Changeset 2725 in MondoRescue for branches/2.2.9/mindi-busybox/libbb/update_passwd.c

Timestamp:

Feb 25, 2011, 9:26:54 PM (13 years ago)

Author:

Bruno Cornec

Message:

• Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3

File:

• branches/2.2.9/mindi-busybox/libbb/update_passwd.c (modified) (6 diffs)

branches/2.2.9/mindi-busybox/libbb/update_passwd.c

@@ -8 +8 @@
  *
  * 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"
 
-int update_passwd(const char *filename, const char *username,
-            const char *new_pw)
+#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 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
+
+ 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;
@@ -21 +82 @@
     char *fnamesfx;
     char *sfx_char;
+    char *name_colon;
     unsigned user_len;
     int old_fd;
     int new_fd;
     int i;
-    int cnt = 0;
+    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;
+
+    check_selinux_update_passwd(name);
 
     /* New passwd file, "/etc/passwd+" for now */
     fnamesfx = xasprintf("%s+", filename);
     sfx_char = &fnamesfx[strlen(fnamesfx)-1];
-    username = xasprintf("%s:", username);
-    user_len = strlen(username);
-
-    old_fp = fopen(filename, "r+");
-    if (!old_fp)
+    name_colon = xasprintf("%s:", name);
+    user_len = strlen(name_colon);
+
+    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. */
@@ -48 +130 @@
         usleep(100000); /* 0.1 sec */
     } while (--i);
-    bb_perror_msg("cannot create '%s'", fnamesfx);
+    bb_perror_msg("can't create '%s'", fnamesfx);
     goto close_old_fp;
 
  created:
-    if (!fstat(old_fd, &sb)) {
+    if (fstat(old_fd, &sb) == 0) {
         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;
-    }
+    errno = 0;
+    new_fp = xfdopen_for_write(new_fd);
 
     /* Backup file is "/etc/passwd-" */
@@ -68 +147 @@
     /* Create backup as a hardlink to current */
     if (i || link(filename, fnamesfx))
-        bb_perror_msg("warning: cannot create backup copy '%s'", fnamesfx);
+        bb_perror_msg("warning: can't create backup copy '%s'",
+                fnamesfx);
     *sfx_char = '+';
 
@@ -77 +157 @@
     lock.l_len = 0;
     if (fcntl(old_fd, F_SETLK, &lock) < 0)
-        bb_perror_msg("warning: cannot lock '%s'", filename);
+        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 *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 = strchrnul(cp, ':');
-            /* now cp -> ':' after old passwd or -> "" */
-            fprintf(new_fp, "%s%s%s", username, new_pw, cp);
-            cnt++;
+        char *cp, *line;
+
+        line = xmalloc_fgetline(old_fp);
+        if (!line) /* EOF/error */
+            break;
+        if (strncmp(name_colon, 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
-            fputs(line, new_fp);
+#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;
     }
-    ret = cnt; /* whee, success! */
+    /* Success: ret >= 0 */
+    ret = changed_lines;
 
  unlink_new:
-    if (ret < 0) unlink(fnamesfx);
+    if (ret < 0)
+        unlink(fnamesfx);
 
  close_old_fp:
@@ -115 +280 @@
  free_mem:
     free(fnamesfx);
-    free((char*)username);
+    free((char *)filename);
+    free(name_colon);
     return ret;
 }