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NFSv4.2: add client side XDR handling for extended attributes
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Define the argument and response structures that will be used for
RFC 8276 extended attribute RPC calls, and implement the necessary
functions to encode/decode the extended attribute operations.

Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
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Frank van der Linden authored and Trond Myklebust committed Jul 13, 2020
1 parent b78ef84 commit 3e1f021
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Showing 3 changed files with 430 additions and 3 deletions.
368 changes: 366 additions & 2 deletions fs/nfs/nfs42xdr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,6 @@
decode_clone_maxsz + \
decode_getattr_maxsz)

#ifdef CONFIG_NFS_V4_2
/* Not limited by NFS itself, limited by the generic xattr code */
#define nfs4_xattr_name_maxsz XDR_QUADLEN(XATTR_NAME_MAX)

Expand Down Expand Up @@ -241,7 +240,6 @@ const u32 nfs42_maxlistxattrs_overhead = ((RPC_MAX_HEADER_WITH_AUTH +
compound_decode_hdr_maxsz +
decode_sequence_maxsz +
decode_putfh_maxsz + 3) * XDR_UNIT);
#endif

static void encode_fallocate(struct xdr_stream *xdr,
const struct nfs42_falloc_args *args)
Expand Down Expand Up @@ -407,6 +405,210 @@ static void encode_layouterror(struct xdr_stream *xdr,
encode_device_error(xdr, &args->errors[0]);
}

static void encode_setxattr(struct xdr_stream *xdr,
const struct nfs42_setxattrargs *arg,
struct compound_hdr *hdr)
{
__be32 *p;

BUILD_BUG_ON(XATTR_CREATE != SETXATTR4_CREATE);
BUILD_BUG_ON(XATTR_REPLACE != SETXATTR4_REPLACE);

encode_op_hdr(xdr, OP_SETXATTR, decode_setxattr_maxsz, hdr);
p = reserve_space(xdr, 4);
*p = cpu_to_be32(arg->xattr_flags);
encode_string(xdr, strlen(arg->xattr_name), arg->xattr_name);
p = reserve_space(xdr, 4);
*p = cpu_to_be32(arg->xattr_len);
if (arg->xattr_len)
xdr_write_pages(xdr, arg->xattr_pages, 0, arg->xattr_len);
}

static int decode_setxattr(struct xdr_stream *xdr,
struct nfs4_change_info *cinfo)
{
int status;

status = decode_op_hdr(xdr, OP_SETXATTR);
if (status)
goto out;
status = decode_change_info(xdr, cinfo);
out:
return status;
}


static void encode_getxattr(struct xdr_stream *xdr, const char *name,
struct compound_hdr *hdr)
{
encode_op_hdr(xdr, OP_GETXATTR, decode_getxattr_maxsz, hdr);
encode_string(xdr, strlen(name), name);
}

static int decode_getxattr(struct xdr_stream *xdr,
struct nfs42_getxattrres *res,
struct rpc_rqst *req)
{
int status;
__be32 *p;
u32 len, rdlen;

status = decode_op_hdr(xdr, OP_GETXATTR);
if (status)
return status;

p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
return -EIO;

len = be32_to_cpup(p);
if (len > req->rq_rcv_buf.page_len)
return -ERANGE;

res->xattr_len = len;

if (len > 0) {
rdlen = xdr_read_pages(xdr, len);
if (rdlen < len)
return -EIO;
}

return 0;
}

static void encode_removexattr(struct xdr_stream *xdr, const char *name,
struct compound_hdr *hdr)
{
encode_op_hdr(xdr, OP_REMOVEXATTR, decode_removexattr_maxsz, hdr);
encode_string(xdr, strlen(name), name);
}


static int decode_removexattr(struct xdr_stream *xdr,
struct nfs4_change_info *cinfo)
{
int status;

status = decode_op_hdr(xdr, OP_REMOVEXATTR);
if (status)
goto out;

status = decode_change_info(xdr, cinfo);
out:
return status;
}

static void encode_listxattrs(struct xdr_stream *xdr,
const struct nfs42_listxattrsargs *arg,
struct compound_hdr *hdr)
{
__be32 *p;

encode_op_hdr(xdr, OP_LISTXATTRS, decode_listxattrs_maxsz + 1, hdr);

p = reserve_space(xdr, 12);
if (unlikely(!p))
return;

p = xdr_encode_hyper(p, arg->cookie);
/*
* RFC 8276 says to specify the full max length of the LISTXATTRS
* XDR reply. Count is set to the XDR length of the names array
* plus the EOF marker. So, add the cookie and the names count.
*/
*p = cpu_to_be32(arg->count + 8 + 4);
}

static int decode_listxattrs(struct xdr_stream *xdr,
struct nfs42_listxattrsres *res)
{
int status;
__be32 *p;
u32 count, len, ulen;
size_t left, copied;
char *buf;

status = decode_op_hdr(xdr, OP_LISTXATTRS);
if (status) {
/*
* Special case: for LISTXATTRS, NFS4ERR_TOOSMALL
* should be translated to ERANGE.
*/
if (status == -ETOOSMALL)
status = -ERANGE;
goto out;
}

p = xdr_inline_decode(xdr, 8);
if (unlikely(!p))
return -EIO;

xdr_decode_hyper(p, &res->cookie);

p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
return -EIO;

left = res->xattr_len;
buf = res->xattr_buf;

count = be32_to_cpup(p);
copied = 0;

/*
* We have asked for enough room to encode the maximum number
* of possible attribute names, so everything should fit.
*
* But, don't rely on that assumption. Just decode entries
* until they don't fit anymore, just in case the server did
* something odd.
*/
while (count--) {
p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
return -EIO;

len = be32_to_cpup(p);
if (len > (XATTR_NAME_MAX - XATTR_USER_PREFIX_LEN)) {
status = -ERANGE;
goto out;
}

p = xdr_inline_decode(xdr, len);
if (unlikely(!p))
return -EIO;

ulen = len + XATTR_USER_PREFIX_LEN + 1;
if (buf) {
if (ulen > left) {
status = -ERANGE;
goto out;
}

memcpy(buf, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
memcpy(buf + XATTR_USER_PREFIX_LEN, p, len);

buf[ulen - 1] = 0;
buf += ulen;
left -= ulen;
}
copied += ulen;
}

p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
return -EIO;

res->eof = be32_to_cpup(p);
res->copied = copied;

out:
if (status == -ERANGE && res->xattr_len == XATTR_LIST_MAX)
status = -E2BIG;

return status;
}

/*
* Encode ALLOCATE request
*/
Expand Down Expand Up @@ -1062,4 +1264,166 @@ static int nfs4_xdr_dec_layouterror(struct rpc_rqst *rqstp,
return status;
}

#ifdef CONFIG_NFS_V4_2
static void nfs4_xdr_enc_setxattr(struct rpc_rqst *req, struct xdr_stream *xdr,
const void *data)
{
const struct nfs42_setxattrargs *args = data;
struct compound_hdr hdr = {
.minorversion = nfs4_xdr_minorversion(&args->seq_args),
};

encode_compound_hdr(xdr, req, &hdr);
encode_sequence(xdr, &args->seq_args, &hdr);
encode_putfh(xdr, args->fh, &hdr);
encode_setxattr(xdr, args, &hdr);
encode_nops(&hdr);
}

static int nfs4_xdr_dec_setxattr(struct rpc_rqst *req, struct xdr_stream *xdr,
void *data)
{
struct nfs42_setxattrres *res = data;
struct compound_hdr hdr;
int status;

status = decode_compound_hdr(xdr, &hdr);
if (status)
goto out;
status = decode_sequence(xdr, &res->seq_res, req);
if (status)
goto out;
status = decode_putfh(xdr);
if (status)
goto out;

status = decode_setxattr(xdr, &res->cinfo);
out:
return status;
}

static void nfs4_xdr_enc_getxattr(struct rpc_rqst *req, struct xdr_stream *xdr,
const void *data)
{
const struct nfs42_getxattrargs *args = data;
struct compound_hdr hdr = {
.minorversion = nfs4_xdr_minorversion(&args->seq_args),
};
size_t plen;

encode_compound_hdr(xdr, req, &hdr);
encode_sequence(xdr, &args->seq_args, &hdr);
encode_putfh(xdr, args->fh, &hdr);
encode_getxattr(xdr, args->xattr_name, &hdr);

plen = args->xattr_len ? args->xattr_len : XATTR_SIZE_MAX;

rpc_prepare_reply_pages(req, args->xattr_pages, 0, plen,
hdr.replen);
req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;

encode_nops(&hdr);
}

static int nfs4_xdr_dec_getxattr(struct rpc_rqst *rqstp,
struct xdr_stream *xdr, void *data)
{
struct nfs42_getxattrres *res = data;
struct compound_hdr hdr;
int status;

status = decode_compound_hdr(xdr, &hdr);
if (status)
goto out;
status = decode_sequence(xdr, &res->seq_res, rqstp);
if (status)
goto out;
status = decode_putfh(xdr);
if (status)
goto out;
status = decode_getxattr(xdr, res, rqstp);
out:
return status;
}

static void nfs4_xdr_enc_listxattrs(struct rpc_rqst *req,
struct xdr_stream *xdr, const void *data)
{
const struct nfs42_listxattrsargs *args = data;
struct compound_hdr hdr = {
.minorversion = nfs4_xdr_minorversion(&args->seq_args),
};

encode_compound_hdr(xdr, req, &hdr);
encode_sequence(xdr, &args->seq_args, &hdr);
encode_putfh(xdr, args->fh, &hdr);
encode_listxattrs(xdr, args, &hdr);

rpc_prepare_reply_pages(req, args->xattr_pages, 0, args->count,
hdr.replen);
req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;

encode_nops(&hdr);
}

static int nfs4_xdr_dec_listxattrs(struct rpc_rqst *rqstp,
struct xdr_stream *xdr, void *data)
{
struct nfs42_listxattrsres *res = data;
struct compound_hdr hdr;
int status;

xdr_set_scratch_buffer(xdr, page_address(res->scratch), PAGE_SIZE);

status = decode_compound_hdr(xdr, &hdr);
if (status)
goto out;
status = decode_sequence(xdr, &res->seq_res, rqstp);
if (status)
goto out;
status = decode_putfh(xdr);
if (status)
goto out;
status = decode_listxattrs(xdr, res);
out:
return status;
}

static void nfs4_xdr_enc_removexattr(struct rpc_rqst *req,
struct xdr_stream *xdr, const void *data)
{
const struct nfs42_removexattrargs *args = data;
struct compound_hdr hdr = {
.minorversion = nfs4_xdr_minorversion(&args->seq_args),
};

encode_compound_hdr(xdr, req, &hdr);
encode_sequence(xdr, &args->seq_args, &hdr);
encode_putfh(xdr, args->fh, &hdr);
encode_removexattr(xdr, args->xattr_name, &hdr);
encode_nops(&hdr);
}

static int nfs4_xdr_dec_removexattr(struct rpc_rqst *req,
struct xdr_stream *xdr, void *data)
{
struct nfs42_removexattrres *res = data;
struct compound_hdr hdr;
int status;

status = decode_compound_hdr(xdr, &hdr);
if (status)
goto out;
status = decode_sequence(xdr, &res->seq_res, req);
if (status)
goto out;
status = decode_putfh(xdr);
if (status)
goto out;

status = decode_removexattr(xdr, &res->cinfo);
out:
return status;
}
#endif
#endif /* __LINUX_FS_NFS_NFS4_2XDR_H */
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