From 4aca87515a5083ae0e31ce3177189fd43b6d05ac Mon Sep 17 00:00:00 2001 From: Andreas Baumann Date: Sat, 3 Jan 2015 13:58:15 +0100 Subject: patch to Vanilla Tomato 1.28 --- release/src/router/busybox/libbb/update_passwd.c | 266 +++++++++++++++++++++++ 1 file changed, 266 insertions(+) create mode 100644 release/src/router/busybox/libbb/update_passwd.c (limited to 'release/src/router/busybox/libbb/update_passwd.c') diff --git a/release/src/router/busybox/libbb/update_passwd.c b/release/src/router/busybox/libbb/update_passwd.c new file mode 100644 index 00000000..35b89a5b --- /dev/null +++ b/release/src/router/busybox/libbb/update_passwd.c @@ -0,0 +1,266 @@ +/* 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 + * + * Modified to be able to add or delete users, groups and users to/from groups + * by Tito Ragusa + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + */ +#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) { + if (checkPasswdAccess(PASSWD__PASSWD) != 0) + 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 passord: 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 + + 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; + unsigned user_len; + int old_fd; + int new_fd; + int i; + int changed_lines; + int ret = -1; /* failure */ + + filename = xmalloc_follow_symlinks(filename); + if (filename == NULL) + return ret; + + check_selinux_update_passwd(name); + + /* New passwd file, "/etc/passwd+" for now */ + fnamesfx = xasprintf("%s+", filename); + sfx_char = &fnamesfx[strlen(fnamesfx)-1]; + name = xasprintf("%s:", name); + user_len = strlen(name); + + if (strstr(filename, "shadow")) + old_fp = fopen(filename, "r+"); + else + old_fp = fopen_or_warn(filename, "r+"); + if (!old_fp) + 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)) { + fchmod(new_fd, sb.st_mode & 0777); /* ignore errors */ + fchown(new_fd, sb.st_uid, sb.st_gid); + } + errno = 0; + new_fp = fdopen(new_fd, "w"); + if (!new_fp) { + bb_perror_nomsg(); + close(new_fd); + goto unlink_new; + } + + /* 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 (strncmp(name, line, user_len) != 0) { + fprintf(new_fp, "%s\n", line); + goto next; + } + + /* We have a match with "name:"... */ + cp = line + user_len; /* move 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 */ + /* name: + new_passwd + :rest of line */ + fprintf(new_fp, "%s%s%s\n", name, new_passwd, cp); + changed_lines++; + } /* else delete user or group: skip the line */ + next: + free(line); + } + + if (changed_lines == 0) { +#if ENABLE_FEATURE_DEL_USER_FROM_GROUP + if (member) + 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, 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((char *)name); + return ret; +} -- cgit v1.2.3-54-g00ecf