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cc731525f2
linux-brain/arch/parisc/kernel/signal32.c
Eric W. Biederman cc731525f2 signal: Remove kernel interal si_code magic 
struct siginfo is a union and the kernel since 2.4 has been hiding a union
tag in the high 16bits of si_code using the values:
__SI_KILL
__SI_TIMER
__SI_POLL
__SI_FAULT
__SI_CHLD
__SI_RT
__SI_MESGQ
__SI_SYS

While this looks plausible on the surface, in practice this situation has
not worked well.

- Injected positive signals are not copied to user space properly
  unless they have these magic high bits set.

- Injected positive signals are not reported properly by signalfd
  unless they have these magic high bits set.

- These kernel internal values leaked to userspace via ptrace_peek_siginfo

- It was possible to inject these kernel internal values and cause the
  the kernel to misbehave.

- Kernel developers got confused and expected these kernel internal values
  in userspace in kernel self tests.

- Kernel developers got confused and set si_code to __SI_FAULT which
  is SI_USER in userspace which causes userspace to think an ordinary user
  sent the signal and that it was not kernel generated.

- The values make it impossible to reorganize the code to transform
  siginfo_copy_to_user into a plain copy_to_user.  As si_code must
  be massaged before being passed to userspace.

So remove these kernel internal si codes and make the kernel code simpler
and more maintainable.

To replace these kernel internal magic si_codes introduce the helper
function siginfo_layout, that takes a signal number and an si_code and
computes which union member of siginfo is being used.  Have
siginfo_layout return an enumeration so that gcc will have enough
information to warn if a switch statement does not handle all of union
members.

A couple of architectures have a messed up ABI that defines signal
specific duplications of SI_USER which causes more special cases in
siginfo_layout than I would like.  The good news is only problem
architectures pay the cost.

Update all of the code that used the previous magic __SI_ values to
use the new SIL_ values and to call siginfo_layout to get those
values.  Escept where not all of the cases are handled remove the
defaults in the switch statements so that if a new case is missed in
the future the lack will show up at compile time.

Modify the code that copies siginfo si_code to userspace to just copy
the value and not cast si_code to a short first.  The high bits are no
longer used to hold a magic union member.

Fixup the siginfo header files to stop including the __SI_ values in
their constants and for the headers that were missing it to properly
update the number of si_codes for each signal type.

The fixes to copy_siginfo_from_user32 implementations has the
interesting property that several of them perviously should never have
worked as the __SI_ values they depended up where kernel internal.
With that dependency gone those implementations should work much
better.

The idea of not passing the __SI_ values out to userspace and then
not reinserting them has been tested with criu and criu worked without
changes.

Ref: 2.4.0-test1
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-24 14:30:28 -05:00

382 lines
13 KiB
C
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/* Signal support for 32-bit kernel builds
*
* Copyright (C) 2001 Matthew Wilcox <willy at parisc-linux.org>
* Copyright (C) 2006 Kyle McMartin <kyle at parisc-linux.org>
*
* Code was mostly borrowed from kernel/signal.c.
* See kernel/signal.c for additional Copyrights.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/compat.h>
#include <linux/module.h>
#include <linux/unistd.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/uaccess.h>
#include "signal32.h"
#define DEBUG_COMPAT_SIG 0
#define DEBUG_COMPAT_SIG_LEVEL 2
#if DEBUG_COMPAT_SIG
#define DBG(LEVEL, ...) \
((DEBUG_COMPAT_SIG_LEVEL >= LEVEL) \
? printk(__VA_ARGS__) : (void) 0)
#else
#define DBG(LEVEL, ...)
#endif
inline void
sigset_32to64(sigset_t *s64, compat_sigset_t *s32)
{
s64->sig[0] = s32->sig[0] | ((unsigned long)s32->sig[1] << 32);
}
inline void
sigset_64to32(compat_sigset_t *s32, sigset_t *s64)
{
s32->sig[0] = s64->sig[0] & 0xffffffffUL;
s32->sig[1] = (s64->sig[0] >> 32) & 0xffffffffUL;
}
long
restore_sigcontext32(struct compat_sigcontext __user *sc, struct compat_regfile __user * rf,
struct pt_regs *regs)
{
long err = 0;
compat_uint_t compat_reg;
compat_uint_t compat_regt;
int regn;
/* When loading 32-bit values into 64-bit registers make
sure to clear the upper 32-bits */
DBG(2,"restore_sigcontext32: PER_LINUX32 process\n");
DBG(2,"restore_sigcontext32: sc = 0x%p, rf = 0x%p, regs = 0x%p\n", sc, rf, regs);
DBG(2,"restore_sigcontext32: compat_sigcontext is %#lx bytes\n", sizeof(*sc));
for(regn=0; regn < 32; regn++){
err |= __get_user(compat_reg,&sc->sc_gr[regn]);
regs->gr[regn] = compat_reg;
/* Load upper half */
err |= __get_user(compat_regt,&rf->rf_gr[regn]);
regs->gr[regn] = ((u64)compat_regt << 32) | (u64)compat_reg;
DBG(3,"restore_sigcontext32: gr%02d = %#lx (%#x / %#x)\n",
regn, regs->gr[regn], compat_regt, compat_reg);
}
DBG(2,"restore_sigcontext32: sc->sc_fr = 0x%p (%#lx)\n",sc->sc_fr, sizeof(sc->sc_fr));
/* XXX: BE WARNED FR's are 64-BIT! */
err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
/* Better safe than sorry, pass __get_user two things of
the same size and let gcc do the upward conversion to
64-bits */
err |= __get_user(compat_reg, &sc->sc_iaoq[0]);
/* Load upper half */
err |= __get_user(compat_regt, &rf->rf_iaoq[0]);
regs->iaoq[0] = ((u64)compat_regt << 32) | (u64)compat_reg;
DBG(2,"restore_sigcontext32: upper half of iaoq[0] = %#lx\n", compat_regt);
DBG(2,"restore_sigcontext32: sc->sc_iaoq[0] = %p => %#x\n",
&sc->sc_iaoq[0], compat_reg);
err |= __get_user(compat_reg, &sc->sc_iaoq[1]);
/* Load upper half */
err |= __get_user(compat_regt, &rf->rf_iaoq[1]);
regs->iaoq[1] = ((u64)compat_regt << 32) | (u64)compat_reg;
DBG(2,"restore_sigcontext32: upper half of iaoq[1] = %#lx\n", compat_regt);
DBG(2,"restore_sigcontext32: sc->sc_iaoq[1] = %p => %#x\n",
&sc->sc_iaoq[1],compat_reg);
DBG(2,"restore_sigcontext32: iaoq is %#lx / %#lx\n",
regs->iaoq[0],regs->iaoq[1]);
err |= __get_user(compat_reg, &sc->sc_iasq[0]);
/* Load the upper half for iasq */
err |= __get_user(compat_regt, &rf->rf_iasq[0]);
regs->iasq[0] = ((u64)compat_regt << 32) | (u64)compat_reg;
DBG(2,"restore_sigcontext32: upper half of iasq[0] = %#lx\n", compat_regt);
err |= __get_user(compat_reg, &sc->sc_iasq[1]);
/* Load the upper half for iasq */
err |= __get_user(compat_regt, &rf->rf_iasq[1]);
regs->iasq[1] = ((u64)compat_regt << 32) | (u64)compat_reg;
DBG(2,"restore_sigcontext32: upper half of iasq[1] = %#lx\n", compat_regt);
DBG(2,"restore_sigcontext32: iasq is %#lx / %#lx\n",
regs->iasq[0],regs->iasq[1]);
err |= __get_user(compat_reg, &sc->sc_sar);
/* Load the upper half for sar */
err |= __get_user(compat_regt, &rf->rf_sar);
regs->sar = ((u64)compat_regt << 32) | (u64)compat_reg;
DBG(2,"restore_sigcontext32: upper_half & sar = %#lx\n", compat_regt);
DBG(2,"restore_sigcontext32: sar is %#lx\n", regs->sar);
DBG(2,"restore_sigcontext32: r28 is %ld\n", regs->gr[28]);
return err;
}
/*
* Set up the sigcontext structure for this process.
* This is not an easy task if the kernel is 64-bit, it will require
* that we examine the process personality to determine if we need to
* truncate for a 32-bit userspace.
*/
long
setup_sigcontext32(struct compat_sigcontext __user *sc, struct compat_regfile __user * rf,
struct pt_regs *regs, int in_syscall)
{
compat_int_t flags = 0;
long err = 0;
compat_uint_t compat_reg;
compat_uint_t compat_regb;
int regn;
if (on_sig_stack((unsigned long) sc))
flags |= PARISC_SC_FLAG_ONSTACK;
if (in_syscall) {
DBG(1,"setup_sigcontext32: in_syscall\n");
flags |= PARISC_SC_FLAG_IN_SYSCALL;
/* Truncate gr31 */
compat_reg = (compat_uint_t)(regs->gr[31]);
/* regs->iaoq is undefined in the syscall return path */
err |= __put_user(compat_reg, &sc->sc_iaoq[0]);
DBG(2,"setup_sigcontext32: sc->sc_iaoq[0] = %p <= %#x\n",
&sc->sc_iaoq[0], compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->gr[31] >> 32);
err |= __put_user(compat_reg, &rf->rf_iaoq[0]);
DBG(2,"setup_sigcontext32: upper half iaoq[0] = %#x\n", compat_reg);
compat_reg = (compat_uint_t)(regs->gr[31]+4);
err |= __put_user(compat_reg, &sc->sc_iaoq[1]);
DBG(2,"setup_sigcontext32: sc->sc_iaoq[1] = %p <= %#x\n",
&sc->sc_iaoq[1], compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)((regs->gr[31]+4) >> 32);
err |= __put_user(compat_reg, &rf->rf_iaoq[1]);
DBG(2,"setup_sigcontext32: upper half iaoq[1] = %#x\n", compat_reg);
/* Truncate sr3 */
compat_reg = (compat_uint_t)(regs->sr[3]);
err |= __put_user(compat_reg, &sc->sc_iasq[0]);
err |= __put_user(compat_reg, &sc->sc_iasq[1]);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->sr[3] >> 32);
err |= __put_user(compat_reg, &rf->rf_iasq[0]);
err |= __put_user(compat_reg, &rf->rf_iasq[1]);
DBG(2,"setup_sigcontext32: upper half iasq[0] = %#x\n", compat_reg);
DBG(2,"setup_sigcontext32: upper half iasq[1] = %#x\n", compat_reg);
DBG(1,"setup_sigcontext32: iaoq %#lx / %#lx\n",
regs->gr[31], regs->gr[31]+4);
} else {
compat_reg = (compat_uint_t)(regs->iaoq[0]);
err |= __put_user(compat_reg, &sc->sc_iaoq[0]);
DBG(2,"setup_sigcontext32: sc->sc_iaoq[0] = %p <= %#x\n",
&sc->sc_iaoq[0], compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->iaoq[0] >> 32);
err |= __put_user(compat_reg, &rf->rf_iaoq[0]);
DBG(2,"setup_sigcontext32: upper half iaoq[0] = %#x\n", compat_reg);
compat_reg = (compat_uint_t)(regs->iaoq[1]);
err |= __put_user(compat_reg, &sc->sc_iaoq[1]);
DBG(2,"setup_sigcontext32: sc->sc_iaoq[1] = %p <= %#x\n",
&sc->sc_iaoq[1], compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->iaoq[1] >> 32);
err |= __put_user(compat_reg, &rf->rf_iaoq[1]);
DBG(2,"setup_sigcontext32: upper half iaoq[1] = %#x\n", compat_reg);
compat_reg = (compat_uint_t)(regs->iasq[0]);
err |= __put_user(compat_reg, &sc->sc_iasq[0]);
DBG(2,"setup_sigcontext32: sc->sc_iasq[0] = %p <= %#x\n",
&sc->sc_iasq[0], compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->iasq[0] >> 32);
err |= __put_user(compat_reg, &rf->rf_iasq[0]);
DBG(2,"setup_sigcontext32: upper half iasq[0] = %#x\n", compat_reg);
compat_reg = (compat_uint_t)(regs->iasq[1]);
err |= __put_user(compat_reg, &sc->sc_iasq[1]);
DBG(2,"setup_sigcontext32: sc->sc_iasq[1] = %p <= %#x\n",
&sc->sc_iasq[1], compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->iasq[1] >> 32);
err |= __put_user(compat_reg, &rf->rf_iasq[1]);
DBG(2,"setup_sigcontext32: upper half iasq[1] = %#x\n", compat_reg);
/* Print out the IAOQ for debugging */
DBG(1,"setup_sigcontext32: ia0q %#lx / %#lx\n",
regs->iaoq[0], regs->iaoq[1]);
}
err |= __put_user(flags, &sc->sc_flags);
DBG(1,"setup_sigcontext32: Truncating general registers.\n");
for(regn=0; regn < 32; regn++){
/* Truncate a general register */
compat_reg = (compat_uint_t)(regs->gr[regn]);
err |= __put_user(compat_reg, &sc->sc_gr[regn]);
/* Store upper half */
compat_regb = (compat_uint_t)(regs->gr[regn] >> 32);
err |= __put_user(compat_regb, &rf->rf_gr[regn]);
/* DEBUG: Write out the "upper / lower" register data */
DBG(2,"setup_sigcontext32: gr%02d = %#x / %#x\n", regn,
compat_regb, compat_reg);
}
/* Copy the floating point registers (same size)
XXX: BE WARNED FR's are 64-BIT! */
DBG(1,"setup_sigcontext32: Copying from regs to sc, "
"sc->sc_fr size = %#lx, regs->fr size = %#lx\n",
sizeof(regs->fr), sizeof(sc->sc_fr));
err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
compat_reg = (compat_uint_t)(regs->sar);
err |= __put_user(compat_reg, &sc->sc_sar);
DBG(2,"setup_sigcontext32: sar is %#x\n", compat_reg);
/* Store upper half */
compat_reg = (compat_uint_t)(regs->sar >> 32);
err |= __put_user(compat_reg, &rf->rf_sar);
DBG(2,"setup_sigcontext32: upper half sar = %#x\n", compat_reg);
DBG(1,"setup_sigcontext32: r28 is %ld\n", regs->gr[28]);
return err;
}
int
copy_siginfo_from_user32 (siginfo_t *to, compat_siginfo_t __user *from)
{
compat_uptr_t addr;
int err;
if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t)))
return -EFAULT;
err = __get_user(to->si_signo, &from->si_signo);
err |= __get_user(to->si_errno, &from->si_errno);
err |= __get_user(to->si_code, &from->si_code);
if (to->si_code < 0)
err |= __copy_from_user(&to->_sifields._pad, &from->_sifields._pad, SI_PAD_SIZE);
else {
switch (siginfo_layout(to->si_signo, to->si_code)) {
case SIL_CHLD:
err |= __get_user(to->si_utime, &from->si_utime);
err |= __get_user(to->si_stime, &from->si_stime);
err |= __get_user(to->si_status, &from->si_status);
default:
case SIL_KILL:
err |= __get_user(to->si_pid, &from->si_pid);
err |= __get_user(to->si_uid, &from->si_uid);
break;
case SIL_FAULT:
err |= __get_user(addr, &from->si_addr);
to->si_addr = compat_ptr(addr);
break;
case SIL_POLL:
err |= __get_user(to->si_band, &from->si_band);
err |= __get_user(to->si_fd, &from->si_fd);
break;
case SIL_RT:
err |= __get_user(to->si_pid, &from->si_pid);
err |= __get_user(to->si_uid, &from->si_uid);
err |= __get_user(to->si_int, &from->si_int);
break;
}
}
return err;
}
int
copy_siginfo_to_user32 (compat_siginfo_t __user *to, const siginfo_t *from)
{
compat_uptr_t addr;
compat_int_t val;
int err;
if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
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(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 (siginfo_layout(from->si_signo, from->si_code)) {
case SIL_CHLD:
err |= __put_user(from->si_utime, &to->si_utime);
err |= __put_user(from->si_stime, &to->si_stime);
err |= __put_user(from->si_status, &to->si_status);
case SIL_KILL:
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
break;
case SIL_FAULT:
addr = ptr_to_compat(from->si_addr);
err |= __put_user(addr, &to->si_addr);
break;
case SIL_POLL:
err |= __put_user(from->si_band, &to->si_band);
err |= __put_user(from->si_fd, &to->si_fd);
break;
case SIL_TIMER:
err |= __put_user(from->si_tid, &to->si_tid);
err |= __put_user(from->si_overrun, &to->si_overrun);
val = (compat_int_t)from->si_int;
err |= __put_user(val, &to->si_int);
break;
case SIL_RT:
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user(from->si_pid, &to->si_pid);
val = (compat_int_t)from->si_int;
err |= __put_user(val, &to->si_int);
break;
case SIL_SYS:
err |= __put_user(ptr_to_compat(from->si_call_addr), &to->si_call_addr);
err |= __put_user(from->si_syscall, &to->si_syscall);
err |= __put_user(from->si_arch, &to->si_arch);
break;
}
}
return err;
}
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