setarch: add support for '-R' (disable randomization)

This commit adds support for the -R flag of setarch, which disables
randomization of the virtual address space.

function                                             old     new   delta
setarch_main                                         115     150     +35
packed_usage                                       30664   30651     -13

Signed-off-by: Jan Heylen <heyleke@gmail.com>
Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 39 insertions, 15 deletions

diff --git a/util-linux/setarch.c b/util-linux/setarch.c
index 7b9421af1..2e989ec2a 100644
--- a/util-linux/setarch.c
+++ b/util-linux/setarch.c
@@ -6,13 +6,30 @@
  *
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config SETARCH
+//config:	bool "setarch"
+//config:	default y
+//config:	select PLATFORM_LINUX
+//config:	help
+//config:	  The linux32 utility is used to create a 32bit environment for the
+//config:	  specified program (usually a shell). It only makes sense to have
+//config:	  this util on a system that supports both 64bit and 32bit userland
+//config:	  (like amd64/x86, ppc64/ppc, sparc64/sparc, etc...).
+
+//applet:IF_SETARCH(APPLET(setarch, BB_DIR_BIN, BB_SUID_DROP))
+//applet:IF_SETARCH(APPLET_ODDNAME(linux32, setarch, BB_DIR_BIN, BB_SUID_DROP, linux32))
+//applet:IF_SETARCH(APPLET_ODDNAME(linux64, setarch, BB_DIR_BIN, BB_SUID_DROP, linux64))
+
+//kbuild:lib-$(CONFIG_SETARCH) += setarch.o
 
 //usage:#define setarch_trivial_usage
-//usage:       "personality PROG ARGS"
+//usage:       "PERSONALITY [-R] PROG ARGS"
 //usage:#define setarch_full_usage "\n\n"
-//usage:       "Personality may be:\n"
-//usage:       "	linux32		Set 32bit uname emulation\n"
-//usage:       "	linux64		Set 64bit uname emulation"
+//usage:       "PERSONALITY may be:"
+//usage:   "\n""	linux32	Set 32bit uname emulation"
+//usage:   "\n""	linux64	Set 64bit uname emulation"
+//usage:   "\n"
+//usage:   "\n""	-R	Disable address space randomization"
 //usage:
 //usage:#define linux32_trivial_usage NOUSAGE_STR
 //usage:#define linux32_full_usage ""
@@ -20,14 +37,18 @@
 //usage:#define linux64_trivial_usage NOUSAGE_STR
 //usage:#define linux64_full_usage ""
 
+#include "libbb.h"
 #include <sys/personality.h>
 
-#include "libbb.h"
+#ifndef ADDR_NO_RANDOMIZE
+# define ADDR_NO_RANDOMIZE       0x0040000
+#endif
 
 int setarch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int setarch_main(int argc UNUSED_PARAM, char **argv)
 {
-	int pers;
+	unsigned opts;
+	unsigned long pers;
 
 	/* Figure out what personality we are supposed to switch to ...
 	 * we can be invoked as either:
@@ -35,7 +56,7 @@ int setarch_main(int argc UNUSED_PARAM, char **argv)
 	 * argv[0]         == "personality"
 	 */
 	if (ENABLE_SETARCH && applet_name[0] == 's'
-	 && argv[1] && strncpy(argv[1], "linux", 5)
+	 && argv[1] && is_prefixed_with(argv[1], "linux")
 	) {
 		applet_name = argv[1];
 		argv++;
@@ -47,15 +68,18 @@ int setarch_main(int argc UNUSED_PARAM, char **argv)
 	else
 		bb_show_usage();
 
-	argv++;
-	if (argv[0] == NULL)
-		bb_show_usage();
+	opts = getopt32(argv, "+R"); /* '+': stop at first non-option */
+	if (opts)
+		pers |= ADDR_NO_RANDOMIZE;
 
 	/* Try to set personality */
-	if (personality(pers) >= 0) {
-		/* Try to execute the program */
-		BB_EXECVP(argv[0], argv);
-	}
+	if (personality(pers) < 0)
+		bb_perror_msg_and_die("personality(0x%lx)", pers);
+
+	argv += optind;
+	if (!argv[0])
+		(--argv)[0] = (char*)"/bin/sh";
 
-	bb_simple_perror_msg_and_die(argv[0]);
+	/* Try to execute the program */
+	BB_EXECVP_or_die(argv);
 }