Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1672 insertions, 0 deletions

diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
new file mode 100644
index 000000000..a6c7566a0
--- /dev/null
+++ b/fs/smb/client/cifsacl.c
@@ -0,0 +1,1672 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ *
+ *   Copyright (C) International Business Machines  Corp., 2007,2008
+ *   Author(s): Steve French (sfrench@us.ibm.com)
+ *
+ *   Contains the routines for mapping CIFS/NTFS ACLs
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/keyctl.h>
+#include <linux/key-type.h>
+#include <keys/user-type.h>
+#include "cifspdu.h"
+#include "cifsglob.h"
+#include "cifsacl.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "fs_context.h"
+
+/* security id for everyone/world system group */
+static const struct cifs_sid sid_everyone = {
+	1, 1, {0, 0, 0, 0, 0, 1}, {0} };
+/* security id for Authenticated Users system group */
+static const struct cifs_sid sid_authusers = {
+	1, 1, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(11)} };
+
+/* S-1-22-1 Unmapped Unix users */
+static const struct cifs_sid sid_unix_users = {1, 1, {0, 0, 0, 0, 0, 22},
+		{cpu_to_le32(1), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} };
+
+/* S-1-22-2 Unmapped Unix groups */
+static const struct cifs_sid sid_unix_groups = { 1, 1, {0, 0, 0, 0, 0, 22},
+		{cpu_to_le32(2), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} };
+
+/*
+ * See https://technet.microsoft.com/en-us/library/hh509017(v=ws.10).aspx
+ */
+
+/* S-1-5-88 MS NFS and Apple style UID/GID/mode */
+
+/* S-1-5-88-1 Unix uid */
+static const struct cifs_sid sid_unix_NFS_users = { 1, 2, {0, 0, 0, 0, 0, 5},
+	{cpu_to_le32(88),
+	 cpu_to_le32(1), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} };
+
+/* S-1-5-88-2 Unix gid */
+static const struct cifs_sid sid_unix_NFS_groups = { 1, 2, {0, 0, 0, 0, 0, 5},
+	{cpu_to_le32(88),
+	 cpu_to_le32(2), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} };
+
+/* S-1-5-88-3 Unix mode */
+static const struct cifs_sid sid_unix_NFS_mode = { 1, 2, {0, 0, 0, 0, 0, 5},
+	{cpu_to_le32(88),
+	 cpu_to_le32(3), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} };
+
+static const struct cred *root_cred;
+
+static int
+cifs_idmap_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
+{
+	char *payload;
+
+	/*
+	 * If the payload is less than or equal to the size of a pointer, then
+	 * an allocation here is wasteful. Just copy the data directly to the
+	 * payload.value union member instead.
+	 *
+	 * With this however, you must check the datalen before trying to
+	 * dereference payload.data!
+	 */
+	if (prep->datalen <= sizeof(key->payload)) {
+		key->payload.data[0] = NULL;
+		memcpy(&key->payload, prep->data, prep->datalen);
+	} else {
+		payload = kmemdup(prep->data, prep->datalen, GFP_KERNEL);
+		if (!payload)
+			return -ENOMEM;
+		key->payload.data[0] = payload;
+	}
+
+	key->datalen = prep->datalen;
+	return 0;
+}
+
+static inline void
+cifs_idmap_key_destroy(struct key *key)
+{
+	if (key->datalen > sizeof(key->payload))
+		kfree(key->payload.data[0]);
+}
+
+static struct key_type cifs_idmap_key_type = {
+	.name        = "cifs.idmap",
+	.instantiate = cifs_idmap_key_instantiate,
+	.destroy     = cifs_idmap_key_destroy,
+	.describe    = user_describe,
+};
+
+static char *
+sid_to_key_str(struct cifs_sid *sidptr, unsigned int type)
+{
+	int i, len;
+	unsigned int saval;
+	char *sidstr, *strptr;
+	unsigned long long id_auth_val;
+
+	/* 3 bytes for prefix */
+	sidstr = kmalloc(3 + SID_STRING_BASE_SIZE +
+			 (SID_STRING_SUBAUTH_SIZE * sidptr->num_subauth),
+			 GFP_KERNEL);
+	if (!sidstr)
+		return sidstr;
+
+	strptr = sidstr;
+	len = sprintf(strptr, "%cs:S-%hhu", type == SIDOWNER ? 'o' : 'g',
+			sidptr->revision);
+	strptr += len;
+
+	/* The authority field is a single 48-bit number */
+	id_auth_val = (unsigned long long)sidptr->authority[5];
+	id_auth_val |= (unsigned long long)sidptr->authority[4] << 8;
+	id_auth_val |= (unsigned long long)sidptr->authority[3] << 16;
+	id_auth_val |= (unsigned long long)sidptr->authority[2] << 24;
+	id_auth_val |= (unsigned long long)sidptr->authority[1] << 32;
+	id_auth_val |= (unsigned long long)sidptr->authority[0] << 48;
+
+	/*
+	 * MS-DTYP states that if the authority is >= 2^32, then it should be
+	 * expressed as a hex value.
+	 */
+	if (id_auth_val <= UINT_MAX)
+		len = sprintf(strptr, "-%llu", id_auth_val);
+	else
+		len = sprintf(strptr, "-0x%llx", id_auth_val);
+
+	strptr += len;
+
+	for (i = 0; i < sidptr->num_subauth; ++i) {
+		saval = le32_to_cpu(sidptr->sub_auth[i]);
+		len = sprintf(strptr, "-%u", saval);
+		strptr += len;
+	}
+
+	return sidstr;
+}
+
+/*
+ * if the two SIDs (roughly equivalent to a UUID for a user or group) are
+ * the same returns zero, if they do not match returns non-zero.
+ */
+static int
+compare_sids(const struct cifs_sid *ctsid, const struct cifs_sid *cwsid)
+{
+	int i;
+	int num_subauth, num_sat, num_saw;
+
+	if ((!ctsid) || (!cwsid))
+		return 1;
+
+	/* compare the revision */
+	if (ctsid->revision != cwsid->revision) {
+		if (ctsid->revision > cwsid->revision)
+			return 1;
+		else
+			return -1;
+	}
+
+	/* compare all of the six auth values */
+	for (i = 0; i < NUM_AUTHS; ++i) {
+		if (ctsid->authority[i] != cwsid->authority[i]) {
+			if (ctsid->authority[i] > cwsid->authority[i])
+				return 1;
+			else
+				return -1;
+		}
+	}
+
+	/* compare all of the subauth values if any */
+	num_sat = ctsid->num_subauth;
+	num_saw = cwsid->num_subauth;
+	num_subauth = num_sat < num_saw ? num_sat : num_saw;
+	if (num_subauth) {
+		for (i = 0; i < num_subauth; ++i) {
+			if (ctsid->sub_auth[i] != cwsid->sub_auth[i]) {
+				if (le32_to_cpu(ctsid->sub_auth[i]) >
+					le32_to_cpu(cwsid->sub_auth[i]))
+					return 1;
+				else
+					return -1;
+			}
+		}
+	}
+
+	return 0; /* sids compare/match */
+}
+
+static bool
+is_well_known_sid(const struct cifs_sid *psid, uint32_t *puid, bool is_group)
+{
+	int i;
+	int num_subauth;
+	const struct cifs_sid *pwell_known_sid;
+
+	if (!psid || (puid == NULL))
+		return false;
+
+	num_subauth = psid->num_subauth;
+
+	/* check if Mac (or Windows NFS) vs. Samba format for Unix owner SID */
+	if (num_subauth == 2) {
+		if (is_group)
+			pwell_known_sid = &sid_unix_groups;
+		else
+			pwell_known_sid = &sid_unix_users;
+	} else if (num_subauth == 3) {
+		if (is_group)
+			pwell_known_sid = &sid_unix_NFS_groups;
+		else
+			pwell_known_sid = &sid_unix_NFS_users;
+	} else
+		return false;
+
+	/* compare the revision */
+	if (psid->revision != pwell_known_sid->revision)
+		return false;
+
+	/* compare all of the six auth values */
+	for (i = 0; i < NUM_AUTHS; ++i) {
+		if (psid->authority[i] != pwell_known_sid->authority[i]) {
+			cifs_dbg(FYI, "auth %d did not match\n", i);
+			return false;
+		}
+	}
+
+	if (num_subauth == 2) {
+		if (psid->sub_auth[0] != pwell_known_sid->sub_auth[0])
+			return false;
+
+		*puid = le32_to_cpu(psid->sub_auth[1]);
+	} else /* 3 subauths, ie Windows/Mac style */ {
+		*puid = le32_to_cpu(psid->sub_auth[0]);
+		if ((psid->sub_auth[0] != pwell_known_sid->sub_auth[0]) ||
+		    (psid->sub_auth[1] != pwell_known_sid->sub_auth[1]))
+			return false;
+
+		*puid = le32_to_cpu(psid->sub_auth[2]);
+	}
+
+	cifs_dbg(FYI, "Unix UID %d returned from SID\n", *puid);
+	return true; /* well known sid found, uid returned */
+}
+
+static __u16
+cifs_copy_sid(struct cifs_sid *dst, const struct cifs_sid *src)
+{
+	int i;
+	__u16 size = 1 + 1 + 6;
+
+	dst->revision = src->revision;
+	dst->num_subauth = min_t(u8, src->num_subauth, SID_MAX_SUB_AUTHORITIES);
+	for (i = 0; i < NUM_AUTHS; ++i)
+		dst->authority[i] = src->authority[i];
+	for (i = 0; i < dst->num_subauth; ++i)
+		dst->sub_auth[i] = src->sub_auth[i];
+	size += (dst->num_subauth * 4);
+
+	return size;
+}
+
+static int
+id_to_sid(unsigned int cid, uint sidtype, struct cifs_sid *ssid)
+{
+	int rc;
+	struct key *sidkey;
+	struct cifs_sid *ksid;
+	unsigned int ksid_size;
+	char desc[3 + 10 + 1]; /* 3 byte prefix + 10 bytes for value + NULL */
+	const struct cred *saved_cred;
+
+	rc = snprintf(desc, sizeof(desc), "%ci:%u",
+			sidtype == SIDOWNER ? 'o' : 'g', cid);
+	if (rc >= sizeof(desc))
+		return -EINVAL;
+
+	rc = 0;
+	saved_cred = override_creds(root_cred);
+	sidkey = request_key(&cifs_idmap_key_type, desc, "");
+	if (IS_ERR(sidkey)) {
+		rc = -EINVAL;
+		cifs_dbg(FYI, "%s: Can't map %cid %u to a SID\n",
+			 __func__, sidtype == SIDOWNER ? 'u' : 'g', cid);
+		goto out_revert_creds;
+	} else if (sidkey->datalen < CIFS_SID_BASE_SIZE) {
+		rc = -EIO;
+		cifs_dbg(FYI, "%s: Downcall contained malformed key (datalen=%hu)\n",
+			 __func__, sidkey->datalen);
+		goto invalidate_key;
+	}
+
+	/*
+	 * A sid is usually too large to be embedded in payload.value, but if
+	 * there are no subauthorities and the host has 8-byte pointers, then
+	 * it could be.
+	 */
+	ksid = sidkey->datalen <= sizeof(sidkey->payload) ?
+		(struct cifs_sid *)&sidkey->payload :
+		(struct cifs_sid *)sidkey->payload.data[0];
+
+	ksid_size = CIFS_SID_BASE_SIZE + (ksid->num_subauth * sizeof(__le32));
+	if (ksid_size > sidkey->datalen) {
+		rc = -EIO;
+		cifs_dbg(FYI, "%s: Downcall contained malformed key (datalen=%hu, ksid_size=%u)\n",
+			 __func__, sidkey->datalen, ksid_size);
+		goto invalidate_key;
+	}
+
+	cifs_copy_sid(ssid, ksid);
+out_key_put:
+	key_put(sidkey);
+out_revert_creds:
+	revert_creds(saved_cred);
+	return rc;
+
+invalidate_key:
+	key_invalidate(sidkey);
+	goto out_key_put;
+}
+
+int
+sid_to_id(struct cifs_sb_info *cifs_sb, struct cifs_sid *psid,
+		struct cifs_fattr *fattr, uint sidtype)
+{
+	int rc = 0;
+	struct key *sidkey;
+	char *sidstr;
+	const struct cred *saved_cred;
+	kuid_t fuid = cifs_sb->ctx->linux_uid;
+	kgid_t fgid = cifs_sb->ctx->linux_gid;
+
+	/*
+	 * If we have too many subauthorities, then something is really wrong.
+	 * Just return an error.
+	 */
+	if (unlikely(psid->num_subauth > SID_MAX_SUB_AUTHORITIES)) {
+		cifs_dbg(FYI, "%s: %u subauthorities is too many!\n",
+			 __func__, psid->num_subauth);
+		return -EIO;
+	}
+
+	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UID_FROM_ACL) ||
+	    (cifs_sb_master_tcon(cifs_sb)->posix_extensions)) {
+		uint32_t unix_id;
+		bool is_group;
+
+		if (sidtype != SIDOWNER)
+			is_group = true;
+		else
+			is_group = false;
+
+		if (is_well_known_sid(psid, &unix_id, is_group) == false)
+			goto try_upcall_to_get_id;
+
+		if (is_group) {
+			kgid_t gid;
+			gid_t id;
+
+			id = (gid_t)unix_id;
+			gid = make_kgid(&init_user_ns, id);
+			if (gid_valid(gid)) {
+				fgid = gid;
+				goto got_valid_id;
+			}
+		} else {
+			kuid_t uid;
+			uid_t id;
+
+			id = (uid_t)unix_id;
+			uid = make_kuid(&init_user_ns, id);
+			if (uid_valid(uid)) {
+				fuid = uid;
+				goto got_valid_id;
+			}
+		}
+		/* If unable to find uid/gid easily from SID try via upcall */
+	}
+
+try_upcall_to_get_id:
+	sidstr = sid_to_key_str(psid, sidtype);
+	if (!sidstr)
+		return -ENOMEM;
+
+	saved_cred = override_creds(root_cred);
+	sidkey = request_key(&cifs_idmap_key_type, sidstr, "");
+	if (IS_ERR(sidkey)) {
+		cifs_dbg(FYI, "%s: Can't map SID %s to a %cid\n",
+			 __func__, sidstr, sidtype == SIDOWNER ? 'u' : 'g');
+		goto out_revert_creds;
+	}
+
+	/*
+	 * FIXME: Here we assume that uid_t and gid_t are same size. It's
+	 * probably a safe assumption but might be better to check based on
+	 * sidtype.
+	 */
+	BUILD_BUG_ON(sizeof(uid_t) != sizeof(gid_t));
+	if (sidkey->datalen != sizeof(uid_t)) {
+		cifs_dbg(FYI, "%s: Downcall contained malformed key (datalen=%hu)\n",
+			 __func__, sidkey->datalen);
+		key_invalidate(sidkey);
+		goto out_key_put;
+	}
+
+	if (sidtype == SIDOWNER) {
+		kuid_t uid;
+		uid_t id;
+		memcpy(&id, &sidkey->payload.data[0], sizeof(uid_t));
+		uid = make_kuid(&init_user_ns, id);
+		if (uid_valid(uid))
+			fuid = uid;
+	} else {
+		kgid_t gid;
+		gid_t id;
+		memcpy(&id, &sidkey->payload.data[0], sizeof(gid_t));
+		gid = make_kgid(&init_user_ns, id);
+		if (gid_valid(gid))
+			fgid = gid;
+	}
+
+out_key_put:
+	key_put(sidkey);
+out_revert_creds:
+	revert_creds(saved_cred);
+	kfree(sidstr);
+
+	/*
+	 * Note that we return 0 here unconditionally. If the mapping
+	 * fails then we just fall back to using the ctx->linux_uid/linux_gid.
+	 */
+got_valid_id:
+	rc = 0;
+	if (sidtype == SIDOWNER)
+		fattr->cf_uid = fuid;
+	else
+		fattr->cf_gid = fgid;
+	return rc;
+}
+
+int
+init_cifs_idmap(void)
+{
+	struct cred *cred;
+	struct key *keyring;
+	int ret;
+
+	cifs_dbg(FYI, "Registering the %s key type\n",
+		 cifs_idmap_key_type.name);
+
+	/* create an override credential set with a special thread keyring in
+	 * which requests are cached
+	 *
+	 * this is used to prevent malicious redirections from being installed
+	 * with add_key().
+	 */
+	cred = prepare_kernel_cred(NULL);
+	if (!cred)
+		return -ENOMEM;
+
+	keyring = keyring_alloc(".cifs_idmap",
+				GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
+				(KEY_POS_ALL & ~KEY_POS_SETATTR) |
+				KEY_USR_VIEW | KEY_USR_READ,
+				KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
+	if (IS_ERR(keyring)) {
+		ret = PTR_ERR(keyring);
+		goto failed_put_cred;
+	}
+
+	ret = register_key_type(&cifs_idmap_key_type);
+	if (ret < 0)
+		goto failed_put_key;
+
+	/* instruct request_key() to use this special keyring as a cache for
+	 * the results it looks up */
+	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
+	cred->thread_keyring = keyring;
+	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+	root_cred = cred;
+
+	cifs_dbg(FYI, "cifs idmap keyring: %d\n", key_serial(keyring));
+	return 0;
+
+failed_put_key:
+	key_put(keyring);
+failed_put_cred:
+	put_cred(cred);
+	return ret;
+}
+
+void
+exit_cifs_idmap(void)
+{
+	key_revoke(root_cred->thread_keyring);
+	unregister_key_type(&cifs_idmap_key_type);
+	put_cred(root_cred);
+	cifs_dbg(FYI, "Unregistered %s key type\n", cifs_idmap_key_type.name);
+}
+
+/* copy ntsd, owner sid, and group sid from a security descriptor to another */
+static __u32 copy_sec_desc(const struct cifs_ntsd *pntsd,
+				struct cifs_ntsd *pnntsd,
+				__u32 sidsoffset,
+				struct cifs_sid *pownersid,
+				struct cifs_sid *pgrpsid)
+{
+	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
+	struct cifs_sid *nowner_sid_ptr, *ngroup_sid_ptr;
+
+	/* copy security descriptor control portion */
+	pnntsd->revision = pntsd->revision;
+	pnntsd->type = pntsd->type;
+	pnntsd->dacloffset = cpu_to_le32(sizeof(struct cifs_ntsd));
+	pnntsd->sacloffset = 0;
+	pnntsd->osidoffset = cpu_to_le32(sidsoffset);
+	pnntsd->gsidoffset = cpu_to_le32(sidsoffset + sizeof(struct cifs_sid));
+
+	/* copy owner sid */
+	if (pownersid)
+		owner_sid_ptr = pownersid;
+	else
+		owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+				le32_to_cpu(pntsd->osidoffset));
+	nowner_sid_ptr = (struct cifs_sid *)((char *)pnntsd + sidsoffset);
+	cifs_copy_sid(nowner_sid_ptr, owner_sid_ptr);
+
+	/* copy group sid */
+	if (pgrpsid)
+		group_sid_ptr = pgrpsid;
+	else
+		group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+				le32_to_cpu(pntsd->gsidoffset));
+	ngroup_sid_ptr = (struct cifs_sid *)((char *)pnntsd + sidsoffset +
+					sizeof(struct cifs_sid));
+	cifs_copy_sid(ngroup_sid_ptr, group_sid_ptr);
+
+	return sidsoffset + (2 * sizeof(struct cifs_sid));
+}
+
+
+/*
+   change posix mode to reflect permissions
+   pmode is the existing mode (we only want to overwrite part of this
+   bits to set can be: S_IRWXU, S_IRWXG or S_IRWXO ie 00700 or 00070 or 00007
+*/
+static void access_flags_to_mode(__le32 ace_flags, int type, umode_t *pmode,
+				 umode_t *pdenied, umode_t mask)
+{
+	__u32 flags = le32_to_cpu(ace_flags);
+	/*
+	 * Do not assume "preferred" or "canonical" order.
+	 * The first DENY or ALLOW ACE which matches perfectly is
+	 * the permission to be used. Once allowed or denied, same
+	 * permission in later ACEs do not matter.
+	 */
+
+	/* If not already allowed, deny these bits */
+	if (type == ACCESS_DENIED) {
+		if (flags & GENERIC_ALL &&
+				!(*pmode & mask & 0777))
+			*pdenied |= mask & 0777;
+
+		if (((flags & GENERIC_WRITE) ||
+				((flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS)) &&
+				!(*pmode & mask & 0222))
+			*pdenied |= mask & 0222;
+
+		if (((flags & GENERIC_READ) ||
+				((flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS)) &&
+				!(*pmode & mask & 0444))
+			*pdenied |= mask & 0444;
+
+		if (((flags & GENERIC_EXECUTE) ||
+				((flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS)) &&
+				!(*pmode & mask & 0111))
+			*pdenied |= mask & 0111;
+
+		return;
+	} else if (type != ACCESS_ALLOWED) {
+		cifs_dbg(VFS, "unknown access control type %d\n", type);
+		return;
+	}
+	/* else ACCESS_ALLOWED type */
+
+	if ((flags & GENERIC_ALL) &&
+			!(*pdenied & mask & 0777)) {
+		*pmode |= mask & 0777;
+		cifs_dbg(NOISY, "all perms\n");
+		return;
+	}
+
+	if (((flags & GENERIC_WRITE) ||
+			((flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS)) &&
+			!(*pdenied & mask & 0222))
+		*pmode |= mask & 0222;
+
+	if (((flags & GENERIC_READ) ||
+			((flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS)) &&
+			!(*pdenied & mask & 0444))
+		*pmode |= mask & 0444;
+
+	if (((flags & GENERIC_EXECUTE) ||
+			((flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS)) &&
+			!(*pdenied & mask & 0111))
+		*pmode |= mask & 0111;
+
+	/* If DELETE_CHILD is set only on an owner ACE, set sticky bit */
+	if (flags & FILE_DELETE_CHILD) {
+		if (mask == ACL_OWNER_MASK) {
+			if (!(*pdenied & 01000))
+				*pmode |= 01000;
+		} else if (!(*pdenied & 01000)) {
+			*pmode &= ~01000;
+			*pdenied |= 01000;
+		}
+	}
+
+	cifs_dbg(NOISY, "access flags 0x%x mode now %04o\n", flags, *pmode);
+	return;
+}
+
+/*
+   Generate access flags to reflect permissions mode is the existing mode.
+   This function is called for every ACE in the DACL whose SID matches
+   with either owner or group or everyone.
+*/
+
+static void mode_to_access_flags(umode_t mode, umode_t bits_to_use,
+				__u32 *pace_flags)
+{
+	/* reset access mask */
+	*pace_flags = 0x0;
+
+	/* bits to use are either S_IRWXU or S_IRWXG or S_IRWXO */
+	mode &= bits_to_use;
+
+	/* check for R/W/X UGO since we do not know whose flags
+	   is this but we have cleared all the bits sans RWX for
+	   either user or group or other as per bits_to_use */
+	if (mode & S_IRUGO)
+		*pace_flags |= SET_FILE_READ_RIGHTS;
+	if (mode & S_IWUGO)
+		*pace_flags |= SET_FILE_WRITE_RIGHTS;
+	if (mode & S_IXUGO)
+		*pace_flags |= SET_FILE_EXEC_RIGHTS;
+
+	cifs_dbg(NOISY, "mode: %04o, access flags now 0x%x\n",
+		 mode, *pace_flags);
+	return;
+}
+
+static __u16 cifs_copy_ace(struct cifs_ace *dst, struct cifs_ace *src, struct cifs_sid *psid)
+{
+	__u16 size = 1 + 1 + 2 + 4;
+
+	dst->type = src->type;
+	dst->flags = src->flags;
+	dst->access_req = src->access_req;
+
+	/* Check if there's a replacement sid specified */
+	if (psid)
+		size += cifs_copy_sid(&dst->sid, psid);
+	else
+		size += cifs_copy_sid(&dst->sid, &src->sid);
+
+	dst->size = cpu_to_le16(size);
+
+	return size;
+}
+
+static __u16 fill_ace_for_sid(struct cifs_ace *pntace,
+			const struct cifs_sid *psid, __u64 nmode,
+			umode_t bits, __u8 access_type,
+			bool allow_delete_child)
+{
+	int i;
+	__u16 size = 0;
+	__u32 access_req = 0;
+
+	pntace->type = access_type;
+	pntace->flags = 0x0;
+	mode_to_access_flags(nmode, bits, &access_req);
+
+	if (access_type == ACCESS_ALLOWED && allow_delete_child)
+		access_req |= FILE_DELETE_CHILD;
+
+	if (access_type == ACCESS_ALLOWED && !access_req)
+		access_req = SET_MINIMUM_RIGHTS;
+	else if (access_type == ACCESS_DENIED)
+		access_req &= ~SET_MINIMUM_RIGHTS;
+
+	pntace->access_req = cpu_to_le32(access_req);
+
+	pntace->sid.revision = psid->revision;
+	pntace->sid.num_subauth = psid->num_subauth;
+	for (i = 0; i < NUM_AUTHS; i++)
+		pntace->sid.authority[i] = psid->authority[i];
+	for (i = 0; i < psid->num_subauth; i++)
+		pntace->sid.sub_auth[i] = psid->sub_auth[i];
+
+	size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth * 4);
+	pntace->size = cpu_to_le16(size);
+
+	return size;
+}
+
+
+#ifdef CONFIG_CIFS_DEBUG2
+static void dump_ace(struct cifs_ace *pace, char *end_of_acl)
+{
+	int num_subauth;
+
+	/* validate that we do not go past end of acl */
+
+	if (le16_to_cpu(pace->size) < 16) {
+		cifs_dbg(VFS, "ACE too small %d\n", le16_to_cpu(pace->size));
+		return;
+	}
+
+	if (end_of_acl < (char *)pace + le16_to_cpu(pace->size)) {
+		cifs_dbg(VFS, "ACL too small to parse ACE\n");
+		return;
+	}
+
+	num_subauth = pace->sid.num_subauth;
+	if (num_subauth) {
+		int i;
+		cifs_dbg(FYI, "ACE revision %d num_auth %d type %d flags %d size %d\n",
+			 pace->sid.revision, pace->sid.num_subauth, pace->type,
+			 pace->flags, le16_to_cpu(pace->size));
+		for (i = 0; i < num_subauth; ++i) {
+			cifs_dbg(FYI, "ACE sub_auth[%d]: 0x%x\n",
+				 i, le32_to_cpu(pace->sid.sub_auth[i]));
+		}
+
+		/* BB add length check to make sure that we do not have huge
+			num auths and therefore go off the end */
+	}
+
+	return;
+}
+#endif
+
+static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
+		       struct cifs_sid *pownersid, struct cifs_sid *pgrpsid,
+		       struct cifs_fattr *fattr, bool mode_from_special_sid)
+{
+	int i;
+	int num_aces = 0;
+	int acl_size;
+	char *acl_base;
+	struct cifs_ace **ppace;
+
+	/* BB need to add parm so we can store the SID BB */
+
+	if (!pdacl) {
+		/* no DACL in the security descriptor, set
+		   all the permissions for user/group/other */
+		fattr->cf_mode |= 0777;
+		return;
+	}
+
+	/* validate that we do not go past end of acl */
+	if (end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
+		cifs_dbg(VFS, "ACL too small to parse DACL\n");
+		return;
+	}
+
+	cifs_dbg(NOISY, "DACL revision %d size %d num aces %d\n",
+		 le16_to_cpu(pdacl->revision), le16_to_cpu(pdacl->size),
+		 le32_to_cpu(pdacl->num_aces));
+
+	/* reset rwx permissions for user/group/other.
+	   Also, if num_aces is 0 i.e. DACL has no ACEs,
+	   user/group/other have no permissions */
+	fattr->cf_mode &= ~(0777);
+
+	acl_base = (char *)pdacl;
+	acl_size = sizeof(struct cifs_acl);
+
+	num_aces = le32_to_cpu(pdacl->num_aces);
+	if (num_aces > 0) {
+		umode_t denied_mode = 0;
+
+		if (num_aces > ULONG_MAX / sizeof(struct cifs_ace *))
+			return;
+		ppace = kmalloc_array(num_aces, sizeof(struct cifs_ace *),
+				      GFP_KERNEL);
+		if (!ppace)
+			return;
+
+		for (i = 0; i < num_aces; ++i) {
+			ppace[i] = (struct cifs_ace *) (acl_base + acl_size);
+#ifdef CONFIG_CIFS_DEBUG2
+			dump_ace(ppace[i], end_of_acl);
+#endif
+			if (mode_from_special_sid &&
+			    (compare_sids(&(ppace[i]->sid),
+					  &sid_unix_NFS_mode) == 0)) {
+				/*
+				 * Full permissions are:
+				 * 07777 = S_ISUID | S_ISGID | S_ISVTX |
+				 *         S_IRWXU | S_IRWXG | S_IRWXO
+				 */
+				fattr->cf_mode &= ~07777;
+				fattr->cf_mode |=
+					le32_to_cpu(ppace[i]->sid.sub_auth[2]);
+				break;
+			} else {
+				if (compare_sids(&(ppace[i]->sid), pownersid) == 0) {
+					access_flags_to_mode(ppace[i]->access_req,
+							ppace[i]->type,
+							&fattr->cf_mode,
+							&denied_mode,
+							ACL_OWNER_MASK);
+				} else if (compare_sids(&(ppace[i]->sid), pgrpsid) == 0) {
+					access_flags_to_mode(ppace[i]->access_req,
+							ppace[i]->type,
+							&fattr->cf_mode,
+							&denied_mode,
+							ACL_GROUP_MASK);
+				} else if ((compare_sids(&(ppace[i]->sid), &sid_everyone) == 0) ||
+						(compare_sids(&(ppace[i]->sid), &sid_authusers) == 0)) {
+					access_flags_to_mode(ppace[i]->access_req,
+							ppace[i]->type,
+							&fattr->cf_mode,
+							&denied_mode,
+							ACL_EVERYONE_MASK);
+				}
+			}
+
+
+/*			memcpy((void *)(&(cifscred->aces[i])),
+				(void *)ppace[i],
+				sizeof(struct cifs_ace)); */
+
+			acl_base = (char *)ppace[i];
+			acl_size = le16_to_cpu(ppace[i]->size);
+		}
+
+		kfree(ppace);
+	}
+
+	return;
+}
+
+unsigned int setup_authusers_ACE(struct cifs_ace *pntace)
+{
+	int i;
+	unsigned int ace_size = 20;
+
+	pntace->type = ACCESS_ALLOWED_ACE_TYPE;
+	pntace->flags = 0x0;
+	pntace->access_req = cpu_to_le32(GENERIC_ALL);
+	pntace->sid.num_subauth = 1;
+	pntace->sid.revision = 1;
+	for (i = 0; i < NUM_AUTHS; i++)
+		pntace->sid.authority[i] =  sid_authusers.authority[i];
+
+	pntace->sid.sub_auth[0] =  sid_authusers.sub_auth[0];
+
+	/* size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth*4) */
+	pntace->size = cpu_to_le16(ace_size);
+	return ace_size;
+}
+
+/*
+ * Fill in the special SID based on the mode. See
+ * https://technet.microsoft.com/en-us/library/hh509017(v=ws.10).aspx
+ */
+unsigned int setup_special_mode_ACE(struct cifs_ace *pntace, __u64 nmode)
+{
+	int i;
+	unsigned int ace_size = 28;
+
+	pntace->type = ACCESS_DENIED_ACE_TYPE;
+	pntace->flags = 0x0;
+	pntace->access_req = 0;
+	pntace->sid.num_subauth = 3;
+	pntace->sid.revision = 1;
+	for (i = 0; i < NUM_AUTHS; i++)
+		pntace->sid.authority[i] = sid_unix_NFS_mode.authority[i];
+
+	pntace->sid.sub_auth[0] = sid_unix_NFS_mode.sub_auth[0];
+	pntace->sid.sub_auth[1] = sid_unix_NFS_mode.sub_auth[1];
+	pntace->sid.sub_auth[2] = cpu_to_le32(nmode & 07777);
+
+	/* size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth*4) */
+	pntace->size = cpu_to_le16(ace_size);
+	return ace_size;
+}
+
+unsigned int setup_special_user_owner_ACE(struct cifs_ace *pntace)
+{
+	int i;
+	unsigned int ace_size = 28;
+
+	pntace->type = ACCESS_ALLOWED_ACE_TYPE;
+	pntace->flags = 0x0;
+	pntace->access_req = cpu_to_le32(GENERIC_ALL);
+	pntace->sid.num_subauth = 3;
+	pntace->sid.revision = 1;
+	for (i = 0; i < NUM_AUTHS; i++)
+		pntace->sid.authority[i] = sid_unix_NFS_users.authority[i];
+
+	pntace->sid.sub_auth[0] = sid_unix_NFS_users.sub_auth[0];
+	pntace->sid.sub_auth[1] = sid_unix_NFS_users.sub_auth[1];
+	pntace->sid.sub_auth[2] = cpu_to_le32(current_fsgid().val);
+
+	/* size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth*4) */
+	pntace->size = cpu_to_le16(ace_size);
+	return ace_size;
+}
+
+static void populate_new_aces(char *nacl_base,
+		struct cifs_sid *pownersid,
+		struct cifs_sid *pgrpsid,
+		__u64 *pnmode, u32 *pnum_aces, u16 *pnsize,
+		bool modefromsid)
+{
+	__u64 nmode;
+	u32 num_aces = 0;
+	u16 nsize = 0;
+	__u64 user_mode;
+	__u64 group_mode;
+	__u64 other_mode;
+	__u64 deny_user_mode = 0;
+	__u64 deny_group_mode = 0;
+	bool sticky_set = false;
+	struct cifs_ace *pnntace = NULL;
+
+	nmode = *pnmode;
+	num_aces = *pnum_aces;
+	nsize = *pnsize;
+
+	if (modefromsid) {
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+		nsize += setup_special_mode_ACE(pnntace, nmode);
+		num_aces++;
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+		nsize += setup_authusers_ACE(pnntace);
+		num_aces++;
+		goto set_size;
+	}
+
+	/*
+	 * We'll try to keep the mode as requested by the user.
+	 * But in cases where we cannot meaningfully convert that
+	 * into ACL, return back the updated mode, so that it is
+	 * updated in the inode.
+	 */
+
+	if (!memcmp(pownersid, pgrpsid, sizeof(struct cifs_sid))) {
+		/*
+		 * Case when owner and group SIDs are the same.
+		 * Set the more restrictive of the two modes.
+		 */
+		user_mode = nmode & (nmode << 3) & 0700;
+		group_mode = nmode & (nmode >> 3) & 0070;
+	} else {
+		user_mode = nmode & 0700;
+		group_mode = nmode & 0070;
+	}
+
+	other_mode = nmode & 0007;
+
+	/* We need DENY ACE when the perm is more restrictive than the next sets. */
+	deny_user_mode = ~(user_mode) & ((group_mode << 3) | (other_mode << 6)) & 0700;
+	deny_group_mode = ~(group_mode) & (other_mode << 3) & 0070;
+
+	*pnmode = user_mode | group_mode | other_mode | (nmode & ~0777);
+
+	/* This tells if we should allow delete child for group and everyone. */
+	if (nmode & 01000)
+		sticky_set = true;
+
+	if (deny_user_mode) {
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+		nsize += fill_ace_for_sid(pnntace, pownersid, deny_user_mode,
+				0700, ACCESS_DENIED, false);
+		num_aces++;
+	}
+
+	/* Group DENY ACE does not conflict with owner ALLOW ACE. Keep in preferred order*/
+	if (deny_group_mode && !(deny_group_mode & (user_mode >> 3))) {
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+		nsize += fill_ace_for_sid(pnntace, pgrpsid, deny_group_mode,
+				0070, ACCESS_DENIED, false);
+		num_aces++;
+	}
+
+	pnntace = (struct cifs_ace *) (nacl_base + nsize);
+	nsize += fill_ace_for_sid(pnntace, pownersid, user_mode,
+			0700, ACCESS_ALLOWED, true);
+	num_aces++;
+
+	/* Group DENY ACE conflicts with owner ALLOW ACE. So keep it after. */
+	if (deny_group_mode && (deny_group_mode & (user_mode >> 3))) {
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+		nsize += fill_ace_for_sid(pnntace, pgrpsid, deny_group_mode,
+				0070, ACCESS_DENIED, false);
+		num_aces++;
+	}
+
+	pnntace = (struct cifs_ace *) (nacl_base + nsize);
+	nsize += fill_ace_for_sid(pnntace, pgrpsid, group_mode,
+			0070, ACCESS_ALLOWED, !sticky_set);
+	num_aces++;
+
+	pnntace = (struct cifs_ace *) (nacl_base + nsize);
+	nsize += fill_ace_for_sid(pnntace, &sid_everyone, other_mode,
+			0007, ACCESS_ALLOWED, !sticky_set);
+	num_aces++;
+
+set_size:
+	*pnum_aces = num_aces;
+	*pnsize = nsize;
+}
+
+static __u16 replace_sids_and_copy_aces(struct cifs_acl *pdacl, struct cifs_acl *pndacl,
+		struct cifs_sid *pownersid, struct cifs_sid *pgrpsid,
+		struct cifs_sid *pnownersid, struct cifs_sid *pngrpsid)
+{
+	int i;
+	u16 size = 0;
+	struct cifs_ace *pntace = NULL;
+	char *acl_base = NULL;
+	u32 src_num_aces = 0;
+	u16 nsize = 0;
+	struct cifs_ace *pnntace = NULL;
+	char *nacl_base = NULL;
+	u16 ace_size = 0;
+
+	acl_base = (char *)pdacl;
+	size = sizeof(struct cifs_acl);
+	src_num_aces = le32_to_cpu(pdacl->num_aces);
+
+	nacl_base = (char *)pndacl;
+	nsize = sizeof(struct cifs_acl);
+
+	/* Go through all the ACEs */
+	for (i = 0; i < src_num_aces; ++i) {
+		pntace = (struct cifs_ace *) (acl_base + size);
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+
+		if (pnownersid && compare_sids(&pntace->sid, pownersid) == 0)
+			ace_size = cifs_copy_ace(pnntace, pntace, pnownersid);
+		else if (pngrpsid && compare_sids(&pntace->sid, pgrpsid) == 0)
+			ace_size = cifs_copy_ace(pnntace, pntace, pngrpsid);
+		else
+			ace_size = cifs_copy_ace(pnntace, pntace, NULL);
+
+		size += le16_to_cpu(pntace->size);
+		nsize += ace_size;
+	}
+
+	return nsize;
+}
+
+static int set_chmod_dacl(struct cifs_acl *pdacl, struct cifs_acl *pndacl,
+		struct cifs_sid *pownersid,	struct cifs_sid *pgrpsid,
+		__u64 *pnmode, bool mode_from_sid)
+{
+	int i;
+	u16 size = 0;
+	struct cifs_ace *pntace = NULL;
+	char *acl_base = NULL;
+	u32 src_num_aces = 0;
+	u16 nsize = 0;
+	struct cifs_ace *pnntace = NULL;
+	char *nacl_base = NULL;
+	u32 num_aces = 0;
+	bool new_aces_set = false;
+
+	/* Assuming that pndacl and pnmode are never NULL */
+	nacl_base = (char *)pndacl;
+	nsize = sizeof(struct cifs_acl);
+
+	/* If pdacl is NULL, we don't have a src. Simply populate new ACL. */
+	if (!pdacl) {
+		populate_new_aces(nacl_base,
+				pownersid, pgrpsid,
+				pnmode, &num_aces, &nsize,
+				mode_from_sid);
+		goto finalize_dacl;
+	}
+
+	acl_base = (char *)pdacl;
+	size = sizeof(struct cifs_acl);
+	src_num_aces = le32_to_cpu(pdacl->num_aces);
+
+	/* Retain old ACEs which we can retain */
+	for (i = 0; i < src_num_aces; ++i) {
+		pntace = (struct cifs_ace *) (acl_base + size);
+
+		if (!new_aces_set && (pntace->flags & INHERITED_ACE)) {
+			/* Place the new ACEs in between existing explicit and inherited */
+			populate_new_aces(nacl_base,
+					pownersid, pgrpsid,
+					pnmode, &num_aces, &nsize,
+					mode_from_sid);
+
+			new_aces_set = true;
+		}
+
+		/* If it's any one of the ACE we're replacing, skip! */
+		if (((compare_sids(&pntace->sid, &sid_unix_NFS_mode) == 0) ||
+				(compare_sids(&pntace->sid, pownersid) == 0) ||
+				(compare_sids(&pntace->sid, pgrpsid) == 0) ||
+				(compare_sids(&pntace->sid, &sid_everyone) == 0) ||
+				(compare_sids(&pntace->sid, &sid_authusers) == 0))) {
+			goto next_ace;
+		}
+
+		/* update the pointer to the next ACE to populate*/
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+
+		nsize += cifs_copy_ace(pnntace, pntace, NULL);
+		num_aces++;
+
+next_ace:
+		size += le16_to_cpu(pntace->size);
+	}
+
+	/* If inherited ACEs are not present, place the new ones at the tail */
+	if (!new_aces_set) {
+		populate_new_aces(nacl_base,
+				pownersid, pgrpsid,
+				pnmode, &num_aces, &nsize,
+				mode_from_sid);
+
+		new_aces_set = true;
+	}
+
+finalize_dacl:
+	pndacl->num_aces = cpu_to_le32(num_aces);
+	pndacl->size = cpu_to_le16(nsize);
+
+	return 0;
+}
+
+static int parse_sid(struct cifs_sid *psid, char *end_of_acl)
+{
+	/* BB need to add parm so we can store the SID BB */
+
+	/* validate that we do not go past end of ACL - sid must be at least 8
+	   bytes long (assuming no sub-auths - e.g. the null SID */
+	if (end_of_acl < (char *)psid + 8) {
+		cifs_dbg(VFS, "ACL too small to parse SID %p\n", psid);
+		return -EINVAL;
+	}
+
+#ifdef CONFIG_CIFS_DEBUG2
+	if (psid->num_subauth) {
+		int i;
+		cifs_dbg(FYI, "SID revision %d num_auth %d\n",
+			 psid->revision, psid->num_subauth);
+
+		for (i = 0; i < psid->num_subauth; i++) {
+			cifs_dbg(FYI, "SID sub_auth[%d]: 0x%x\n",
+				 i, le32_to_cpu(psid->sub_auth[i]));
+		}
+
+		/* BB add length check to make sure that we do not have huge
+			num auths and therefore go off the end */
+		cifs_dbg(FYI, "RID 0x%x\n",
+			 le32_to_cpu(psid->sub_auth[psid->num_subauth-1]));
+	}
+#endif
+
+	return 0;
+}
+
+
+/* Convert CIFS ACL to POSIX form */
+static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
+		struct cifs_ntsd *pntsd, int acl_len, struct cifs_fattr *fattr,
+		bool get_mode_from_special_sid)
+{
+	int rc = 0;
+	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
+	struct cifs_acl *dacl_ptr; /* no need for SACL ptr */
+	char *end_of_acl = ((char *)pntsd) + acl_len;
+	__u32 dacloffset;
+
+	if (pntsd == NULL)
+		return -EIO;
+
+	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+				le32_to_cpu(pntsd->osidoffset));
+	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+				le32_to_cpu(pntsd->gsidoffset));
+	dacloffset = le32_to_cpu(pntsd->dacloffset);
+	dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
+	cifs_dbg(NOISY, "revision %d type 0x%x ooffset 0x%x goffset 0x%x sacloffset 0x%x dacloffset 0x%x\n",
+		 pntsd->revision, pntsd->type, le32_to_cpu(pntsd->osidoffset),
+		 le32_to_cpu(pntsd->gsidoffset),
+		 le32_to_cpu(pntsd->sacloffset), dacloffset);
+/*	cifs_dump_mem("owner_sid: ", owner_sid_ptr, 64); */
+	rc = parse_sid(owner_sid_ptr, end_of_acl);
+	if (rc) {
+		cifs_dbg(FYI, "%s: Error %d parsing Owner SID\n", __func__, rc);
+		return rc;
+	}
+	rc = sid_to_id(cifs_sb, owner_sid_ptr, fattr, SIDOWNER);
+	if (rc) {
+		cifs_dbg(FYI, "%s: Error %d mapping Owner SID to uid\n",
+			 __func__, rc);
+		return rc;
+	}
+
+	rc = parse_sid(group_sid_ptr, end_of_acl);
+	if (rc) {
+		cifs_dbg(FYI, "%s: Error %d mapping Owner SID to gid\n",
+			 __func__, rc);
+		return rc;
+	}
+	rc = sid_to_id(cifs_sb, group_sid_ptr, fattr, SIDGROUP);
+	if (rc) {
+		cifs_dbg(FYI, "%s: Error %d mapping Group SID to gid\n",
+			 __func__, rc);
+		return rc;
+	}
+
+	if (dacloffset)
+		parse_dacl(dacl_ptr, end_of_acl, owner_sid_ptr,
+			   group_sid_ptr, fattr, get_mode_from_special_sid);
+	else
+		cifs_dbg(FYI, "no ACL\n"); /* BB grant all or default perms? */
+
+	return rc;
+}
+
+/* Convert permission bits from mode to equivalent CIFS ACL */
+static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
+	__u32 secdesclen, __u32 *pnsecdesclen, __u64 *pnmode, kuid_t uid, kgid_t gid,
+	bool mode_from_sid, bool id_from_sid, int *aclflag)
+{
+	int rc = 0;
+	__u32 dacloffset;
+	__u32 ndacloffset;
+	__u32 sidsoffset;
+	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
+	struct cifs_sid *nowner_sid_ptr = NULL, *ngroup_sid_ptr = NULL;
+	struct cifs_acl *dacl_ptr = NULL;  /* no need for SACL ptr */
+	struct cifs_acl *ndacl_ptr = NULL; /* no need for SACL ptr */
+	char *end_of_acl = ((char *)pntsd) + secdesclen;
+	u16 size = 0;
+
+	dacloffset = le32_to_cpu(pntsd->dacloffset);
+	if (dacloffset) {
+		dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
+		if (end_of_acl < (char *)dacl_ptr + le16_to_cpu(dacl_ptr->size)) {
+			cifs_dbg(VFS, "Server returned illegal ACL size\n");
+			return -EINVAL;
+		}
+	}
+
+	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+			le32_to_cpu(pntsd->osidoffset));
+	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+			le32_to_cpu(pntsd->gsidoffset));
+
+	if (pnmode && *pnmode != NO_CHANGE_64) { /* chmod */
+		ndacloffset = sizeof(struct cifs_ntsd);
+		ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
+		ndacl_ptr->revision =
+			dacloffset ? dacl_ptr->revision : cpu_to_le16(ACL_REVISION);
+
+		ndacl_ptr->size = cpu_to_le16(0);
+		ndacl_ptr->num_aces = cpu_to_le32(0);
+
+		rc = set_chmod_dacl(dacl_ptr, ndacl_ptr, owner_sid_ptr, group_sid_ptr,
+				    pnmode, mode_from_sid);
+
+		sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
+		/* copy the non-dacl portion of secdesc */
+		*pnsecdesclen = copy_sec_desc(pntsd, pnntsd, sidsoffset,
+				NULL, NULL);
+
+		*aclflag |= CIFS_ACL_DACL;
+	} else {
+		ndacloffset = sizeof(struct cifs_ntsd);
+		ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
+		ndacl_ptr->revision =
+			dacloffset ? dacl_ptr->revision : cpu_to_le16(ACL_REVISION);
+		ndacl_ptr->num_aces = dacl_ptr ? dacl_ptr->num_aces : 0;
+
+		if (uid_valid(uid)) { /* chown */
+			uid_t id;
+			nowner_sid_ptr = kzalloc(sizeof(struct cifs_sid),
+								GFP_KERNEL);
+			if (!nowner_sid_ptr) {
+				rc = -ENOMEM;
+				goto chown_chgrp_exit;
+			}
+			id = from_kuid(&init_user_ns, uid);
+			if (id_from_sid) {
+				struct owner_sid *osid = (struct owner_sid *)nowner_sid_ptr;
+				/* Populate the user ownership fields S-1-5-88-1 */
+				osid->Revision = 1;
+				osid->NumAuth = 3;
+				osid->Authority[5] = 5;
+				osid->SubAuthorities[0] = cpu_to_le32(88);
+				osid->SubAuthorities[1] = cpu_to_le32(1);
+				osid->SubAuthorities[2] = cpu_to_le32(id);
+
+			} else { /* lookup sid with upcall */
+				rc = id_to_sid(id, SIDOWNER, nowner_sid_ptr);
+				if (rc) {
+					cifs_dbg(FYI, "%s: Mapping error %d for owner id %d\n",
+						 __func__, rc, id);
+					goto chown_chgrp_exit;
+				}
+			}
+			*aclflag |= CIFS_ACL_OWNER;
+		}
+		if (gid_valid(gid)) { /* chgrp */
+			gid_t id;
+			ngroup_sid_ptr = kzalloc(sizeof(struct cifs_sid),
+								GFP_KERNEL);
+			if (!ngroup_sid_ptr) {
+				rc = -ENOMEM;
+				goto chown_chgrp_exit;
+			}
+			id = from_kgid(&init_user_ns, gid);
+			if (id_from_sid) {
+				struct owner_sid *gsid = (struct owner_sid *)ngroup_sid_ptr;
+				/* Populate the group ownership fields S-1-5-88-2 */
+				gsid->Revision = 1;
+				gsid->NumAuth = 3;
+				gsid->Authority[5] = 5;
+				gsid->SubAuthorities[0] = cpu_to_le32(88);
+				gsid->SubAuthorities[1] = cpu_to_le32(2);
+				gsid->SubAuthorities[2] = cpu_to_le32(id);
+
+			} else { /* lookup sid with upcall */
+				rc = id_to_sid(id, SIDGROUP, ngroup_sid_ptr);
+				if (rc) {
+					cifs_dbg(FYI, "%s: Mapping error %d for group id %d\n",
+						 __func__, rc, id);
+					goto chown_chgrp_exit;
+				}
+			}
+			*aclflag |= CIFS_ACL_GROUP;
+		}
+
+		if (dacloffset) {
+			/* Replace ACEs for old owner with new one */
+			size = replace_sids_and_copy_aces(dacl_ptr, ndacl_ptr,
+					owner_sid_ptr, group_sid_ptr,
+					nowner_sid_ptr, ngroup_sid_ptr);
+			ndacl_ptr->size = cpu_to_le16(size);
+		}
+
+		sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
+		/* copy the non-dacl portion of secdesc */
+		*pnsecdesclen = copy_sec_desc(pntsd, pnntsd, sidsoffset,
+				nowner_sid_ptr, ngroup_sid_ptr);
+
+chown_chgrp_exit:
+		/* errors could jump here. So make sure we return soon after this */
+		kfree(nowner_sid_ptr);
+		kfree(ngroup_sid_ptr);
+	}
+
+	return rc;
+}
+
+#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
+struct cifs_ntsd *get_cifs_acl_by_fid(struct cifs_sb_info *cifs_sb,
+				      const struct cifs_fid *cifsfid, u32 *pacllen,
+				      u32 __maybe_unused unused)
+{
+	struct cifs_ntsd *pntsd = NULL;
+	unsigned int xid;
+	int rc;
+	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
+
+	if (IS_ERR(tlink))
+		return ERR_CAST(tlink);
+
+	xid = get_xid();
+	rc = CIFSSMBGetCIFSACL(xid, tlink_tcon(tlink), cifsfid->netfid, &pntsd,
+				pacllen);
+	free_xid(xid);
+
+	cifs_put_tlink(tlink);
+
+	cifs_dbg(FYI, "%s: rc = %d ACL len %d\n", __func__, rc, *pacllen);
+	if (rc)
+		return ERR_PTR(rc);
+	return pntsd;
+}
+
+static struct cifs_ntsd *get_cifs_acl_by_path(struct cifs_sb_info *cifs_sb,
+		const char *path, u32 *pacllen)
+{
+	struct cifs_ntsd *pntsd = NULL;
+	int oplock = 0;
+	unsigned int xid;
+	int rc;
+	struct cifs_tcon *tcon;
+	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
+	struct cifs_fid fid;
+	struct cifs_open_parms oparms;
+
+	if (IS_ERR(tlink))
+		return ERR_CAST(tlink);
+
+	tcon = tlink_tcon(tlink);
+	xid = get_xid();
+
+	oparms = (struct cifs_open_parms) {
+		.tcon = tcon,
+		.cifs_sb = cifs_sb,
+		.desired_access = READ_CONTROL,
+		.create_options = cifs_create_options(cifs_sb, 0),
+		.disposition = FILE_OPEN,
+		.path = path,
+		.fid = &fid,
+	};
+
+	rc = CIFS_open(xid, &oparms, &oplock, NULL);
+	if (!rc) {
+		rc = CIFSSMBGetCIFSACL(xid, tcon, fid.netfid, &pntsd, pacllen);
+		CIFSSMBClose(xid, tcon, fid.netfid);
+	}
+
+	cifs_put_tlink(tlink);
+	free_xid(xid);
+
+	cifs_dbg(FYI, "%s: rc = %d ACL len %d\n", __func__, rc, *pacllen);
+	if (rc)
+		return ERR_PTR(rc);
+	return pntsd;
+}
+
+/* Retrieve an ACL from the server */
+struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
+				      struct inode *inode, const char *path,
+			       u32 *pacllen, u32 info)
+{
+	struct cifs_ntsd *pntsd = NULL;
+	struct cifsFileInfo *open_file = NULL;
+
+	if (inode)
+		open_file = find_readable_file(CIFS_I(inode), true);
+	if (!open_file)
+		return get_cifs_acl_by_path(cifs_sb, path, pacllen);
+
+	pntsd = get_cifs_acl_by_fid(cifs_sb, &open_file->fid, pacllen, info);
+	cifsFileInfo_put(open_file);
+	return pntsd;
+}
+
+ /* Set an ACL on the server */
+int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
+			struct inode *inode, const char *path, int aclflag)
+{
+	int oplock = 0;
+	unsigned int xid;
+	int rc, access_flags;
+	struct cifs_tcon *tcon;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
+	struct cifs_fid fid;
+	struct cifs_open_parms oparms;
+
+	if (IS_ERR(tlink))
+		return PTR_ERR(tlink);
+
+	tcon = tlink_tcon(tlink);
+	xid = get_xid();
+
+	if (aclflag == CIFS_ACL_OWNER || aclflag == CIFS_ACL_GROUP)
+		access_flags = WRITE_OWNER;
+	else
+		access_flags = WRITE_DAC;
+
+	oparms = (struct cifs_open_parms) {
+		.tcon = tcon,
+		.cifs_sb = cifs_sb,
+		.desired_access = access_flags,
+		.create_options = cifs_create_options(cifs_sb, 0),
+		.disposition = FILE_OPEN,
+		.path = path,
+		.fid = &fid,
+	};
+
+	rc = CIFS_open(xid, &oparms, &oplock, NULL);
+	if (rc) {
+		cifs_dbg(VFS, "Unable to open file to set ACL\n");
+		goto out;
+	}
+
+	rc = CIFSSMBSetCIFSACL(xid, tcon, fid.netfid, pnntsd, acllen, aclflag);
+	cifs_dbg(NOISY, "SetCIFSACL rc = %d\n", rc);
+
+	CIFSSMBClose(xid, tcon, fid.netfid);
+out:
+	free_xid(xid);
+	cifs_put_tlink(tlink);
+	return rc;
+}
+#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
+
+/* Translate the CIFS ACL (similar to NTFS ACL) for a file into mode bits */
+int
+cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
+		  struct inode *inode, bool mode_from_special_sid,
+		  const char *path, const struct cifs_fid *pfid)
+{
+	struct cifs_ntsd *pntsd = NULL;
+	u32 acllen = 0;
+	int rc = 0;
+	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
+	struct smb_version_operations *ops;
+	const u32 info = 0;
+
+	cifs_dbg(NOISY, "converting ACL to mode for %s\n", path);
+
+	if (IS_ERR(tlink))
+		return PTR_ERR(tlink);
+
+	ops = tlink_tcon(tlink)->ses->server->ops;
+
+	if (pfid && (ops->get_acl_by_fid))
+		pntsd = ops->get_acl_by_fid(cifs_sb, pfid, &acllen, info);
+	else if (ops->get_acl)
+		pntsd = ops->get_acl(cifs_sb, inode, path, &acllen, info);
+	else {
+		cifs_put_tlink(tlink);
+		return -EOPNOTSUPP;
+	}
+	/* if we can retrieve the ACL, now parse Access Control Entries, ACEs */
+	if (IS_ERR(pntsd)) {
+		rc = PTR_ERR(pntsd);
+		cifs_dbg(VFS, "%s: error %d getting sec desc\n", __func__, rc);
+	} else if (mode_from_special_sid) {
+		rc = parse_sec_desc(cifs_sb, pntsd, acllen, fattr, true);
+		kfree(pntsd);
+	} else {
+		/* get approximated mode from ACL */
+		rc = parse_sec_desc(cifs_sb, pntsd, acllen, fattr, false);
+		kfree(pntsd);
+		if (rc)
+			cifs_dbg(VFS, "parse sec desc failed rc = %d\n", rc);
+	}
+
+	cifs_put_tlink(tlink);
+
+	return rc;
+}
+
+/* Convert mode bits to an ACL so we can update the ACL on the server */
+int
+id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
+			kuid_t uid, kgid_t gid)
+{
+	int rc = 0;
+	int aclflag = CIFS_ACL_DACL; /* default flag to set */
+	__u32 secdesclen = 0;
+	__u32 nsecdesclen = 0;
+	__u32 dacloffset = 0;
+	struct cifs_acl *dacl_ptr = NULL;
+	struct cifs_ntsd *pntsd = NULL; /* acl obtained from server */
+	struct cifs_ntsd *pnntsd = NULL; /* modified acl to be sent to server */
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
+	struct smb_version_operations *ops;
+	bool mode_from_sid, id_from_sid;
+	const u32 info = 0;
+
+	if (IS_ERR(tlink))
+		return PTR_ERR(tlink);
+
+	ops = tlink_tcon(tlink)->ses->server->ops;
+
+	cifs_dbg(NOISY, "set ACL from mode for %s\n", path);
+
+	/* Get the security descriptor */
+
+	if (ops->get_acl == NULL) {
+		cifs_put_tlink(tlink);
+		return -EOPNOTSUPP;
+	}
+
+	pntsd = ops->get_acl(cifs_sb, inode, path, &secdesclen, info);
+	if (IS_ERR(pntsd)) {
+		rc = PTR_ERR(pntsd);
+		cifs_dbg(VFS, "%s: error %d getting sec desc\n", __func__, rc);
+		cifs_put_tlink(tlink);
+		return rc;
+	}
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MODE_FROM_SID)
+		mode_from_sid = true;
+	else
+		mode_from_sid = false;
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UID_FROM_ACL)
+		id_from_sid = true;
+	else
+		id_from_sid = false;
+
+	/* Potentially, five new ACEs can be added to the ACL for U,G,O mapping */
+	nsecdesclen = secdesclen;
+	if (pnmode && *pnmode != NO_CHANGE_64) { /* chmod */
+		if (mode_from_sid)
+			nsecdesclen += 2 * sizeof(struct cifs_ace);
+		else /* cifsacl */
+			nsecdesclen += 5 * sizeof(struct cifs_ace);
+	} else { /* chown */
+		/* When ownership changes, changes new owner sid length could be different */
+		nsecdesclen = sizeof(struct cifs_ntsd) + (sizeof(struct cifs_sid) * 2);
+		dacloffset = le32_to_cpu(pntsd->dacloffset);
+		if (dacloffset) {
+			dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
+			if (mode_from_sid)
+				nsecdesclen +=
+					le32_to_cpu(dacl_ptr->num_aces) * sizeof(struct cifs_ace);
+			else /* cifsacl */
+				nsecdesclen += le16_to_cpu(dacl_ptr->size);
+		}
+	}
+
+	/*
+	 * Add three ACEs for owner, group, everyone getting rid of other ACEs
+	 * as chmod disables ACEs and set the security descriptor. Allocate
+	 * memory for the smb header, set security descriptor request security
+	 * descriptor parameters, and security descriptor itself
+	 */
+	nsecdesclen = max_t(u32, nsecdesclen, DEFAULT_SEC_DESC_LEN);
+	pnntsd = kmalloc(nsecdesclen, GFP_KERNEL);
+	if (!pnntsd) {
+		kfree(pntsd);
+		cifs_put_tlink(tlink);
+		return -ENOMEM;
+	}
+
+	rc = build_sec_desc(pntsd, pnntsd, secdesclen, &nsecdesclen, pnmode, uid, gid,
+			    mode_from_sid, id_from_sid, &aclflag);
+
+	cifs_dbg(NOISY, "build_sec_desc rc: %d\n", rc);
+
+	if (ops->set_acl == NULL)
+		rc = -EOPNOTSUPP;
+
+	if (!rc) {
+		/* Set the security descriptor */
+		rc = ops->set_acl(pnntsd, nsecdesclen, inode, path, aclflag);
+		cifs_dbg(NOISY, "set_cifs_acl rc: %d\n", rc);
+	}
+	cifs_put_tlink(tlink);
+
+	kfree(pnntsd);
+	kfree(pntsd);
+	return rc;
+}