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NFSD: Add an xdr_stream-based encoder for NFSv2/3 ACLs 

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2020-11-18 14:55:05 -05:00
parent 8a2cf9f570
commit 8edc064888
2 changed files with 74 additions and 0 deletions
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71
fs/nfs_common/nfsacl.c
View File

@ -136,6 +136,77 @@ int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
}
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;

3
include/linux/nfsacl.h
View File

@ -41,5 +41,8 @@ nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
extern bool
nfs_stream_decode_acl(struct xdr_stream *xdr, unsigned int *aclcnt,
struct posix_acl **pacl);
extern bool
nfs_stream_encode_acl(struct xdr_stream *xdr, struct inode *inode,
struct posix_acl *acl, int encode_entries, int typeflag);
#endif /* __LINUX_NFSACL_H */