diff options
| -rw-r--r-- | docs/nofork_noexec.txt | 27 | ||||
| -rw-r--r-- | include/libbb.h | 1 | ||||
| -rw-r--r-- | shell/Config.src | 9 | ||||
| -rw-r--r-- | shell/hush.c | 11 |
4 files changed, 34 insertions, 14 deletions
diff --git a/docs/nofork_noexec.txt b/docs/nofork_noexec.txt index 06c789a..c58f5a8 100644 --- a/docs/nofork_noexec.txt +++ b/docs/nofork_noexec.txt @@ -44,9 +44,11 @@ NOEXEC trick is disabled for NOMMU build. NOFORK NOFORK applet should work correctly if another applet simply runs -<applet>_main(argc,argv) and then continues with its business (xargs, -find, shells can do it). This poses much more serious limitations -on what applet can/cannot do: +<applet>_main(argc,argv) and then continues with its business. +xargs, find, shells do it (grep for "spawn_and_wait" and +"run_nofork_applet" to find more users). + +This poses much more serious limitations on what applet can do: * all NOEXEC limitations apply. * do not ever exit() or exec(). @@ -56,7 +58,7 @@ on what applet can/cannot do: is taken from xfunc_error_retval. - fflush_stdout_and_exit(n) is ok to use. * do not use shared global data, or save/restore shared global data - prior to returning. (e.g. bb_common_bufsiz1 is off-limits). + (e.g. bb_common_bufsiz1) prior to returning. - getopt32() is ok to use. You do not need to save/restore option_mask32, it is already done by core code. * if you allocate memory, you can use xmalloc() only on the very first @@ -77,3 +79,20 @@ script loops. Applets which mess with signal handlers, termios etc are probably not worth the effort. Any NOFORK applet is also a NOEXEC applet. + + + Relevant CONFIG options + +FEATURE_PREFER_APPLETS + BB_EXECVP(cmd, argv) will try to exec /proc/self/exe + if command's name matches some applet name + applet tables will contain NOFORK/NOEXEC bits + spawn_and_wait(argv) will do NOFORK/NOEXEC tricks + +FEATURE_SH_STANDALONE (needs FEATURE_PREFER_APPLETS=y) + shells will try to exec /proc/self/exe if command's name matches + some applet name + shells will do NOEXEC trick on NOEXEC applets + +FEATURE_SH_NOFORK (needs FEATURE_PREFER_APPLETS=y) + shells will do NOFORK trick on NOFORK applets diff --git a/include/libbb.h b/include/libbb.h index e69e279..88dceb1 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -859,6 +859,7 @@ void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const # define update_utmp(pid, new_type, tty_name, username, hostname) ((void)0) #endif + int execable_file(const char *name) FAST_FUNC; char *find_execable(const char *filename, char **PATHp) FAST_FUNC; int exists_execable(const char *filename) FAST_FUNC; diff --git a/shell/Config.src b/shell/Config.src index c9c2439..e96c216 100644 --- a/shell/Config.src +++ b/shell/Config.src @@ -123,9 +123,9 @@ config FEATURE_SH_NOFORK default n depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS help - This option causes busybox shells [currently only ash] - to not execute typical fork/exec/wait sequence, but call <applet>_main - directly, if possible. (Sometimes it is not possible: for example, + This option causes busybox shells to not execute typical + fork/exec/wait sequence, but call <applet>_main directly, + if possible. (Sometimes it is not possible: for example, this is not possible in pipes). This will be done only for some applets (those which are marked @@ -133,6 +133,7 @@ config FEATURE_SH_NOFORK This may significantly speed up some shell scripts. - This feature is relatively new. Use with care. + This feature is relatively new. Use with care. Report bugs + to project mailing list. endmenu diff --git a/shell/hush.c b/shell/hush.c index 1709fd9..10788b8 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -6615,7 +6615,7 @@ static int checkjobs_and_fg_shell(struct pipe *fg_pipe) * cmd ; ... { list } ; ... * cmd && ... { list } && ... * cmd || ... { list } || ... - * If it is, then we can run cmd as a builtin, NOFORK [do we do this?], + * If it is, then we can run cmd as a builtin, NOFORK, * or (if SH_STANDALONE) an applet, and we can run the { list } * with run_list. If it isn't one of these, we fork and exec cmd. * @@ -6797,13 +6797,12 @@ static NOINLINE int run_pipe(struct pipe *pi) } /* Expand the rest into (possibly) many strings each */ - if (0) {} #if ENABLE_HUSH_BASH_COMPAT - else if (command->cmd_type == CMD_SINGLEWORD_NOGLOB) { + if (command->cmd_type == CMD_SINGLEWORD_NOGLOB) { argv_expanded = expand_strvec_to_strvec_singleword_noglob(argv + command->assignment_cnt); - } + } else #endif - else { + { argv_expanded = expand_strvec_to_strvec(argv + command->assignment_cnt); } @@ -6865,7 +6864,7 @@ static NOINLINE int run_pipe(struct pipe *pi) return rcode; } - if (ENABLE_FEATURE_SH_STANDALONE) { + if (ENABLE_FEATURE_SH_NOFORK) { int n = find_applet_by_name(argv_expanded[0]); if (n >= 0 && APPLET_IS_NOFORK(n)) { rcode = redirect_and_varexp_helper(&new_env, &old_vars, command, squirrel, argv_expanded); |