From c4d2904b362ff7180ee1596632433dabd45f36a7 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Tue, 22 Mar 2011 13:43:57 -0700
Subject: [PATCH] Fix bug #7996 - sgid bit lost on folder rename.

From the chmod 2 man page:

"If the calling process is not privileged, and the group of the file
does not match the effective group ID of the process or one of its
supplementary group IDs, the S_ISGID bit will be turned off, but
this will not cause an error to be returned."

Jeremy.
---
 source3/include/proto.h       |    1 +
 source3/modules/vfs_default.c |   61 +++++++++++++++++++++++++++++++++++++++++
 source3/smbd/posix_acls.c     |    2 +-
 3 files changed, 63 insertions(+), 1 deletions(-)

diff --git a/source3/include/proto.h b/source3/include/proto.h
index ef80b92..4229cc0 100644
--- a/source3/include/proto.h
+++ b/source3/include/proto.h
@@ -6751,6 +6751,7 @@ uint32_t map_canon_ace_perms(int snum,
                                 mode_t perms,
                                 bool directory_ace);
 NTSTATUS unpack_nt_owners(int snum, uid_t *puser, gid_t *pgrp, uint32 security_info_sent, const SEC_DESC *psd);
+bool current_user_in_group(gid_t gid);
 SMB_ACL_T free_empty_sys_acl(connection_struct *conn, SMB_ACL_T the_acl);
 NTSTATUS posix_fget_nt_acl(struct files_struct *fsp, uint32_t security_info,
 			   SEC_DESC **ppdesc);
diff --git a/source3/modules/vfs_default.c b/source3/modules/vfs_default.c
index 60b85d9..f5098a7 100644
--- a/source3/modules/vfs_default.c
+++ b/source3/modules/vfs_default.c
@@ -737,6 +737,7 @@ static int vfswrap_unlink(vfs_handle_struct *handle,
 static int vfswrap_chmod(vfs_handle_struct *handle,  const char *path, mode_t mode)
 {
 	int result;
+	bool as_root = false;
 
 	START_PROFILE(syscall_chmod);
 
@@ -757,7 +758,44 @@ static int vfswrap_chmod(vfs_handle_struct *handle,  const char *path, mode_t mo
 		errno = saved_errno;
 	}
 
+	/*
+	 * From the chmod 2 man page:
+	 *
+	 * "If the calling process is not privileged, and the group of the file
+	 * does not match the effective group ID of the process or one of its
+	 * supplementary group IDs, the S_ISGID bit will be turned off, but
+	 * this will not cause an error to be returned."
+	 *
+	 */
+
+	if ((mode & S_ISGID) && geteuid() != sec_initial_uid()) {
+		SMB_STRUCT_STAT st;
+		struct smb_filename smb_fname;
+
+		ZERO_STRUCT(smb_fname);
+		smb_fname.base_name = discard_const_p(char, path);
+
+		if (lp_posix_pathnames()) {
+			result = SMB_VFS_LSTAT(handle->conn, &smb_fname);
+		} else {
+			result = SMB_VFS_STAT(handle->conn, &smb_fname);
+		}
+
+		if (result != 0) {
+			END_PROFILE(syscall_chmod);
+			return -1;
+		}
+		if (!current_user_in_group(smb_fname.st.st_ex_gid)) {
+			as_root = true;
+		}
+	}
+	if (as_root) {
+		become_root();
+	}
 	result = chmod(path, mode);
+	if (as_root) {
+		unbecome_root();
+	}
 	END_PROFILE(syscall_chmod);
 	return result;
 }
@@ -765,6 +803,7 @@ static int vfswrap_chmod(vfs_handle_struct *handle,  const char *path, mode_t mo
 static int vfswrap_fchmod(vfs_handle_struct *handle, files_struct *fsp, mode_t mode)
 {
 	int result;
+	bool as_root = false;
 
 	START_PROFILE(syscall_fchmod);
 
@@ -785,7 +824,29 @@ static int vfswrap_fchmod(vfs_handle_struct *handle, files_struct *fsp, mode_t m
 	}
 
 #if defined(HAVE_FCHMOD)
+	/*
+	 * From the fchmod 2 man page:
+	 *
+	 * "If the calling process is not privileged, and the group of the file
+	 * does not match the effective group ID of the process or one of its
+	 * supplementary group IDs, the S_ISGID bit will be turned off, but
+	 * this will not cause an error to be returned."
+	 *
+	 */
+
+	if ((mode & S_ISGID) &&
+			VALID_STAT(fsp->fsp_name->st) &&
+			geteuid() != sec_initial_uid() &&
+			!current_user_in_group(fsp->fsp_name->st.st_ex_gid)) {
+		as_root = true;
+	}
+	if (as_root) {
+		become_root();
+	}
 	result = fchmod(fsp->fh->fd, mode);
+	if (as_root) {
+		unbecome_root();
+	}
 #else
 	result = -1;
 	errno = ENOSYS;
diff --git a/source3/smbd/posix_acls.c b/source3/smbd/posix_acls.c
index aaca9f4..714a4d3 100644
--- a/source3/smbd/posix_acls.c
+++ b/source3/smbd/posix_acls.c
@@ -2644,7 +2644,7 @@ static canon_ace *canonicalise_acl(struct connection_struct *conn,
  Check if the current user group list contains a given group.
 ****************************************************************************/
 
-static bool current_user_in_group(gid_t gid)
+bool current_user_in_group(gid_t gid)
 {
 	int i;
 
-- 
1.7.3.1