[26/48] NFSv4: include bitmap in nfsv4 get acl data

From: Greg KH
Date: Mon Jan 16 2012 - 13:51:42 EST

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3.1-stable review patch. If anyone has any objections, please let me know.

------------------

From: Andy Adamson <andros@xxxxxxxxxx>

commit bf118a342f10dafe44b14451a1392c3254629a1f upstream.

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.

Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
fs/nfs/nfs4proc.c | 96 ++++++++++++++++++++++++++-------------------
fs/nfs/nfs4xdr.c | 31 ++++++++++----
include/linux/nfs_xdr.h | 5 ++
include/linux/sunrpc/xdr.h | 2
net/sunrpc/xdr.c | 3 -
5 files changed, 89 insertions(+), 48 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3442,19 +3442,6 @@ static inline int nfs4_server_supports_a
*/
#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)
{
@@ -3551,9 +3538,19 @@ 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,
@@ -3568,41 +3565,60 @@ static ssize_t __nfs4_get_acl_uncached(s
.rpc_argp = &args,
.rpc_resp = &res,
};
- struct page *localpage = NULL;
- int ret;
+ int ret = -ENOMEM, npages, i, acl_len = 0;

- if (buflen < PAGE_SIZE) {
- /* 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);
+ 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. */
+ 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;
}

@@ -3633,6 +3649,8 @@ static ssize_t nfs4_proc_get_acl(struct
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);
}
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2517,11 +2517,13 @@ static void nfs4_xdr_enc_getacl(struct r
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_stre
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 *rqs
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;
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -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;
};

--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -191,6 +191,8 @@ extern int xdr_decode_array2(struct xdr_
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.
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -296,7 +296,7 @@ _copy_to_pages(struct page **pages, size
* 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 **

} while ((len -= copy) != 0);
}
+EXPORT_SYMBOL_GPL(_copy_from_pages);

/*
* xdr_shrink_bufhead

--
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Next message: Greg KH: "[23/48] NFS: Retry mounting NFSROOT"
Previous message: Greg KH: "[24/48] NFSv4.1: fix backchannel slotid off-by-one bug"
In reply to: Greg KH: "[24/48] NFSv4.1: fix backchannel slotid off-by-one bug"
Next in thread: Greg KH: "[23/48] NFS: Retry mounting NFSROOT"
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