* nonlocal-passwd.c
* passwd 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_PW_BUFLEN (sysconf(_SC_GETPW_R_SIZE_MAX) + 7)
+
static service_user *
nss_passwd_nonlocal_database(void)
}
-static __thread int local_only = 0;
-
enum nss_status
-local_getpwuid_r(uid_t uid, struct passwd *pwd,
- char *buffer, size_t buflen, int *errnop)
+check_nonlocal_uid(const char *user, uid_t uid, int *errnop)
{
- int old_local_only = local_only;
- int old_errno = errno;
+ enum nss_status status = NSS_STATUS_SUCCESS;
+ struct passwd pwbuf;
+ struct passwd *pwbufp = &pwbuf;
int ret;
- errno = *errnop;
- local_only = 1;
-
- ret = getpwuid_r(uid, pwd, buffer, buflen, &pwd);
-
- local_only = old_local_only;
- *errnop = errno;
- errno = old_errno;
-
- if (pwd != NULL)
- return NSS_STATUS_SUCCESS;
- else if (ret == 0)
- return NSS_STATUS_NOTFOUND;
- else
+ int old_errno = errno;
+ int buflen = MAGIC_LOCAL_PW_BUFLEN;
+ char *buf = malloc(buflen);
+ if (buf == NULL) {
+ *errnop = ENOMEM;
+ errno = old_errno;
return NSS_STATUS_TRYAGAIN;
+ }
+ ret = getpwuid_r(uid, pwbufp, buf, buflen, &pwbufp);
+ if (ret != 0) {
+ *errnop = errno;
+ status = NSS_STATUS_TRYAGAIN;
+ } else if (pwbufp != NULL) {
+ syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name);
+ status = NSS_STATUS_NOTFOUND;
+ }
+ free(buf);
+ errno = old_errno;
+ return status;
}
enum nss_status
-check_nonlocal_uid(const char *user, uid_t uid, int *errnop)
+check_nonlocal_user(const char *user, int *errnop)
{
- struct passwd local_pwd;
- int local_errno = errno;
- enum nss_status local_status, status = NSS_STATUS_SUCCESS;
- int local_buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
- char *local_buffer = malloc(local_buflen);
- if (local_buffer == NULL) {
+ enum nss_status status = NSS_STATUS_SUCCESS;
+ struct passwd pwbuf;
+ struct passwd *pwbufp = &pwbuf;
+ int ret;
+ int old_errno = errno;
+ int buflen = MAGIC_LOCAL_PW_BUFLEN;
+ char *buf = malloc(buflen);
+ if (buf == NULL) {
*errnop = ENOMEM;
- errno = local_errno;
+ errno = old_errno;
return NSS_STATUS_TRYAGAIN;
}
- local_errno = 0;
- local_status = local_getpwuid_r(uid, &local_pwd, local_buffer,
- local_buflen, &local_errno);
- if (local_status == NSS_STATUS_SUCCESS) {
- syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, local_pwd.pw_name);
+ ret = getpwnam_r(user, pwbufp, buf, buflen, &pwbufp);
+ if (ret != 0) {
+ *errnop = errno;
+ status = NSS_STATUS_TRYAGAIN;
+ } else if (pwbufp != NULL) {
status = NSS_STATUS_NOTFOUND;
- } else if (local_status != NSS_STATUS_NOTFOUND &&
- local_status != NSS_STATUS_UNAVAIL) {
- *errnop = local_errno;
- status = local_status;
}
- free(local_buffer);
+ free(buf);
+ errno = old_errno;
return status;
}
int *errnop)
{
enum nss_status status;
+
+ char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+ if (buflen == MAGIC_LOCAL_PW_BUFLEN ||
+ (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0'))
+ return NSS_STATUS_UNAVAIL;
+
if (pwent_nip == NULL) {
status = _nss_nonlocal_setpwent(0);
if (status != NSS_STATUS_SUCCESS)
else {
int nonlocal_errno;
do
- status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop));
+ status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop));
while (status == NSS_STATUS_SUCCESS &&
check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS);
}
} fct;
int group_errno;
+ char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+ if (buflen == MAGIC_LOCAL_PW_BUFLEN ||
+ (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0'))
+ return NSS_STATUS_UNAVAIL;
+
nip = nss_passwd_nonlocal_database();
if (nip == NULL)
return NSS_STATUS_UNAVAIL;
} fct;
int group_errno;
- if (local_only == 1)
+ char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+ if (buflen == MAGIC_LOCAL_PW_BUFLEN ||
+ (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0'))
return NSS_STATUS_UNAVAIL;
nip = nss_passwd_nonlocal_database();