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, 57 deletions

diff --git a/arch/tile/include/asm/compat.h b/arch/tile/include/asm/compat.h
index c6b7613256b4..769ff6ac0bf5 100644
--- a/arch/tile/include/asm/compat.h
+++ b/arch/tile/include/asm/compat.h
@@ -110,8 +110,6 @@ struct compat_flock64 {
 
 typedef u32               compat_sigset_word;
 
-#define COMPAT_SI_PAD_SIZE	(128/sizeof(int) - 3)
-
 #define COMPAT_OFF_T_MAX	0x7fffffff
 
 struct compat_ipc64_perm {
diff --git a/arch/tile/kernel/compat_signal.c b/arch/tile/kernel/compat_signal.c
index 4e7f40a10eb3..a703bd0e0488 100644
--- a/arch/tile/kernel/compat_signal.c
+++ b/arch/tile/kernel/compat_signal.c
@@ -50,61 +50,6 @@ struct compat_rt_sigframe {
 	struct compat_ucontext uc;
 };
 
-int copy_siginfo_to_user32(struct compat_siginfo __user *to, const siginfo_t *from)
-{
-	int err;
-
-	if (!access_ok(VERIFY_WRITE, to, sizeof(struct compat_siginfo)))
-		return -EFAULT;
-
-	/* If you change siginfo_t structure, please make sure that
-	   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.  */
-	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 |= __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);
-	} else {
-		/*
-		 * First 32bits of unions are always present:
-		 * si_pid === si_band === si_tid === si_addr(LS half)
-		 */
-		err |= __put_user(from->_sifields._pad[0],
-				  &to->_sifields._pad[0]);
-		switch (siginfo_layout(from->si_signo, from->si_code)) {
-		case SIL_FAULT:
-			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);
-			/* FALL THROUGH */
-		default:
-		case SIL_KILL:
-			err |= __put_user(from->si_uid, &to->si_uid);
-			break;
-		case SIL_POLL:
-			err |= __put_user(from->si_fd, &to->si_fd);
-			break;
-		case SIL_TIMER:
-			err |= __put_user(from->si_overrun, &to->si_overrun);
-			err |= __put_user(from->si_int, &to->si_int);
-			break;
-		case SIL_RT:
-			err |= __put_user(from->si_uid, &to->si_uid);
-			err |= __put_user(from->si_int, &to->si_int);
-			break;
-		}
-	}
-	return err;
-}
-
 /* The assembly shim for this function arranges to ignore the return value. */
 long compat_sys_rt_sigreturn(void)
 {