From c903ca6a227cd190b270c52ac3a84ad2148c9651 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 11:55:56 -0800
Subject: [PATCH 01/11] s3: smbd: Create wrapper function for OpenDir in
 preparation for making robust.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index 3805915..cbd32e3 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1588,7 +1588,8 @@ static int smb_Dir_destructor(struct smb_Dir *dirp)
  Open a directory.
 ********************************************************************/
 
-struct smb_Dir *OpenDir(TALLOC_CTX *mem_ctx, connection_struct *conn,
+static struct smb_Dir *OpenDir_internal(TALLOC_CTX *mem_ctx,
+			connection_struct *conn,
 			const char *name,
 			const char *mask,
 			uint32_t attr)
@@ -1628,6 +1629,18 @@ struct smb_Dir *OpenDir(TALLOC_CTX *mem_ctx, connection_struct *conn,
 	return NULL;
 }
 
+struct smb_Dir *OpenDir(TALLOC_CTX *mem_ctx, connection_struct *conn,
+			const char *name,
+			const char *mask,
+			uint32_t attr)
+{
+	return OpenDir_internal(mem_ctx,
+				conn,
+				name,
+				mask,
+				attr);
+}
+
 /*******************************************************************
  Open a directory from an fsp.
 ********************************************************************/
-- 
2.9.3


From ef03034fd0b89f64983444d662ff16d8fe2f2f0b Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 16:25:26 -0800
Subject: [PATCH 02/11] s3: smbd: Opendir_internal() early return if
 SMB_VFS_OPENDIR failed.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index cbd32e3..ea4b301 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1601,20 +1601,12 @@ static struct smb_Dir *OpenDir_internal(TALLOC_CTX *mem_ctx,
 		return NULL;
 	}
 
-	dirp->conn = conn;
-	dirp->name_cache_size = lp_directory_name_cache_size(SNUM(conn));
-
 	dirp->dir_path = talloc_strdup(dirp, name);
 	if (!dirp->dir_path) {
 		errno = ENOMEM;
 		goto fail;
 	}
 
-	if (sconn && !sconn->using_smb2) {
-		sconn->searches.dirhandles_open++;
-	}
-	talloc_set_destructor(dirp, smb_Dir_destructor);
-
 	dirp->dir = SMB_VFS_OPENDIR(conn, dirp->dir_path, mask, attr);
 	if (!dirp->dir) {
 		DEBUG(5,("OpenDir: Can't open %s. %s\n", dirp->dir_path,
@@ -1622,6 +1614,14 @@ static struct smb_Dir *OpenDir_internal(TALLOC_CTX *mem_ctx,
 		goto fail;
 	}
 
+	dirp->conn = conn;
+	dirp->name_cache_size = lp_directory_name_cache_size(SNUM(conn));
+
+	if (sconn && !sconn->using_smb2) {
+		sconn->searches.dirhandles_open++;
+	}
+	talloc_set_destructor(dirp, smb_Dir_destructor);
+
 	return dirp;
 
   fail:
-- 
2.9.3


From 0c3c22f38b0864e9894647aad1a4bc0241b9f4ae Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 16:35:00 -0800
Subject: [PATCH 03/11] s3: smbd: Create and use open_dir_safely(). Use from
 OpenDir().

Hardens OpenDir against TOC/TOU races.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 61 insertions(+), 9 deletions(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index ea4b301..39a6e67 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1601,15 +1601,9 @@ static struct smb_Dir *OpenDir_internal(TALLOC_CTX *mem_ctx,
 		return NULL;
 	}
 
-	dirp->dir_path = talloc_strdup(dirp, name);
-	if (!dirp->dir_path) {
-		errno = ENOMEM;
-		goto fail;
-	}
-
-	dirp->dir = SMB_VFS_OPENDIR(conn, dirp->dir_path, mask, attr);
+	dirp->dir = SMB_VFS_OPENDIR(conn, name, mask, attr);
 	if (!dirp->dir) {
-		DEBUG(5,("OpenDir: Can't open %s. %s\n", dirp->dir_path,
+		DEBUG(5,("OpenDir: Can't open %s. %s\n", name,
 			 strerror(errno) ));
 		goto fail;
 	}
@@ -1629,12 +1623,70 @@ static struct smb_Dir *OpenDir_internal(TALLOC_CTX *mem_ctx,
 	return NULL;
 }
 
+/****************************************************************************
+ Open a directory handle by pathname, ensuring it's under the share path.
+****************************************************************************/
+
+static struct smb_Dir *open_dir_safely(TALLOC_CTX *ctx,
+					connection_struct *conn,
+					const char *name,
+					const char *wcard,
+					uint32_t attr)
+{
+	struct smb_Dir *dir_hnd = NULL;
+	char *saved_dir = vfs_GetWd(ctx, conn);
+	NTSTATUS status;
+
+	if (saved_dir == NULL) {
+		return NULL;
+	}
+
+	if (vfs_ChDir(conn, name) == -1) {
+		goto out;
+	}
+
+	/*
+	 * Now the directory is pinned, use
+	 * REALPATH to ensure we can access it.
+	 */
+	status = check_name(conn, ".");
+	if (!NT_STATUS_IS_OK(status)) {
+		goto out;
+	}
+
+	dir_hnd = OpenDir_internal(ctx,
+				conn,
+				".",
+				wcard,
+				attr);
+
+	if (dir_hnd == NULL) {
+		goto out;
+	}
+
+	/*
+	 * OpenDir_internal only gets "." as the dir name.
+	 * Store the real dir name here.
+	 */
+
+	dir_hnd->dir_path = talloc_strdup(dir_hnd, name);
+	if (!dir_hnd->dir_path) {
+		errno = ENOMEM;
+	}
+
+  out:
+
+	vfs_ChDir(conn, saved_dir);
+	TALLOC_FREE(saved_dir);
+	return dir_hnd;
+}
+
 struct smb_Dir *OpenDir(TALLOC_CTX *mem_ctx, connection_struct *conn,
 			const char *name,
 			const char *mask,
 			uint32_t attr)
 {
-	return OpenDir_internal(mem_ctx,
+	return open_dir_safely(mem_ctx,
 				conn,
 				name,
 				mask,
-- 
2.9.3


From 39589a2b7de5768cc515bce58dd243d711e58fd3 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 12:13:20 -0800
Subject: [PATCH 04/11] s3: smbd: OpenDir_fsp() use early returns.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index 39a6e67..ea4f1ab 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1706,7 +1706,17 @@ static struct smb_Dir *OpenDir_fsp(TALLOC_CTX *mem_ctx, connection_struct *conn,
 	struct smbd_server_connection *sconn = conn->sconn;
 
 	if (!dirp) {
-		return NULL;
+		goto fail;
+	}
+
+	if (!fsp->is_directory) {
+		errno = EBADF;
+		goto fail;
+	}
+
+	if (fsp->fh->fd == -1) {
+		errno = EBADF;
+		goto fail;
 	}
 
 	dirp->conn = conn;
@@ -1723,18 +1733,16 @@ static struct smb_Dir *OpenDir_fsp(TALLOC_CTX *mem_ctx, connection_struct *conn,
 	}
 	talloc_set_destructor(dirp, smb_Dir_destructor);
 
-	if (fsp->is_directory && fsp->fh->fd != -1) {
-		dirp->dir = SMB_VFS_FDOPENDIR(fsp, mask, attr);
-		if (dirp->dir != NULL) {
-			dirp->fsp = fsp;
-		} else {
-			DEBUG(10,("OpenDir_fsp: SMB_VFS_FDOPENDIR on %s returned "
-				"NULL (%s)\n",
-				dirp->dir_path,
-				strerror(errno)));
-			if (errno != ENOSYS) {
-				return NULL;
-			}
+	dirp->dir = SMB_VFS_FDOPENDIR(fsp, mask, attr);
+	if (dirp->dir != NULL) {
+		dirp->fsp = fsp;
+	} else {
+		DEBUG(10,("OpenDir_fsp: SMB_VFS_FDOPENDIR on %s returned "
+			"NULL (%s)\n",
+			dirp->dir_path,
+			strerror(errno)));
+		if (errno != ENOSYS) {
+			return NULL;
 		}
 	}
 
-- 
2.9.3


From 031ba3f1427d97c48e9911dc98a125661d9088ee Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 12:15:59 -0800
Subject: [PATCH 05/11] s3: smbd: OpenDir_fsp() - Fix memory leak on error.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index ea4f1ab..b8034be 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1742,7 +1742,7 @@ static struct smb_Dir *OpenDir_fsp(TALLOC_CTX *mem_ctx, connection_struct *conn,
 			dirp->dir_path,
 			strerror(errno)));
 		if (errno != ENOSYS) {
-			return NULL;
+			goto fail;
 		}
 	}
 
-- 
2.9.3


From 54d9bb3aa5b14e51bb1a2fe60ec20bc1cdad373f Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 12:32:07 -0800
Subject: [PATCH 06/11] s3: smbd: Move the reference counting and destructor
 setup to just before retuning success.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index b8034be..6b62f14 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1728,11 +1728,6 @@ static struct smb_Dir *OpenDir_fsp(TALLOC_CTX *mem_ctx, connection_struct *conn,
 		goto fail;
 	}
 
-	if (sconn && !sconn->using_smb2) {
-		sconn->searches.dirhandles_open++;
-	}
-	talloc_set_destructor(dirp, smb_Dir_destructor);
-
 	dirp->dir = SMB_VFS_FDOPENDIR(fsp, mask, attr);
 	if (dirp->dir != NULL) {
 		dirp->fsp = fsp;
@@ -1757,6 +1752,11 @@ static struct smb_Dir *OpenDir_fsp(TALLOC_CTX *mem_ctx, connection_struct *conn,
 		goto fail;
 	}
 
+	if (sconn && !sconn->using_smb2) {
+		sconn->searches.dirhandles_open++;
+	}
+	talloc_set_destructor(dirp, smb_Dir_destructor);
+
 	return dirp;
 
   fail:
-- 
2.9.3


From 1265c298699e0b3a3000e70e07d815c459ff461e Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 19 Dec 2016 12:35:32 -0800
Subject: [PATCH 07/11] s3: smbd: Correctly fallback to open_dir_safely if
 FDOPENDIR not supported on system.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/dir.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/source3/smbd/dir.c b/source3/smbd/dir.c
index 6b62f14..3432788 100644
--- a/source3/smbd/dir.c
+++ b/source3/smbd/dir.c
@@ -1742,14 +1742,13 @@ static struct smb_Dir *OpenDir_fsp(TALLOC_CTX *mem_ctx, connection_struct *conn,
 	}
 
 	if (dirp->dir == NULL) {
-		/* FDOPENDIR didn't work. Use OPENDIR instead. */
-		dirp->dir = SMB_VFS_OPENDIR(conn, dirp->dir_path, mask, attr);
-	}
-
-	if (!dirp->dir) {
-		DEBUG(5,("OpenDir_fsp: Can't open %s. %s\n", dirp->dir_path,
-			 strerror(errno) ));
-		goto fail;
+		/* FDOPENDIR is not supported. Use OPENDIR instead. */
+		TALLOC_FREE(dirp);
+		return open_dir_safely(mem_ctx,
+					conn,
+					fsp->fsp_name->base_name,
+					mask,
+					attr);
 	}
 
 	if (sconn && !sconn->using_smb2) {
-- 
2.9.3


From 1c0a1c566a9a43c9c81d42e48b85109a34a486dd Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Thu, 15 Dec 2016 12:52:13 -0800
Subject: [PATCH 08/11] s3: smbd: Remove O_NOFOLLOW guards. We insist on
 O_NOFOLLOW existing.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/open.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index 25cf417..03a994a 100644
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -356,8 +356,7 @@ NTSTATUS fd_open(struct connection_struct *conn,
 	struct smb_filename *smb_fname = fsp->fsp_name;
 	NTSTATUS status = NT_STATUS_OK;
 
-#ifdef O_NOFOLLOW
-	/* 
+	/*
 	 * Never follow symlinks on a POSIX client. The
 	 * client should be doing this.
 	 */
@@ -365,12 +364,10 @@ NTSTATUS fd_open(struct connection_struct *conn,
 	if ((fsp->posix_flags & FSP_POSIX_FLAGS_OPEN) || !lp_follow_symlinks(SNUM(conn))) {
 		flags |= O_NOFOLLOW;
 	}
-#endif
 
 	fsp->fh->fd = SMB_VFS_OPEN(conn, smb_fname, fsp, flags, mode);
 	if (fsp->fh->fd == -1) {
 		int posix_errno = errno;
-#ifdef O_NOFOLLOW
 #if defined(ENOTSUP) && defined(OSF1)
 		/* handle special Tru64 errno */
 		if (errno == ENOTSUP) {
@@ -387,7 +384,6 @@ NTSTATUS fd_open(struct connection_struct *conn,
 		if (errno == EMLINK) {
 			posix_errno = ELOOP;
 		}
-#endif /* O_NOFOLLOW */
 		status = map_nt_error_from_unix(posix_errno);
 		if (errno == EMFILE) {
 			static time_t last_warned = 0L;
-- 
2.9.3


From a34ff44b2cbd396c678aebfc299495ddad6b91d1 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Thu, 15 Dec 2016 12:56:08 -0800
Subject: [PATCH 09/11] s3: smbd: Move special handling of symlink errno's into
 a utility function.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/open.c | 43 ++++++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index 03a994a..616363d 100644
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -345,6 +345,31 @@ static NTSTATUS check_base_file_access(struct connection_struct *conn,
 }
 
 /****************************************************************************
+ Handle differing symlink errno's
+****************************************************************************/
+
+static int link_errno_convert(int err)
+{
+#if defined(ENOTSUP) && defined(OSF1)
+	/* handle special Tru64 errno */
+	if (err == ENOTSUP) {
+		err = ELOOP;
+	}
+#endif /* ENOTSUP */
+#ifdef EFTYPE
+	/* fix broken NetBSD errno */
+	if (err == EFTYPE) {
+		err = ELOOP;
+	}
+#endif /* EFTYPE */
+	/* fix broken FreeBSD errno */
+	if (err == EMLINK) {
+		err = ELOOP;
+	}
+	return err;
+}
+
+/****************************************************************************
  fd support routines - attempt to do a dos_open.
 ****************************************************************************/
 
@@ -367,23 +392,7 @@ NTSTATUS fd_open(struct connection_struct *conn,
 
 	fsp->fh->fd = SMB_VFS_OPEN(conn, smb_fname, fsp, flags, mode);
 	if (fsp->fh->fd == -1) {
-		int posix_errno = errno;
-#if defined(ENOTSUP) && defined(OSF1)
-		/* handle special Tru64 errno */
-		if (errno == ENOTSUP) {
-			posix_errno = ELOOP;
-		}
-#endif /* ENOTSUP */
-#ifdef EFTYPE
-		/* fix broken NetBSD errno */
-		if (errno == EFTYPE) {
-			posix_errno = ELOOP;
-		}
-#endif /* EFTYPE */
-		/* fix broken FreeBSD errno */
-		if (errno == EMLINK) {
-			posix_errno = ELOOP;
-		}
+		int posix_errno = link_errno_convert(errno);
 		status = map_nt_error_from_unix(posix_errno);
 		if (errno == EMFILE) {
 			static time_t last_warned = 0L;
-- 
2.9.3


From 6c455324714936063d77ff15997fcaf651d40a5f Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Thu, 15 Dec 2016 13:04:46 -0800
Subject: [PATCH 10/11] s3: smbd: Add the core functions to prevent symlink
 open races.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/open.c | 237 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 237 insertions(+)

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index 616363d..954cd9c 100644
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -369,6 +369,243 @@ static int link_errno_convert(int err)
 	return err;
 }
 
+static int non_widelink_open(struct connection_struct *conn,
+			const char *conn_rootdir,
+			files_struct *fsp,
+			struct smb_filename *smb_fname,
+			int flags,
+			mode_t mode,
+			unsigned int link_depth);
+
+/****************************************************************************
+ Follow a symlink in userspace.
+****************************************************************************/
+
+static int process_symlink_open(struct connection_struct *conn,
+			const char *conn_rootdir,
+			files_struct *fsp,
+			struct smb_filename *smb_fname,
+			int flags,
+			mode_t mode,
+			unsigned int link_depth)
+{
+	int fd = -1;
+	char *link_target = NULL;
+	int link_len = -1;
+	char *oldwd = NULL;
+	size_t rootdir_len = 0;
+	char *resolved_name = NULL;
+	bool matched = false;
+	int saved_errno = 0;
+
+	/*
+	 * Ensure we don't get stuck in a symlink loop.
+	 */
+	link_depth++;
+	if (link_depth >= 20) {
+		errno = ELOOP;
+		goto out;
+	}
+
+	/* Allocate space for the link target. */
+	link_target = talloc_array(talloc_tos(), char, PATH_MAX);
+	if (link_target == NULL) {
+		errno = ENOMEM;
+		goto out;
+	}
+
+	/* Read the link target. */
+	link_len = SMB_VFS_READLINK(conn,
+				smb_fname->base_name,
+				link_target,
+				PATH_MAX - 1);
+	if (link_len == -1) {
+		goto out;
+	}
+
+	/* Ensure it's at least null terminated. */
+	link_target[link_len] = '\0';
+
+	/* Convert to an absolute path. */
+	resolved_name = SMB_VFS_REALPATH(conn, link_target);
+	if (resolved_name == NULL) {
+		goto out;
+	}
+
+	/*
+	 * We know conn_rootdir starts with '/' and
+	 * does not end in '/'. FIXME ! Should we
+	 * smb_assert this ?
+	 */
+	rootdir_len = strlen(conn_rootdir);
+
+	matched = (strncmp(conn_rootdir, resolved_name, rootdir_len) == 0);
+	if (!matched) {
+		errno = EACCES;
+		goto out;
+	}
+
+	/*
+	 * Turn into a path relative to the share root.
+	 */
+	if (resolved_name[rootdir_len] == '\0') {
+		/* Link to the root of the share. */
+		smb_fname->base_name = talloc_strdup(talloc_tos(), ".");
+		if (smb_fname->base_name == NULL) {
+			errno = ENOMEM;
+			goto out;
+		}
+	} else if (resolved_name[rootdir_len] == '/') {
+		smb_fname->base_name = &resolved_name[rootdir_len+1];
+	} else {
+		errno = EACCES;
+		goto out;
+	}
+
+	oldwd = vfs_GetWd(talloc_tos(), conn);
+	if (oldwd == NULL) {
+		goto out;
+	}
+
+	/* Ensure we operate from the root of the share. */
+	if (vfs_ChDir(conn, conn_rootdir) == -1) {
+		goto out;
+	}
+
+	/* And do it all again.. */
+	fd = non_widelink_open(conn,
+				conn_rootdir,
+				fsp,
+				smb_fname,
+				flags,
+				mode,
+				link_depth);
+	if (fd == -1) {
+		saved_errno = errno;
+	}
+
+  out:
+
+	SAFE_FREE(resolved_name);
+	TALLOC_FREE(link_target);
+	if (oldwd != NULL) {
+		int ret = vfs_ChDir(conn, oldwd);
+		if (ret == -1) {
+			smb_panic("unable to get back to old directory\n");
+		}
+		TALLOC_FREE(oldwd);
+	}
+	if (saved_errno != 0) {
+		errno = saved_errno;
+	}
+	return fd;
+}
+
+/****************************************************************************
+ Non-widelink open.
+****************************************************************************/
+
+static int non_widelink_open(struct connection_struct *conn,
+			const char *conn_rootdir,
+			files_struct *fsp,
+			struct smb_filename *smb_fname,
+			int flags,
+			mode_t mode,
+			unsigned int link_depth)
+{
+	NTSTATUS status;
+	int fd = -1;
+	struct smb_filename *smb_fname_rel = NULL;
+	int saved_errno = 0;
+	char *oldwd = NULL;
+	char *parent_dir = NULL;
+	const char *final_component = NULL;
+
+	if (!parent_dirname(talloc_tos(),
+			smb_fname->base_name,
+			&parent_dir,
+			&final_component)) {
+		goto out;
+	}
+
+	oldwd = vfs_GetWd(talloc_tos(), conn);
+	if (oldwd == NULL) {
+		goto out;
+	}
+
+	/* Pin parent directory in place. */
+	if (vfs_ChDir(conn, parent_dir) == -1) {
+		goto out;
+	}
+
+	/* Ensure the relative path is below the share. */
+	status = check_reduced_name(conn, final_component);
+	if (!NT_STATUS_IS_OK(status)) {
+		saved_errno = map_errno_from_nt_status(status);
+		goto out;
+	}
+
+	smb_fname_rel = synthetic_smb_fname(talloc_tos(),
+				final_component,
+				smb_fname->stream_name,
+				&smb_fname->st);
+
+	flags |= O_NOFOLLOW;
+
+	{
+		struct smb_filename *tmp_name = fsp->fsp_name;
+		fsp->fsp_name = smb_fname_rel;
+		fd = SMB_VFS_OPEN(conn, smb_fname_rel, fsp, flags, mode);
+		fsp->fsp_name = tmp_name;
+	}
+
+	if (fd == -1) {
+		saved_errno = link_errno_convert(errno);
+		if (saved_errno == ELOOP) {
+			if (fsp->posix_flags & FSP_POSIX_FLAGS_OPEN) {
+				/* Never follow symlinks on posix open. */
+				goto out;
+			}
+			if (!lp_follow_symlinks(SNUM(conn))) {
+				/* Explicitly no symlinks. */
+				goto out;
+			}
+			/*
+			 * We have a symlink. Follow in userspace
+			 * to ensure it's under the share definition.
+			 */
+			fd = process_symlink_open(conn,
+					conn_rootdir,
+					fsp,
+					smb_fname_rel,
+					flags,
+					mode,
+					link_depth);
+			if (fd == -1) {
+				saved_errno =
+					link_errno_convert(errno);
+			}
+		}
+	}
+
+  out:
+
+	TALLOC_FREE(parent_dir);
+	TALLOC_FREE(smb_fname_rel);
+
+	if (oldwd != NULL) {
+		int ret = vfs_ChDir(conn, oldwd);
+		if (ret == -1) {
+			smb_panic("unable to get back to old directory\n");
+		}
+		TALLOC_FREE(oldwd);
+	}
+	if (saved_errno != 0) {
+		errno = saved_errno;
+	}
+	return fd;
+}
+
 /****************************************************************************
  fd support routines - attempt to do a dos_open.
 ****************************************************************************/
-- 
2.9.3


From 0eb718b5cc05adbcb20ac5b9b0eee71aa2af81ac Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Thu, 15 Dec 2016 13:06:31 -0800
Subject: [PATCH 11/11] s3: smbd: Use the new non_widelink_open() function.

CVE-2017-2619

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12496

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/open.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index 954cd9c..7274ae4 100644
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -627,7 +627,28 @@ NTSTATUS fd_open(struct connection_struct *conn,
 		flags |= O_NOFOLLOW;
 	}
 
-	fsp->fh->fd = SMB_VFS_OPEN(conn, smb_fname, fsp, flags, mode);
+	/* Ensure path is below share definition. */
+	if (!lp_widelinks(SNUM(conn))) {
+		const char *conn_rootdir = SMB_VFS_CONNECTPATH(conn,
+						smb_fname->base_name);
+		if (conn_rootdir == NULL) {
+			return NT_STATUS_NO_MEMORY;
+		}
+		/*
+		 * Only follow symlinks within a share
+		 * definition.
+		 */
+		fsp->fh->fd = non_widelink_open(conn,
+					conn_rootdir,
+					fsp,
+					smb_fname,
+					flags,
+					mode,
+					0);
+	} else {
+		fsp->fh->fd = SMB_VFS_OPEN(conn, smb_fname, fsp, flags, mode);
+	}
+
 	if (fsp->fh->fd == -1) {
 		int posix_errno = link_errno_convert(errno);
 		status = map_nt_error_from_unix(posix_errno);
-- 
2.9.3