From 8edc0648880a151026fe625fa1b76772b5766f68 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Wed, 18 Nov 2020 14:55:05 -0500 Subject: NFSD: Add an xdr_stream-based encoder for NFSv2/3 ACLs Signed-off-by: Chuck Lever --- fs/nfs_common/nfsacl.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) (limited to 'fs/nfs_common') diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c index 79c563c1a5e8..5a5bd85d08f8 100644 --- a/fs/nfs_common/nfsacl.c +++ b/fs/nfs_common/nfsacl.c @@ -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; -- cgit v1.2.3