X-Git-Url: http://andersk.mit.edu/gitweb/nss_nonlocal.git/blobdiff_plain/f7293a540408a83631cd04ec767962f60b96610f..5879a6964b6eb2e8e53e833623f91017b94859b1:/nonlocal-group.c

diff --git a/nonlocal-group.c b/nonlocal-group.c
index aa2e390..05f4d46 100644
--- a/nonlocal-group.c
+++ b/nonlocal-group.c
@@ -2,7 +2,8 @@
  * nonlocal-group.c
  * group database for nss_nonlocal proxy
  *
- * Copyright © 2007 Anders Kaseorg <andersk@mit.edu>
+ * Copyright © 2007 Anders Kaseorg <andersk@mit.edu> and Tim Abbott
+ * <tabbott@mit.edu>
  *
  * Permission is hereby granted, free of charge, to any person
  * obtaining a copy of this software and associated documentation
@@ -41,6 +42,8 @@
 #include "nonlocal.h"
 
 #define MAGIC_LOCAL_GR_BUFLEN (sysconf(_SC_GETGR_R_SIZE_MAX) + 7)
+#define MAGIC_NONLOCAL_GROUPNAME "nss-nonlocal-users"
+#define MAGIC_LOCAL_GROUPNAME "nss-local-users"
 
 
 static service_user *
@@ -49,7 +52,7 @@ nss_group_nonlocal_database(void)
     static service_user *nip = NULL;
     if (nip == NULL)
 	__nss_database_lookup("group_nonlocal", NULL, "", &nip);
-    
+
     return nip;
 }
 
@@ -69,7 +72,6 @@ check_nonlocal_gid(const char *user, gid_t gid, int *errnop)
 	errno = old_errno;
 	return NSS_STATUS_TRYAGAIN;
     }
-    errno = 0;
     ret = getgrgid_r(gid, gbufp, buf, buflen, &gbufp);
     if (ret != 0) {
 	*errnop = old_errno;
@@ -83,6 +85,64 @@ check_nonlocal_gid(const char *user, gid_t gid, int *errnop)
     return status;
 }
 
+enum nss_status
+get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen, int *errnop)
+{
+    enum nss_status status = NSS_STATUS_NOTFOUND;
+    struct group gbuf;
+    struct group *gbufp = &gbuf;
+    int ret, n;
+    int old_errno = errno;
+    int len = MAGIC_LOCAL_GR_BUFLEN;
+    char *buf = malloc(len);
+    if (buf == NULL) {
+	*errnop = ENOMEM;
+	errno = old_errno;
+	return NSS_STATUS_TRYAGAIN;
+    }
+    ret = getgrnam_r(name, gbufp, buf, len, &gbufp);
+    if (ret != 0) {
+	*errnop = old_errno;
+	status = NSS_STATUS_TRYAGAIN;
+    } else if (gbufp != NULL) {
+	status = NSS_STATUS_SUCCESS;
+
+	n = snprintf(buffer, buflen, "%s", gbufp->gr_name);
+	if (n < 0 || n >= buflen) {
+	    *errnop = ERANGE;
+	    status = NSS_STATUS_TRYAGAIN;
+	    goto get_local_group_done;
+	}
+	grp->gr_name = buffer;
+	buffer += n;
+	buflen -= n;
+
+	n = snprintf(buffer, buflen, "%s", gbufp->gr_passwd);
+	if (n < 0 || n >= buflen) {
+	    *errnop = ERANGE;
+	    status = NSS_STATUS_TRYAGAIN;
+	    goto get_local_group_done;
+	}
+	grp->gr_passwd = buffer;
+	buffer += n;
+	buflen -= n;
+
+	grp->gr_gid = gbufp->gr_gid;
+
+	if (buflen < sizeof(void *)) {
+	    *errnop = ERANGE;
+	    status = NSS_STATUS_TRYAGAIN;
+	    goto get_local_group_done;
+	}
+	*(void **)buffer = NULL;
+	buffer += sizeof(void *);
+	buflen -= sizeof(void *);
+    }
+ get_local_group_done:
+    free(buf);
+    errno = old_errno;
+    return status;
+}
 
 static service_user *grent_nip = NULL;
 static void *grent_fct_start;
@@ -161,6 +221,12 @@ _nss_nonlocal_getgrent_r(struct group *grp, char *buffer, size_t buflen,
 			 int *errnop)
 {
     enum nss_status status;
+
+    char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+    if (buflen == MAGIC_LOCAL_GR_BUFLEN ||
+	(nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0'))
+	return NSS_STATUS_UNAVAIL;
+
     if (grent_nip == NULL) {
 	status = _nss_nonlocal_setgrent(0);
 	if (status != NSS_STATUS_SUCCESS)
@@ -202,6 +268,11 @@ _nss_nonlocal_getgrnam_r(const char *name, struct group *grp,
 	void *ptr;
     } fct;
 
+    char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+    if (buflen == MAGIC_LOCAL_GR_BUFLEN ||
+	(nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0'))
+	return NSS_STATUS_UNAVAIL;
+
     nip = nss_group_nonlocal_database();
     if (nip == NULL)
 	return NSS_STATUS_UNAVAIL;
@@ -236,7 +307,9 @@ _nss_nonlocal_getgrgid_r(gid_t gid, struct group *grp,
 	void *ptr;
     } fct;
 
-    if (buflen == MAGIC_LOCAL_GR_BUFLEN)
+    char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+    if (buflen == MAGIC_LOCAL_GR_BUFLEN ||
+	(nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0'))
 	return NSS_STATUS_UNAVAIL;
 
     nip = nss_group_nonlocal_database();
@@ -274,6 +347,100 @@ _nss_nonlocal_initgroups_dyn(const char *user, gid_t group, long int *start,
 			     int *errnop);
 	void *ptr;
     } fct;
+
+    struct group local_users_group, nonlocal_users_group;
+    gid_t local_users_gid, gid;
+    int is_local = 0;
+    int buflen;
+    char *buffer;
+
+    /* Check that the user is a nonlocal user before adding any groups. */
+    status = check_nonlocal_user(user, errnop);
+    if (status == NSS_STATUS_TRYAGAIN)
+	return status;
+    else if (status != NSS_STATUS_SUCCESS)
+	is_local = 1;
+
+    int old_errno = errno;
+
+    buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+    buffer = malloc(buflen);
+    if (buffer == NULL) {
+	*errnop = ENOMEM;
+	errno = old_errno;
+	return NSS_STATUS_TRYAGAIN;
+    }
+    status = get_local_group(MAGIC_LOCAL_GROUPNAME,
+			     &local_users_group, buffer, buflen, errnop);
+    if (status == NSS_STATUS_SUCCESS) {
+	local_users_gid = local_users_group.gr_gid;
+    } else if (status == NSS_STATUS_TRYAGAIN) {
+	return status;
+    } else {
+	syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!",
+	       MAGIC_LOCAL_GROUPNAME);
+	local_users_gid = -1;
+    }
+    free(buffer);
+
+    if (is_local) {
+	gid = local_users_gid;
+    } else {
+	buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	buffer = malloc(buflen);
+	if (buffer == NULL) {
+	    *errnop = ENOMEM;
+	    errno = old_errno;
+	    return NSS_STATUS_TRYAGAIN;
+	}
+ 	status = get_local_group(MAGIC_NONLOCAL_GROUPNAME,
+				 &nonlocal_users_group, buffer, buflen, errnop);
+	if (status == NSS_STATUS_SUCCESS) {
+	    gid = nonlocal_users_group.gr_gid;
+	} else if (status == NSS_STATUS_TRYAGAIN) {
+	    errno = old_errno;
+	    return status;
+	} else {
+	    syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!",
+		   MAGIC_NONLOCAL_GROUPNAME);
+	    gid = -1;
+	}
+	free(buffer);
+    }
+
+    if (gid != -1) {
+	int i;
+	for (i = 0; i < *start; ++i)
+	    if ((*groupsp)[i] == gid)
+		break;
+	if (i >= *start) {
+	    if (*start + 1 > *size) {
+		gid_t *newgroups;
+		long int newsize = 2 * *size;
+		if (limit > 0) {
+		    if (*size >= limit)
+			return NSS_STATUS_SUCCESS;
+		    if (newsize > limit)
+			newsize = limit;
+		}
+		newgroups = realloc(*groupsp, *size * sizeof((*groupsp)[0]));
+		if (newgroups == NULL) {
+		    *errnop = ENOMEM;
+		    errno = old_errno;
+		    return NSS_STATUS_TRYAGAIN;
+		}
+		*groupsp = newgroups;
+		*size = newsize;
+	    }
+	    (*groupsp)[(*start)++] = gid;
+	}
+    }
+
+    errno = old_errno;
+
+    if (is_local)
+	return NSS_STATUS_SUCCESS;
+
     int in = *start, out = *start, i;
 
     nip = nss_group_nonlocal_database();
@@ -303,10 +470,17 @@ _nss_nonlocal_initgroups_dyn(const char *user, gid_t group, long int *start,
 	if (i < out)
 	    continue;
 
+	/* Don't let users get into MAGIC_LOCAL_GROUPNAME from nonlocal reasons. */
+	if (local_users_gid == (*groupsp)[in]) {
+	    syslog(LOG_WARNING, "nss_nonlocal: Nonlocal user %s removed from special local users group %s",
+		   user, MAGIC_LOCAL_GROUPNAME);
+	    continue;
+	}
+
 	status = check_nonlocal_gid(user, (*groupsp)[in], &nonlocal_errno);
 	if (status == NSS_STATUS_SUCCESS) {
 	    (*groupsp)[out++] = (*groupsp)[in];
-	} else if (status != NSS_STATUS_NOTFOUND) {
+	} else if (status == NSS_STATUS_TRYAGAIN) {
 	    *start = out;
 	    *errnop = nonlocal_errno;
 	    return status;