signal: Unify and correct copy_siginfo_from_user32

The function copy_siginfo_from_user32 is used for two things, in ptrace
since the dawn of siginfo for arbirarily modifying a signal that
user space sees, and in sigqueueinfo to send a signal with arbirary
siginfo data.

Create a single copy of copy_siginfo_from_user32 that all architectures
share, and teach it to handle all of the cases in the siginfo union.

In the generic version of copy_siginfo_from_user32 ensure that all
of the fields in siginfo are initialized so that the siginfo structure
can be safely copied to userspace if necessary.

When copying the embedded sigval union copy the si_int member.  That
ensures the 32bit values passes through the kernel unchanged.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 4c3f4448c5f1..5211b1b57163 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2814,6 +2814,87 @@ int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
 	return err;
 }
 
+#ifdef CONFIG_COMPAT
+int copy_siginfo_from_user32(struct siginfo *to,
+			     const struct compat_siginfo __user *ufrom)
+{
+	struct compat_siginfo from;
+
+	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
+		return -EFAULT;
+
+	clear_siginfo(to);
+	to->si_signo = from.si_signo;
+	to->si_errno = from.si_errno;
+	to->si_code  = from.si_code;
+	switch(siginfo_layout(from.si_signo, from.si_code)) {
+	case SIL_KILL:
+		to->si_pid = from.si_pid;
+		to->si_uid = from.si_uid;
+		break;
+	case SIL_TIMER:
+		to->si_tid     = from.si_tid;
+		to->si_overrun = from.si_overrun;
+		to->si_int     = from.si_int;
+		break;
+	case SIL_POLL:
+		to->si_band = from.si_band;
+		to->si_fd   = from.si_fd;
+		break;
+	case SIL_FAULT:
+		to->si_addr = compat_ptr(from.si_addr);
+#ifdef __ARCH_SI_TRAPNO
+		to->si_trapno = from.si_trapno;
+#endif
+#ifdef BUS_MCEERR_AR
+		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AR))
+			to->si_addr_lsb = from.si_addr_lsb;
+#endif
+#ifdef BUS_MCEER_AO
+		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AO))
+			to->si_addr_lsb = from.si_addr_lsb;
+#endif
+#ifdef SEGV_BNDERR
+		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
+			to->si_lower = compat_ptr(from.si_lower);
+			to->si_upper = compat_ptr(from.si_upper);
+		}
+#endif
+#ifdef SEGV_PKUERR
+		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
+			to->si_pkey = from.si_pkey;
+#endif
+		break;
+	case SIL_CHLD:
+		to->si_pid    = from.si_pid;
+		to->si_uid    = from.si_uid;
+		to->si_status = from.si_status;
+#ifdef CONFIG_X86_X32_ABI
+		if (in_x32_syscall()) {
+			to->si_utime = from._sifields._sigchld_x32._utime;
+			to->si_stime = from._sifields._sigchld_x32._stime;
+		} else
+#endif
+		{
+			to->si_utime = from.si_utime;
+			to->si_stime = from.si_stime;
+		}
+		break;
+	case SIL_RT:
+		to->si_pid = from.si_pid;
+		to->si_uid = from.si_uid;
+		to->si_int = from.si_int;
+		break;
+	case SIL_SYS:
+		to->si_call_addr = compat_ptr(from.si_call_addr);
+		to->si_syscall   = from.si_syscall;
+		to->si_arch      = from.si_arch;
+		break;
+	}
+	return 0;
+}
+#endif /* CONFIG_COMPAT */
+
 /**
  *  do_sigtimedwait - wait for queued signals specified in @which
  *  @which: queued signals to wait for