fs/nfs_common/nfsacl.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * fs/nfs_common/nfsacl.c
  *
  *  Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
  */

 /*
  * The Solaris nfsacl protocol represents some ACLs slightly differently
  * than POSIX 1003.1e draft 17 does (and we do):
  *
  *  - Minimal ACLs always have an ACL_MASK entry, so they have
  *    four instead of three entries.
  *  - The ACL_MASK entry in such minimal ACLs always has the same
  *    permissions as the ACL_GROUP_OBJ entry. (In extended ACLs
  *    the ACL_MASK and ACL_GROUP_OBJ entries may differ.)
  *  - The identifier fields of the ACL_USER_OBJ and ACL_GROUP_OBJ
  *    entries contain the identifiers of the owner and owning group.
  *    (In POSIX ACLs we always set them to ACL_UNDEFINED_ID).
  *  - ACL entries in the kernel are kept sorted in ascending order
  *    of (e_tag, e_id). Solaris ACLs are unsorted.
  */

 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/gfp.h>
 #include <linux/sunrpc/xdr.h>
 #include <linux/nfsacl.h>
 #include <linux/nfs3.h>
 #include <linux/sort.h>

 MODULE_LICENSE("GPL");

 struct nfsacl_encode_desc {
 	struct xdr_array2_desc desc;
 	unsigned int count;
 	struct posix_acl *acl;
 	int typeflag;
 	kuid_t uid;
 	kgid_t gid;
 };

 struct nfsacl_simple_acl {
 	struct posix_acl acl;
 	struct posix_acl_entry ace[4];
 };

 static int
 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
 {
 	struct nfsacl_encode_desc *nfsacl_desc =
 		(struct nfsacl_encode_desc *) desc;
 	__be32 *p = elem;

 	struct posix_acl_entry *entry =
 		&nfsacl_desc->acl->a_entries[nfsacl_desc->count++];

 	*p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
 	switch(entry->e_tag) {
 		case ACL_USER_OBJ:
 			*p++ = htonl(from_kuid(&init_user_ns, nfsacl_desc->uid));
 			break;
 		case ACL_GROUP_OBJ:
 			*p++ = htonl(from_kgid(&init_user_ns, nfsacl_desc->gid));
 			break;
 		case ACL_USER:
 			*p++ = htonl(from_kuid(&init_user_ns, entry->e_uid));
 			break;
 		case ACL_GROUP:
 			*p++ = htonl(from_kgid(&init_user_ns, entry->e_gid));
 			break;
 		default:  /* Solaris depends on that! */
 			*p++ = 0;
 			break;
 	}
 	*p++ = htonl(entry->e_perm & S_IRWXO);
 	return 0;
 }

 /**
  * nfsacl_encode - Encode an NFSv3 ACL
  *
  * @buf: destination xdr_buf to contain XDR encoded ACL
  * @base: byte offset in xdr_buf where XDR'd ACL begins
  * @inode: inode of file whose ACL this is
  * @acl: posix_acl to encode
  * @encode_entries: whether to encode ACEs as well
  * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
  *
  * Returns size of encoded ACL in bytes or a negative errno value.
  */
 int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
 		  struct posix_acl *acl, int encode_entries, int typeflag)
 {
 	int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
 	struct nfsacl_encode_desc nfsacl_desc = {
 		.desc = {
 			.elem_size = 12,
 			.array_len = encode_entries ? entries : 0,
 			.xcode = xdr_nfsace_encode,
 		},
 		.acl = acl,
 		.typeflag = typeflag,
 		.uid = inode->i_uid,
 		.gid = inode->i_gid,
 	};
 	struct nfsacl_simple_acl aclbuf;
 	int err;

 	if (entries > NFS_ACL_MAX_ENTRIES ||
 	    xdr_encode_word(buf, base, entries))
 		return -EINVAL;
 	if (encode_entries && acl && acl->a_count == 3) {
 		struct posix_acl *acl2 = &aclbuf.acl;

 		/* Avoid the use of posix_acl_alloc().  nfsacl_encode() is
 		 * invoked in contexts where a memory allocation failure is
 		 * fatal.  Fortunately this fake ACL is small enough to
 		 * construct on the stack. */
 		posix_acl_init(acl2, 4);

 		/* Insert entries in canonical order: other orders seem
 		 to confuse Solaris VxFS. */
 		acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
 		acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
 		acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
 		acl2->a_entries[2].e_tag = ACL_MASK;
 		acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
 		nfsacl_desc.acl = acl2;
 	}
 	err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
 	if (!err)
 		err = 8 + nfsacl_desc.desc.elem_size *
 			  nfsacl_desc.desc.array_len;
 	return err;
 }
 EXPORT_SYMBOL_GPL(nfsacl_encode);

 /**
  * nfs_stream_encode_acl - Encode an NFSv3 ACL
  *
  * @xdr: an xdr_stream positioned to receive an encoded ACL
  * @inode: inode of file whose ACL this is
  * @acl: posix_acl to encode
  * @encode_entries: whether to encode ACEs as well
  * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
  *
  * Return values:
  *   %false: The ACL could not be encoded
  *   %true: @xdr is advanced to the next available position
  */
 bool nfs_stream_encode_acl(struct xdr_stream *xdr, struct inode *inode,
 			   struct posix_acl *acl, int encode_entries,
 			   int typeflag)
 {
 	const size_t elem_size = XDR_UNIT * 3;
 	u32 entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
 	struct nfsacl_encode_desc nfsacl_desc = {
 		.desc = {
 			.elem_size = elem_size,
 			.array_len = encode_entries ? entries : 0,
 			.xcode = xdr_nfsace_encode,
 		},
 		.acl = acl,
 		.typeflag = typeflag,
 		.uid = inode->i_uid,
 		.gid = inode->i_gid,
 	};
 	struct nfsacl_simple_acl aclbuf;
 	unsigned int base;
 	int err;

 	if (entries > NFS_ACL_MAX_ENTRIES)
 		return false;
 	if (xdr_stream_encode_u32(xdr, entries) < 0)
 		return false;

 	if (encode_entries && acl && acl->a_count == 3) {
 		struct posix_acl *acl2 = &aclbuf.acl;

 		/* Avoid the use of posix_acl_alloc().  nfsacl_encode() is
 		 * invoked in contexts where a memory allocation failure is
 		 * fatal.  Fortunately this fake ACL is small enough to
 		 * construct on the stack. */
 		posix_acl_init(acl2, 4);

 		/* Insert entries in canonical order: other orders seem
 		 to confuse Solaris VxFS. */
 		acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
 		acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
 		acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
 		acl2->a_entries[2].e_tag = ACL_MASK;
 		acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
 		nfsacl_desc.acl = acl2;
 	}

 	base = xdr_stream_pos(xdr);
 	if (!xdr_reserve_space(xdr, XDR_UNIT +
 			       elem_size * nfsacl_desc.desc.array_len))
 		return false;
 	err = xdr_encode_array2(xdr->buf, base, &nfsacl_desc.desc);
 	if (err)
 		return false;

 	return true;
 }
 EXPORT_SYMBOL_GPL(nfs_stream_encode_acl);


 struct nfsacl_decode_desc {
 	struct xdr_array2_desc desc;
 	unsigned int count;
 	struct posix_acl *acl;
 };

 static int
 xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
 {
 	struct nfsacl_decode_desc *nfsacl_desc =
 		(struct nfsacl_decode_desc *) desc;
 	__be32 *p = elem;
 	struct posix_acl_entry *entry;
 	unsigned int id;

 	if (!nfsacl_desc->acl) {
 		if (desc->array_len > NFS_ACL_MAX_ENTRIES)
 			return -EINVAL;
 		nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
 		if (!nfsacl_desc->acl)
 			return -ENOMEM;
 		nfsacl_desc->count = 0;
 	}

 	entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
 	entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
 	id = ntohl(*p++);
 	entry->e_perm = ntohl(*p++);

 	switch(entry->e_tag) {
 		case ACL_USER:
 			entry->e_uid = make_kuid(&init_user_ns, id);
 			if (!uid_valid(entry->e_uid))
 				return -EINVAL;
 			break;
 		case ACL_GROUP:
 			entry->e_gid = make_kgid(&init_user_ns, id);
 			if (!gid_valid(entry->e_gid))
 				return -EINVAL;
 			break;
 		case ACL_USER_OBJ:
 		case ACL_GROUP_OBJ:
 		case ACL_OTHER:
 			if (entry->e_perm & ~S_IRWXO)
 				return -EINVAL;
 			break;
 		case ACL_MASK:
 			/* Solaris sometimes sets additional bits in the mask */
 			entry->e_perm &= S_IRWXO;
 			break;
 		default:
 			return -EINVAL;
 	}

 	return 0;
 }

 static int
 cmp_acl_entry(const void *x, const void *y)
 {
 	const struct posix_acl_entry *a = x, *b = y;

 	if (a->e_tag != b->e_tag)
 		return a->e_tag - b->e_tag;
 	else if ((a->e_tag == ACL_USER) && uid_gt(a->e_uid, b->e_uid))
 		return 1;
 	else if ((a->e_tag == ACL_USER) && uid_lt(a->e_uid, b->e_uid))
 		return -1;
 	else if ((a->e_tag == ACL_GROUP) && gid_gt(a->e_gid, b->e_gid))
 		return 1;
 	else if ((a->e_tag == ACL_GROUP) && gid_lt(a->e_gid, b->e_gid))
 		return -1;
 	else
 		return 0;
 }

 /*
  * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
  */
 static int
 posix_acl_from_nfsacl(struct posix_acl *acl)
 {
 	struct posix_acl_entry *pa, *pe,
 	       *group_obj = NULL, *mask = NULL;

 	if (!acl)
 		return 0;

 	sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
 	     cmp_acl_entry, NULL);

 	/* Find the ACL_GROUP_OBJ and ACL_MASK entries. */
 	FOREACH_ACL_ENTRY(pa, acl, pe) {
 		switch(pa->e_tag) {
 			case ACL_USER_OBJ:
 				break;
 			case ACL_GROUP_OBJ:
 				group_obj = pa;
 				break;
 			case ACL_MASK:
 				mask = pa;
 				fallthrough;
 			case ACL_OTHER:
 				break;
 		}
 	}
 	if (acl->a_count == 4 && group_obj && mask &&
 	    mask->e_perm == group_obj->e_perm) {
 		/* remove bogus ACL_MASK entry */
 		memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
 				      sizeof(struct posix_acl_entry));
 		acl->a_count = 3;
 	}
 	return 0;
 }

 /**
  * nfsacl_decode - Decode an NFSv3 ACL
  *
  * @buf: xdr_buf containing XDR'd ACL data to decode
  * @base: byte offset in xdr_buf where XDR'd ACL begins
  * @aclcnt: count of ACEs in decoded posix_acl
  * @pacl: buffer in which to place decoded posix_acl
  *
  * Returns the length of the decoded ACL in bytes, or a negative errno value.
  */
 int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
 		  struct posix_acl **pacl)
 {
 	struct nfsacl_decode_desc nfsacl_desc = {
 		.desc = {
 			.elem_size = 12,
 			.xcode = pacl ? xdr_nfsace_decode : NULL,
 		},
 	};
 	u32 entries;
 	int err;

 	if (xdr_decode_word(buf, base, &entries) ||
 	    entries > NFS_ACL_MAX_ENTRIES)
 		return -EINVAL;
 	nfsacl_desc.desc.array_maxlen = entries;
 	err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
 	if (err)
 		return err;
 	if (pacl) {
 		if (entries != nfsacl_desc.desc.array_len ||
 		    posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
 			posix_acl_release(nfsacl_desc.acl);
 			return -EINVAL;
 		}
 		*pacl = nfsacl_desc.acl;
 	}
 	if (aclcnt)
 		*aclcnt = entries;
 	return 8 + nfsacl_desc.desc.elem_size *
 		   nfsacl_desc.desc.array_len;
 }
 EXPORT_SYMBOL_GPL(nfsacl_decode);

 /**
  * nfs_stream_decode_acl - Decode an NFSv3 ACL
  *
  * @xdr: an xdr_stream positioned at an encoded ACL
  * @aclcnt: OUT: count of ACEs in decoded posix_acl
  * @pacl: OUT: a dynamically-allocated buffer containing the decoded posix_acl
  *
  * Return values:
  *   %false: The encoded ACL is not valid
  *   %true: @pacl contains a decoded ACL, and @xdr is advanced
  *
  * On a successful return, caller must release *pacl using posix_acl_release().
  */
 bool nfs_stream_decode_acl(struct xdr_stream *xdr, unsigned int *aclcnt,
 			   struct posix_acl **pacl)
 {
 	const size_t elem_size = XDR_UNIT * 3;
 	struct nfsacl_decode_desc nfsacl_desc = {
 		.desc = {
 			.elem_size = elem_size,
 			.xcode = pacl ? xdr_nfsace_decode : NULL,
 		},
 	};
 	unsigned int base;
 	u32 entries;

 	if (xdr_stream_decode_u32(xdr, &entries) < 0)
 		return false;
 	if (entries > NFS_ACL_MAX_ENTRIES)
 		return false;

 	base = xdr_stream_pos(xdr);
 	if (!xdr_inline_decode(xdr, XDR_UNIT + elem_size * entries))
 		return false;
 	nfsacl_desc.desc.array_maxlen = entries;
 	if (xdr_decode_array2(xdr->buf, base, &nfsacl_desc.desc))
 		return false;

 	if (pacl) {
 		if (entries != nfsacl_desc.desc.array_len ||
 		    posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
 			posix_acl_release(nfsacl_desc.acl);
 			return false;
 		}
 		*pacl = nfsacl_desc.acl;
 	}
 	if (aclcnt)
 		*aclcnt = entries;
 	return true;
 }
 EXPORT_SYMBOL_GPL(nfs_stream_decode_acl);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* fs/nfs_common/nfsacl.c
	*
	* Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
	*/

	/*
	* The Solaris nfsacl protocol represents some ACLs slightly differently
	* than POSIX 1003.1e draft 17 does (and we do):
	*
	* - Minimal ACLs always have an ACL_MASK entry, so they have
	* four instead of three entries.
	* - The ACL_MASK entry in such minimal ACLs always has the same
	* permissions as the ACL_GROUP_OBJ entry. (In extended ACLs
	* the ACL_MASK and ACL_GROUP_OBJ entries may differ.)
	* - The identifier fields of the ACL_USER_OBJ and ACL_GROUP_OBJ
	* entries contain the identifiers of the owner and owning group.
	* (In POSIX ACLs we always set them to ACL_UNDEFINED_ID).
	* - ACL entries in the kernel are kept sorted in ascending order
	* of (e_tag, e_id). Solaris ACLs are unsorted.
	*/

	#include <linux/module.h>
	#include <linux/fs.h>
	#include <linux/gfp.h>
	#include <linux/sunrpc/xdr.h>
	#include <linux/nfsacl.h>
	#include <linux/nfs3.h>
	#include <linux/sort.h>

	MODULE_LICENSE("GPL");

	struct nfsacl_encode_desc {
	struct xdr_array2_desc desc;
	unsigned int count;
	struct posix_acl *acl;
	int typeflag;
	kuid_t uid;
	kgid_t gid;
	};

	struct nfsacl_simple_acl {
	struct posix_acl acl;
	struct posix_acl_entry ace[4];
	};

	static int
	xdr_nfsace_encode(struct xdr_array2_desc desc, void elem)
	{
	struct nfsacl_encode_desc *nfsacl_desc =
	(struct nfsacl_encode_desc *) desc;
	__be32 *p = elem;

	struct posix_acl_entry *entry =
	&nfsacl_desc->acl->a_entries[nfsacl_desc->count++];

	*p++ = htonl(entry->e_tag \| nfsacl_desc->typeflag);
	switch(entry->e_tag) {
	case ACL_USER_OBJ:
	*p++ = htonl(from_kuid(&init_user_ns, nfsacl_desc->uid));
	break;
	case ACL_GROUP_OBJ:
	*p++ = htonl(from_kgid(&init_user_ns, nfsacl_desc->gid));
	break;
	case ACL_USER:
	*p++ = htonl(from_kuid(&init_user_ns, entry->e_uid));
	break;
	case ACL_GROUP:
	*p++ = htonl(from_kgid(&init_user_ns, entry->e_gid));
	break;
	default: /* Solaris depends on that! */
	*p++ = 0;
	break;
	}
	*p++ = htonl(entry->e_perm & S_IRWXO);
	return 0;
	}

	/**
	* nfsacl_encode - Encode an NFSv3 ACL
	*
	* @buf: destination xdr_buf to contain XDR encoded ACL
	* @base: byte offset in xdr_buf where XDR'd ACL begins
	* @inode: inode of file whose ACL this is
	* @acl: posix_acl to encode
	* @encode_entries: whether to encode ACEs as well
	* @typeflag: ACL type: NFS_ACL_DEFAULT or zero
	*
	* Returns size of encoded ACL in bytes or a negative errno value.
	*/
	int nfsacl_encode(struct xdr_buf buf, unsigned int base, struct inode inode,
	struct posix_acl *acl, int encode_entries, int typeflag)
	{
	int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
	struct nfsacl_encode_desc nfsacl_desc = {
	.desc = {
	.elem_size = 12,
	.array_len = encode_entries ? entries : 0,
	.xcode = xdr_nfsace_encode,
	},
	.acl = acl,
	.typeflag = typeflag,
	.uid = inode->i_uid,
	.gid = inode->i_gid,
	};
	struct nfsacl_simple_acl aclbuf;
	int err;

	if (entries > NFS_ACL_MAX_ENTRIES \|\|
	xdr_encode_word(buf, base, entries))
	return -EINVAL;
	if (encode_entries && acl && acl->a_count == 3) {
	struct posix_acl *acl2 = &aclbuf.acl;

	/* Avoid the use of posix_acl_alloc(). nfsacl_encode() is
	* invoked in contexts where a memory allocation failure is
	* fatal. Fortunately this fake ACL is small enough to
	* construct on the stack. */
	posix_acl_init(acl2, 4);

	/* Insert entries in canonical order: other orders seem
	to confuse Solaris VxFS. */
	acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */
	acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */
	acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */
	acl2->a_entries[2].e_tag = ACL_MASK;
	acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */
	nfsacl_desc.acl = acl2;
	}
	err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
	if (!err)
	err = 8 + nfsacl_desc.desc.elem_size *
	nfsacl_desc.desc.array_len;
	return err;
	}
	EXPORT_SYMBOL_GPL(nfsacl_encode);

	/**
	* nfs_stream_encode_acl - Encode an NFSv3 ACL
	*
	* @xdr: an xdr_stream positioned to receive an encoded ACL
	* @inode: inode of file whose ACL this is
	* @acl: posix_acl to encode
	* @encode_entries: whether to encode ACEs as well
	* @typeflag: ACL type: NFS_ACL_DEFAULT or zero
	*
	* Return values:
	* %false: The ACL could not be encoded
	* %true: @xdr is advanced to the next available position
	*/
	bool nfs_stream_encode_acl(struct xdr_stream xdr, struct inode inode,
	struct posix_acl *acl, int encode_entries,
	int typeflag)
	{
	const size_t elem_size = XDR_UNIT * 3;
	u32 entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
	struct nfsacl_encode_desc nfsacl_desc = {
	.desc = {
	.elem_size = elem_size,
	.array_len = encode_entries ? entries : 0,
	.xcode = xdr_nfsace_encode,
	},
	.acl = acl,
	.typeflag = typeflag,
	.uid = inode->i_uid,
	.gid = inode->i_gid,
	};
	struct nfsacl_simple_acl aclbuf;
	unsigned int base;
	int err;

	if (entries > NFS_ACL_MAX_ENTRIES)
	return false;
	if (xdr_stream_encode_u32(xdr, entries) < 0)
	return false;

	if (encode_entries && acl && acl->a_count == 3) {
	struct posix_acl *acl2 = &aclbuf.acl;

	/* Avoid the use of posix_acl_alloc(). nfsacl_encode() is
	* invoked in contexts where a memory allocation failure is
	* fatal. Fortunately this fake ACL is small enough to
	* construct on the stack. */
	posix_acl_init(acl2, 4);

	/* Insert entries in canonical order: other orders seem
	to confuse Solaris VxFS. */
	acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */
	acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */
	acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */
	acl2->a_entries[2].e_tag = ACL_MASK;
	acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */
	nfsacl_desc.acl = acl2;
	}

	base = xdr_stream_pos(xdr);
	if (!xdr_reserve_space(xdr, XDR_UNIT +
	elem_size * nfsacl_desc.desc.array_len))
	return false;
	err = xdr_encode_array2(xdr->buf, base, &nfsacl_desc.desc);
	if (err)
	return false;

	return true;
	}
	EXPORT_SYMBOL_GPL(nfs_stream_encode_acl);


	struct nfsacl_decode_desc {
	struct xdr_array2_desc desc;
	unsigned int count;
	struct posix_acl *acl;
	};

	static int
	xdr_nfsace_decode(struct xdr_array2_desc desc, void elem)
	{
	struct nfsacl_decode_desc *nfsacl_desc =
	(struct nfsacl_decode_desc *) desc;
	__be32 *p = elem;
	struct posix_acl_entry *entry;
	unsigned int id;

	if (!nfsacl_desc->acl) {
	if (desc->array_len > NFS_ACL_MAX_ENTRIES)
	return -EINVAL;
	nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
	if (!nfsacl_desc->acl)
	return -ENOMEM;
	nfsacl_desc->count = 0;
	}

	entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
	entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
	id = ntohl(*p++);
	entry->e_perm = ntohl(*p++);

	switch(entry->e_tag) {
	case ACL_USER:
	entry->e_uid = make_kuid(&init_user_ns, id);
	if (!uid_valid(entry->e_uid))
	return -EINVAL;
	break;
	case ACL_GROUP:
	entry->e_gid = make_kgid(&init_user_ns, id);
	if (!gid_valid(entry->e_gid))
	return -EINVAL;
	break;
	case ACL_USER_OBJ:
	case ACL_GROUP_OBJ:
	case ACL_OTHER:
	if (entry->e_perm & ~S_IRWXO)
	return -EINVAL;
	break;
	case ACL_MASK:
	/* Solaris sometimes sets additional bits in the mask */
	entry->e_perm &= S_IRWXO;
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static int
	cmp_acl_entry(const void x, const void y)
	{
	const struct posix_acl_entry a = x, b = y;

	if (a->e_tag != b->e_tag)
	return a->e_tag - b->e_tag;
	else if ((a->e_tag == ACL_USER) && uid_gt(a->e_uid, b->e_uid))
	return 1;
	else if ((a->e_tag == ACL_USER) && uid_lt(a->e_uid, b->e_uid))
	return -1;
	else if ((a->e_tag == ACL_GROUP) && gid_gt(a->e_gid, b->e_gid))
	return 1;
	else if ((a->e_tag == ACL_GROUP) && gid_lt(a->e_gid, b->e_gid))
	return -1;
	else
	return 0;
	}

	/*
	* Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
	*/
	static int
	posix_acl_from_nfsacl(struct posix_acl *acl)
	{
	struct posix_acl_entry pa, pe,
	group_obj = NULL, mask = NULL;

	if (!acl)
	return 0;

	sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
	cmp_acl_entry, NULL);

	/* Find the ACL_GROUP_OBJ and ACL_MASK entries. */
	FOREACH_ACL_ENTRY(pa, acl, pe) {
	switch(pa->e_tag) {
	case ACL_USER_OBJ:
	break;
	case ACL_GROUP_OBJ:
	group_obj = pa;
	break;
	case ACL_MASK:
	mask = pa;
	fallthrough;
	case ACL_OTHER:
	break;
	}
	}
	if (acl->a_count == 4 && group_obj && mask &&
	mask->e_perm == group_obj->e_perm) {
	/* remove bogus ACL_MASK entry */
	memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
	sizeof(struct posix_acl_entry));
	acl->a_count = 3;
	}
	return 0;
	}

	/**
	* nfsacl_decode - Decode an NFSv3 ACL
	*
	* @buf: xdr_buf containing XDR'd ACL data to decode
	* @base: byte offset in xdr_buf where XDR'd ACL begins
	* @aclcnt: count of ACEs in decoded posix_acl
	* @pacl: buffer in which to place decoded posix_acl
	*
	* Returns the length of the decoded ACL in bytes, or a negative errno value.
	*/
	int nfsacl_decode(struct xdr_buf buf, unsigned int base, unsigned int aclcnt,
	struct posix_acl **pacl)
	{
	struct nfsacl_decode_desc nfsacl_desc = {
	.desc = {
	.elem_size = 12,
	.xcode = pacl ? xdr_nfsace_decode : NULL,
	},
	};
	u32 entries;
	int err;

	if (xdr_decode_word(buf, base, &entries) \|\|
	entries > NFS_ACL_MAX_ENTRIES)
	return -EINVAL;
	nfsacl_desc.desc.array_maxlen = entries;
	err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
	if (err)
	return err;
	if (pacl) {
	if (entries != nfsacl_desc.desc.array_len \|\|
	posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
	posix_acl_release(nfsacl_desc.acl);
	return -EINVAL;
	}
	*pacl = nfsacl_desc.acl;
	}
	if (aclcnt)
	*aclcnt = entries;
	return 8 + nfsacl_desc.desc.elem_size *
	nfsacl_desc.desc.array_len;
	}
	EXPORT_SYMBOL_GPL(nfsacl_decode);

	/**
	* nfs_stream_decode_acl - Decode an NFSv3 ACL
	*
	* @xdr: an xdr_stream positioned at an encoded ACL
	* @aclcnt: OUT: count of ACEs in decoded posix_acl
	* @pacl: OUT: a dynamically-allocated buffer containing the decoded posix_acl
	*
	* Return values:
	* %false: The encoded ACL is not valid
	* %true: @pacl contains a decoded ACL, and @xdr is advanced
	*
	* On a successful return, caller must release *pacl using posix_acl_release().
	*/
	bool nfs_stream_decode_acl(struct xdr_stream xdr, unsigned int aclcnt,
	struct posix_acl **pacl)
	{
	const size_t elem_size = XDR_UNIT * 3;
	struct nfsacl_decode_desc nfsacl_desc = {
	.desc = {
	.elem_size = elem_size,
	.xcode = pacl ? xdr_nfsace_decode : NULL,
	},
	};
	unsigned int base;
	u32 entries;

	if (xdr_stream_decode_u32(xdr, &entries) < 0)
	return false;
	if (entries > NFS_ACL_MAX_ENTRIES)
	return false;

	base = xdr_stream_pos(xdr);
	if (!xdr_inline_decode(xdr, XDR_UNIT + elem_size * entries))
	return false;
	nfsacl_desc.desc.array_maxlen = entries;
	if (xdr_decode_array2(xdr->buf, base, &nfsacl_desc.desc))
	return false;

	if (pacl) {
	if (entries != nfsacl_desc.desc.array_len \|\|
	posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
	posix_acl_release(nfsacl_desc.acl);
	return false;
	}
	*pacl = nfsacl_desc.acl;
	}
	if (aclcnt)
	*aclcnt = entries;
	return true;
	}
	EXPORT_SYMBOL_GPL(nfs_stream_decode_acl);