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nfsd4: fix READ permission checking

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In the case we already have a struct file (derived from a stateid), we
still need to do permission-checking; otherwise an unauthorized user
could gain access to a file by sniffing or guessing somebody else's
stateid.

Cc: stable@vger.kernel.org
Fixes: dc97618ddd "nfsd4: separate splice and readv cases"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2015-04-03 17:19:41 -04:00
parent 980608fb50
commit 6e4891dc28
1 changed files with 8 additions and 4 deletions
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12
fs/nfsd/nfs4xdr.c
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@ -3422,6 +3422,7 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
unsigned long maxcount;
struct xdr_stream *xdr = &resp->xdr;
struct file *file = read->rd_filp;
struct svc_fh *fhp = read->rd_fhp;
int starting_len = xdr->buf->len;
struct raparms *ra;
__be32 *p;
@ -3445,12 +3446,15 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
maxcount = min_t(unsigned long, maxcount, (xdr->buf->buflen - xdr->buf->len));
maxcount = min_t(unsigned long, maxcount, read->rd_length);
if (!read->rd_filp) {
if (read->rd_filp)
err = nfsd_permission(resp->rqstp, fhp->fh_export,
fhp->fh_dentry,
NFSD_MAY_READ|NFSD_MAY_OWNER_OVERRIDE);
else
err = nfsd_get_tmp_read_open(resp->rqstp, read->rd_fhp,
&file, &ra);
if (err)
goto err_truncate;
}
if (err)
goto err_truncate;
if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags))
err = nfsd4_encode_splice_read(resp, read, file, maxcount);