beea5a70c
Denys Vlasenko
2011-03-22
Subject
mesg: make group/all writability configurable
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Commit Diff GitHub →
init/mesg.c+35 -25
| @@ -7,16 +7,28 @@ | |
| * Licensed under GPLv2 or later, see file LICENSE in this source tree. | |
| */ | |
| - | //applet:IF_MESG(APPLET(mesg, BB_DIR_USR_BIN, BB_SUID_DROP)) |
| - | |
| - | //kbuild:lib-$(CONFIG_MESG) += mesg.o |
| - | |
| //config:config MESG | |
| //config: bool "mesg" | |
| //config: default y | |
| //config: help | |
| //config: Mesg controls access to your terminal by others. It is typically | |
| //config: used to allow or disallow other users to write to your terminal | |
| + | //config: |
| + | //config:config FEATURE_MESG_ENABLE_ONLY_GROUP |
| + | //config: bool "Enable writing to tty only by group, not by everybody" |
| + | //config: default y |
| + | //config: depends on MESG |
| + | //config: help |
| + | //config: Usually, ttys are owned by group "tty", and "write" tool is |
| + | //config: setgid to this group. This way, "mesg y" only needs to enable |
| + | //config: "write by owning group" bit in tty mode. |
| + | //config: |
| + | //config: If you set this option to N, "mesg y" will enable writing |
| + | //config: by anybody at all. This is not recommended. |
| + | |
| + | //applet:IF_MESG(APPLET(mesg, BB_DIR_USR_BIN, BB_SUID_DROP)) |
| + | |
| + | //kbuild:lib-$(CONFIG_MESG) += mesg.o |
| //usage:#define mesg_trivial_usage | |
| //usage: "[y|n]" | |
| @@ -27,7 +39,7 @@ | |
| #include "libbb.h" | |
| - | #ifdef USE_TTY_GROUP |
| + | #if ENABLE_FEATURE_MESG_ENABLE_ONLY_GROUP |
| #define S_IWGRP_OR_S_IWOTH S_IWGRP | |
| #else | |
| #define S_IWGRP_OR_S_IWOTH (S_IWGRP | S_IWOTH) | |
| @@ -37,30 +49,28 @@ int mesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; | |
| int mesg_main(int argc UNUSED_PARAM, char **argv) | |
| { | |
| struct stat sb; | |
| - | const char *tty; |
| + | mode_t m; |
| char c = 0; | |
| argv++; | |
| - | if (!argv[0] |
| - | || (!argv[1] && ((c = argv[0][0]) == 'y' || c == 'n')) |
| + | if (argv[0] |
| + | && (argv[1] || ((c = argv[0][0]) != 'y' && c != 'n')) |
| ) { | |
| - | tty = xmalloc_ttyname(STDERR_FILENO); |
| - | if (tty == NULL) { |
| - | tty = "ttyname"; |
| - | } else if (stat(tty, &sb) == 0) { |
| - | mode_t m; |
| - | if (c == 0) { |
| - | puts((sb.st_mode & (S_IWGRP|S_IWOTH)) ? "is y" : "is n"); |
| - | return EXIT_SUCCESS; |
| - | } |
| - | m = (c == 'y') ? sb.st_mode | S_IWGRP_OR_S_IWOTH |
| - | : sb.st_mode & ~(S_IWGRP|S_IWOTH); |
| - | if (chmod(tty, m) == 0) { |
| - | return EXIT_SUCCESS; |
| - | } |
| - | } |
| - | bb_simple_perror_msg_and_die(tty); |
| + | bb_show_usage(); |
| + | } |
| + | |
| + | if (!isatty(STDERR_FILENO)) |
| + | bb_error_msg_and_die("not a tty"); |
| + | |
| + | xfstat(STDERR_FILENO, &sb, "stderr"); |
| + | if (c == 0) { |
| + | puts((sb.st_mode & (S_IWGRP|S_IWOTH)) ? "is y" : "is n"); |
| + | return EXIT_SUCCESS; |
| } | |
| - | bb_show_usage(); |
| + | m = (c == 'y') ? sb.st_mode | S_IWGRP_OR_S_IWOTH |
| + | : sb.st_mode & ~(S_IWGRP|S_IWOTH); |
| + | if (fchmod(STDERR_FILENO, m) != 0) |
| + | bb_perror_nomsg_and_die(); |
| + | return EXIT_SUCCESS; |
| } | |