static binaries self-mprotect their relro in crt0. mimmutable() also works

here.
ok kettenis

diff --git a/lib/csu/boot.h b/lib/csu/boot.h
index f9b6a64..72cbfee 100644 (file)
--- a/lib/csu/boot.h
+++ b/lib/csu/boot.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: boot.h,v 1.33 2022/01/12 21:41:06 guenther Exp $ */
+/*     $OpenBSD: boot.h,v 1.34 2022/10/21 18:14:09 deraadt Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -50,6 +50,7 @@ void _dl_exit(int);
  */
 #define REDIRECT_SYSCALL(x)    typeof(x) x asm("_libc_"#x) __dso_hidden
 REDIRECT_SYSCALL(mprotect);
+REDIRECT_SYSCALL(mimmutable);
 
 #if RELOC_TAG == DT_RELA
 typedef        Elf_RelA        RELOC_TYPE;
@@ -63,8 +64,10 @@ static void *relro_addr;
 static size_t relro_size;
 #define RCRT0_RELRO()                                                  \
        do {                                                            \
-               if (relro_addr != NULL && relro_size != 0)              \
+               if (relro_addr != NULL && relro_size != 0) {            \
                        mprotect(relro_addr, relro_size, PROT_READ);    \
+                       mimmutable(relro_addr, relro_size);             \
+               }                                                       \
        } while (0)
 
 /*