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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 e5012d1 "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: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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androsadamson authored and Trond Myklebust committed Dec 7, 2011
1 parent 3476f11 commit bf118a342f10dafe44b14451a1392c3254629a1f
Showing with 89 additions and 48 deletions.
  1. +57 −39 fs/nfs/nfs4proc.c
  2. +23 −8 fs/nfs/nfs4xdr.c
  3. +5 −0 include/linux/nfs_xdr.h
  4. +2 −0 include/linux/sunrpc/xdr.h
  5. +2 −1 net/sunrpc/xdr.c
@@ -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 @@ static void nfs4_write_cached_acl(struct inode *inode, const char *buf, size_t a
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) {
/* 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;
}
if (npages > 1) {
/* for decoding across pages */
args.acl_scratch = alloc_page(GFP_KERNEL);
if (!args.acl_scratch)
goto out_free;
}
ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode), &msg, &args.seq_args, &res.seq_res, 0);
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);
}
@@ -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;
@@ -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;
};

@@ -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.
@@ -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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