Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 | /* vi: set sw=4 ts=4: */
/*
* update_passwd
*
* update_passwd is a common function for passwd and chpasswd applets;
* it is responsible for updating password file (i.e. /etc/passwd or
* /etc/shadow) for a given user and password.
*
* Moved from loginutils/passwd.c by Alexander Shishkin <virtuoso@slind.org>
*
* Modified to be able to add or delete users, groups and users to/from groups
* by Tito Ragusa <farmatito@tiscali.it>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "libbb.h"
#if ENABLE_SELINUX
static void check_selinux_update_passwd(const char *username)
{
security_context_t context;
char *seuser;
if (getuid() != (uid_t)0 || is_selinux_enabled() == 0)
return; /* No need to check */
if (getprevcon_raw(&context) < 0)
bb_perror_msg_and_die("getprevcon failed");
seuser = strtok(context, ":");
if (!seuser)
bb_error_msg_and_die("invalid context '%s'", context);
if (strcmp(seuser, username) != 0) {
security_class_t tclass;
access_vector_t av;
tclass = string_to_security_class("passwd");
if (tclass == 0)
goto die;
av = string_to_av_perm(tclass, "passwd");
if (av == 0)
goto die;
if (selinux_check_passwd_access(av) != 0)
die:
bb_error_msg_and_die("SELinux: access denied");
}
if (ENABLE_FEATURE_CLEAN_UP)
freecon(context);
}
#else
# define check_selinux_update_passwd(username) ((void)0)
#endif
/*
1) add a user: update_passwd(FILE, USER, REMAINING_PWLINE, NULL)
only if CONFIG_ADDUSER=y and applet_name[0] == 'a' like in adduser
2) add a group: update_passwd(FILE, GROUP, REMAINING_GRLINE, NULL)
only if CONFIG_ADDGROUP=y and applet_name[0] == 'a' like in addgroup
3) add a user to a group: update_passwd(FILE, GROUP, NULL, MEMBER)
only if CONFIG_FEATURE_ADDUSER_TO_GROUP=y, applet_name[0] == 'a'
like in addgroup and member != NULL
4) delete a user: update_passwd(FILE, USER, NULL, NULL)
5) delete a group: update_passwd(FILE, GROUP, NULL, NULL)
6) delete a user from a group: update_passwd(FILE, GROUP, NULL, MEMBER)
only if CONFIG_FEATURE_DEL_USER_FROM_GROUP=y and member != NULL
7) change user's password: update_passwd(FILE, USER, NEW_PASSWD, NULL)
only if CONFIG_PASSWD=y and applet_name[0] == 'p' like in passwd
or if CONFIG_CHPASSWD=y and applet_name[0] == 'c' like in chpasswd
8) delete a user from all groups: update_passwd(FILE, NULL, NULL, MEMBER)
This function does not validate the arguments fed to it
so the calling program should take care of that.
Returns number of lines changed, or -1 on error.
*/
int FAST_FUNC update_passwd(const char *filename,
const char *name,
const char *new_passwd,
const char *member)
{
#if !(ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP)
#define member NULL
#endif
struct stat sb;
struct flock lock;
FILE *old_fp;
FILE *new_fp;
char *fnamesfx;
char *sfx_char;
char *name_colon;
int old_fd;
int new_fd;
int i;
int changed_lines;
int ret = -1; /* failure */
/* used as a bool: "are we modifying /etc/shadow?" */
#if ENABLE_FEATURE_SHADOWPASSWDS
const char *shadow = strstr(filename, "shadow");
#else
# define shadow NULL
#endif
filename = xmalloc_follow_symlinks(filename);
if (filename == NULL)
return ret;
if (name)
check_selinux_update_passwd(name);
/* New passwd file, "/etc/passwd+" for now */
fnamesfx = xasprintf("%s+", filename);
sfx_char = &fnamesfx[strlen(fnamesfx)-1];
name_colon = xasprintf("%s:", name ? name : "");
if (shadow)
old_fp = fopen(filename, "r+");
else
old_fp = fopen_or_warn(filename, "r+");
if (!old_fp) {
if (shadow)
ret = 0; /* missing shadow is not an error */
goto free_mem;
}
old_fd = fileno(old_fp);
selinux_preserve_fcontext(old_fd);
/* Try to create "/etc/passwd+". Wait if it exists. */
i = 30;
do {
// FIXME: on last iteration try w/o O_EXCL but with O_TRUNC?
new_fd = open(fnamesfx, O_WRONLY|O_CREAT|O_EXCL, 0600);
if (new_fd >= 0) goto created;
if (errno != EEXIST) break;
usleep(100000); /* 0.1 sec */
} while (--i);
bb_perror_msg("can't create '%s'", fnamesfx);
goto close_old_fp;
created:
if (fstat(old_fd, &sb) == 0) {
fchmod(new_fd, sb.st_mode & 0777); /* ignore errors */
fchown(new_fd, sb.st_uid, sb.st_gid);
}
errno = 0;
new_fp = xfdopen_for_write(new_fd);
/* Backup file is "/etc/passwd-" */
*sfx_char = '-';
/* Delete old backup */
i = (unlink(fnamesfx) && errno != ENOENT);
/* Create backup as a hardlink to current */
if (i || link(filename, fnamesfx))
bb_perror_msg("warning: can't create backup copy '%s'",
fnamesfx);
*sfx_char = '+';
/* Lock the password file before updating */
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
if (fcntl(old_fd, F_SETLK, &lock) < 0)
bb_perror_msg("warning: can't lock '%s'", filename);
lock.l_type = F_UNLCK;
/* Read current password file, write updated /etc/passwd+ */
changed_lines = 0;
while (1) {
char *cp, *line;
line = xmalloc_fgetline(old_fp);
if (!line) /* EOF/error */
break;
#if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP
if (!name && member) {
/* Delete member from all groups */
/* line is "GROUP:PASSWD:[member1[,member2]...]" */
unsigned member_len = strlen(member);
char *list = strrchr(line, ':');
while (list) {
list++;
next_list_element:
if (is_prefixed_with(list, member)) {
char c;
changed_lines++;
c = list[member_len];
if (c == '\0') {
if (list[-1] == ',')
list--;
*list = '\0';
break;
}
if (c == ',') {
overlapping_strcpy(list, list + member_len + 1);
goto next_list_element;
}
changed_lines--;
}
list = strchr(list, ',');
}
fprintf(new_fp, "%s\n", line);
goto next;
}
#endif
cp = is_prefixed_with(line, name_colon);
if (!cp) {
fprintf(new_fp, "%s\n", line);
goto next;
}
/* We have a match with "name:"... */
/* cp points past "name:" */
#if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP
if (member) {
/* It's actually /etc/group+, not /etc/passwd+ */
if (ENABLE_FEATURE_ADDUSER_TO_GROUP
&& applet_name[0] == 'a'
) {
/* Add user to group */
fprintf(new_fp, "%s%s%s\n", line,
last_char_is(line, ':') ? "" : ",",
member);
changed_lines++;
} else if (ENABLE_FEATURE_DEL_USER_FROM_GROUP
/* && applet_name[0] == 'd' */
) {
/* Delete user from group */
char *tmp;
const char *fmt = "%s";
/* find the start of the member list: last ':' */
cp = strrchr(line, ':');
/* cut it */
*cp++ = '\0';
/* write the cut line name:passwd:gid:
* or name:!:: */
fprintf(new_fp, "%s:", line);
/* parse the tokens of the member list */
tmp = cp;
while ((cp = strsep(&tmp, ",")) != NULL) {
if (strcmp(member, cp) != 0) {
fprintf(new_fp, fmt, cp);
fmt = ",%s";
} else {
/* found member, skip it */
changed_lines++;
}
}
fprintf(new_fp, "\n");
}
} else
#endif
if ((ENABLE_PASSWD && applet_name[0] == 'p')
|| (ENABLE_CHPASSWD && applet_name[0] == 'c')
) {
/* Change passwd */
cp = strchrnul(cp, ':'); /* move past old passwd */
if (shadow && *cp == ':') {
/* /etc/shadow's field 3 (passwd change date) needs updating */
/* move past old change date */
cp = strchrnul(cp + 1, ':');
/* "name:" + "new_passwd" + ":" + "change date" + ":rest of line" */
fprintf(new_fp, "%s%s:%u%s\n", name_colon, new_passwd,
(unsigned)(time(NULL)) / (24*60*60), cp);
} else {
/* "name:" + "new_passwd" + ":rest of line" */
fprintf(new_fp, "%s%s%s\n", name_colon, new_passwd, cp);
}
changed_lines++;
} /* else delete user or group: skip the line */
next:
free(line);
}
if (changed_lines == 0) {
#if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP
if (member) {
if (ENABLE_ADDGROUP && applet_name[0] == 'a')
bb_error_msg("can't find %s in %s", name, filename);
if (ENABLE_DELGROUP && applet_name[0] == 'd')
bb_error_msg("can't find %s in %s", member, filename);
}
#endif
if ((ENABLE_ADDUSER || ENABLE_ADDGROUP)
&& applet_name[0] == 'a' && !member
) {
/* add user or group */
fprintf(new_fp, "%s%s\n", name_colon, new_passwd);
changed_lines++;
}
}
fcntl(old_fd, F_SETLK, &lock);
/* We do want all of them to execute, thus | instead of || */
errno = 0;
if ((ferror(old_fp) | fflush(new_fp) | fsync(new_fd) | fclose(new_fp))
|| rename(fnamesfx, filename)
) {
/* At least one of those failed */
bb_perror_nomsg();
goto unlink_new;
}
/* Success: ret >= 0 */
ret = changed_lines;
unlink_new:
if (ret < 0)
unlink(fnamesfx);
close_old_fp:
fclose(old_fp);
free_mem:
free(fnamesfx);
free((char *)filename);
free(name_colon);
return ret;
}
|