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linux-stable/arch/arm64/kernel/signal32.c
Linus Torvalds dd198ce714 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 
Pull namespace updates from Eric Biederman:
 "Life has been busy and I have not gotten half as much done this round
  as I would have liked. I delayed it so that a minor conflict
  resolution with the mips tree could spend a little time in linux-next
  before I sent this pull request.

  This includes two long delayed user namespace changes from Kirill
  Tkhai. It also includes a very useful change from Serge Hallyn that
  allows the security capability attribute to be used inside of user
  namespaces. The practical effect of this is people can now untar
  tarballs and install rpms in user namespaces. It had been suggested to
  generalize this and encode some of the namespace information
  information in the xattr name. Upon close inspection that makes the
  things that should be hard easy and the things that should be easy
  more expensive.

  Then there is my bugfix/cleanup for signal injection that removes the
  magic encoding of the siginfo union member from the kernel internal
  si_code. The mips folks reported the case where I had used FPE_FIXME
  me is impossible so I have remove FPE_FIXME from mips, while at the
  same time including a return statement in that case to keep gcc from
  complaining about unitialized variables.

  I almost finished the work to get make copy_siginfo_to_user a trivial
  copy to user. The code is available at:

     git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git neuter-copy_siginfo_to_user-v3

  But I did not have time/energy to get the code posted and reviewed
  before the merge window opened.

  I was able to see that the security excuse for just copying fields
  that we know are initialized doesn't work in practice there are buggy
  initializations that don't initialize the proper fields in siginfo. So
  we still sometimes copy unitialized data to userspace"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  Introduce v3 namespaced file capabilities
  mips/signal: In force_fcr31_sig return in the impossible case
  signal: Remove kernel interal si_code magic
  fcntl: Don't use ambiguous SIG_POLL si_codes
  prctl: Allow local CAP_SYS_ADMIN changing exe_file
  security: Use user_namespace::level to avoid redundant iterations in cap_capable()
  userns,pidns: Verify the userns for new pid namespaces
  signal/testing: Don't look for __SI_FAULT in userspace
  signal/mips: Document a conflict with SI_USER with SIGFPE
  signal/sparc: Document a conflict with SI_USER with SIGFPE
  signal/ia64: Document a conflict with SI_USER with SIGFPE
  signal/alpha: Document a conflict with SI_USER for SIGTRAP
2017-09-11 18:34:47 -07:00

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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/esr.h>
#include <asm/fpsimd.h>
#include <asm/signal32.h>
#include <linux/uaccess.h>
#include <asm/unistd.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)
#define FSR_WRITE_SHIFT (11)
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)))
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, const 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(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_KILL:
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
break;
case SIL_TIMER:
err |= __put_user(from->si_tid, &to->si_tid);
err |= __put_user(from->si_overrun, &to->si_overrun);
err |= __put_user(from->si_int, &to->si_int);
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_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 explicitly for the right codes here.
*/
if (from->si_signo == SIGBUS &&
(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 SIL_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 SIL_RT:
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user(from->si_int, &to->si_int);
break;
case SIL_SYS:
err |= __put_user((compat_uptr_t)(unsigned long)
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;
}
int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
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.
*
* We have to be careful with endianness, since the fpsimd context-switch
* code operates on 128-bit (Q) register values whereas the compat ABI
* uses an array of 64-bit (D) registers. Consequently, we need to swap
* the two halves of each Q register when running on a big-endian CPU.
*/
union __fpsimd_vreg {
__uint128_t raw;
struct {
#ifdef __AARCH64EB__
u64 hi;
u64 lo;
#else
u64 lo;
u64 hi;
#endif
};
};
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 i, 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_preserve_current_state();
/* 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.
*/
for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
union __fpsimd_vreg vreg = {
.raw = fpsimd->vregs[i >> 1],
};
__put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
__put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
}
/* 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 i, 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. */
for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
union __fpsimd_vreg vreg;
__get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
__get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
fpsimd.vregs[i >> 1] = vreg.raw;
}
/* 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)
fpsimd_update_current_state(&fpsimd);
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.
*/
forget_syscall(regs);
err |= !valid_user_regs(&regs->user_regs, current);
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->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->compat_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->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->compat_sp);
force_sig(SIGSEGV, current);
return 0;
}
static void __user *compat_get_sigframe(struct ksignal *ksig,
struct pt_regs *regs,
int framesize)
{
compat_ulong_t sp = sigsp(regs->compat_sp, ksig);
void __user *frame;
/*
* 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 | COMPAT_PSR_E_BIT);
int thumb;
/* Check if the handler is written for ARM or Thumb */
thumb = handler & 1;
if (thumb)
spsr |= COMPAT_PSR_T_BIT;
else
spsr &= ~COMPAT_PSR_T_BIT;
/* The IT state must be cleared for both ARM and Thumb-2 */
spsr &= ~COMPAT_PSR_IT_MASK;
/* Restore the original endianness */
spsr |= COMPAT_PSR_ENDSTATE;
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);
/* set the compat FSR WnR */
__put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
FSR_WRITE_SHIFT, &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 ksignal *ksig,
sigset_t *set, struct pt_regs *regs)
{
struct compat_rt_sigframe __user *frame;
int err = 0;
frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
if (!frame)
return 1;
err |= copy_siginfo_to_user32(&frame->info, &ksig->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, &ksig->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 ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct compat_sigframe __user *frame;
int err = 0;
frame = compat_get_sigframe(ksig, 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, &ksig->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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