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);
 }