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update_passwd 732 734 +2 chpasswd_main 318 292 -26 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 2/-26) Total: -24 bytes text data bss dec hex filename 781564 1168 11900 794632 c2008 busybox_old 781548 1168 11900 794616 c1ff8 busybox_unstripped
120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* update_passwd
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*
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* update_passwd is a common function for passwd and chpasswd applets;
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* it is responsible for updating password file (i.e. /etc/passwd or
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* /etc/shadow) for a given user and password.
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*
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* Moved from loginutils/passwd.c by Alexander Shishkin <virtuoso@slind.org>
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*/
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#include "libbb.h"
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int update_passwd(const char *filename, const char *username,
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const char *new_pw)
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{
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struct stat sb;
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struct flock lock;
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FILE *old_fp;
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FILE *new_fp;
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char *fnamesfx;
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char *sfx_char;
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unsigned user_len;
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int old_fd;
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int new_fd;
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int i;
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int cnt = 0;
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int ret = -1; /* failure */
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/* New passwd file, "/etc/passwd+" for now */
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fnamesfx = xasprintf("%s+", filename);
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sfx_char = &fnamesfx[strlen(fnamesfx)-1];
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username = xasprintf("%s:", username);
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user_len = strlen(username);
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old_fp = fopen(filename, "r+");
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if (!old_fp)
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goto free_mem;
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old_fd = fileno(old_fp);
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/* Try to create "/etc/passwd+". Wait if it exists. */
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i = 30;
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do {
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// FIXME: on last iteration try w/o O_EXCL but with O_TRUNC?
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new_fd = open(fnamesfx, O_WRONLY|O_CREAT|O_EXCL, 0600);
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if (new_fd >= 0) goto created;
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if (errno != EEXIST) break;
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usleep(100000); /* 0.1 sec */
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} while (--i);
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bb_perror_msg("cannot create '%s'", fnamesfx);
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goto close_old_fp;
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created:
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if (!fstat(old_fd, &sb)) {
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fchmod(new_fd, sb.st_mode & 0777); /* ignore errors */
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fchown(new_fd, sb.st_uid, sb.st_gid);
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}
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new_fp = fdopen(new_fd, "w");
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if (!new_fp) {
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close(new_fd);
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goto unlink_new;
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}
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/* Backup file is "/etc/passwd-" */
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*sfx_char = '-';
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/* Delete old backup */
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i = (unlink(fnamesfx) && errno != ENOENT);
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/* Create backup as a hardlink to current */
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if (i || link(filename, fnamesfx))
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bb_perror_msg("warning: cannot create backup copy '%s'", fnamesfx);
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*sfx_char = '+';
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/* Lock the password file before updating */
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lock.l_type = F_WRLCK;
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lock.l_whence = SEEK_SET;
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lock.l_start = 0;
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lock.l_len = 0;
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if (fcntl(old_fd, F_SETLK, &lock) < 0)
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bb_perror_msg("warning: cannot lock '%s'", filename);
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lock.l_type = F_UNLCK;
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/* Read current password file, write updated /etc/passwd+ */
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while (1) {
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char *line = xmalloc_fgets(old_fp);
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if (!line) break; /* EOF/error */
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if (strncmp(username, line, user_len) == 0) {
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/* we have a match with "username:"... */
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const char *cp = line + user_len;
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/* now cp -> old passwd, skip it: */
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cp = strchrnul(cp, ':');
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/* now cp -> ':' after old passwd or -> "" */
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fprintf(new_fp, "%s%s%s", username, new_pw, cp);
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cnt++;
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} else
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fputs(line, new_fp);
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free(line);
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}
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fcntl(old_fd, F_SETLK, &lock);
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/* We do want all of them to execute, thus | instead of || */
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if ((ferror(old_fp) | fflush(new_fp) | fsync(new_fd) | fclose(new_fp))
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|| rename(fnamesfx, filename)
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) {
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/* At least one of those failed */
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goto unlink_new;
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}
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ret = cnt; /* whee, success! */
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unlink_new:
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if (ret < 0) unlink(fnamesfx);
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close_old_fp:
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fclose(old_fp);
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free_mem:
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free(fnamesfx);
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free((char*)username);
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return ret;
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}
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