util-linux/setarch.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * linux32/linux64 allows for changing uname emulation.
   4  *
   5  * Copyright 2002 Andi Kleen, SuSE Labs.
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9 //config:config SETARCH
  10 //config:       bool "setarch (3.6 kb)"
  11 //config:       default y
  12 //config:       select PLATFORM_LINUX
  13 //config:       help
  14 //config:       The linux32 utility is used to create a 32bit environment for the
  15 //config:       specified program (usually a shell). It only makes sense to have
  16 //config:       this util on a system that supports both 64bit and 32bit userland
  17 //config:       (like amd64/x86, ppc64/ppc, sparc64/sparc, etc...).
  18 //config:
  19 //config:config LINUX32
  20 //config:       bool "linux32 (3.3 kb)"
  21 //config:       default y
  22 //config:       select PLATFORM_LINUX
  23 //config:       help
  24 //config:       Alias to "setarch linux32".
  25 //config:
  26 //config:config LINUX64
  27 //config:       bool "linux64 (3.3 kb)"
  28 //config:       default y
  29 //config:       select PLATFORM_LINUX
  30 //config:       help
  31 //config:       Alias to "setarch linux64".
  32
  33 //applet:IF_SETARCH(APPLET_NOEXEC(setarch, setarch, BB_DIR_BIN, BB_SUID_DROP, setarch))
  34 //                  APPLET_NOEXEC:name     main     location    suid_type     help
  35 //applet:IF_LINUX32(APPLET_NOEXEC(linux32, setarch, BB_DIR_BIN, BB_SUID_DROP, linux32))
  36 //applet:IF_LINUX64(APPLET_NOEXEC(linux64, setarch, BB_DIR_BIN, BB_SUID_DROP, linux64))
  37
  38 //kbuild:lib-$(CONFIG_SETARCH) += setarch.o
  39 //kbuild:lib-$(CONFIG_LINUX32) += setarch.o
  40 //kbuild:lib-$(CONFIG_LINUX64) += setarch.o
  41
  42 //usage:#define setarch_trivial_usage
  43 //usage:       "PERSONALITY [-R] PROG ARGS"
  44 //usage:#define setarch_full_usage "\n\n"
  45 //usage:       "PERSONALITY may be:"
  46 //usage:   "\n""        linux32 Set 32bit uname emulation"
  47 //usage:   "\n""        linux64 Set 64bit uname emulation"
  48 //usage:   "\n"
  49 //usage:   "\n""        -R      Disable address space randomization"
  50 //usage:
  51 //usage:#define linux32_trivial_usage NOUSAGE_STR
  52 //usage:#define linux32_full_usage ""
  53 //usage:
  54 //usage:#define linux64_trivial_usage NOUSAGE_STR
  55 //usage:#define linux64_full_usage ""
  56
  57 #include "libbb.h"
  58 #include <sys/personality.h>
  59
  60 #ifndef ADDR_NO_RANDOMIZE
  61 # define ADDR_NO_RANDOMIZE       0x0040000
  62 #endif
  63
  64 int setarch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  65 int setarch_main(int argc UNUSED_PARAM, char **argv)
  66 {
  67         unsigned opts;
  68         unsigned long pers;
  69
  70         /* Figure out what personality we are supposed to switch to ...
  71          * we can be invoked as either:
  72          * argv[0],argv[1] == "setarch","personality"
  73          * argv[0]         == "personality"
  74          */
  75         if (ENABLE_SETARCH && applet_name[0] == 's'
  76          && argv[1] && is_prefixed_with(argv[1], "linux")
  77         ) {
  78                 argv++;
  79                 applet_name = argv[0];
  80         }
  81         if ((!ENABLE_SETARCH && !ENABLE_LINUX32) || applet_name[5] == '6')
  82                 /* linux64 */
  83                 pers = PER_LINUX;
  84         else
  85         if ((!ENABLE_SETARCH && !ENABLE_LINUX64) || applet_name[5] == '3')
  86                 /* linux32 */
  87                 pers = PER_LINUX32;
  88         else
  89                 bb_show_usage();
  90
  91         opts = getopt32(argv, "+R"); /* '+': stop at first non-option */
  92         if (opts)
  93                 pers |= ADDR_NO_RANDOMIZE;
  94
  95         /* Try to set personality */
  96         if (personality(pers) < 0)
  97                 bb_perror_msg_and_die("personality(0x%lx)", pers);
  98
  99         argv += optind;
 100         if (!argv[0])
 101                 (--argv)[0] = (char*)"/bin/sh";
 102
 103         /* Try to execute the program */
 104         BB_EXECVP_or_die(argv);
 105 }