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jwd@ reported a problem via email to freebsd-fs@ on Aug 25, 2011

Browse Source 
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
This commit is contained in:
Rick Macklem 2012-01-31 02:11:05 +00:00
parent 688aaa098d
commit a8122d16b5
1 changed files with 46 additions and 28 deletions
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74
sys/nlm/nlm_prot_impl.c
View File

@ -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, struct svc_req *rqstp,
}
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, struct svc_req *rqstp,
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_testres *result, struct svc_req *rqstp,
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_testres *result, struct svc_req *rqstp,
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_res *result, struct svc_req *rqstp,
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_res *result, struct svc_req *rqstp,
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_res *result, struct svc_req *rqstp,
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, nlm4_res *result, struct svc_req *rqstp,
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;