From: Andy Adamson <andros@xxxxxxxxxx>
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.
Cc:stable@xxxxxxxxxx
Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
---
fs/nfs/nfs4proc.c | 20 ++++++++++++++++++--
fs/nfs/nfs4xdr.c | 15 ++++++++++++---
2 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index deb88d9..97014dd 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3671,6 +3671,22 @@ static void nfs4_zap_acl_attr(struct inode *inode)
nfs4_set_cached_acl(inode, NULL);
}
+/*
+ * The bitmap xdr length, bitmasks, and the attr xdr length are stored in
+ * the acl cache to handle variable length bitmasks. Just copy the acl data.
+ */
+static void nfs4_copy_acl(char *buf, char *acl_data, size_t acl_len)
+{
+ __be32 *q, *p = (__be32 *)acl_data;
+ int32_t len;
+
+ len = be32_to_cpup(p); /* number of bitmasks */
+ len += 2; /* add words for bitmap and attr xdr len */
+ q = p + len;
+ len = len << 2; /* convert to bytes for acl_len math */
+ memcpy(buf, (char *)q, acl_len - len);
+}
+
static inline ssize_t nfs4_read_cached_acl(struct inode *inode, char *buf, size_t buflen)
{
struct nfs_inode *nfsi = NFS_I(inode);
@@ -3688,7 +3704,7 @@ static inline ssize_t nfs4_read_cached_acl(struct inode *inode, char *buf, size_
ret = -ERANGE; /* see getxattr(2) man page */
if (acl->len > buflen)
goto out;
- memcpy(buf, acl->data, acl->len);
+ nfs4_copy_acl(buf, acl->data, acl->len);
out_len:
ret = acl->len;
out:
@@ -3763,7 +3779,7 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
if (res.acl_len > buflen)
goto out_free;
if (localpage)
- memcpy(buf, resp_buf, res.acl_len);
+ nfs4_copy_acl(buf, resp_buf, res.acl_len);
}
ret = res.acl_len;
out_free:
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index f9fd96d..9c07380 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2513,7 +2513,7 @@ 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,
@@ -4955,7 +4955,7 @@ decode_restorefh(struct xdr_stream *xdr)
static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
size_t *acl_len)
{
- __be32 *savep;
+ __be32 *savep, *bm_p;
uint32_t attrlen,
bitmap[3] = {0};
struct kvec *iov = req->rq_rcv_buf.head;
@@ -4964,6 +4964,7 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
*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)
@@ -4972,12 +4973,20 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
if (unlikely(bitmap[0] & (FATTR4_WORD0_ACL - 1U)))
return -EIO;
if (likely(bitmap[0] & FATTR4_WORD0_ACL)) {
- size_t hdrlen;
+ size_t hdrlen, len;
u32 recvd;
+ /*The bitmap (xdr len + bitmasks) and the attr xdr len words
+ * are stored with the acl data to handle the problem of
+ * variable length bitmasks.*/
+ xdr->p = bm_p;
+ len = be32_to_cpup(bm_p);
+ len += 2; /* add bitmap and attr xdr len words */
+
/* 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 += len << 2; /* attrlen is in bytes */
recvd = req->rq_rcv_buf.len - hdrlen;
if (attrlen > recvd) {
dprintk("NFS: server cheating in getattr"
--
1.7.6.4
--
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