Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

kernel/seccomp.c

@@ -0,0 +1,56 @@
+/*
+ * linux/kernel/seccomp.c
+ *
+ * Copyright 2004-2005  Andrea Arcangeli <andrea@cpushare.com>
+ *
+ * This defines a simple but solid secure-computing mode.
+ */
+
+#include <linux/seccomp.h>
+#include <linux/sched.h>
+
+/* #define SECCOMP_DEBUG 1 */
+
+/*
+ * Secure computing mode 1 allows only read/write/exit/sigreturn.
+ * To be fully secure this must be combined with rlimit
+ * to limit the stack allocations too.
+ */
+static int mode1_syscalls[] = {
+	__NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
+	0, /* null terminated */
+};
+
+#ifdef TIF_32BIT
+static int mode1_syscalls_32[] = {
+	__NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
+	0, /* null terminated */
+};
+#endif
+
+void __secure_computing(int this_syscall)
+{
+	int mode = current->seccomp.mode;
+	int * syscall;
+
+	switch (mode) {
+	case 1:
+		syscall = mode1_syscalls;
+#ifdef TIF_32BIT
+		if (test_thread_flag(TIF_32BIT))
+			syscall = mode1_syscalls_32;
+#endif
+		do {
+			if (*syscall == this_syscall)
+				return;
+		} while (*++syscall);
+		break;
+	default:
+		BUG();
+	}
+
+#ifdef SECCOMP_DEBUG
+	dump_stack();
+#endif
+	do_exit(SIGKILL);
+}