2 files changed, 196 insertions, 0 deletions

diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
new file mode 100644
index 000000000..5572db547
--- /dev/null
+++ b/libbb/update_passwd.c
@@ -0,0 +1,119 @@
+/* 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>
+ */
+
+#include "libbb.h"
+
+int update_passwd(const char *filename, const char *username,
+                        const char *new_pw)
+{
+        struct stat sb;
+        struct flock lock;
+        FILE *old_fp;
+        FILE *new_fp;
+        char *new_name;
+        char *last_char;
+        unsigned user_len;
+        int old_fd;
+        int new_fd;
+        int i;
+        int cnt = 0;
+        int ret = 1; /* failure */
+
+        /* New passwd file, "/etc/passwd+" for now */
+        new_name = xasprintf("%s+", filename);
+        last_char = &new_name[strlen(new_name)-1];
+        username = xasprintf("%s:", username);
+        user_len = strlen(username);
+
+        old_fp = fopen(filename, "r+");
+        if (!old_fp)
+                goto free_mem;
+        old_fd = fileno(old_fp);
+
+        /* 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(new_name, 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("cannot create '%s'", new_name);
+        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);
+        }
+        new_fp = fdopen(new_fd, "w");
+        if (!new_fp) {
+                close(new_fd);
+                goto unlink_new;
+        }
+
+        /* Backup file is "/etc/passwd-" */
+        last_char[0] = '-';
+        /* Delete old one, create new as a hardlink to current */
+        i = (unlink(new_name) && errno != ENOENT);
+        if (i || link(filename, new_name))
+                bb_perror_msg("warning: cannot create backup copy '%s'", new_name);
+        last_char[0] = '+';
+
+        /* 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: cannot lock '%s'", filename);
+        lock.l_type = F_UNLCK;
+
+        /* Read current password file, write updated one */
+        while (1) {
+                char *line = xmalloc_fgets(old_fp);
+                if (!line) break; /* EOF/error */
+                if (strncmp(username, line, user_len) == 0) {
+                        /* we have a match with "username:"... */
+                        const char *cp = line + user_len;
+                        /* now cp -> old passwd, skip it: */
+                        cp = strchr(cp, ':');
+                        if (!cp) cp = "";
+                        /* now cp -> ':' after old passwd or -> "" */
+                        fprintf(new_fp, "%s%s%s", username, new_pw, cp);
+                        cnt++;
+                } else
+                        fputs(line, new_fp);
+                free(line);
+        }
+        fcntl(old_fd, F_SETLK, &lock);
+
+        /* We do want all of them to execute, thus | instead of || */
+        if ((ferror(old_fp) | fflush(new_fp) | fsync(new_fd) | fclose(new_fp))
+         || rename(new_name, filename)
+        ) {
+                /* At least one of those failed */
+                goto unlink_new;
+        }
+        ret = cnt; /* whee, success! */
+
+ unlink_new:
+        if (ret) unlink(new_name);
+
+ close_old_fp:
+        fclose(old_fp);
+
+ free_mem:
+        if (ENABLE_FEATURE_CLEAN_UP) free(new_name);
+        if (ENABLE_FEATURE_CLEAN_UP) free((char*)username);
+        return ret;
+}
diff --git a/loginutils/chpasswd.c b/loginutils/chpasswd.c
new file mode 100644
index 000000000..124fc86e2
--- /dev/null
+++ b/loginutils/chpasswd.c
@@ -0,0 +1,77 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * chpasswd.c
+ *
+ * Written for SLIND (from passwd.c) by Alexander Shishkin <virtuoso@slind.org>
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
+
+#if ENABLE_GETOPT_LONG
+#include <getopt.h>
+
+static const struct option chpasswd_opts[] = {
+        { "encrypted", no_argument, NULL, 'e' },
+        { "md5", no_argument, NULL, 'm' },
+        { NULL, 0, NULL, 0 }
+};
+#endif
+
+#define OPT_ENC         1
+#define OPT_MD5         2
+
+int chpasswd_main(int argc, char **argv);
+int chpasswd_main(int argc, char **argv)
+{
+        char *name, *pass;
+        char salt[sizeof("$N$XXXXXXXX")];
+        int opt, rc;
+        int rnd = rnd; /* we *want* it to be non-initialized! */
+        const char *pwfile = bb_path_passwd_file;
+
+        if (getuid() != 0)
+                bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
+
+#if ENABLE_FEATURE_SHADOWPASSWDS
+        if (access(bb_path_shadow_file, F_OK) == 0)
+                pwfile = bb_path_shadow_file;
+#endif
+
+        opt_complementary = "m--e";
+        USE_GETOPT_LONG(applet_long_options = chpasswd_opts;)
+        opt = getopt32(argc, argv, "em");
+
+        while ((name = xmalloc_getline(stdin)) != NULL) {
+                pass = strchr(name, ':');
+                if (!pass)
+                        bb_error_msg_and_die("missing new password");
+                *pass++ = '\0';
+
+                //if (!getpwnam(name))
+                //      bb_error_msg_and_die("unknown user %s", name);
+
+                if (!(opt & OPT_ENC)) {
+                        rnd = crypt_make_salt(salt, 1, rnd);
+                        if (opt & OPT_MD5) {
+                                strcpy(salt, "$1$");
+                                rnd = crypt_make_salt(salt + 3, 4, rnd);
+                        }
+                        pass = pw_encrypt(pass, salt);
+                }
+
+                rc = update_passwd(pwfile, name, pass);
+                /* LOGMODE_BOTH logs to syslog */
+                logmode = LOGMODE_BOTH;
+                if (rc < 0)
+                        bb_error_msg_and_die("an error occurred updating %s", pwfile);
+                if (rc > 0)
+                        bb_info_msg("Password for '%s' changed", name);
+                else
+                        bb_info_msg("User '%s' not found", name);
+                logmode = LOGMODE_STDIO;
+                free(name);
+        }
+
+        return 0;
+}