Commit 7007c90f authored by Neil Brown's avatar Neil Brown Committed by J. Bruce Fields
Browse files

nfsd: avoid permission checks on EXCLUSIVE_CREATE replay 



With NFSv4, if we create a file then open it we explicit avoid checking
the permissions on the file during the open because the fact that we
created it ensures we should be allow to open it (the create and the
open should appear to be a single operation).

However if the reply to an EXCLUSIVE create gets lots and the client
resends the create, the current code will perform the permission check -
because it doesn't realise that it did the open already..

This patch should fix this.

Note that I haven't actually seen this cause a problem.  I was just
looking at the code trying to figure out a different EXCLUSIVE open
related issue, and this looked wrong.

(Fix confirmed with pynfs 4.0 test OPEN4--bfields)

Cc: stable@kernel.org
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
[bfields: use OWNER_OVERRIDE and update for 4.1]
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 756933ee

fs/nfsd/nfs4proc.c

+5 −3
Original line number Diff line number Diff line
@@ -195,6 +195,7 @@ static __be32 
do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)

{

	struct svc_fh *resfh;

	int accmode;

	__be32 status;



	resfh = kmalloc(sizeof(struct svc_fh), GFP_KERNEL);
@@ -254,9 +255,10 @@ do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_o 
	/* set reply cache */

	fh_copy_shallow(&open->op_openowner->oo_owner.so_replay.rp_openfh,

			&resfh->fh_handle);

	if (!open->op_created)

		status = do_open_permission(rqstp, resfh, open,

					    NFSD_MAY_NOP);

	accmode = NFSD_MAY_NOP;

	if (open->op_created)

		accmode |= NFSD_MAY_OWNER_OVERRIDE;

	status = do_open_permission(rqstp, resfh, open, accmode);

	set_change_info(&open->op_cinfo, current_fh);

	fh_dup2(current_fh, resfh);

out:

fs/nfsd/vfs.c

+8 −2
Original line number Diff line number Diff line
@@ -1471,13 +1471,19 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp, 
		case NFS3_CREATE_EXCLUSIVE:

			if (   dchild->d_inode->i_mtime.tv_sec == v_mtime

			    && dchild->d_inode->i_atime.tv_sec == v_atime

			    && dchild->d_inode->i_size  == 0 )

			    && dchild->d_inode->i_size  == 0 ) {

				if (created)

					*created = 1;

				break;

			}

		case NFS4_CREATE_EXCLUSIVE4_1:

			if (   dchild->d_inode->i_mtime.tv_sec == v_mtime

			    && dchild->d_inode->i_atime.tv_sec == v_atime

			    && dchild->d_inode->i_size  == 0 )

			    && dchild->d_inode->i_size  == 0 ) {

				if (created)

					*created = 1;

				goto set_attr;

			}

			 /* fallthru */

		case NFS3_CREATE_GUARDED:

			err = nfserr_exist;

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