SEO

On Mon, 27 Mar 2006, rick@snowhite.cis.uoguelph.ca wrote:

> Ok, I took a look at the tcpdump and it does seem weird. OpenBSD is
> returning EPERM for a setattr of mtime, when the client user does have
> write permission for the file.
>
> Looking at the OpenBSD3.8 code, the only thing I can see that would do
> this is if the IMMUTABLE flag was set on the file system?
>
> Otherwise, I think it must be caused by some post 3.8 change, assuming
> that the server file system is ufs.
> (Normally, the errors generated would be EROFS or EACCES, not EPERM.)

I think the issue is that the v3 setattr timestamp
NFSV3SATTRTIME_TOSERVER is governed by the same rectrictions as a
setattr timestamp TOCLIENT. I would expect TOSERVER (which means "set
timestamp to current server time", i.e. exactly what utimes(NULL)
does), to be allowed if we have write permission to the file. I
checked Solaris and Linux NFS v3 code, and both implement exactly
that.

To demonstrate what I mean, here's an ugly diff, which makes the access
check of setattr TOSERVER behave like utimes(NULL). Han, could you try
this on your server? If it works, we at least know a bit more what is
going on.

My touch(1) test case which i posted earlier is resolved by this.

-Otto

PS: my earlier comments about time coherency on linux only applies to
NFS v2.

Index: nfs_serv.c
================================================== =================
RCS file: /cvs/src/sys/nfs/nfs_serv.c,v
retrieving revision 1.39
diff -u -p -r1.39 nfs_serv.c
--- nfs_serv.c 18 Jun 2005 18:09:43 -0000 1.39
+++ nfs_serv.c 27 Mar 2006 18:43:57 -0000
@@ -224,6 +224,7 @@ nfsrv_setattr(nfsd, slp, procp, mrq)
caddr_t bpos;
int error = 0, rdonly, preat_ret = 1, postat_ret = 1;
int v3 = (nfsd->nd_flag & ND_NFSV3), gcheck = 0;
+ int toserver;
char *cp2;
struct mbuf *mb, *mb2, *mreq;
u_quad_t frev;
@@ -233,7 +234,7 @@ nfsrv_setattr(nfsd, slp, procp, mrq)
nfsm_srvmtofh(fhp);
VATTR_NULL(&va);
if (v3) {
- nfsm_srvsattr(&va);
+ nfsm_srvsattr(&va, toserver);
nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED);
gcheck = fxdr_unsigned(int, *tl);
if (gcheck) {
@@ -312,6 +313,8 @@ nfsrv_setattr(nfsd, slp, procp, mrq)
procp, 0)) != 0)
goto out;
}
+ if (toserver == 2)
+ va.va_vaflags |= VA_UTIMES_NULL;
error = VOP_SETATTR(vp, &va, cred, procp);
postat_ret = VOP_GETATTR(vp, &va, cred, procp);
if (!error)
@@ -1280,6 +1283,8 @@ nfsrv_create(nfsd, slp, procp, mrq)
}
VATTR_NULL(&va);
if (v3) {
+ int toserver;
+
nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED);
how = fxdr_unsigned(int, *tl);
switch (how) {
@@ -1289,7 +1294,7 @@ nfsrv_create(nfsd, slp, procp, mrq)
break;
}
case NFSV3CREATE_UNCHECKED:
- nfsm_srvsattr(&va);
+ nfsm_srvsattr(&va, toserver);
break;
case NFSV3CREATE_EXCLUSIVE:
nfsm_dissect(cp, caddr_t, NFSX_V3CREATEVERF);
@@ -1479,6 +1484,7 @@ nfsrv_mknod(nfsd, slp, procp, mrq)
int32_t t1;
caddr_t bpos;
int error = 0, len, dirfor_ret = 1, diraft_ret = 1;
+ int toserver;
u_int32_t major, minor;
enum vtype vtyp;
char *cp2;
@@ -1517,7 +1523,7 @@ nfsrv_mknod(nfsd, slp, procp, mrq)
goto out;
}
VATTR_NULL(&va);
- nfsm_srvsattr(&va);
+ nfsm_srvsattr(&va, toserver);
if (vtyp == VCHR || vtyp == VBLK) {
nfsm_dissect(tl, u_int32_t *, 2 * NFSX_UNSIGNED);
major = fxdr_unsigned(u_int32_t, *tl++);
@@ -2018,8 +2024,10 @@ nfsrv_symlink(nfsd, slp, procp, mrq)
if (error)
goto out;
VATTR_NULL(&va);
- if (v3)
- nfsm_srvsattr(&va);
+ if (v3) {
+ int toserver;
+ nfsm_srvsattr(&va, toserver);
+ }
nfsm_strsiz(len2, NFS_MAXPATHLEN);
MALLOC(pathcp, caddr_t, len2 + 1, M_TEMP, M_WAITOK);
iv.iov_base = pathcp;
@@ -2164,7 +2172,8 @@ nfsrv_mkdir(nfsd, slp, procp, mrq)
}
VATTR_NULL(&va);
if (v3) {
- nfsm_srvsattr(&va);
+ int toserver;
+ nfsm_srvsattr(&va, toserver);
} else {
nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED);
va.va_mode = nfstov_mode(*tl++);
Index: nfsm_subs.h
================================================== =================
RCS file: /cvs/src/sys/nfs/nfsm_subs.h,v
retrieving revision 1.15
diff -u -p -r1.15 nfsm_subs.h
--- nfsm_subs.h 24 Jun 2004 19:35:26 -0000 1.15
+++ nfsm_subs.h 27 Mar 2006 18:43:57 -0000
@@ -443,7 +443,7 @@
#define nfsm_srvpostop_attr(r, a) \
nfsm_srvpostopattr(nfsd, (r), (a), &mb, &bpos)

-#define nfsm_srvsattr(a) \
+#define nfsm_srvsattr(a, toserver) \
{ nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED); \
if (*tl == nfs_true) { \
nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED); \
@@ -464,6 +464,7 @@
nfsm_dissect(tl, u_int32_t *, 2 * NFSX_UNSIGNED); \
(a)->va_size = fxdr_hyper(tl); \
} \
+ (toserver) = 0; \
nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED); \
switch (fxdr_unsigned(int, *tl)) { \
case NFSV3SATTRTIME_TOCLIENT: \
@@ -471,6 +472,7 @@
fxdr_nfsv3time(tl, &(a)->va_atime); \
break; \
case NFSV3SATTRTIME_TOSERVER: \
+ (toserver)++; \
getnanotime(&(a)->va_atime); \
break; \
}; \
@@ -481,6 +483,7 @@
fxdr_nfsv3time(tl, &(a)->va_mtime); \
break; \
case NFSV3SATTRTIME_TOSERVER: \
+ (toserver)++; \
getnanotime(&(a)->va_mtime); \
break; \
}; }