From eb27f9b7bf9c1dc902d9545eecf805831bd4e46c Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Tue, 5 Jan 2016 11:18:12 -0800
Subject: [PATCH 1/8] CVE-2015-7560: s3: smbd: Add refuse_symlink() function
that can be used to prevent operations on a symlink.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=11648
Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
---
source3/smbd/trans2.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
--- a/source3/smbd/trans2.c
+++ b/source3/smbd/trans2.c
@@ -51,6 +51,34 @@ static char *store_file_unix_basic_info2
files_struct *fsp,
const SMB_STRUCT_STAT *psbuf);
+/****************************************************************************
+ Check if an open file handle or pathname is a symlink.
+****************************************************************************/
+
+static NTSTATUS refuse_symlink(connection_struct *conn,
+ const files_struct *fsp,
+ const char *name)
+{
+ SMB_STRUCT_STAT sbuf;
+ const SMB_STRUCT_STAT *pst = NULL;
+
+ if (fsp) {
+ pst = &fsp->fsp_name->st;
+ } else {
+ int ret = vfs_stat_smb_fname(conn,
+ name,
+ &sbuf);
+ if (ret == -1) {
+ return map_nt_error_from_unix(errno);
+ }
+ pst = &sbuf;
+ }
+ if (S_ISLNK(pst->st_ex_mode)) {
+ return NT_STATUS_ACCESS_DENIED;
+ }
+ return NT_STATUS_OK;
+}
+
/********************************************************************
Roundup a value to the nearest allocation roundup size boundary.
Only do this for Windows clients.
@@ -181,12 +209,22 @@ NTSTATUS get_ea_names_from_file(TALLOC_C
char **names, **tmp;
size_t num_names;
ssize_t sizeret = -1;
+ NTSTATUS status;
+
+ if (pnames) {
+ *pnames = NULL;
+ }
+ *pnum_names = 0;
if (!lp_ea_support(SNUM(conn))) {
- if (pnames) {
- *pnames = NULL;
- }
- *pnum_names = 0;
+ return NT_STATUS_OK;
+ }
+
+ status = refuse_symlink(conn, fsp, fname);
+ if (!NT_STATUS_IS_OK(status)) {
+ /*
+ * Just return no EA's on a symlink.
+ */
return NT_STATUS_OK;
}
@@ -236,10 +274,6 @@ NTSTATUS get_ea_names_from_file(TALLOC_C
if (sizeret == 0) {
TALLOC_FREE(names);
- if (pnames) {
- *pnames = NULL;
- }
- *pnum_names = 0;
return NT_STATUS_OK;
}
@@ -550,6 +584,7 @@ NTSTATUS set_ea(connection_struct *conn,
const struct smb_filename *smb_fname, struct ea_list *ea_list)
{
char *fname = NULL;
+ NTSTATUS status;
if (!lp_ea_support(SNUM(conn))) {
return NT_STATUS_EAS_NOT_SUPPORTED;
@@ -559,6 +594,12 @@ NTSTATUS set_ea(connection_struct *conn,
return NT_STATUS_ACCESS_DENIED;
}
+ status = refuse_symlink(conn, fsp, smb_fname->base_name);
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+
+
/* For now setting EAs on streams isn't supported. */
fname = smb_fname->base_name;
@@ -4931,6 +4972,13 @@ NTSTATUS smbd_do_qfilepathinfo(connectio
uint16 num_file_acls = 0;
uint16 num_def_acls = 0;
+ status = refuse_symlink(conn,
+ fsp,
+ smb_fname->base_name);
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+
if (fsp && fsp->fh->fd != -1) {
file_acl = SMB_VFS_SYS_ACL_GET_FD(fsp);
} else {
@@ -6452,6 +6500,7 @@ static NTSTATUS smb_set_posix_acl(connec
uint16 num_def_acls;
bool valid_file_acls = True;
bool valid_def_acls = True;
+ NTSTATUS status;
if (total_data < SMB_POSIX_ACL_HEADER_SIZE) {
return NT_STATUS_INVALID_PARAMETER;
@@ -6479,6 +6528,11 @@ static NTSTATUS smb_set_posix_acl(connec
return NT_STATUS_INVALID_PARAMETER;
}
+ status = refuse_symlink(conn, fsp, smb_fname->base_name);
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+
DEBUG(10,("smb_set_posix_acl: file %s num_file_acls = %u, num_def_acls = %u\n",
smb_fname ? smb_fname_str_dbg(smb_fname) : fsp_str_dbg(fsp),
(unsigned int)num_file_acls,
--- a/source3/smbd/nttrans.c
+++ b/source3/smbd/nttrans.c
@@ -877,6 +877,12 @@ NTSTATUS set_sd(files_struct *fsp, struc
return NT_STATUS_OK;
}
+ if (S_ISLNK(fsp->fsp_name->st.st_ex_mode)) {
+ DEBUG(10, ("ACL set on symlink %s denied.\n",
+ fsp_str_dbg(fsp)));
+ return NT_STATUS_ACCESS_DENIED;
+ }
+
if (psd->owner_sid == NULL) {
security_info_sent &= ~SECINFO_OWNER;
}
@@ -1925,6 +1931,12 @@ NTSTATUS smbd_do_query_security_desc(con
return NT_STATUS_ACCESS_DENIED;
}
+ if (S_ISLNK(fsp->fsp_name->st.st_ex_mode)) {
+ DEBUG(10, ("ACL get on symlink %s denied.\n",
+ fsp_str_dbg(fsp)));
+ return NT_STATUS_ACCESS_DENIED;
+ }
+
if (security_info_wanted & (SECINFO_DACL|SECINFO_OWNER|
SECINFO_GROUP|SECINFO_SACL)) {
/* Don't return SECINFO_LABEL if anything else was