* 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
#include "nsswitch-internal.h"
#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 *
nss_group_nonlocal_database(void)
static service_user *nip = NULL;
if (nip == NULL)
__nss_database_lookup("group_nonlocal", NULL, "", &nip);
-
+
return nip;
}
-static __thread int local_only = 0;
-
enum nss_status
-local_getgrgid_r(gid_t gid, struct group *grp,
- char *buffer, size_t buflen, int *errnop)
+check_nonlocal_gid(const char *user, gid_t gid, int *errnop)
{
- int old_local_only = local_only;
- int old_errno = errno;
+ enum nss_status status = NSS_STATUS_SUCCESS;
+ struct group gbuf;
+ struct group *gbufp = &gbuf;
int ret;
- errno = *errnop;
- local_only = 1;
-
- ret = getgrgid_r(gid, grp, buffer, buflen, &grp);
-
- local_only = old_local_only;
- *errnop = errno;
- errno = old_errno;
-
- if (grp != NULL)
- return NSS_STATUS_SUCCESS;
- else if (ret == 0)
- return NSS_STATUS_NOTFOUND;
- else
+ int old_errno = errno;
+ int buflen = MAGIC_LOCAL_GR_BUFLEN;
+ char *buf = malloc(buflen);
+ if (buf == NULL) {
+ *errnop = ENOMEM;
+ errno = old_errno;
return NSS_STATUS_TRYAGAIN;
+ }
+ errno = 0;
+ ret = getgrgid_r(gid, gbufp, buf, buflen, &gbufp);
+ if (ret != 0) {
+ *errnop = old_errno;
+ status = NSS_STATUS_TRYAGAIN;
+ } else if (gbufp != NULL) {
+ syslog(LOG_WARNING, "nss_nonlocal: removing local group %u (%s) from non-local user %s\n", gbuf.gr_gid, gbuf.gr_name, user);
+ status = NSS_STATUS_NOTFOUND;
+ }
+ free(buf);
+ errno = old_errno;
+ return status;
}
enum nss_status
-check_nonlocal_gid(const char *user, gid_t gid, int *errnop)
+get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen, int *errnop)
{
- struct group local_grp;
- int local_errno = errno;
- enum nss_status local_status, status = NSS_STATUS_SUCCESS;
- int local_buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
- char *local_buffer = malloc(local_buflen);
- if (local_buffer == NULL) {
+ enum nss_status status = NSS_STATUS_NOTFOUND;
+ struct group gbuf;
+ struct group *gbufp = &gbuf;
+ int ret;
+ int old_errno = errno;
+ int len = MAGIC_LOCAL_GR_BUFLEN;
+ char *buf = malloc(len);
+ if (buf == NULL) {
*errnop = ENOMEM;
- errno = local_errno;
+ errno = old_errno;
return NSS_STATUS_TRYAGAIN;
}
- local_errno = 0;
- local_status = local_getgrgid_r(gid, &local_grp, local_buffer,
- local_buflen, &local_errno);
- if (local_status == NSS_STATUS_SUCCESS) {
- syslog(LOG_WARNING, "nss_nonlocal: removing local group %u (%s) from non-local user %s\n", local_grp.gr_gid, local_grp.gr_name, user);
- status = NSS_STATUS_NOTFOUND;
- } else if (local_status != NSS_STATUS_NOTFOUND &&
- local_status != NSS_STATUS_UNAVAIL) {
- *errnop = local_errno;
- status = local_status;
+ errno = 0;
+ 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;
+ grp->gr_name = strncpy(buffer, gbufp->gr_name, buflen);
+ buffer = buffer + strlen(grp->gr_name);
+ buflen = buflen - strlen(grp->gr_name);
+ grp->gr_passwd = strncpy(buffer, gbufp->gr_passwd, buflen);
+ buffer = buffer + strlen(grp->gr_passwd);
+ buflen = buflen - strlen(grp->gr_passwd);
+ grp->gr_gid = gbufp->gr_gid;
+ if (buflen < sizeof(void *)) {
+ *errnop = ERANGE;
+ status = NSS_STATUS_TRYAGAIN;
+ }
+ else {
+ grp->gr_mem = memset(buffer, 0, sizeof(void *));
+ }
}
- free(local_buffer);
+ free(buf);
+ errno = old_errno;
return status;
}
-
static service_user *grent_nip = NULL;
static void *grent_fct_start;
static union {
void *ptr;
} fct;
+ if (buflen == MAGIC_LOCAL_GR_BUFLEN)
+ return NSS_STATUS_UNAVAIL;
+
nip = nss_group_nonlocal_database();
if (nip == NULL)
return NSS_STATUS_UNAVAIL;
void *ptr;
} fct;
- if (local_only == 1)
+ if (buflen == MAGIC_LOCAL_GR_BUFLEN)
return NSS_STATUS_UNAVAIL;
nip = nss_group_nonlocal_database();
void *ptr;
} fct;
int in = *start, out = *start, i;
+ gid_t local_users_gid;
+ int is_local = 0;
+
+ // Check that the user is a nonlocal user before adding any groups
+ status = check_nonlocal_user(user, errnop);
+ if (status == NSS_STATUS_NOTFOUND) {
+ is_local = 1;
+ }
+ else if (status != NSS_STATUS_SUCCESS) {
+ return status;
+ }
+
+ int buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+ char *buffer = malloc(buflen);
+ if (buffer == NULL) {
+ *errnop = ENOMEM;
+ return NSS_STATUS_TRYAGAIN;
+ }
+ struct group local_users_group;
+ status = get_local_group(MAGIC_LOCAL_GROUPNAME,
+ &local_users_group, buffer, buflen, errnop);
+ free(buffer);
+ if (status == NSS_STATUS_NOTFOUND) {
+ syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!",
+ MAGIC_LOCAL_GROUPNAME);
+ local_users_gid = 0;
+ }
+ else if (status == NSS_STATUS_SUCCESS) {
+ if (is_local == 1) {
+ // add the (local) user to the magic local users group, and finish
+ (*groupsp)[out++] = local_users_group.gr_gid;
+ syslog(LOG_DEBUG, "nss_nonlocal: Added %s to special group %s",
+ user, MAGIC_LOCAL_GROUPNAME);
+ *start = out;
+ return NSS_STATUS_SUCCESS;
+ }
+ else {
+ local_users_gid = local_users_group.gr_gid;
+ }
+ }
+ else {
+ return status;
+ }
nip = nss_group_nonlocal_database();
if (nip == NULL)
status = check_nonlocal_gid(user, (*groupsp)[in], &nonlocal_errno);
if (status == NSS_STATUS_SUCCESS) {
- (*groupsp)[out++] = (*groupsp)[in];
+ // Don't let users get into MAGIC_LOCAL_GROUPNAME from nonlocal reasons.
+ if ((*groupsp)[in] == local_users_gid) {
+ syslog(LOG_WARNING, "nss_nonlocal: Nonlocal user %s removed from special local users group %s",
+ user, MAGIC_LOCAL_GROUPNAME);
+ }
+ else {
+ (*groupsp)[out++] = (*groupsp)[in];
+ }
} else if (status != NSS_STATUS_NOTFOUND) {
*start = out;
*errnop = nonlocal_errno;
}
}
+ // add the (nonlocal) user to the magic nonlocal users group
+ buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+ buffer = malloc(buflen);
+ if (buffer == NULL) {
+ *errnop = ENOMEM;
+ return NSS_STATUS_TRYAGAIN;
+ }
+ struct group nonlocal_users_group;
+ status = get_local_group(MAGIC_NONLOCAL_GROUPNAME,
+ &nonlocal_users_group, buffer, buflen, errnop);
+ if (status == NSS_STATUS_NOTFOUND) {
+ syslog(LOG_WARNING, "nss_nonlocal: (local) group %s does not exist!",
+ MAGIC_NONLOCAL_GROUPNAME);
+ }
+ else if (status == NSS_STATUS_SUCCESS) {
+ (*groupsp)[out++] = nonlocal_users_group.gr_gid;
+ syslog(LOG_DEBUG, "nss_nonlocal: Added %s to special group %s",
+ user, MAGIC_NONLOCAL_GROUPNAME);
+ }
+ free(buffer);
+
*start = out;
return NSS_STATUS_SUCCESS;
}