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>

2 files changed, 0 insertions, 59 deletions

diff --git a/arch/mips/include/asm/compat.h b/arch/mips/include/asm/compat.h
index fe7d445f675f..946681db8dc3 100644
--- a/arch/mips/include/asm/compat.h
+++ b/arch/mips/include/asm/compat.h
@@ -126,8 +126,6 @@ typedef u32		compat_old_sigset_t;	/* at least 32 bits */
 
 typedef u32		compat_sigset_word;
 
-#define SI_PAD_SIZE32	(128/sizeof(int) - 3)
-
 #define COMPAT_OFF_T_MAX	0x7fffffff
 
 /*
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c
index 500b5e4634ea..c4db910a8794 100644
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -76,60 +76,3 @@ SYSCALL_DEFINE3(32_sigaction, long, sig, const struct compat_sigaction __user *,
 
 	return ret;
 }
-
-int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
-{
-	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_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_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:
-			err |= __put_user((unsigned long)from->si_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_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 |= __copy_to_user(&to->si_call_addr, &from->si_call_addr,
-					      sizeof(compat_uptr_t));
-			err |= __put_user(from->si_syscall, &to->si_syscall);
-			err |= __put_user(from->si_arch, &to->si_arch);
-			break;
-		}
-	}
-	return err;
-}