[PATCH] NFSD: Add server support for NFSv3 ACLs.

 This adds functions for encoding and decoding POSIX ACLs for the NFSACL
 protocol extension, and the GETACL and SETACL RPCs.  The implementation is
 compatible with NFSACL in Solaris.

 Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
 Acked-by: Olaf Kirch <okir@suse.de>
 Signed-off-by: Andrew Morton <akpm@osdl.org>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 264 insertions, 0 deletions

diff --git a/fs/nfs_common/Makefile b/fs/nfs_common/Makefile
new file mode 100644
index 000000000000..f689ed82af3a
--- /dev/null
+++ b/fs/nfs_common/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for Linux filesystem routines that are shared by client and server.
+#
+
+obj-$(CONFIG_NFS_ACL_SUPPORT) += nfs_acl.o
+
+nfs_acl-objs := nfsacl.o
diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c
new file mode 100644
index 000000000000..18c58c32e326
--- /dev/null
+++ b/fs/nfs_common/nfsacl.c
@@ -0,0 +1,257 @@
+/*
+ * 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/sunrpc/xdr.h>
+#include <linux/nfsacl.h>
+#include <linux/nfs3.h>
+#include <linux/sort.h>
+
+MODULE_LICENSE("GPL");
+
+EXPORT_SYMBOL(nfsacl_encode);
+EXPORT_SYMBOL(nfsacl_decode);
+
+struct nfsacl_encode_desc {
+	struct xdr_array2_desc desc;
+	unsigned int count;
+	struct posix_acl *acl;
+	int typeflag;
+	uid_t uid;
+	gid_t gid;
+};
+
+static int
+xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
+{
+	struct nfsacl_encode_desc *nfsacl_desc =
+		(struct nfsacl_encode_desc *) desc;
+	u32 *p = (u32 *) elem;
+
+	if (nfsacl_desc->count < nfsacl_desc->acl->a_count) {
+		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(nfsacl_desc->uid);
+				break;
+			case ACL_GROUP_OBJ:
+				*p++ = htonl(nfsacl_desc->gid);
+				break;
+			case ACL_USER:
+			case ACL_GROUP:
+				*p++ = htonl(entry->e_id);
+				break;
+			default:  /* Solaris depends on that! */
+				*p++ = 0;
+				break;
+		}
+		*p++ = htonl(entry->e_perm & S_IRWXO);
+	} else {
+		const struct posix_acl_entry *pa, *pe;
+		int group_obj_perm = ACL_READ|ACL_WRITE|ACL_EXECUTE;
+
+		FOREACH_ACL_ENTRY(pa, nfsacl_desc->acl, pe) {
+			if (pa->e_tag == ACL_GROUP_OBJ) {
+				group_obj_perm = pa->e_perm & S_IRWXO;
+				break;
+			}
+		}
+		/* fake up ACL_MASK entry */
+		*p++ = htonl(ACL_MASK | nfsacl_desc->typeflag);
+		*p++ = htonl(0);
+		*p++ = htonl(group_obj_perm);
+	}
+
+	return 0;
+}
+
+unsigned 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,
+	};
+	int err;
+
+	if (entries > NFS_ACL_MAX_ENTRIES ||
+	    xdr_encode_word(buf, base, entries))
+		return -EINVAL;
+	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;
+}
+
+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;
+	u32 *p = (u32 *) elem;
+	struct posix_acl_entry *entry;
+
+	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;
+	entry->e_id = ntohl(*p++);
+	entry->e_perm = ntohl(*p++);
+
+	switch(entry->e_tag) {
+		case ACL_USER_OBJ:
+		case ACL_USER:
+		case ACL_GROUP_OBJ:
+		case ACL_GROUP:
+		case ACL_OTHER:
+			if (entry->e_perm & ~S_IRWXO)
+				return -EINVAL;
+			break;
+		case ACL_MASK:
+			/* Solaris sometimes sets additonal 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_id > b->e_id)
+		return 1;
+	else if (a->e_id < b->e_id)
+		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);
+
+	/* Clear undefined identifier fields and find the ACL_GROUP_OBJ
+	   and ACL_MASK entries. */
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+		switch(pa->e_tag) {
+			case ACL_USER_OBJ:
+				pa->e_id = ACL_UNDEFINED_ID;
+				break;
+			case ACL_GROUP_OBJ:
+				pa->e_id = ACL_UNDEFINED_ID;
+				group_obj = pa;
+				break;
+			case ACL_MASK:
+				mask = pa;
+				/* fall through */
+			case ACL_OTHER:
+				pa->e_id = ACL_UNDEFINED_ID;
+				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;
+}
+
+unsigned 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;
+	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;
+}