Fix faccessat(,0) and access() semantics.

* fhandler.h (fhandler_base::fhaccess): Add parameter.
* security.h (check_file_access, check_registry_access): Likewise.
* security.cc (check_file_access, check_registry_access)
(check_access): Implement new parameter.
* fhandler.cc (fhandler_base::fhaccess): Likewise.
(device_access_denied): Update caller.
* syscalls.cc (access, faccessat): Update callers.
* spawn.cc (find_exec, fixup): Likewise.

7 files changed, 38 insertions, 25 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index c62fe7ce9..f7cc25d6b 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,14 @@
+2009-09-25  Eric Blake  <ebb9@byu.net>
+
+	* fhandler.h (fhandler_base::fhaccess): Add parameter.
+	* security.h (check_file_access, check_registry_access): Likewise.
+	* security.cc (check_file_access, check_registry_access)
+	(check_access): Implement new parameter.
+	* fhandler.cc (fhandler_base::fhaccess): Likewise.
+	(device_access_denied): Update caller.
+	* syscalls.cc (access, faccessat): Update callers.
+	* spawn.cc (find_exec, fixup): Likewise.
+
 2009-09-24  Corinna Vinschen  <corinna@vinschen.de>
 
 	* posix_ipc.cc (mq_open): Avoid closing the same descriptor twice in
diff --git a/winsup/cygwin/fhandler.cc b/winsup/cygwin/fhandler.cc
index b52d7c2f1..5f501a7b6 100644
--- a/winsup/cygwin/fhandler.cc
+++ b/winsup/cygwin/fhandler.cc
@@ -344,11 +344,11 @@ fhandler_base::device_access_denied (int flags)
   if (!mode)
     mode |= R_OK;
 
-  return fhaccess (mode);
+  return fhaccess (mode, true);
 }
 
 int
-fhandler_base::fhaccess (int flags)
+fhandler_base::fhaccess (int flags, bool effective)
 {
   int res = -1;
   if (error ())
@@ -373,12 +373,12 @@ fhandler_base::fhaccess (int flags)
     goto eaccess_done;
   else if (has_acls ())
     {
-      res = check_file_access (pc, flags);
+      res = check_file_access (pc, flags, effective);
       goto done;
     }
   else if (get_device () == FH_REGISTRY && open (O_RDONLY, 0) && get_handle ())
     {
-      res = check_registry_access (get_handle (), flags);
+      res = check_registry_access (get_handle (), flags, effective);
       close ();
       return res;
     }
@@ -389,12 +389,12 @@ fhandler_base::fhaccess (int flags)
 
   if (flags & R_OK)
     {
-      if (st.st_uid == myself->uid)
+      if (st.st_uid == (effective ? myself->uid : cygheap->user.real_uid))
 	{
 	  if (!(st.st_mode & S_IRUSR))
 	    goto eaccess_done;
 	}
-      else if (st.st_gid == myself->gid)
+      else if (st.st_gid == (effective ? myself->gid : cygheap->user.real_gid))
 	{
 	  if (!(st.st_mode & S_IRGRP))
 	    goto eaccess_done;
@@ -405,12 +405,12 @@ fhandler_base::fhaccess (int flags)
 
   if (flags & W_OK)
     {
-      if (st.st_uid == myself->uid)
+      if (st.st_uid == (effective ? myself->uid : cygheap->user.real_uid))
 	{
 	  if (!(st.st_mode & S_IWUSR))
 	    goto eaccess_done;
 	}
-      else if (st.st_gid == myself->gid)
+      else if (st.st_gid == (effective ? myself->gid : cygheap->user.real_gid))
 	{
 	  if (!(st.st_mode & S_IWGRP))
 	    goto eaccess_done;
@@ -421,12 +421,12 @@ fhandler_base::fhaccess (int flags)
 
   if (flags & X_OK)
     {
-      if (st.st_uid == myself->uid)
+      if (st.st_uid == (effective ? myself->uid : cygheap->user.real_uid))
 	{
 	  if (!(st.st_mode & S_IXUSR))
 	    goto eaccess_done;
 	}
-      else if (st.st_gid == myself->gid)
+      else if (st.st_gid == (effective ? myself->gid : cygheap->user.real_gid))
 	{
 	  if (!(st.st_mode & S_IXGRP))
 	    goto eaccess_done;
diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 1544cc60c..dd9b59184 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -392,7 +392,7 @@ class fhandler_base
   bool is_fs_special () {return pc.is_fs_special ();}
   bool issymlink () {return pc.issymlink ();}
   bool device_access_denied (int) __attribute__ ((regparm (2)));
-  int fhaccess (int flags) __attribute__ ((regparm (2)));
+  int fhaccess (int flags, bool) __attribute__ ((regparm (3)));
 };
 
 class fhandler_mailslot : public fhandler_base
diff --git a/winsup/cygwin/security.cc b/winsup/cygwin/security.cc
index 00a8c32cd..c33be76c7 100644
--- a/winsup/cygwin/security.cc
+++ b/winsup/cygwin/security.cc
@@ -1,7 +1,7 @@
 /* security.cc: NT file access control functions
 
    Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
-   2006, 2007 Red Hat, Inc.
+   2006, 2007, 2008, 2009 Red Hat, Inc.
 
    Originaly written by Gunther Ebert, gunther.ebert@ixos-leipzig.de
    Completely rewritten by Corinna Vinschen <corinna@vinschen.de>
@@ -725,15 +725,16 @@ set_file_attribute (HANDLE handle, path_conv &pc,
 
 static int
 check_access (security_descriptor &sd, GENERIC_MAPPING &mapping,
-	      DWORD desired, int flags)
+	      DWORD desired, int flags, bool effective)
 {
   int ret = -1;
   BOOL status;
   DWORD granted;
   DWORD plen = sizeof (PRIVILEGE_SET) + 3 * sizeof (LUID_AND_ATTRIBUTES);
   PPRIVILEGE_SET pset = (PPRIVILEGE_SET) alloca (plen);
-  HANDLE tok = cygheap->user.issetuid () ? cygheap->user.imp_token ()
-					 : hProcImpToken;
+  HANDLE tok = ((effective && cygheap->user.issetuid ())
+		? cygheap->user.imp_token ()
+		: hProcImpToken);
 
   if (!tok && !DuplicateTokenEx (hProcToken, MAXIMUM_ALLOWED, NULL,
 				 SecurityImpersonation, TokenImpersonation,
@@ -794,7 +795,7 @@ check_access (security_descriptor &sd, GENERIC_MAPPING &mapping,
 }
 
 int
-check_file_access (path_conv &pc, int flags)
+check_file_access (path_conv &pc, int flags, bool effective)
 {
   security_descriptor sd;
   int ret = -1;
@@ -810,13 +811,13 @@ check_file_access (path_conv &pc, int flags)
   if (flags & X_OK)
     desired |= FILE_EXECUTE;
   if (!get_file_sd (NULL, pc, sd))
-    ret = check_access (sd, mapping, desired, flags);
+    ret = check_access (sd, mapping, desired, flags, effective);
   debug_printf ("flags %x, ret %d", flags, ret);
   return ret;
 }
 
 int
-check_registry_access (HANDLE hdl, int flags)
+check_registry_access (HANDLE hdl, int flags, bool effective)
 {
   security_descriptor sd;
   int ret = -1;
@@ -832,7 +833,7 @@ check_registry_access (HANDLE hdl, int flags)
   if (flags & X_OK)
     desired |= KEY_QUERY_VALUE;
   if (!get_reg_sd (hdl, sd))
-    ret = check_access (sd, mapping, desired, flags);
+    ret = check_access (sd, mapping, desired, flags, effective);
   /* As long as we can't write the registry... */
   if (flags & W_OK)
     {
diff --git a/winsup/cygwin/security.h b/winsup/cygwin/security.h
index 7b09bc0ad..781def9d5 100644
--- a/winsup/cygwin/security.h
+++ b/winsup/cygwin/security.h
@@ -350,8 +350,8 @@ LONG __stdcall set_file_sd (HANDLE fh, path_conv &, security_descriptor &sd,
 			    bool is_chown);
 bool __stdcall add_access_allowed_ace (PACL acl, int offset, DWORD attributes, PSID sid, size_t &len_add, DWORD inherit);
 bool __stdcall add_access_denied_ace (PACL acl, int offset, DWORD attributes, PSID sid, size_t &len_add, DWORD inherit);
-int __stdcall check_file_access (path_conv &, int);
-int __stdcall check_registry_access (HANDLE, int);
+int __stdcall check_file_access (path_conv &, int, bool);
+int __stdcall check_registry_access (HANDLE, int, bool);
 
 void set_security_attribute (path_conv &pc, int attribute,
 			     PSECURITY_ATTRIBUTES psa,
diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index c5b5bee9a..5c86c4b5c 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -169,7 +169,7 @@ find_exec (const char *name, path_conv& buf, const char *mywinenv,
 
       if ((suffix = perhaps_suffix (tmp, buf, err, opt)) != NULL)
 	{
-	  if (buf.has_acls () && check_file_access (buf, X_OK))
+	  if (buf.has_acls () && check_file_access (buf, X_OK, true))
 	    continue;
 
 	  if (posix == tmp)
@@ -1083,7 +1083,8 @@ just_shell:
 
       /* Check if script is executable.  Otherwise we start non-executable
 	 scripts successfully, which is incorrect behaviour. */
-      if (real_path.has_acls () && check_file_access (real_path, X_OK) < 0)
+      if (real_path.has_acls ()
+	  && check_file_access (real_path, X_OK, true) < 0)
 	return -1;	/* errno is already set. */
 
       /* Replace argv[0] with the full path to the script if this is the
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 542a122d7..3eb77fd07 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -1572,7 +1572,7 @@ access (const char *fn, int flags)
       fhandler_base *fh = build_fh_name (fn, NULL, PC_SYM_FOLLOW, stat_suffixes);
       if (fh)
 	{
-	  res =  fh->fhaccess (flags);
+	  res =  fh->fhaccess (flags, false);
 	  delete fh;
 	}
     }
@@ -3862,7 +3862,7 @@ faccessat (int dirfd, const char *pathname, int mode, int flags)
 					     stat_suffixes);
 	  if (fh)
 	    {
-	      res =  fh->fhaccess (mode);
+	      res =  fh->fhaccess (mode, flags & AT_EACCESS);
 	      delete fh;
 	    }
 	}