/*
* 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");
EXPORT_SYMBOL_GPL(nfsacl_encode);
EXPORT_SYMBOL_GPL(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;
};
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(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);
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;
}
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;
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 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_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;
}
/**
* 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;
}
