Commit bf118a34 authored by Andy Adamson's avatar Andy Adamson Committed by Trond Myklebust
Browse files

NFSv4: include bitmap in nfsv4 get acl data 



The NFSv4 bitmap size is unbounded: a server can return an arbitrary
sized bitmap in an FATTR4_WORD0_ACL request.  Replace using the
nfs4_fattr_bitmap_maxsz as a guess to the maximum bitmask returned by a server
with the inclusion of the bitmap (xdr length plus bitmasks) and the acl data
xdr length to the (cached) acl page data.

This is a general solution to commit e5012d1f "NFSv4.1: update
nfs4_fattr_bitmap_maxsz" and fixes hitting a BUG_ON in xdr_shrink_bufhead
when getting ACLs.

Fix a bug in decode_getacl that returned -EINVAL on ACLs > page when getxattr
was called with a NULL buffer, preventing ACL > PAGE_SIZE from being retrieved.

Cc: stable@kernel.org
Signed-off-by: default avatarAndy Adamson <andros@netapp.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 3476f114

fs/nfs/nfs4proc.c

+57 −39
Original line number Diff line number Diff line
@@ -3426,19 +3426,6 @@ static inline int nfs4_server_supports_acls(struct nfs_server *server) 
 */

#define NFS4ACL_MAXPAGES (XATTR_SIZE_MAX >> PAGE_CACHE_SHIFT)



static void buf_to_pages(const void *buf, size_t buflen,

		struct page **pages, unsigned int *pgbase)

{

	const void *p = buf;



	*pgbase = offset_in_page(buf);

	p -= *pgbase;

	while (p < buf + buflen) {

		*(pages++) = virt_to_page(p);

		p += PAGE_CACHE_SIZE;

	}

}



static int buf_to_pages_noslab(const void *buf, size_t buflen,

		struct page **pages, unsigned int *pgbase)

{
@@ -3535,9 +3522,19 @@ out: 
	nfs4_set_cached_acl(inode, acl);

}



/*

 * The getxattr API returns the required buffer length when called with a

 * NULL buf. The NFSv4 acl tool then calls getxattr again after allocating

 * the required buf.  On a NULL buf, we send a page of data to the server

 * guessing that the ACL request can be serviced by a page. If so, we cache

 * up to the page of ACL data, and the 2nd call to getxattr is serviced by

 * the cache. If not so, we throw away the page, and cache the required

 * length. The next getxattr call will then produce another round trip to

 * the server, this time with the input buf of the required size.

 */

static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)

{

	struct page *pages[NFS4ACL_MAXPAGES];

	struct page *pages[NFS4ACL_MAXPAGES] = {NULL, };

	struct nfs_getaclargs args = {

		.fh = NFS_FH(inode),

		.acl_pages = pages,
@@ -3552,41 +3549,60 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu 
		.rpc_argp = &args,

		.rpc_resp = &res,

	};

	struct page *localpage = NULL;

	int ret;

	int ret = -ENOMEM, npages, i, acl_len = 0;



	if (buflen < PAGE_SIZE) {

	npages = (buflen + PAGE_SIZE - 1) >> PAGE_SHIFT;

	/* As long as we're doing a round trip to the server anyway,

	 * let's be prepared for a page of acl data. */

		localpage = alloc_page(GFP_KERNEL);

		resp_buf = page_address(localpage);

		if (localpage == NULL)

			return -ENOMEM;

		args.acl_pages[0] = localpage;

		args.acl_pgbase = 0;

		args.acl_len = PAGE_SIZE;

	} else {

		resp_buf = buf;

		buf_to_pages(buf, buflen, args.acl_pages, &args.acl_pgbase);

	if (npages == 0)

		npages = 1;



	for (i = 0; i < npages; i++) {

		pages[i] = alloc_page(GFP_KERNEL);

		if (!pages[i])

			goto out_free;

	}

	ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode), &msg, &args.seq_args, &res.seq_res, 0);

	if (npages > 1) {

		/* for decoding across pages */

		args.acl_scratch = alloc_page(GFP_KERNEL);

		if (!args.acl_scratch)

			goto out_free;

	}

	args.acl_len = npages * PAGE_SIZE;

	args.acl_pgbase = 0;

	/* Let decode_getfacl know not to fail if the ACL data is larger than

	 * the page we send as a guess */

	if (buf == NULL)

		res.acl_flags |= NFS4_ACL_LEN_REQUEST;

	resp_buf = page_address(pages[0]);



	dprintk("%s  buf %p buflen %ld npages %d args.acl_len %ld\n",

		__func__, buf, buflen, npages, args.acl_len);

	ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode),

			     &msg, &args.seq_args, &res.seq_res, 0);

	if (ret)

		goto out_free;

	if (res.acl_len > args.acl_len)

		nfs4_write_cached_acl(inode, NULL, res.acl_len);



	acl_len = res.acl_len - res.acl_data_offset;

	if (acl_len > args.acl_len)

		nfs4_write_cached_acl(inode, NULL, acl_len);

	else

		nfs4_write_cached_acl(inode, resp_buf, res.acl_len);

		nfs4_write_cached_acl(inode, resp_buf + res.acl_data_offset,

				      acl_len);

	if (buf) {

		ret = -ERANGE;

		if (res.acl_len > buflen)

		if (acl_len > buflen)

			goto out_free;

		if (localpage)

			memcpy(buf, resp_buf, res.acl_len);

		_copy_from_pages(buf, pages, res.acl_data_offset,

				res.acl_len);

	}

	ret = res.acl_len;

	ret = acl_len;

out_free:

	if (localpage)

		__free_page(localpage);

	for (i = 0; i < npages; i++)

		if (pages[i])

			__free_page(pages[i]);

	if (args.acl_scratch)

		__free_page(args.acl_scratch);

	return ret;

}
@@ -3617,6 +3633,8 @@ static ssize_t nfs4_proc_get_acl(struct inode *inode, void *buf, size_t buflen) 
		nfs_zap_acl_cache(inode);

	ret = nfs4_read_cached_acl(inode, buf, buflen);

	if (ret != -ENOENT)

		/* -ENOENT is returned if there is no ACL or if there is an ACL

		 * but no cached acl data, just the acl length */

		return ret;

	return nfs4_get_acl_uncached(inode, buf, buflen);

}

fs/nfs/nfs4xdr.c

+23 −8
Original line number Diff line number Diff line
@@ -2517,11 +2517,13 @@ static void nfs4_xdr_enc_getacl(struct rpc_rqst *req, struct xdr_stream *xdr, 
	encode_compound_hdr(xdr, req, &hdr);

	encode_sequence(xdr, &args->seq_args, &hdr);

	encode_putfh(xdr, args->fh, &hdr);

	replen = hdr.replen + op_decode_hdr_maxsz + nfs4_fattr_bitmap_maxsz + 1;

	replen = hdr.replen + op_decode_hdr_maxsz + 1;

	encode_getattr_two(xdr, FATTR4_WORD0_ACL, 0, &hdr);



	xdr_inline_pages(&req->rq_rcv_buf, replen << 2,

		args->acl_pages, args->acl_pgbase, args->acl_len);

	xdr_set_scratch_buffer(xdr, page_address(args->acl_scratch), PAGE_SIZE);



	encode_nops(&hdr);

}
@@ -4957,17 +4959,18 @@ decode_restorefh(struct xdr_stream *xdr) 
}



static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,

		size_t *acl_len)

			 struct nfs_getaclres *res)

{

	__be32 *savep;

	__be32 *savep, *bm_p;

	uint32_t attrlen,

		 bitmap[3] = {0};

	struct kvec *iov = req->rq_rcv_buf.head;

	int status;



	*acl_len = 0;

	res->acl_len = 0;

	if ((status = decode_op_hdr(xdr, OP_GETATTR)) != 0)

		goto out;

	bm_p = xdr->p;

	if ((status = decode_attr_bitmap(xdr, bitmap)) != 0)

		goto out;

	if ((status = decode_attr_length(xdr, &attrlen, &savep)) != 0)
@@ -4979,18 +4982,30 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req, 
		size_t hdrlen;

		u32 recvd;



		/* The bitmap (xdr len + bitmaps) and the attr xdr len words

		 * are stored with the acl data to handle the problem of

		 * variable length bitmaps.*/

		xdr->p = bm_p;

		res->acl_data_offset = be32_to_cpup(bm_p) + 2;

		res->acl_data_offset <<= 2;



		/* We ignore &savep and don't do consistency checks on

		 * the attr length.  Let userspace figure it out.... */

		hdrlen = (u8 *)xdr->p - (u8 *)iov->iov_base;

		attrlen += res->acl_data_offset;

		recvd = req->rq_rcv_buf.len - hdrlen;

		if (attrlen > recvd) {

			dprintk("NFS: server cheating in getattr"

					" acl reply: attrlen %u > recvd %u\n",

			if (res->acl_flags & NFS4_ACL_LEN_REQUEST) {

				/* getxattr interface called with a NULL buf */

				res->acl_len = attrlen;

				goto out;

			}

			dprintk("NFS: acl reply: attrlen %u > recvd %u\n",

					attrlen, recvd);

			return -EINVAL;

		}

		xdr_read_pages(xdr, attrlen);

		*acl_len = attrlen;

		res->acl_len = attrlen;

	} else

		status = -EOPNOTSUPP;
@@ -6028,7 +6043,7 @@ nfs4_xdr_dec_getacl(struct rpc_rqst *rqstp, struct xdr_stream *xdr, 
	status = decode_putfh(xdr);

	if (status)

		goto out;

	status = decode_getacl(xdr, rqstp, &res->acl_len);

	status = decode_getacl(xdr, rqstp, res);



out:

	return status;

include/linux/nfs_xdr.h

+5 −0
Original line number Diff line number Diff line
@@ -602,11 +602,16 @@ struct nfs_getaclargs { 
	size_t				acl_len;

	unsigned int			acl_pgbase;

	struct page **			acl_pages;

	struct page *			acl_scratch;

	struct nfs4_sequence_args 	seq_args;

};



/* getxattr ACL interface flags */

#define NFS4_ACL_LEN_REQUEST	0x0001	/* zero length getxattr buffer */

struct nfs_getaclres {

	size_t				acl_len;

	size_t				acl_data_offset;

	int				acl_flags;

	struct nfs4_sequence_res	seq_res;

};

include/linux/sunrpc/xdr.h

+2 −0
Original line number Diff line number Diff line
@@ -191,6 +191,8 @@ extern int xdr_decode_array2(struct xdr_buf *buf, unsigned int base, 
			     struct xdr_array2_desc *desc);

extern int xdr_encode_array2(struct xdr_buf *buf, unsigned int base,

			     struct xdr_array2_desc *desc);

extern void _copy_from_pages(char *p, struct page **pages, size_t pgbase,

			     size_t len);



/*

 * Provide some simple tools for XDR buffer overflow-checking etc.

net/sunrpc/xdr.c

+2 −1
Original line number Diff line number Diff line
@@ -296,7 +296,7 @@ _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len) 
 * Copies data into an arbitrary memory location from an array of pages

 * The copy is assumed to be non-overlapping.

 */

static void

void

_copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)

{

	struct page **pgfrom;
@@ -324,6 +324,7 @@ _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len) 


	} while ((len -= copy) != 0);

}

EXPORT_SYMBOL_GPL(_copy_from_pages);



/*

 * xdr_shrink_bufhead

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