[RFC v3 42/45] nfs: Add richacl support

[Andreas Gruenbacher <andreas.gruenbacher@gmail.com>]

Changes nfs to support the "system.richacl" xattr instead of "system.nfs4_acl".

The "system.nfs4_acl" xattr nfs uses directly exposes the on-the-wire format of
NFSv4's acl attribute to user space. This has at least two downsides: (1) the
format is different from other file systems, so user-space code needs to be nfs
filesystem aware; (2) when symbolic user@domain and group@domain names are used
in the acl, user-space needs to perform ID mapping in the same way as the
kernel.

Previously, when user-space requested only the length of the "system.nfs4_acl"
attribute, nfs didn't need to retrieve the entire "system.nfs4_acl" attribute;
retrieving its length was enough.  With the "system.richacl" xattr, the length
of "system.richacl" cannot be computed from the length of the NFSv4 acl
attribute, so we always need to retrieve and cache the acl even when user-space
only asks for the length of the "system.richacl" attribute.

Because the nfs client now knows which kind of acl the user is trying to set,
it will now no longer sends acls with deny entries to servers which didn't
declare support for that feature.  The maximum supported size of the NFSv4 acl
attribute is now hard coded in the client code and no longer depends on the
size of the buffer the user provides to the getxattr system call.  When an acl
exceeds this limit, getxattr fails with errno set to ENOMEM.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/nfs/inode.c            |   3 -
 fs/nfs/nfs4proc.c         | 354 ++++++++++++++++++++--------------------------
 fs/nfs/nfs4xdr.c          | 224 +++++++++++++++++++++++++----
 fs/nfs/super.c            |   4 +-
 include/linux/nfs_fs.h    |   1 -
 include/linux/nfs_fs_sb.h |   2 +
 include/linux/nfs_xdr.h   |   8 +-
 7 files changed, 357 insertions(+), 239 deletions(-)

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index d42dff6..e67f72e 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1824,9 +1824,6 @@ struct inode *nfs_alloc_inode(struct super_block *sb)
 		return NULL;
 	nfsi->flags = 0UL;
 	nfsi->cache_validity = 0UL;
-#if IS_ENABLED(CONFIG_NFS_V4)
-	nfsi->nfs4_acl = NULL;
-#endif /* CONFIG_NFS_V4 */
 	return &nfsi->vfs_inode;
 }
 EXPORT_SYMBOL_GPL(nfs_alloc_inode);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8c50670..c2ba4f0 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -55,6 +55,8 @@
 #include <linux/xattr.h>
 #include <linux/utsname.h>
 #include <linux/freezer.h>
+#include <linux/richacl.h>
+#include <linux/richacl_xattr.h>
 
 #include "nfs4_fs.h"
 #include "delegation.h"
@@ -2892,15 +2894,18 @@ static int _nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *f
 			res.attr_bitmask[2] &= FATTR4_WORD2_NFS42_MASK;
 		}
 		memcpy(server->attr_bitmask, res.attr_bitmask, sizeof(server->attr_bitmask));
-		server->caps &= ~(NFS_CAP_ACLS|NFS_CAP_HARDLINKS|
-				NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
+		server->caps &= ~(NFS_CAP_ALLOW_ACLS|NFS_CAP_DENY_ACLS|
+				NFS_CAP_HARDLINKS|NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
 				NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|
 				NFS_CAP_OWNER_GROUP|NFS_CAP_ATIME|
 				NFS_CAP_CTIME|NFS_CAP_MTIME|
 				NFS_CAP_SECURITY_LABEL);
-		if (res.attr_bitmask[0] & FATTR4_WORD0_ACL &&
-				res.acl_bitmask & ACL4_SUPPORT_ALLOW_ACL)
-			server->caps |= NFS_CAP_ACLS;
+		if (res.attr_bitmask[0] & FATTR4_WORD0_ACL) {
+			if (res.acl_bitmask & ACL4_SUPPORT_ALLOW_ACL)
+				server->caps |= NFS_CAP_ALLOW_ACLS;
+			if (res.acl_bitmask & ACL4_SUPPORT_DENY_ACL)
+				server->caps |= NFS_CAP_DENY_ACLS;
+		}
 		if (res.has_links != 0)
 			server->caps |= NFS_CAP_HARDLINKS;
 		if (res.has_symlinks != 0)
@@ -4428,45 +4433,11 @@ static int nfs4_proc_renew(struct nfs_client *clp, struct rpc_cred *cred)
 	return 0;
 }
 
-static inline int nfs4_server_supports_acls(struct nfs_server *server)
-{
-	return server->caps & NFS_CAP_ACLS;
-}
-
-/* Assuming that XATTR_SIZE_MAX is a multiple of PAGE_SIZE, and that
- * it's OK to put sizeof(void) * (XATTR_SIZE_MAX/PAGE_SIZE) bytes on
- * the stack.
+/* A arbitrary limit; we allocate at most DIV_ROUND_UP(NFS4ACL_SIZE_MAX,
+ * PAGE_SIZE) pages and put an array of DIV_ROUND_UP(NFS4ACL_SIZE_MAX,
+ * PAGE_SIZE) pages on the stack when encoding or decoding acls.
  */
-#define NFS4ACL_MAXPAGES DIV_ROUND_UP(XATTR_SIZE_MAX, PAGE_SIZE)
-
-static int buf_to_pages_noslab(const void *buf, size_t buflen,
-		struct page **pages)
-{
-	struct page *newpage, **spages;
-	int rc = 0;
-	size_t len;
-	spages = pages;
-
-	do {
-		len = min_t(size_t, PAGE_SIZE, buflen);
-		newpage = alloc_page(GFP_KERNEL);
-
-		if (newpage == NULL)
-			goto unwind;
-		memcpy(page_address(newpage), buf, len);
-                buf += len;
-                buflen -= len;
-		*pages++ = newpage;
-		rc++;
-	} while (buflen != 0);
-
-	return rc;
-
-unwind:
-	for(; rc > 0; rc--)
-		__free_page(spages[rc-1]);
-	return -ENOMEM;
-}
+#define NFS4ACL_SIZE_MAX 65536
 
 struct nfs4_cached_acl {
 	int cached;
@@ -4474,66 +4445,9 @@ struct nfs4_cached_acl {
 	char data[0];
 };
 
-static void nfs4_set_cached_acl(struct inode *inode, struct nfs4_cached_acl *acl)
-{
-	struct nfs_inode *nfsi = NFS_I(inode);
-
-	spin_lock(&inode->i_lock);
-	kfree(nfsi->nfs4_acl);
-	nfsi->nfs4_acl = acl;
-	spin_unlock(&inode->i_lock);
-}
-
 static void nfs4_zap_acl_attr(struct inode *inode)
 {
-	nfs4_set_cached_acl(inode, NULL);
-}
-
-static inline ssize_t nfs4_read_cached_acl(struct inode *inode, char *buf, size_t buflen)
-{
-	struct nfs_inode *nfsi = NFS_I(inode);
-	struct nfs4_cached_acl *acl;
-	int ret = -ENOENT;
-
-	spin_lock(&inode->i_lock);
-	acl = nfsi->nfs4_acl;
-	if (acl == NULL)
-		goto out;
-	if (buf == NULL) /* user is just asking for length */
-		goto out_len;
-	if (acl->cached == 0)
-		goto out;
-	ret = -ERANGE; /* see getxattr(2) man page */
-	if (acl->len > buflen)
-		goto out;
-	memcpy(buf, acl->data, acl->len);
-out_len:
-	ret = acl->len;
-out:
-	spin_unlock(&inode->i_lock);
-	return ret;
-}
-
-static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, size_t pgbase, size_t acl_len)
-{
-	struct nfs4_cached_acl *acl;
-	size_t buflen = sizeof(*acl) + acl_len;
-
-	if (buflen <= PAGE_SIZE) {
-		acl = kmalloc(buflen, GFP_KERNEL);
-		if (acl == NULL)
-			goto out;
-		acl->cached = 1;
-		_copy_from_pages(acl->data, pages, pgbase, acl_len);
-	} else {
-		acl = kmalloc(sizeof(*acl), GFP_KERNEL);
-		if (acl == NULL)
-			goto out;
-		acl->cached = 0;
-	}
-	acl->len = acl_len;
-out:
-	nfs4_set_cached_acl(inode, acl);
+	forget_cached_richacl(inode);
 }
 
 /*
@@ -4546,121 +4460,128 @@ out:
  * length. The next getxattr call will then produce another round trip to
  * the server, this time with the input buf of the required size.
  */
-static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
+static struct richacl *__nfs4_get_acl_uncached(struct inode *inode)
 {
-	struct page *pages[NFS4ACL_MAXPAGES] = {NULL, };
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct page *pages[DIV_ROUND_UP(NFS4ACL_SIZE_MAX, PAGE_SIZE)] = {};
 	struct nfs_getaclargs args = {
 		.fh = NFS_FH(inode),
 		.acl_pages = pages,
-		.acl_len = buflen,
+		.acl_len = ARRAY_SIZE(pages) * PAGE_SIZE,
 	};
 	struct nfs_getaclres res = {
-		.acl_len = buflen,
+		.server = server,
 	};
 	struct rpc_message msg = {
 		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETACL],
 		.rpc_argp = &args,
 		.rpc_resp = &res,
 	};
-	unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE);
-	int ret = -ENOMEM, i;
+	mode_t mode;
+	int err, i;
 
-	/* As long as we're doing a round trip to the server anyway,
-	 * let's be prepared for a page of acl data. */
-	if (npages == 0)
-		npages = 1;
-	if (npages > ARRAY_SIZE(pages))
-		return -ERANGE;
-
-	for (i = 0; i < npages; i++) {
-		pages[i] = alloc_page(GFP_KERNEL);
-		if (!pages[i])
+	if (ARRAY_SIZE(pages) > 1) {
+		/* for decoding across pages */
+		res.acl_scratch = alloc_page(GFP_KERNEL);
+		err = -ENOMEM;
+		if (!res.acl_scratch)
 			goto out_free;
 	}
 
-	/* for decoding across pages */
-	res.acl_scratch = alloc_page(GFP_KERNEL);
-	if (!res.acl_scratch)
-		goto out_free;
-
-	args.acl_len = npages * PAGE_SIZE;
-
-	dprintk("%s  buf %p buflen %zu npages %d args.acl_len %zu\n",
-		__func__, buf, buflen, npages, args.acl_len);
-	ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode),
+	dprintk("%s  args.acl_len %zu\n",
+		__func__, args.acl_len);
+	err = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode),
 			     &msg, &args.seq_args, &res.seq_res, 0);
-	if (ret)
+	if (err)
 		goto out_free;
 
-	/* Handle the case where the passed-in buffer is too short */
-	if (res.acl_flags & NFS4_ACL_TRUNC) {
-		/* Did the user only issue a request for the acl length? */
-		if (buf == NULL)
-			goto out_ok;
-		ret = -ERANGE;
-		goto out_free;
-	}
-	nfs4_write_cached_acl(inode, pages, res.acl_data_offset, res.acl_len);
-	if (buf) {
-		if (res.acl_len > buflen) {
-			ret = -ERANGE;
-			goto out_free;
-		}
-		_copy_from_pages(buf, pages, res.acl_data_offset, res.acl_len);
-	}
-out_ok:
-	ret = res.acl_len;
+	mode = inode->i_mode & S_IFMT;
+	if (__richacl_equiv_mode(res.acl, &mode) == 0 &&
+	    ((mode ^ res.mode) & S_IRWXUGO) == 0) {
+		richacl_put(res.acl);
+		res.acl = NULL;
+	} else
+		richacl_compute_max_masks(res.acl);
+	/* FIXME: Set inode->i_mode from res->mode?  */
+	set_cached_richacl(inode, res.acl);
+	err = 0;
+
 out_free:
-	for (i = 0; i < npages; i++)
-		if (pages[i])
-			__free_page(pages[i]);
+	if (err) {
+		richacl_put(res.acl);
+		res.acl = ERR_PTR(err);
+	}
+	for (i = 0; i < ARRAY_SIZE(pages) && pages[i]; i++)
+		__free_page(pages[i]);
 	if (res.acl_scratch)
 		__free_page(res.acl_scratch);
-	return ret;
+	return res.acl;
 }
 
-static ssize_t nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
+static struct richacl *nfs4_get_acl_uncached(struct inode *inode)
 {
 	struct nfs4_exception exception = { };
-	ssize_t ret;
+	struct richacl *acl;
 	do {
-		ret = __nfs4_get_acl_uncached(inode, buf, buflen);
-		trace_nfs4_get_acl(inode, ret);
-		if (ret >= 0)
+		acl = __nfs4_get_acl_uncached(inode);
+		trace_nfs4_get_acl(inode, IS_ERR(acl) ? PTR_ERR(acl) : 0);
+		if (!IS_ERR(acl))
 			break;
-		ret = nfs4_handle_exception(NFS_SERVER(inode), ret, &exception);
+		acl = ERR_PTR(nfs4_handle_exception(NFS_SERVER(inode), PTR_ERR(acl), &exception));
 	} while (exception.retry);
-	return ret;
+	return acl;
 }
 
-static ssize_t nfs4_proc_get_acl(struct inode *inode, void *buf, size_t buflen)
+static struct richacl *nfs4_proc_get_acl(struct inode *inode)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
+	struct richacl *acl;
 	int ret;
 
-	if (!nfs4_server_supports_acls(server))
-		return -EOPNOTSUPP;
+	if (!(server->caps & (NFS_CAP_ALLOW_ACLS | NFS_CAP_DENY_ACLS)))
+		return ERR_PTR(-EOPNOTSUPP);
 	ret = nfs_revalidate_inode(server, inode);
 	if (ret < 0)
-		return ret;
+		return ERR_PTR(ret);
 	if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_ACL)
 		nfs_zap_acl_cache(inode);
-	ret = nfs4_read_cached_acl(inode, buf, buflen);
-	if (ret != -ENOENT)
-		/* -ENOENT is returned if there is no ACL or if there is an ACL
-		 * but no cached acl data, just the acl length */
-		return ret;
-	return nfs4_get_acl_uncached(inode, buf, buflen);
+	acl = get_cached_richacl(inode);
+	if (acl != ACL_NOT_CACHED)
+		return acl;
+	return nfs4_get_acl_uncached(inode);
+}
+
+static int
+richacl_supported(struct nfs_server *server, struct richacl *acl)
+{
+	struct richace *ace;
+
+	if (!(server->caps & (NFS_CAP_ALLOW_ACLS | NFS_CAP_DENY_ACLS)))
+		return -EOPNOTSUPP;
+
+	richacl_for_each_entry(ace, acl) {
+		if (richace_is_allow(ace)) {
+			if (!(server->caps & NFS_CAP_ALLOW_ACLS))
+				return -EINVAL;
+		} else if (richace_is_deny(ace)) {
+			if (!(server->caps & NFS_CAP_DENY_ACLS))
+				return -EINVAL;
+		} else
+			return -EINVAL;
+	}
+	return 0;
 }
 
-static int __nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t buflen)
+static int __nfs4_proc_set_acl(struct inode *inode, struct richacl *acl)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
-	struct page *pages[NFS4ACL_MAXPAGES];
+	struct page *pages[DIV_ROUND_UP(NFS4ACL_SIZE_MAX, PAGE_SIZE) + 1 /* scratch */] = {};
 	struct nfs_setaclargs arg = {
+		.server		= server,
 		.fh		= NFS_FH(inode),
+		.acl		= acl,
 		.acl_pages	= pages,
-		.acl_len	= buflen,
+		.acl_len	= ARRAY_SIZE(pages) * PAGE_SIZE,
 	};
 	struct nfs_setaclres res;
 	struct rpc_message msg = {
@@ -4668,16 +4589,12 @@ static int __nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t bufl
 		.rpc_argp	= &arg,
 		.rpc_resp	= &res,
 	};
-	unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE);
 	int ret, i;
 
-	if (!nfs4_server_supports_acls(server))
-		return -EOPNOTSUPP;
-	if (npages > ARRAY_SIZE(pages))
-		return -ERANGE;
-	i = buf_to_pages_noslab(buf, buflen, arg.acl_pages);
-	if (i < 0)
-		return i;
+	ret = richacl_supported(server, acl);
+	if (ret)
+		return ret;
+
 	nfs4_inode_return_delegation(inode);
 	ret = nfs4_call_sync(server->client, server, &msg, &arg.seq_args, &res.seq_res, 1);
 
@@ -4685,8 +4602,8 @@ static int __nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t bufl
 	 * Free each page after tx, so the only ref left is
 	 * held by the network stack
 	 */
-	for (; i > 0; i--)
-		put_page(pages[i-1]);
+	for (i = 0; pages[i]; i++)
+		put_page(pages[i]);
 
 	/*
 	 * Acl update can result in inode attribute update.
@@ -4700,12 +4617,12 @@ static int __nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t bufl
 	return ret;
 }
 
-static int nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t buflen)
+static int nfs4_proc_set_acl(struct inode *inode, struct richacl *acl)
 {
 	struct nfs4_exception exception = { };
 	int err;
 	do {
-		err = __nfs4_proc_set_acl(inode, buf, buflen);
+		err = __nfs4_proc_set_acl(inode, acl);
 		trace_nfs4_set_acl(inode, err);
 		err = nfs4_handle_exception(NFS_SERVER(inode), err,
 				&exception);
@@ -6102,38 +6019,69 @@ nfs4_release_lockowner(struct nfs_server *server, struct nfs4_lock_state *lsp)
 	rpc_call_async(server->client, &msg, 0, &nfs4_release_lockowner_ops, data);
 }
 
-#define XATTR_NAME_NFSV4_ACL "system.nfs4_acl"
-
-static int nfs4_xattr_set_nfs4_acl(struct dentry *dentry, const char *key,
-				   const void *buf, size_t buflen,
-				   int flags, int type)
+static int nfs4_xattr_set_richacl(struct dentry *dentry, const char *key,
+				  const void *buf, size_t buflen,
+				  int flags, int handler_flags)
 {
+	struct richacl *acl;
+	int error;
+
 	if (strcmp(key, "") != 0)
 		return -EINVAL;
 
-	return nfs4_proc_set_acl(dentry->d_inode, buf, buflen);
+	if (buf) {
+		acl = richacl_from_xattr(&init_user_ns, buf, buflen);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+		error = richacl_apply_masks(&acl);
+	} else {
+		/*
+		 * "Remove the acl"; only permissions granted by the mode
+		 * remain.  We are using the cached mode here which could be
+		 * outdated; should we do a GETATTR first to narrow down the
+		 * race window?
+		 */
+		acl = richacl_from_mode_unmasked(dentry->d_inode->i_mode);
+		error = 0;
+	}
+
+	if (!error)
+		error = nfs4_proc_set_acl(dentry->d_inode, acl);
+	richacl_put(acl);
+	return error;
 }
 
-static int nfs4_xattr_get_nfs4_acl(struct dentry *dentry, const char *key,
-				   void *buf, size_t buflen, int type)
+static int nfs4_xattr_get_richacl(struct dentry *dentry, const char *key,
+				  void *buf, size_t buflen, int handler_flags)
 {
+	struct richacl *acl;
+	int error;
+
 	if (strcmp(key, "") != 0)
 		return -EINVAL;
 
-	return nfs4_proc_get_acl(dentry->d_inode, buf, buflen);
+	acl = nfs4_proc_get_acl(dentry->d_inode);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (acl == NULL)
+		return -ENODATA;
+	error = richacl_to_xattr(&init_user_ns, acl, buf, buflen);
+	richacl_put(acl);
+	return error;
 }
 
-static size_t nfs4_xattr_list_nfs4_acl(struct dentry *dentry, char *list,
-				       size_t list_len, const char *name,
-				       size_t name_len, int type)
+static size_t nfs4_xattr_list_richacl(struct dentry *dentry, char *list,
+				      size_t list_len, const char *name,
+				      size_t name_len, int handler_flags)
 {
-	size_t len = sizeof(XATTR_NAME_NFSV4_ACL);
+	struct nfs_server *server = NFS_SERVER(dentry->d_inode);
+	size_t len = sizeof(XATTR_NAME_RICHACL);
 
-	if (!nfs4_server_supports_acls(NFS_SERVER(dentry->d_inode)))
+	if (!(server->caps & (NFS_CAP_ALLOW_ACLS | NFS_CAP_DENY_ACLS)))
 		return 0;
 
 	if (list && len <= list_len)
-		memcpy(list, XATTR_NAME_NFSV4_ACL, len);
+		memcpy(list, XATTR_NAME_RICHACL, len);
 	return len;
 }
 
@@ -8656,15 +8604,15 @@ const struct nfs_rpc_ops nfs_v4_clientops = {
 	.clone_server	= nfs_clone_server,
 };
 
-static const struct xattr_handler nfs4_xattr_nfs4_acl_handler = {
-	.prefix	= XATTR_NAME_NFSV4_ACL,
-	.list	= nfs4_xattr_list_nfs4_acl,
-	.get	= nfs4_xattr_get_nfs4_acl,
-	.set	= nfs4_xattr_set_nfs4_acl,
+static const struct xattr_handler nfs4_xattr_richacl_handler = {
+	.prefix	= XATTR_NAME_RICHACL,
+	.list	= nfs4_xattr_list_richacl,
+	.get	= nfs4_xattr_get_richacl,
+	.set	= nfs4_xattr_set_richacl,
 };
 
 const struct xattr_handler *nfs4_xattr_handlers[] = {
-	&nfs4_xattr_nfs4_acl_handler,
+	&nfs4_xattr_richacl_handler,
 #ifdef CONFIG_NFS_V4_SECURITY_LABEL
 	&nfs4_xattr_nfs4_label_handler,
 #endif
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 4372fc4..8ccc2a0 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -53,6 +53,9 @@
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_idmap.h>
+#include <linux/richacl.h>
+#include <linux/richacl_xattr.h>  /* for RICHACL_XATTR_MAX_COUNT */
+#include <linux/nfs4acl.h>
 
 #include "nfs4_fs.h"
 #include "internal.h"
@@ -1632,19 +1635,131 @@ encode_restorefh(struct xdr_stream *xdr, struct compound_hdr *hdr)
 	encode_op_hdr(xdr, OP_RESTOREFH, decode_restorefh_maxsz, hdr);
 }
 
-static void
-encode_setacl(struct xdr_stream *xdr, struct nfs_setaclargs *arg, struct compound_hdr *hdr)
+static int
+nfs4_encode_user(struct xdr_stream *xdr, const struct nfs_server *server, kuid_t uid)
+{
+	char name[IDMAP_NAMESZ];
+	int len;
+	__be32 *p;
+
+	len = nfs_map_uid_to_name(server, uid, name, IDMAP_NAMESZ);
+	if (len < 0) {
+		dprintk("nfs: couldn't resolve uid %d to string\n",
+				from_kuid(&init_user_ns, uid));
+		return -ENOENT;
+	}
+	p = xdr_reserve_space(xdr, 4 + len);
+	if (!p)
+		return -EIO;
+	p = xdr_encode_opaque(p, name, len);
+	return 0;
+}
+
+static int
+nfs4_encode_group(struct xdr_stream *xdr, const struct nfs_server *server, kgid_t gid)
+{
+	char name[IDMAP_NAMESZ];
+	int len;
+	__be32 *p;
+
+	len = nfs_map_gid_to_group(server, gid, name, IDMAP_NAMESZ);
+	if (len < 0) {
+		dprintk("nfs: couldn't resolve gid %d to string\n",
+				from_kgid(&init_user_ns, gid));
+		return -ENOENT;
+	}
+	p = xdr_reserve_space(xdr, 4 + len);
+	if (!p)
+		return -EIO;
+	p = xdr_encode_opaque(p, name, len);
+	return 0;
+}
+
+static int
+nfs4_encode_ace_who(struct xdr_stream *xdr, const struct nfs_server *server,
+		    struct richace *ace)
 {
 	__be32 *p;
 
+	if (ace->e_flags & RICHACE_SPECIAL_WHO) {
+		unsigned int special_id = ace->e_id.special;
+		const char *who;
+		unsigned int len;
+
+		if (!nfs4acl_special_id_to_who(special_id, &who, &len)) {
+			WARN_ON_ONCE(1);
+			return -EIO;
+		}
+		p = xdr_reserve_space(xdr, 4 + len);
+		if (!p)
+			return -EIO;
+		p = xdr_encode_opaque(p, who, len);
+		return 0;
+	}
+	if (ace->e_flags & RICHACE_IDENTIFIER_GROUP)
+		return nfs4_encode_group(xdr, server, ace->e_id.gid);
+	else
+		return nfs4_encode_user(xdr, server, ace->e_id.uid);
+}
+
+static int
+encode_setacl(struct xdr_stream *xdr, struct nfs_setaclargs *arg, struct compound_hdr *hdr)
+{
+	int attrlen_offset;
+	__be32 attrlen, *p;
+	struct richace *ace;
+
 	encode_op_hdr(xdr, OP_SETATTR, decode_setacl_maxsz, hdr);
 	encode_nfs4_stateid(xdr, &zero_stateid);
+
+	/* Encode attribute bitmap. */
 	p = reserve_space(xdr, 2*4);
 	*p++ = cpu_to_be32(1);
 	*p = cpu_to_be32(FATTR4_WORD0_ACL);
-	p = reserve_space(xdr, 4);
-	*p = cpu_to_be32(arg->acl_len);
-	xdr_write_pages(xdr, arg->acl_pages, 0, arg->acl_len);
+
+	attrlen_offset = xdr->buf->len;
+	p = xdr_reserve_space(xdr, 4);
+	if (!p)
+		goto fail;
+	p++;  /* to be backfilled later */
+
+	p = xdr_reserve_space(xdr, 4);
+	if (!p)
+		goto fail;
+	if (arg->acl == NULL) {
+		*p++ = cpu_to_be32(0);
+		return 0;
+	}
+	*p++ = cpu_to_be32(arg->acl->a_count);
+
+	/* Add space for the acl entries. */
+	xdr_inline_pages(xdr->buf, xdr->buf->len, arg->acl_pages, 0, arg->acl_len);
+
+	if (arg->acl->a_flags)
+		return -EINVAL;
+
+	richacl_for_each_entry(ace, arg->acl) {
+		if (ace->e_flags & RICHACE_INHERITED_ACE)
+			return -EINVAL;
+		if (ace->e_mask & ~NFS4_ACE_MASK_ALL)
+			return -EINVAL;
+
+		p = xdr_reserve_space(xdr, 4*3);
+		if (!p)
+			goto fail;
+		*p++ = cpu_to_be32(ace->e_type);
+		*p++ = cpu_to_be32(ace->e_flags & ~RICHACE_SPECIAL_WHO);
+		*p++ = cpu_to_be32(ace->e_mask & NFS4_ACE_MASK_ALL);
+		if (nfs4_encode_ace_who(xdr, arg->server, ace) != 0)
+			goto fail;
+	}
+
+	attrlen = htonl(xdr->buf->len - attrlen_offset - 4);
+	write_bytes_to_xdr_buf(xdr->buf, attrlen_offset, &attrlen, 4);
+	return 0;
+
+fail:
+	return -ENOMEM;
 }
 
 static void
@@ -2514,7 +2629,7 @@ static int nfs4_xdr_enc_getacl(struct rpc_rqst *req, struct xdr_stream *xdr,
 	encode_sequence(xdr, &args->seq_args, &hdr);
 	encode_putfh(xdr, args->fh, &hdr);
 	replen = hdr.replen + op_decode_hdr_maxsz + 1;
-	encode_getattr_two(xdr, FATTR4_WORD0_ACL, 0, &hdr);
+	encode_getattr_two(xdr, FATTR4_WORD0_ACL, FATTR4_WORD1_MODE, &hdr);
 
 	xdr_inline_pages(&req->rq_rcv_buf, replen << 2,
 		args->acl_pages, 0, args->acl_len);
@@ -5236,27 +5351,64 @@ decode_restorefh(struct xdr_stream *xdr)
 	return decode_op_hdr(xdr, OP_RESTOREFH);
 }
 
+static int
+nfs4_decode_ace_who(struct richace *ace, const struct nfs_server *server,
+		    struct xdr_stream *xdr)
+{
+	char *who;
+	u32 len;
+	int special_id;
+	__be32 *p;
+	int error;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (!p)
+		return -ENOMEM;  /* acl truncated */
+	len = be32_to_cpup(p++);
+	if (len >= XDR_MAX_NETOBJ) {
+		dprintk("%s: name too long (%u)!\n",
+			__func__, len);
+		return -EIO;
+	}
+	who = (char *)xdr_inline_decode(xdr, len);
+	if (!who)
+		return -ENOMEM;  /* acl truncated */
+
+	special_id = nfs4acl_who_to_special_id(who, len);
+	if (special_id >= 0) {
+		ace->e_flags |= RICHACE_SPECIAL_WHO;
+		ace->e_flags &= ~RICHACE_IDENTIFIER_GROUP;
+		ace->e_id.special = special_id;
+		return 0;
+	}
+	if (ace->e_flags & RICHACE_IDENTIFIER_GROUP) {
+		error = nfs_map_group_to_gid(server, who, len, &ace->e_id.gid);
+		if (error)
+			dprintk("%s: nfs_map_group_to_gid failed!\n",
+					__func__);
+	} else {
+		error = nfs_map_name_to_uid(server, who, len, &ace->e_id.uid);
+		if (error)
+			dprintk("%s: nfs_map_name_to_uid failed!\n",
+					__func__);
+	}
+	return error;
+}
+
 static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
 			 struct nfs_getaclres *res)
 {
 	static const uint32_t attrs_allowed[3] = {
 		[0] = FATTR4_WORD0_ACL,
+		[1] = FATTR4_WORD1_MODE,
 	};
 	unsigned int savep;
 	uint32_t attrlen,
 		 bitmap[3] = {0};
 	int status;
-	unsigned int pg_offset;
 
-	res->acl_len = 0;
 	if ((status = decode_op_hdr(xdr, OP_GETATTR)) != 0)
 		goto out;
-
-	xdr_enter_page(xdr, xdr->buf->page_len);
-
-	/* Calculate the offset of the page data */
-	pg_offset = xdr->buf->head[0].iov_len;
-
 	if ((status = decode_attr_bitmap(xdr, bitmap)) != 0)
 		goto out;
 	if ((status = verify_attrs_allowed(bitmap, attrs_allowed)) != 0)
@@ -5265,22 +5417,37 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
 		goto out;
 
 	if (likely(bitmap[0] & FATTR4_WORD0_ACL)) {
+		struct richace *ace;
+		uint32_t count;
+		__be32 *p;
 
-		/* The bitmap (xdr len + bitmaps) and the attr xdr len words
-		 * are stored with the acl data to handle the problem of
-		 * variable length bitmaps.*/
-		res->acl_data_offset = xdr_stream_pos(xdr) - pg_offset;
-		res->acl_len = attrlen;
-
-		/* Check for receive buffer overflow */
-		if (res->acl_len > (xdr->nwords << 2) ||
-		    res->acl_len + res->acl_data_offset > xdr->buf->page_len) {
-			res->acl_flags |= NFS4_ACL_TRUNC;
-			dprintk("NFS: acl reply: attrlen %u > page_len %u\n",
-					attrlen, xdr->nwords << 2);
+		p = xdr_inline_decode(xdr, 4);
+		if (unlikely(!p))
+			return -ENOMEM;  /* acl truncated */
+		count = be32_to_cpup(p);
+		if (count > RICHACL_XATTR_MAX_COUNT)
+			return -EIO;
+		res->acl = richacl_alloc(count, GFP_KERNEL);
+		if (!res->acl)
+			return -ENOMEM;
+		richacl_for_each_entry(ace, res->acl) {
+			p = xdr_inline_decode(xdr, 4*3);
+			if (unlikely(!p))
+				return -ENOMEM;  /* acl truncated */
+			ace->e_type = be32_to_cpup(p++);
+			ace->e_flags = be32_to_cpup(p++);
+			if (ace->e_flags & RICHACE_SPECIAL_WHO)
+				return -EIO;
+			ace->e_mask = be32_to_cpup(p++);
+			status = nfs4_decode_ace_who(ace, res->server, xdr);
+			if (status)
+				goto out;
 		}
 	} else
 		status = -EOPNOTSUPP;
+	if ((status = decode_attr_mode(xdr, bitmap, &res->mode)) < 0)
+		goto out;
+	status = 0;
 
 out:
 	return status;
@@ -6298,6 +6465,7 @@ out:
 static int nfs4_xdr_enc_setacl(struct rpc_rqst *req, struct xdr_stream *xdr,
 			       void *obj)
 {
+	int error;
 	struct nfs_setaclargs *args = obj;
 	struct compound_hdr hdr = {
 		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
@@ -6306,7 +6474,9 @@ static int nfs4_xdr_enc_setacl(struct rpc_rqst *req, struct xdr_stream *xdr,
 	encode_compound_hdr(xdr, req, &hdr);
 	encode_sequence(xdr, &args->seq_args, &hdr);
 	encode_putfh(xdr, args->fh, &hdr);
-	encode_setacl(xdr, args, &hdr);
+	error = encode_setacl(xdr, args, &hdr);
+	if (error)
+		return error;
 	encode_nops(&hdr);
 	return 0;
 }
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 322b2de02..fb904ec 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2318,7 +2318,7 @@ void nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
 		/* The VFS shouldn't apply the umask to mode bits. We will do
 		 * so ourselves when necessary.
 		 */
-		sb->s_flags |= MS_POSIXACL;
+		sb->s_flags |= MS_RICHACL;
 		sb->s_time_gran = 1;
 	}
 
@@ -2345,7 +2345,7 @@ void nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
 		/* The VFS shouldn't apply the umask to mode bits. We will do
 		 * so ourselves when necessary.
 		 */
-		sb->s_flags |= MS_POSIXACL;
+		sb->s_flags |= MS_RICHACL;
 	}
 
  	nfs_initialise_sb(sb);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index b01ccf3..4eac89d7 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -176,7 +176,6 @@ struct nfs_inode {
 	wait_queue_head_t	waitqueue;
 
 #if IS_ENABLED(CONFIG_NFS_V4)
-	struct nfs4_cached_acl	*nfs4_acl;
         /* NFSv4 state */
 	struct list_head	open_states;
 	struct nfs_delegation __rcu *delegation;
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 5e1273d..df994aa 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -237,5 +237,7 @@ struct nfs_server {
 #define NFS_CAP_SEEK		(1U << 19)
 #define NFS_CAP_ALLOCATE	(1U << 20)
 #define NFS_CAP_DEALLOCATE	(1U << 21)
+#define NFS_CAP_ALLOW_ACLS	(1U << 22)
+#define NFS_CAP_DENY_ACLS	(1U << 23)
 
 #endif
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 92134cf..77097ec 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -638,7 +638,9 @@ struct nfs_setattrargs {
 
 struct nfs_setaclargs {
 	struct nfs4_sequence_args	seq_args;
+	const struct nfs_server *	server;
 	struct nfs_fh *			fh;
+	struct richacl *		acl;
 	size_t				acl_len;
 	struct page **			acl_pages;
 };
@@ -658,9 +660,9 @@ struct nfs_getaclargs {
 #define NFS4_ACL_TRUNC		0x0001	/* ACL was truncated */
 struct nfs_getaclres {
 	struct nfs4_sequence_res	seq_res;
-	size_t				acl_len;
-	size_t				acl_data_offset;
-	int				acl_flags;
+	const struct nfs_server *	server;
+	struct richacl *		acl;
+	umode_t				mode;
 	struct page *			acl_scratch;
 };
 
-- 
2.1.0