first attempt at making unix setuid/setgid code that is independent of
authorLuke Leighton <lkcl@samba.org>
Mon, 7 Dec 1998 20:28:51 +0000 (20:28 +0000)
committerLuke Leighton <lkcl@samba.org>
Mon, 7 Dec 1998 20:28:51 +0000 (20:28 +0000)
cnums and snums.

source/lib/unix_sec_ctxt.c [new file with mode: 0644]

diff --git a/source/lib/unix_sec_ctxt.c b/source/lib/unix_sec_ctxt.c
new file mode 100644 (file)
index 0000000..ead1f3c
--- /dev/null
@@ -0,0 +1,303 @@
+/* 
+   Unix SMB/Netbios implementation.
+   Version 1.9.
+   uid/user handling
+   Copyright (C) Andrew Tridgell 1992-1998
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+extern int DEBUGLEVEL;
+
+static uid_t initial_uid;
+static gid_t initial_gid;
+
+/* what context is current */
+struct unix_sec_ctxt curr_ctxt;
+
+/****************************************************************************
+initialise the security context routines
+****************************************************************************/
+void init_sec_ctxt(void)
+{
+       initial_uid = curr_ctxt.uid = geteuid();
+       initial_gid = curr_ctxt.gid = getegid();
+
+       if (initial_gid != 0 && initial_uid == 0) {
+#ifdef HAVE_SETRESUID
+               setresgid(0,0,0);
+#else
+               setgid(0);
+               setegid(0);
+#endif
+       }
+
+       initial_uid = geteuid();
+       initial_gid = getegid();
+}
+
+
+/****************************************************************************
+  become the specified uid 
+****************************************************************************/
+static BOOL become_uid(uid_t uid)
+{
+       if (initial_uid != 0)
+       {
+               return(True);
+       }
+       
+       if (uid == (uid_t)-1 || ((sizeof(uid_t) == 2) && (uid == (uid_t)65535)))
+       {
+               static int done;
+               if (!done) {
+                       DEBUG(1,("WARNING: using uid %d is a security risk\n",(int)uid));
+                       done=1;
+               }
+       }
+
+#ifdef HAVE_TRAPDOOR_UID
+#ifdef HAVE_SETUIDX
+       /* AIX3 has setuidx which is NOT a trapoor function (tridge) */
+       if (setuidx(ID_EFFECTIVE, uid) != 0) {
+               if (seteuid(uid) != 0) {
+                       DEBUG(1,("Can't set uid %d (setuidx)\n", (int)uid));
+                       return False;
+               }
+       }
+#endif
+#endif
+
+#ifdef HAVE_SETRESUID
+    if (setresuid(-1,uid,-1) != 0)
+#else
+    if ((seteuid(uid) != 0) && 
+       (setuid(uid) != 0))
+#endif
+      {
+       DEBUG(0,("Couldn't set uid %d currently set to (%d,%d)\n",
+                (int)uid,(int)getuid(), (int)geteuid()));
+       if (uid > (uid_t)32000) {
+               DEBUG(0,("Looks like your OS doesn't like high uid values - try using a different account\n"));
+       }
+       return(False);
+      }
+
+    if (((uid == (uid_t)-1) || ((sizeof(uid_t) == 2) && (uid == 65535))) && (geteuid() != uid))
+       {
+           DEBUG(0,("Invalid uid -1. perhaps you have a account with uid 65535?\n"));
+           return(False);
+    }
+
+    curr_ctxt.uid = uid;
+
+    return(True);
+}
+
+
+/****************************************************************************
+  become the specified gid
+****************************************************************************/
+static BOOL become_gid(gid_t gid)
+{
+  if (initial_uid != 0)
+    return(True);
+
+  if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) && (gid == (gid_t)65535))) {
+    DEBUG(1,("WARNING: using gid %d is a security risk\n",(int)gid));    
+  }
+  
+#ifdef HAVE_SETRESUID
+  if (setresgid(-1,gid,-1) != 0)
+#else
+  if (setgid(gid) != 0)
+#endif
+      {
+       DEBUG(0,("Couldn't set gid %d currently set to (%d,%d)\n",
+                (int)gid,(int)getgid(),(int)getegid()));
+       if (gid > 32000) {
+               DEBUG(0,("Looks like your OS doesn't like high gid values - try using a different account\n"));
+       }
+       return(False);
+      }
+
+  curr_ctxt.gid = gid;
+
+  return(True);
+}
+
+
+/****************************************************************************
+  become the user of a connection number
+****************************************************************************/
+BOOL become_unix_sec_ctxt(struct unix_sec_ctxt const *ctxt)
+{
+       if (curr_ctxt.uid == ctxt->uid)
+       {
+               DEBUG(4,("Skipping become_unix_sec_ctxt - already user\n"));
+               return(True);
+       }
+
+       unbecome_unix_sec_ctxt();
+
+       curr_ctxt.ngroups = ctxt->ngroups;
+       curr_ctxt.groups  = ctxt->groups;
+       curr_ctxt.name    = ctxt->name;
+
+       if (initial_uid == 0)
+       {
+               if (!become_uid(ctxt->uid)) return(False);
+#ifdef HAVE_SETGROUPS      
+               if (curr_ctxt.ngroups > 0)
+               {
+                       if (setgroups(curr_ctxt.ngroups,
+                                             curr_ctxt.groups) < 0)
+                       {
+                               DEBUG(0,("setgroups call failed!\n"));
+                       }
+               }
+#endif
+               if (!become_gid(ctxt->gid)) return(False);
+
+       }
+       
+       DEBUG(5,("become_unix_sec_ctxt uid=(%d,%d) gid=(%d,%d)\n",
+                (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
+  
+       return(True);
+}
+
+/****************************************************************************
+  unbecome the user of a connection number
+****************************************************************************/
+BOOL unbecome_unix_sec_ctxt(void)
+{
+  if (initial_uid == 0)
+    {
+#ifdef HAVE_SETRESUID
+      setresuid(-1,getuid(),-1);
+      setresgid(-1,getgid(),-1);
+#else
+      if (seteuid(initial_uid) != 0) 
+       setuid(initial_uid);
+      setgid(initial_gid);
+#endif
+    }
+
+#ifdef NO_EID
+  if (initial_uid == 0)
+    DEBUG(2,("Running with no EID\n"));
+  initial_uid = getuid();
+  initial_gid = getgid();
+#else
+  if (geteuid() != initial_uid) {
+         DEBUG(0,("Warning: You appear to have a trapdoor uid system\n"));
+         initial_uid = geteuid();
+  }
+  if (getegid() != initial_gid) {
+         DEBUG(0,("Warning: You appear to have a trapdoor gid system\n"));
+         initial_gid = getegid();
+  }
+#endif
+
+  curr_ctxt.uid = initial_uid;
+  curr_ctxt.gid = initial_gid;
+  curr_ctxt.name = NULL;
+
+  curr_ctxt.ngroups = 0;
+  curr_ctxt.groups  = NULL;
+
+  DEBUG(5,("unbecome_unix_sec_ctxt now uid=(%d,%d) gid=(%d,%d)\n",
+       (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
+
+  return(True);
+}
+
+static struct unix_sec_ctxt curr_ctxt_saved;
+static int become_root_depth;
+
+/****************************************************************************
+This is used when we need to do a privileged operation (such as mucking
+with share mode files) and temporarily need root access to do it. This
+call should always be paired with an unbecome_root() call immediately
+after the operation
+
+Set save_dir if you also need to save/restore the CWD 
+****************************************************************************/
+void become_unix_root_sec_ctxt(void) 
+{
+       if (become_root_depth) {
+               DEBUG(0,("ERROR: become root depth is non zero\n"));
+       }
+
+       curr_ctxt_saved = curr_ctxt;
+       become_root_depth = 1;
+
+       become_uid(0);
+       become_gid(0);
+}
+
+/****************************************************************************
+When the privileged operation is over call this
+
+Set save_dir if you also need to save/restore the CWD 
+****************************************************************************/
+void unbecome_unix_root_sec_ctxt(void)
+{
+       if (become_root_depth != 1)
+       {
+               DEBUG(0,("ERROR: unbecome root depth is %d\n",
+                        become_root_depth));
+       }
+
+       /* we might have done a become_user() while running as root,
+          if we have then become root again in order to become 
+          non root! */
+       if (curr_ctxt.uid != 0)
+       {
+               become_uid(0);
+       }
+
+       /* restore our gid first */
+       if (!become_gid(curr_ctxt_saved.gid))
+       {
+               DEBUG(0,("ERROR: Failed to restore gid\n"));
+               exit(-1);
+       }
+
+#ifdef HAVE_SETGROUPS      
+       if (curr_ctxt_saved.ngroups > 0)
+       {
+               if (setgroups(curr_ctxt_saved.ngroups,
+                                     curr_ctxt_saved.groups) < 0)
+               {
+                       DEBUG(0,("setgroups call failed!\n"));
+               }
+       }
+#endif
+       /* now restore our uid */
+       if (!become_uid(curr_ctxt_saved.uid))
+       {
+               DEBUG(0,("ERROR: Failed to restore uid\n"));
+               exit(-1);
+       }
+
+       curr_ctxt = curr_ctxt_saved;
+
+       become_root_depth = 0;
+}
+