[RFC PATCH 30/35] nfsd: add xattr XDR encode functions

From: Frank van der Linden <fllinden@amazon.com>
To: <linux-nfs@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>
Subject: [RFC PATCH 30/35] nfsd: add xattr XDR encode functions
Date: Mon, 2 Sep 2019 20:09:40 +0000	[thread overview]
Message-ID: <0e544dca79417c9943ccb480c0fd829c2efe057c.1568309119.git.fllinden@amazon.com> (raw)
In-Reply-To: <cover.1568309119.git.fllinden@amazon.com>

Implement the XDR encode functions for the user extended attribute
operations.

Signed-off-by: Frank van der Linden <fllinden@amazon.com>
---
 fs/nfsd/nfs4xdr.c | 231 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 231 insertions(+)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index acf606f764a2..be57dc09a468 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4547,6 +4547,224 @@ nfsd4_encode_noop(struct nfsd4_compoundres *resp, __be32 nfserr, void *p)
 	return nfserr;
 }
 
+#ifdef CONFIG_NFSD_V4_XATTR
+/*
+ * Encode kmalloc-ed buffer in to XDR stream.
+ */
+static int
+nfsd4_vbuf_to_stream(struct xdr_stream *xdr, char *buf, u32 buflen)
+{
+	u32 cplen;
+	__be32 *p;
+
+	cplen = min_t(unsigned long, buflen,
+		      ((void *)xdr->end - (void *)xdr->p));
+	p = xdr_reserve_space(xdr, cplen);
+	if (!p)
+		return nfserr_resource;
+
+	memcpy(p, buf, cplen);
+	buf += cplen;
+	buflen -= cplen;
+
+	while (buflen) {
+		cplen = min_t(u32, buflen, PAGE_SIZE);
+		p = xdr_reserve_space(xdr, cplen);
+		if (!p)
+			return nfserr_resource;
+
+		memcpy(p, buf, cplen);
+
+		if (cplen < PAGE_SIZE) {
+			/*
+			 * We're done, with a length that wasn't page
+			 * aligned, so possibly not word aligned. Pad
+			 * any trailing bytes with 0.
+			 */
+			xdr_encode_opaque_fixed(p, NULL, cplen);
+			break;
+		}
+
+		buflen -= PAGE_SIZE;
+		buf += PAGE_SIZE;
+	}
+
+	return 0;
+}
+
+static __be32
+nfsd4_encode_getxattr(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_getxattr *getxattr)
+{
+	struct xdr_stream *xdr = &resp->xdr;
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 4);
+	if (!p)
+		return nfserr_resource;
+
+	*p = cpu_to_be32(getxattr->getxa_len);
+
+	if (getxattr->getxa_len == 0)
+		return 0;
+
+	return nfsd4_vbuf_to_stream(xdr, getxattr->getxa_buf,
+				    getxattr->getxa_len);
+}
+
+static __be32
+nfsd4_encode_setxattr(struct nfsd4_compoundres *resp, __be32 nfserr, struct
+		      nfsd4_setxattr *setxattr)
+{
+	struct xdr_stream *xdr = &resp->xdr;
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 20);
+	if (!p)
+		return nfserr_resource;
+
+	encode_cinfo(p, &setxattr->setxa_cinfo);
+
+	return 0;
+}
+
+/*
+ * See if there are cookie values that can be rejected outright.
+ */
+static int
+nfsd4_listxattr_validate_cookie(struct nfsd4_listxattrs *listxattrs,
+				u32 *offsetp)
+{
+	u64 cookie = listxattrs->lsxa_cookie;
+
+	/*
+	 * If the cookie is larger than the maximum number we can fit
+	 * in either the buffer we just got back from vfs_listxattr, or,
+	 * XDR-encoded, in the return buffer, it's invalid.
+	 */
+	if (cookie > (listxattrs->lsxa_len) / (XATTR_USER_PREFIX_LEN + 2))
+		return nfserr_badcookie;
+
+	if (cookie > (listxattrs->lsxa_maxcount /
+		      (XDR_QUADLEN(XATTR_USER_PREFIX_LEN + 2) + 4)))
+		return nfserr_badcookie;
+
+	*offsetp = (u32)cookie;
+	return 0;
+}
+
+static __be32
+nfsd4_encode_listxattrs(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_listxattrs *listxattrs)
+{
+	struct xdr_stream *xdr = &resp->xdr;
+	u32 cookie_offset, count_offset, eof;
+	u32 left, xdrleft, slen, count;
+	u32 xdrlen, offset;
+	u64 cookie;
+	char *sp;
+	int status;
+	__be32 *p;
+	u32 nuser;
+
+	eof = 1;
+
+	status = nfsd4_listxattr_validate_cookie(listxattrs, &offset);
+	if (status)
+		return status;
+
+	/*
+	 * Reserve space for the cookie and the name array count. Record
+	 * the offsets to save them later.
+	 */
+	cookie_offset = xdr->buf->len;
+	count_offset = cookie_offset + 8;
+	p = xdr_reserve_space(xdr, 12);
+	if (!p)
+		return nfserr_resource;
+
+	count = 0;
+	left = listxattrs->lsxa_len;
+	sp = listxattrs->lsxa_buf;
+	nuser = 0;
+
+	xdrleft = listxattrs->lsxa_maxcount;
+
+	while (left > 0 && xdrleft > 0) {
+		slen = strlen(sp);
+
+		/*
+		 * Check if this a user. attribute, skip it if not.
+		 */
+		if (strncmp(sp, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
+			goto contloop;
+
+		slen -= XATTR_USER_PREFIX_LEN;
+		xdrlen = 4 + ((slen + 3) & ~3);
+		if (xdrlen > xdrleft) {
+			if (count == 0) {
+				/*
+				 * Can't even fit the first attribute name.
+				 */
+				return nfserr_toosmall;
+			}
+			eof = 0;
+			goto wreof;
+		}
+
+		left -= XATTR_USER_PREFIX_LEN;
+		sp += XATTR_USER_PREFIX_LEN;
+		if (nuser++ < offset)
+			goto contloop;
+
+
+		p = xdr_reserve_space(xdr, xdrlen);
+		if (!p)
+			return nfserr_resource;
+
+		p = xdr_encode_opaque(p, sp, slen);
+
+		xdrleft -= xdrlen;
+		count++;
+contloop:
+		sp += slen + 1;
+		left -= slen + 1;
+	}
+
+	/*
+	 * If there were user attributes to copy, but we didn't copy
+	 * any, the offset was too large (e.g. the cookie was invalid).
+	 */
+	if (nuser > 0 && count == 0)
+		return nfserr_badcookie;
+
+wreof:
+	p = xdr_reserve_space(xdr, 4);
+	if (!p)
+		return nfserr_resource;
+	*p = cpu_to_be32(eof);
+
+	cookie = offset + count;
+
+	write_bytes_to_xdr_buf(xdr->buf, cookie_offset, &cookie, 8);
+	count = htonl(count);
+	write_bytes_to_xdr_buf(xdr->buf, count_offset, &count, 4);
+	return 0;
+}
+
+static __be32
+nfsd4_encode_removexattr(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_removexattr *removexattr)
+{
+	struct xdr_stream *xdr = &resp->xdr;
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 20);
+	if (!p)
+		return nfserr_resource;
+
+	p = encode_cinfo(p, &removexattr->rmxa_cinfo);
+	return 0;
+}
+#endif
+
 typedef __be32(* nfsd4_enc)(struct nfsd4_compoundres *, __be32, void *);
 
 /*
@@ -4636,6 +4854,19 @@ static const nfsd4_enc nfsd4_enc_ops[] = {
 	[OP_SEEK]		= (nfsd4_enc)nfsd4_encode_seek,
 	[OP_WRITE_SAME]		= (nfsd4_enc)nfsd4_encode_noop,
 	[OP_CLONE]		= (nfsd4_enc)nfsd4_encode_noop,
+
+#ifdef CONFIG_NFSD_V4_XATTR
+	/* RFC 8276 extended atributes operations */
+	[OP_GETXATTR]		= (nfsd4_enc)nfsd4_encode_getxattr,
+	[OP_SETXATTR]		= (nfsd4_enc)nfsd4_encode_setxattr,
+	[OP_LISTXATTRS]		= (nfsd4_enc)nfsd4_encode_listxattrs,
+	[OP_REMOVEXATTR]	= (nfsd4_enc)nfsd4_encode_removexattr,
+#else
+	[OP_GETXATTR]		= (nfsd4_enc)nfsd4_encode_noop,
+	[OP_SETXATTR]		= (nfsd4_enc)nfsd4_encode_noop,
+	[OP_LISTXATTRS]		= (nfsd4_enc)nfsd4_encode_noop,
+	[OP_REMOVEXATTR]	= (nfsd4_enc)nfsd4_encode_noop,
+#endif
 };
 
 /*
-- 
2.17.2

