1 /* vi: set sw=4 ts=4: */
5 * update_passwd is a common function for passwd and chpasswd applets;
6 * it is responsible for updating password file (i.e. /etc/passwd or
7 * /etc/shadow) for a given user and password.
9 * Moved from loginutils/passwd.c by Alexander Shishkin <virtuoso@slind.org>
11 * Modified to be able to add or delete users, groups and users to/from groups
12 * by Tito Ragusa <farmatito@tiscali.it>
14 * Licensed under GPLv2, see file LICENSE in this tarball for details.
19 static void check_selinux_update_passwd(const char *username)
21 security_context_t context;
24 if (getuid() != (uid_t)0 || is_selinux_enabled() == 0)
25 return; /* No need to check */
27 if (getprevcon_raw(&context) < 0)
28 bb_perror_msg_and_die("getprevcon failed");
29 seuser = strtok(context, ":");
31 bb_error_msg_and_die("invalid context '%s'", context);
32 if (strcmp(seuser, username) != 0) {
33 if (checkPasswdAccess(PASSWD__PASSWD) != 0)
34 bb_error_msg_and_die("SELinux: access denied");
36 if (ENABLE_FEATURE_CLEAN_UP)
40 # define check_selinux_update_passwd(username) ((void)0)
44 1) add a user: update_passwd(FILE, USER, REMAINING_PWLINE, NULL)
45 only if CONFIG_ADDUSER=y and applet_name[0] == 'a' like in adduser
47 2) add a group: update_passwd(FILE, GROUP, REMAINING_GRLINE, NULL)
48 only if CONFIG_ADDGROUP=y and applet_name[0] == 'a' like in addgroup
50 3) add a user to a group: update_passwd(FILE, GROUP, NULL, MEMBER)
51 only if CONFIG_FEATURE_ADDUSER_TO_GROUP=y, applet_name[0] == 'a'
52 like in addgroup and member != NULL
54 4) delete a user: update_passwd(FILE, USER, NULL, NULL)
56 5) delete a group: update_passwd(FILE, GROUP, NULL, NULL)
58 6) delete a user from a group: update_passwd(FILE, GROUP, NULL, MEMBER)
59 only if CONFIG_FEATURE_DEL_USER_FROM_GROUP=y and member != NULL
61 7) change user's passord: update_passwd(FILE, USER, NEW_PASSWD, NULL)
62 only if CONFIG_PASSWD=y and applet_name[0] == 'p' like in passwd
63 or if CONFIG_CHPASSWD=y and applet_name[0] == 'c' like in chpasswd
65 This function does not validate the arguments fed to it
66 so the calling program should take care of that.
68 Returns number of lines changed, or -1 on error.
70 int FAST_FUNC update_passwd(const char *filename,
72 const char *new_passwd,
75 #if !(ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP)
89 int ret = -1; /* failure */
90 /* used as a bool: "are we modifying /etc/shadow?" */
91 #if ENABLE_FEATURE_SHADOWPASSWDS
92 const char *shadow = strstr(filename, "shadow");
97 filename = xmalloc_follow_symlinks(filename);
101 check_selinux_update_passwd(name);
103 /* New passwd file, "/etc/passwd+" for now */
104 fnamesfx = xasprintf("%s+", filename);
105 sfx_char = &fnamesfx[strlen(fnamesfx)-1];
106 name = xasprintf("%s:", name);
107 user_len = strlen(name);
110 old_fp = fopen(filename, "r+");
112 old_fp = fopen_or_warn(filename, "r+");
115 old_fd = fileno(old_fp);
117 selinux_preserve_fcontext(old_fd);
119 /* Try to create "/etc/passwd+". Wait if it exists. */
122 // FIXME: on last iteration try w/o O_EXCL but with O_TRUNC?
123 new_fd = open(fnamesfx, O_WRONLY|O_CREAT|O_EXCL, 0600);
124 if (new_fd >= 0) goto created;
125 if (errno != EEXIST) break;
126 usleep(100000); /* 0.1 sec */
128 bb_perror_msg("can't create '%s'", fnamesfx);
132 if (!fstat(old_fd, &sb)) {
133 fchmod(new_fd, sb.st_mode & 0777); /* ignore errors */
134 fchown(new_fd, sb.st_uid, sb.st_gid);
137 new_fp = fdopen(new_fd, "w");
144 /* Backup file is "/etc/passwd-" */
146 /* Delete old backup */
147 i = (unlink(fnamesfx) && errno != ENOENT);
148 /* Create backup as a hardlink to current */
149 if (i || link(filename, fnamesfx))
150 bb_perror_msg("warning: can't create backup copy '%s'",
154 /* Lock the password file before updating */
155 lock.l_type = F_WRLCK;
156 lock.l_whence = SEEK_SET;
159 if (fcntl(old_fd, F_SETLK, &lock) < 0)
160 bb_perror_msg("warning: can't lock '%s'", filename);
161 lock.l_type = F_UNLCK;
163 /* Read current password file, write updated /etc/passwd+ */
168 line = xmalloc_fgetline(old_fp);
169 if (!line) /* EOF/error */
171 if (strncmp(name, line, user_len) != 0) {
172 fprintf(new_fp, "%s\n", line);
176 /* We have a match with "name:"... */
177 cp = line + user_len; /* move past name: */
179 #if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP
181 /* It's actually /etc/group+, not /etc/passwd+ */
182 if (ENABLE_FEATURE_ADDUSER_TO_GROUP
183 && applet_name[0] == 'a'
185 /* Add user to group */
186 fprintf(new_fp, "%s%s%s\n", line,
187 last_char_is(line, ':') ? "" : ",",
190 } else if (ENABLE_FEATURE_DEL_USER_FROM_GROUP
191 /* && applet_name[0] == 'd' */
193 /* Delete user from group */
195 const char *fmt = "%s";
197 /* find the start of the member list: last ':' */
198 cp = strrchr(line, ':');
201 /* write the cut line name:passwd:gid:
203 fprintf(new_fp, "%s:", line);
204 /* parse the tokens of the member list */
206 while ((cp = strsep(&tmp, ",")) != NULL) {
207 if (strcmp(member, cp) != 0) {
208 fprintf(new_fp, fmt, cp);
211 /* found member, skip it */
215 fprintf(new_fp, "\n");
219 if ((ENABLE_PASSWD && applet_name[0] == 'p')
220 || (ENABLE_CHPASSWD && applet_name[0] == 'c')
223 cp = strchrnul(cp, ':'); /* move past old passwd */
225 if (shadow && *cp == ':') {
226 /* /etc/shadow's field 3 (passwd change date) needs updating */
227 /* move past old change date */
228 cp = strchrnul(cp + 1, ':');
229 /* "name:" + "new_passwd" + ":" + "change date" + ":rest of line" */
230 fprintf(new_fp, "%s%s:%u%s\n", name, new_passwd,
231 (unsigned)(time(NULL)) / (24*60*60), cp);
233 /* "name:" + "new_passwd" + ":rest of line" */
234 fprintf(new_fp, "%s%s%s\n", name, new_passwd, cp);
237 } /* else delete user or group: skip the line */
242 if (changed_lines == 0) {
243 #if ENABLE_FEATURE_DEL_USER_FROM_GROUP
245 bb_error_msg("can't find %s in %s", member, filename);
247 if ((ENABLE_ADDUSER || ENABLE_ADDGROUP)
248 && applet_name[0] == 'a' && !member
250 /* add user or group */
251 fprintf(new_fp, "%s%s\n", name, new_passwd);
256 fcntl(old_fd, F_SETLK, &lock);
258 /* We do want all of them to execute, thus | instead of || */
260 if ((ferror(old_fp) | fflush(new_fp) | fsync(new_fd) | fclose(new_fp))
261 || rename(fnamesfx, filename)
263 /* At least one of those failed */
267 /* Success: ret >= 0 */
279 free((char *)filename);