From: anton <anton@openbsd.org>
Date: Sun, 27 Nov 2022 15:12:57 +0000 (+0000)
Subject: Applying mimmutable(2) to bss, data and text made the sys/kern/noexec tests fail
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=511bcdc49140787e0039904e43c14b7b929509c3;p=openbsd

Applying mimmutable(2) to bss, data and text made the sys/kern/noexec tests fail
since they try to mutate the permissions of the aforementioned sections which is
no longer possible. Instead, "mimic" the sections by allocating and operating on
memory with the same initial permissions.

With help from deraadt@
---

diff --git a/regress/sys/kern/noexec/Makefile b/regress/sys/kern/noexec/Makefile
index 9c78ed73af7..c5f16b37bf5 100644
--- a/regress/sys/kern/noexec/Makefile
+++ b/regress/sys/kern/noexec/Makefile
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.25 2022/10/11 05:45:41 anton Exp $
+#	$OpenBSD: Makefile,v 1.26 2022/11/27 15:12:57 anton Exp $
 
 PROG=		noexec
 SRCS=		noexec.c testfly.S
@@ -12,6 +12,7 @@ REGRESS_TARGETS=	nxtext-mmap	nxtext-mprotect \
 		nxheap	nxheap-mmap	nxheap-mprotect \
 		nxmmap			nxmmap-mprotect \
 		nxstack	nxstack-mmap	nxstack-mprotect
+REGRESS_TARGETS+=	nxmutable nxmutable-mmap nxmutable-mprotect
 .PHONY: ${REGRESS_TARGETS}
 
 nxtext-mmap: ${PROG}
@@ -62,6 +63,15 @@ nxmmap: ${PROG}
 nxmmap-mprotect: ${PROG}
 	./${PROG} -m -p
 
+nxmutable: ${PROG}
+	./${PROG} -M
+
+nxmutable-mmap: ${PROG}
+	./${PROG} -M -m
+
+nxmutable-mprotect: ${PROG}
+	./${PROG} -M -p
+
 .if ${MACHINE} != "alpha" && \
     ${MACHINE} != "amd64" && \
     ${MACHINE} != "arm64" && \
diff --git a/regress/sys/kern/noexec/noexec.c b/regress/sys/kern/noexec/noexec.c
index 950082321ad..e42314689aa 100644
--- a/regress/sys/kern/noexec/noexec.c
+++ b/regress/sys/kern/noexec/noexec.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: noexec.c,v 1.22 2022/10/11 05:45:41 anton Exp $	*/
+/*	$OpenBSD: noexec.c,v 1.23 2022/11/27 15:12:57 anton Exp $	*/
 
 /*
  * Copyright (c) 2002,2003 Michael Shalayeff
@@ -49,10 +49,12 @@ int page_size;
 char label[64] = "non-exec ";
 
 #define PAD 64*1024
+#define PAGESIZE (1ULL << _MAX_PAGE_SHIFT)
 #define	MAXPAGESIZE 16384
 #define TESTSZ 256	/* assuming the testfly() will fit */
-u_int64_t data[(PAD + TESTSZ + PAD + MAXPAGESIZE) / 8] = { 0 };
-u_int64_t bss[(PAD + TESTSZ + PAD + MAXPAGESIZE) / 8];
+static u_int64_t mutable[(PAD + TESTSZ + PAD + MAXPAGESIZE) / 8]
+	__attribute__((aligned(PAGESIZE)))
+	__attribute__((section(".openbsd.mutable")));
 
 void testfly(void);
 
@@ -205,24 +207,65 @@ worker(void *arg)
 	pflags = MAP_PRIVATE|MAP_ANON|MAP_FIXED;
 	func = &noexec;
 	size = TESTSZ;
-	while ((ch = getopt(ctx->argc, ctx->argv, "TDBHSmps:")) != -1) {
+	while ((ch = getopt(ctx->argc, ctx->argv, "TDBMHSmps:")) != -1) {
 		if (p == NULL) {
 			switch (ch) {
-			case 'T':
-				p = &testfly;
+			case 'T': {
+				u_int64_t *text;
+				size_t textsiz = TESTSZ;
+
+				text = mmap(NULL, textsiz,
+				    PROT_READ | PROT_WRITE,
+				    MAP_PRIVATE | MAP_ANON, -1, 0);
+				if (text == MAP_FAILED)
+					err(1, "mmap");
+				memcpy(text, &testfly, textsiz);
+				if (mprotect(text, textsiz,
+				    PROT_READ | PROT_EXEC) == -1)
+					err(1, "mprotect");
+				p = text;
 				pflags &=~ MAP_FIXED;
 				(void) strlcat(label, "text", sizeof(label));
 				continue;
-			case 'D':
+			}
+
+			case 'D': {
+				u_int64_t *data;
+				size_t datasiz = (PAD + TESTSZ + PAD +
+				    MAXPAGESIZE) / 8;
+
+				data = mmap(NULL, datasiz,
+				    PROT_READ | PROT_WRITE,
+				    MAP_PRIVATE | MAP_ANON, -1, 0);
+				if (data == MAP_FAILED)
+					err(1, "mmap");
 				p = &data[(PAD + page_size) / 8];
 				p = (void *)((long)p & ~(page_size - 1));
 				(void) strlcat(label, "data", sizeof(label));
 				continue;
-			case 'B':
+			}
+
+			case 'B': {
+				u_int64_t *bss;
+				size_t bsssiz = (PAD + TESTSZ + PAD +
+				    MAXPAGESIZE) / 8;
+
+				bss = mmap(NULL, bsssiz,
+				    PROT_READ | PROT_WRITE,
+				    MAP_PRIVATE | MAP_ANON, -1, 0);
+				if (bss == MAP_FAILED)
+					err(1, "mmap");
 				p = &bss[(PAD + page_size) / 8];
 				p = (void *)((long)p & ~(page_size - 1));
 				(void) strlcat(label, "bss", sizeof(label));
 				continue;
+			}
+
+			case 'M':
+				p = &mutable[(PAD + page_size) / 8];
+				p = (void *)((long)p & ~(page_size - 1));
+				(void)strlcat(label, "mutable", sizeof(label));
+				continue;
 			case 'H':
 				p = malloc(size + 2 * page_size);
 				if (p == NULL)