[2725] | 1 | /*
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| 2 | * add-shell and remove-shell implementation for busybox
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| 3 | *
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| 4 | * Copyright (C) 2010 Nokia Corporation. All rights reserved.
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| 5 | * Written by Alexander Shishkin <virtuoso@slind.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see the LICENSE file in this source tree
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| 8 | * for details.
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| 9 | */
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| 10 |
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| 11 | //applet:IF_ADD_SHELL( APPLET_ODDNAME(add-shell , add_remove_shell, _BB_DIR_USR_BIN, _BB_SUID_DROP, add_shell ))
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| 12 | //applet:IF_REMOVE_SHELL(APPLET_ODDNAME(remove-shell, add_remove_shell, _BB_DIR_USR_BIN, _BB_SUID_DROP, remove_shell))
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| 13 |
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| 14 | //kbuild:lib-$(CONFIG_ADD_SHELL) += add-remove-shell.o
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| 15 | //kbuild:lib-$(CONFIG_REMOVE_SHELL) += add-remove-shell.o
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| 16 |
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| 17 | //config:config ADD_SHELL
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| 18 | //config: bool "add-shell"
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| 19 | //config: default y if DESKTOP
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| 20 | //config: help
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| 21 | //config: Add shells to /etc/shells.
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| 22 | //config:
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| 23 | //config:config REMOVE_SHELL
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| 24 | //config: bool "remove-shell"
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| 25 | //config: default y if DESKTOP
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| 26 | //config: help
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| 27 | //config: Remove shells from /etc/shells.
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| 28 |
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| 29 | //usage:#define add_shell_trivial_usage
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| 30 | //usage: "SHELL..."
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| 31 | //usage:#define add_shell_full_usage "\n\n"
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| 32 | //usage: "Add SHELLs to /etc/shells"
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| 33 |
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| 34 | //usage:#define remove_shell_trivial_usage
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| 35 | //usage: "SHELL..."
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| 36 | //usage:#define remove_shell_full_usage "\n\n"
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| 37 | //usage: "Remove SHELLs from /etc/shells"
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| 38 |
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| 39 | #include "libbb.h"
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| 40 |
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| 41 | #define SHELLS_FILE "/etc/shells"
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| 42 |
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| 43 | #define REMOVE_SHELL (ENABLE_REMOVE_SHELL && (!ENABLE_ADD_SHELL || applet_name[0] == 'r'))
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| 44 | #define ADD_SHELL (ENABLE_ADD_SHELL && (!ENABLE_REMOVE_SHELL || applet_name[0] == 'a'))
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| 45 |
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| 46 | /* NB: we use the _address_, not the value, of this string
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| 47 | * as a "special value of pointer" in the code.
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| 48 | */
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| 49 | static const char dont_add[] ALIGN1 = "\n";
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| 50 |
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| 51 | int add_remove_shell_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 52 | int add_remove_shell_main(int argc UNUSED_PARAM, char **argv)
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| 53 | {
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| 54 | FILE *orig_fp;
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| 55 | char *orig_fn;
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| 56 | char *new_fn;
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| 57 |
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| 58 | argv++;
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| 59 |
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| 60 | orig_fn = xmalloc_follow_symlinks(SHELLS_FILE);
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| 61 | if (!orig_fn)
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| 62 | return EXIT_FAILURE;
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| 63 | orig_fp = fopen_for_read(orig_fn);
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| 64 |
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| 65 | new_fn = xasprintf("%s.tmp", orig_fn);
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| 66 | /*
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| 67 | * O_TRUNC or O_EXCL? At the first glance, O_EXCL looks better,
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| 68 | * since it prevents races. But: (1) it requires a retry loop,
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| 69 | * (2) if /etc/shells.tmp is *stale*, then retry loop
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| 70 | * with O_EXCL will never succeed - it should have a timeout,
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| 71 | * after which it should revert to O_TRUNC.
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| 72 | * For now, I settle for O_TRUNC instead.
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| 73 | */
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| 74 | xmove_fd(xopen(new_fn, O_WRONLY | O_CREAT | O_TRUNC), STDOUT_FILENO);
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| 75 |
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| 76 | /* TODO:
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| 77 | struct stat sb;
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| 78 | xfstat(fileno(orig_fp), &sb);
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| 79 | xfchown(STDOUT_FILENO, sb.st_uid, sb.st_gid);
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| 80 | xfchmod(STDOUT_FILENO, sb.st_mode);
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| 81 | */
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| 82 |
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| 83 | if (orig_fp) {
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| 84 | /* Copy old file, possibly skipping removed shell names */
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| 85 | char *line;
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| 86 | while ((line = xmalloc_fgetline(orig_fp)) != NULL) {
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| 87 | char **cpp = argv;
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| 88 | while (*cpp) {
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| 89 | if (strcmp(*cpp, line) == 0) {
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| 90 | /* Old file has this shell name */
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| 91 | if (REMOVE_SHELL) {
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| 92 | /* we are remove-shell */
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| 93 | /* delete this name by not copying it */
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| 94 | goto next_line;
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| 95 | }
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| 96 | /* we are add-shell */
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| 97 | /* mark this name as "do not add" */
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| 98 | *cpp = (char*)dont_add;
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| 99 | }
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| 100 | cpp++;
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| 101 | }
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| 102 | /* copy shell name from old to new file */
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| 103 | printf("%s\n", line);
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| 104 | next_line:
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| 105 | free(line);
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| 106 | }
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| 107 | if (ENABLE_FEATURE_CLEAN_UP)
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| 108 | fclose(orig_fp);
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| 109 | }
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| 110 |
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| 111 | if (ADD_SHELL) {
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| 112 | char **cpp = argv;
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| 113 | while (*cpp) {
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| 114 | if (*cpp != dont_add)
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| 115 | printf("%s\n", *cpp);
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| 116 | cpp++;
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| 117 | }
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| 118 | }
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| 119 |
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| 120 | /* Ensure we wrote out everything */
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| 121 | if (fclose(stdout) != 0) {
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| 122 | xunlink(new_fn);
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| 123 | bb_perror_msg_and_die("%s: write error", new_fn);
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| 124 | }
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| 125 |
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| 126 | /* Small hole: if rename fails, /etc/shells.tmp is not removed */
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| 127 | xrename(new_fn, orig_fn);
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| 128 |
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| 129 | if (ENABLE_FEATURE_CLEAN_UP) {
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| 130 | free(orig_fn);
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| 131 | free(new_fn);
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| 132 | }
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| 133 |
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| 134 | return EXIT_SUCCESS;
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| 135 | }
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