sulogin: allow system maintenance login if root password is empty
The current password checking is unable to distinguish between the user entering an empty password or pressing Control-D. As a result, an empty password always results in normal startup. We modify bb_ask to return NULL if Control-D is pressed without entering a password. The sulogin applet is then modified to only proceed to normal startup if bb_ask returns NULL. This covers EOF with no password, interrupt by timeout and ^C. Signed-off-by: Jonathan Liu <net147@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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@ -65,7 +65,9 @@ char* FAST_FUNC bb_ask(const int fd, int timeout, const char *prompt)
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i = 0;
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while (1) {
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int r = read(fd, &ret[i], 1);
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if (r < 0) {
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if ((i == 0 && r == 0) /* EOF (^D) with no password */
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|| r < 0
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) {
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/* read is interrupted by timeout or ^C */
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ret = NULL;
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break;
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@ -83,8 +83,8 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv)
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cp = bb_ask(STDIN_FILENO, timeout,
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"Give root password for system maintenance\n"
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"(or type Control-D for normal startup):");
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if (!cp || !*cp) {
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if (!cp) {
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/* ^D, ^C, timeout, or read error */
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bb_info_msg("Normal startup");
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return 0;
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}
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