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[nss_nonlocal.git] / nonlocal-passwd.c

diff --git a/nonlocal-passwd.c b/nonlocal-passwd.c
index 15173416b0a24180bd8c877369da8eee5e3de174..e915ea0a2fa15d4b1ffe22f1812e8781806a19f7 100644 (file)
--- a/nonlocal-passwd.c
+++ b/nonlocal-passwd.c
@@ -2,7 +2,8 @@
  * 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
@@ -42,7 +43,13 @@
 #include "nsswitch-internal.h"
 #include "nonlocal.h"
 
-#define MAGIC_LOCAL_PW_BUFLEN (sysconf(_SC_GETPW_R_SIZE_MAX) + 7)
+
+enum nss_status
+_nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd,
+                        char *buffer, size_t buflen, int *errnop);
+enum nss_status
+_nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd,
+                        char *buffer, size_t buflen, int *errnop);
 
 
 static service_user *
@@ -59,29 +66,120 @@ nss_passwd_nonlocal_database(void)
 enum nss_status
 check_nonlocal_uid(const char *user, uid_t uid, int *errnop)
 {
-    enum nss_status status = NSS_STATUS_SUCCESS;
+    static const char *fct_name = "getpwuid_r";
+    static service_user *startp = NULL;
+    static void *fct_start = NULL;
+    enum nss_status status;
+    service_user *nip;
+    union {
+       enum nss_status (*l)(uid_t uid, struct passwd *pwd,
+                            char *buffer, size_t buflen, int *errnop);
+       void *ptr;
+    } fct;
     struct passwd pwbuf;
-    struct passwd *pwbufp = &pwbuf;
-    int ret;
     int old_errno = errno;
-    int buflen = MAGIC_LOCAL_PW_BUFLEN;
+
+    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
     char *buf = malloc(buflen);
     if (buf == NULL) {
        *errnop = ENOMEM;
        errno = old_errno;
        return NSS_STATUS_TRYAGAIN;
     }
-    errno = 0;
-    ret = getpwuid_r(uid, pwbufp, buf, buflen, &pwbufp);
-    if (ret != 0) {
-       *errnop = errno;
-       status = NSS_STATUS_TRYAGAIN;
-    } else if (pwbufp != NULL) {
+
+    if (fct_start == NULL &&
+       __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) {
+       free(buf);
+       return NSS_STATUS_UNAVAIL;
+    }
+    nip = startp;
+    fct.ptr = fct_start;
+    do {
+    morebuf:
+       if (fct.l == _nss_nonlocal_getpwuid_r)
+           status = NSS_STATUS_NOTFOUND;
+       else
+           status = DL_CALL_FCT(fct.l, (uid, &pwbuf, buf, buflen, errnop));
+       if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) {
+           free(buf);
+           buflen *= 2;
+           buf = malloc(buflen);
+           if (buf == NULL) {
+               *errnop = ENOMEM;
+               errno = old_errno;
+               return NSS_STATUS_TRYAGAIN;
+           }
+           goto morebuf;
+       }
+    } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
+
+    if (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, pwbuf.pw_name);
        status = NSS_STATUS_NOTFOUND;
+    } else if (status != NSS_STATUS_TRYAGAIN) {
+       status = NSS_STATUS_SUCCESS;
     }
+
+    free(buf);
+    return status;
+}
+
+enum nss_status
+check_nonlocal_user(const char *user, int *errnop)
+{
+    static const char *fct_name = "getpwnam_r";
+    static service_user *startp = NULL;
+    static void *fct_start = NULL;
+    enum nss_status status;
+    service_user *nip;
+    union {
+       enum nss_status (*l)(const char *name, struct passwd *pwd,
+                            char *buffer, size_t buflen, int *errnop);
+       void *ptr;
+    } fct;
+    struct passwd pwbuf;
+    int old_errno = errno;
+
+    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+    char *buf = malloc(buflen);
+    if (buf == NULL) {
+       *errnop = ENOMEM;
+       errno = old_errno;
+       return NSS_STATUS_TRYAGAIN;
+    }
+
+    if (fct_start == NULL &&
+       __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) {
+       free(buf);
+       return NSS_STATUS_UNAVAIL;
+    }
+    nip = startp;
+    fct.ptr = fct_start;
+    do {
+    morebuf:
+       if (fct.l == _nss_nonlocal_getpwnam_r)
+           status = NSS_STATUS_NOTFOUND;
+       else
+           status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop));
+       if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) {
+           free(buf);
+           buflen *= 2;
+           buf = malloc(buflen);
+           if (buf == NULL) {
+               *errnop = ENOMEM;
+               errno = old_errno;
+               return NSS_STATUS_TRYAGAIN;
+           }
+           goto morebuf;
+       }
+    } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
+
+    if (status == NSS_STATUS_SUCCESS)
+       status = NSS_STATUS_NOTFOUND;
+    else if (status != NSS_STATUS_TRYAGAIN)
+       status = NSS_STATUS_SUCCESS;
+
     free(buf);
-    errno = old_errno;
     return status;
 }
 
@@ -163,6 +261,11 @@ _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen,
                         int *errnop)
 {
     enum nss_status status;
+
+    char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+    if (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)
@@ -174,7 +277,7 @@ _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen,
        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);
        }
@@ -205,6 +308,10 @@ _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd,
     } fct;
     int group_errno;
 
+    char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+    if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0')
+       return NSS_STATUS_UNAVAIL;
+
     nip = nss_passwd_nonlocal_database();
     if (nip == NULL)
        return NSS_STATUS_UNAVAIL;
@@ -247,7 +354,8 @@ _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd,
     } fct;
     int group_errno;
 
-    if (buflen == MAGIC_LOCAL_PW_BUFLEN)
+    char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV);
+    if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0')
        return NSS_STATUS_UNAVAIL;
 
     nip = nss_passwd_nonlocal_database();