle_signal32(struct ksignal *ksig, sigset_t *oldset,
struct pt_regs *regs)
{
int ret;
/* Set up the stack frame */
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame32(ksig, oldset, regs);
else
ret = setup_frame32(ksig, oldset, regs);
signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
}
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