Author: rmacklem
Date: Tue Jan 31 02:11:05 2012
New Revision: 230801
URL: http://svn.freebsd.org/changeset/base/230801
Log:
jwd@ reported a problem via email to freebsd-fs@ on Aug 25, 2011
under the subject "F_RDLCK lock to FreeBSD NFS fails to R/O target file".
This occurred because the server side NLM always checked for VWRITE
access, irrespective of the type of lock request. This patch
replaces VOP_ACCESS(..VWRITE..) with one appropriate to
the lock operation. It allows unlock and lock cancellation
to be done without a check of VOP_ACCESS(), so that files
can't be left locked indefinitely after the file permissions
have been changed.
Discussed with: zack
Submitted by: jwd (earlier version)
Reviewed by: dfr
MFC after: 2 weeks
Modified:
head/sys/nlm/nlm_prot_impl.c
Modified: head/sys/nlm/nlm_prot_impl.c
==============================================================================
--- head/sys/nlm/nlm_prot_impl.c Tue Jan 31 01:51:30 2012
(r230800)
+++ head/sys/nlm/nlm_prot_impl.c Tue Jan 31 02:11:05 2012
(r230801)
@@ -1775,10 +1775,10 @@ struct vfs_state {
static int
nlm_get_vfs_state(struct nlm_host *host, struct svc_req *rqstp,
- fhandle_t *fhp, struct vfs_state *vs)
+ fhandle_t *fhp, struct vfs_state *vs, accmode_t accmode)
{
int error, exflags;
- struct ucred *cred = NULL, *credanon;
+ struct ucred *cred = NULL, *credanon = NULL;
memset(vs, 0, sizeof(*vs));
@@ -1788,14 +1788,19 @@ nlm_get_vfs_state(struct nlm_host *host,
}
vs->vs_vfslocked = VFS_LOCK_GIANT(vs->vs_mp);
- error = VFS_CHECKEXP(vs->vs_mp, (struct sockaddr *)&host->nh_addr,
- &exflags, &credanon, NULL, NULL);
- if (error)
- goto out;
+ /* accmode == 0 means don't check, since it is an unlock. */
+ if (accmode != 0) {
+ error = VFS_CHECKEXP(vs->vs_mp,
+ (struct sockaddr *)&host->nh_addr, &exflags, &credanon,
+ NULL, NULL);
+ if (error)
+ goto out;
- if (exflags & MNT_EXRDONLY || (vs->vs_mp->mnt_flag & MNT_RDONLY)) {
- error = EROFS;
- goto out;
+ if (exflags & MNT_EXRDONLY ||
+ (vs->vs_mp->mnt_flag & MNT_RDONLY)) {
+ error = EROFS;
+ goto out;
+ }
}
error = VFS_FHTOVP(vs->vs_mp, &fhp->fh_fid, LK_EXCLUSIVE, &vs->vs_vp);
@@ -1803,22 +1808,31 @@ nlm_get_vfs_state(struct nlm_host *host,
goto out;
vs->vs_vnlocked = TRUE;
- if (!svc_getcred(rqstp, &cred, NULL)) {
- error = EINVAL;
- goto out;
- }
- if (cred->cr_uid == 0 || (exflags & MNT_EXPORTANON)) {
- crfree(cred);
- cred = credanon;
- credanon = NULL;
- }
+ if (accmode != 0) {
+ if (!svc_getcred(rqstp, &cred, NULL)) {
+ error = EINVAL;
+ goto out;
+ }
+ if (cred->cr_uid == 0 || (exflags & MNT_EXPORTANON)) {
+ crfree(cred);
+ cred = credanon;
+ credanon = NULL;
+ }
- /*
- * Check cred.
- */
- error = VOP_ACCESS(vs->vs_vp, VWRITE, cred, curthread);
- if (error)
- goto out;
+ /*
+ * Check cred.
+ */
+ error = VOP_ACCESS(vs->vs_vp, accmode, cred, curthread);
+ /*
+ * If this failed and accmode != VWRITE, try again with
+ * VWRITE to maintain backwards compatibility with the
+ * old code that always used VWRITE.
+ */
+ if (error != 0 && accmode != VWRITE)
+ error = VOP_ACCESS(vs->vs_vp, VWRITE, cred, curthread);
+ if (error)
+ goto out;
+ }
#if __FreeBSD_version < 800011
VOP_UNLOCK(vs->vs_vp, 0, curthread);
@@ -1872,6 +1886,7 @@ nlm_do_test(nlm4_testargs *argp, nlm4_te
struct nlm_host *host, *bhost;
int error, sysid;
struct flock fl;
+ accmode_t accmode;
memset(result, 0, sizeof(*result));
memset(&vs, 0, sizeof(vs));
@@ -1897,7 +1912,8 @@ nlm_do_test(nlm4_testargs *argp, nlm4_te
goto out;
}
- error = nlm_get_vfs_state(host, rqstp, &fh, &vs);
+ accmode = argp->exclusive ? VWRITE : VREAD;
+ error = nlm_get_vfs_state(host, rqstp, &fh, &vs, accmode);
if (error) {
result->stat.stat = nlm_convert_error(error);
goto out;
@@ -1968,6 +1984,7 @@ nlm_do_lock(nlm4_lockargs *argp, nlm4_re
struct nlm_host *host;
int error, sysid;
struct flock fl;
+ accmode_t accmode;
memset(result, 0, sizeof(*result));
memset(&vs, 0, sizeof(vs));
@@ -2002,7 +2019,8 @@ nlm_do_lock(nlm4_lockargs *argp, nlm4_re
goto out;
}
- error = nlm_get_vfs_state(host, rqstp, &fh, &vs);
+ accmode = argp->exclusive ? VWRITE : VREAD;
+ error = nlm_get_vfs_state(host, rqstp, &fh, &vs, accmode);
if (error) {
result->stat.stat = nlm_convert_error(error);
goto out;
@@ -2181,7 +2199,7 @@ nlm_do_cancel(nlm4_cancargs *argp, nlm4_
goto out;
}
- error = nlm_get_vfs_state(host, rqstp, &fh, &vs);
+ error = nlm_get_vfs_state(host, rqstp, &fh, &vs, (accmode_t)0);
if (error) {
result->stat.stat = nlm_convert_error(error);
goto out;
@@ -2270,7 +2288,7 @@ nlm_do_unlock(nlm4_unlockargs *argp, nlm
goto out;
}
- error = nlm_get_vfs_state(host, rqstp, &fh, &vs);
+ error = nlm_get_vfs_state(host, rqstp, &fh, &vs, (accmode_t)0);
if (error) {
result->stat.stat = nlm_convert_error(error);
goto out;
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