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nfs_request: a workaround for servers doing "maproot". 

for i/o requests which are expected not to fail due to permission
to mimic unix file open semantics (READ, WRITE, COMMIT),
try two credentials.  namely, the file owner's one and open time one.
remember which credential worked in per-file basis and try it first
next time to minimize number of retries.
ideas from Chuck Silvers.  PR/23716 and PR/24987.
This commit is contained in:
yamt 2004-08-24 20:09:44 +00:00
parent b63de69b76
commit 4fd5a025bf
2 changed files with 77 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
sys/nfs/nfs_socket.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: nfs_socket.c,v 1.109 2004/08/18 23:44:47 yamt Exp $ */
/* $NetBSD: nfs_socket.c,v 1.110 2004/08/24 20:09:44 yamt Exp $ */
/*
* Copyright (c) 1989, 1991, 1993, 1995
@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nfs_socket.c,v 1.109 2004/08/18 23:44:47 yamt Exp $");
__KERNEL_RCSID(0, "$NetBSD: nfs_socket.c,v 1.110 2004/08/24 20:09:44 yamt Exp $");
#include "fs_nfs.h"
#include "opt_nfs.h"
@ -951,7 +951,7 @@ nfs_request(np, mrest, procnum, procp, cred, mrp, mdp, dposp, rexmitp)
struct nfsreq *rep;
u_int32_t *tl;
int i;
struct nfsmount *nmp;
struct nfsmount *nmp = VFSTONFS(np->n_vnode->v_mount);
struct mbuf *md, *mheadend;
char nickv[RPCX_NICKVERF];
time_t reqtime, waituntil;
@ -967,12 +967,16 @@ nfs_request(np, mrest, procnum, procp, cred, mrp, mdp, dposp, rexmitp)
int nqlflag, cachable;
u_quad_t frev;
#endif
struct mbuf *mrest_backup = NULL;
struct ucred *origcred = NULL; /* XXX: gcc */
boolean_t retry_cred = TRUE;
boolean_t use_opencred = (np->n_flag & NUSEOPENCRED) != 0;
if (rexmitp != NULL)
*rexmitp = 0;
tryagain_cred:
KASSERT(cred != NULL);
nmp = VFSTONFS(np->n_vnode->v_mount);
MALLOC(rep, struct nfsreq *, sizeof(struct nfsreq), M_NFSREQ, M_WAITOK);
rep->r_nmp = nmp;
rep->r_procp = procp;
@ -1005,18 +1009,53 @@ kerbauth:
return (error);
}
}
retry_cred = FALSE;
} else {
/* AUTH_UNIX */
uid_t uid;
gid_t gid;
/*
* on the most unix filesystems, permission checks are
* done when the file is open(2)'ed.
* ie. once a file is successfully open'ed,
* following i/o operations never fail with EACCES.
* we try to follow the semantics as far as possible.
*
* note that we expect that the nfs server always grant
* accesses by the file's owner.
*/
origcred = cred;
switch (procnum) {
case NFSPROC_READ:
case NFSPROC_WRITE:
case NFSPROC_COMMIT:
acred.cr_uid = np->n_vattr->va_uid;
acred.cr_gid = np->n_vattr->va_gid;
uid = np->n_vattr->va_uid;
gid = np->n_vattr->va_gid;
if (cred->cr_uid == uid && cred->cr_gid == gid) {
retry_cred = FALSE;
break;
}
if (use_opencred)
break;
acred.cr_uid = uid;
acred.cr_gid = gid;
acred.cr_ngroups = 0;
acred.cr_ref = 2; /* Just to be safe.. */
cred = &acred;
break;
default:
retry_cred = FALSE;
break;
}
/*
* backup mbuf chain if we can need it later to retry.
*
* XXX maybe we can keep a direct reference to
* mrest without doing m_copym, but it's ...ugly.
*/
if (retry_cred)
mrest_backup = m_copym(mrest, 0, M_COPYALL, M_WAIT);
auth_type = RPCAUTH_UNIX;
auth_len = (((cred->cr_ngroups > nmp->nm_numgrps) ?
nmp->nm_numgrps : cred->cr_ngroups) << 2) +
@ -1130,11 +1169,8 @@ tryagain:
mrep = rep->r_mrep;
md = rep->r_md;
dpos = rep->r_dpos;
if (error) {
m_freem(rep->r_mreq);
free((caddr_t)rep, M_NFSREQ);
return (error);
}
if (error)
goto nfsmout;
/*
* break down the rpc header and check if ok
@ -1155,9 +1191,7 @@ tryagain:
} else
error = EACCES;
m_freem(mrep);
m_freem(rep->r_mreq);
free((caddr_t)rep, M_NFSREQ);
return (error);
goto nfsmout;
}
/*
@ -1177,6 +1211,20 @@ tryagain:
nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED);
if (*tl != 0) {
error = fxdr_unsigned(int, *tl);
if (error == NFSERR_ACCES && retry_cred) {
m_freem(mrep);
m_freem(rep->r_mreq);
FREE(rep, M_NFSREQ);
use_opencred = !use_opencred;
if (mrest_backup == NULL)
return ENOMEM; /* m_copym failure */
mrest = mrest_backup;
mrest_backup = NULL;
cred = origcred;
error = 0;
retry_cred = FALSE;
goto tryagain_cred;
}
if ((nmp->nm_flag & NFSMNT_NFSV3) &&
error == NFSERR_TRYLATER) {
m_freem(mrep);
@ -1210,11 +1258,17 @@ tryagain:
error |= NFSERR_RETERR;
} else
m_freem(mrep);
m_freem(rep->r_mreq);
free((caddr_t)rep, M_NFSREQ);
return (error);
goto nfsmout;
}
/*
* note which credential worked to minimize number of retries.
*/
if (use_opencred)
np->n_flag |= NUSEOPENCRED;
else
np->n_flag &= ~NUSEOPENCRED;
#ifndef NFS_V2_ONLY
/*
* For nqnfs, get any lease in reply
@ -1237,15 +1291,16 @@ tryagain:
*mrp = mrep;
*mdp = md;
*dposp = dpos;
m_freem(rep->r_mreq);
FREE((caddr_t)rep, M_NFSREQ);
return (0);
KASSERT(error == 0);
goto nfsmout;
}
m_freem(mrep);
error = EPROTONOSUPPORT;
nfsmout:
m_freem(rep->r_mreq);
free((caddr_t)rep, M_NFSREQ);
m_freem(mrest_backup);
return (error);
}
#endif /* NFS */

3
sys/nfs/nfsnode.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: nfsnode.h,v 1.47 2004/05/27 12:55:07 yamt Exp $ */
/* $NetBSD: nfsnode.h,v 1.48 2004/08/24 20:09:44 yamt Exp $ */
/*
* Copyright (c) 1989, 1993
@ -203,6 +203,7 @@ LIST_HEAD(nfsnodehashhead, nfsnode);
#define NCHG 0x0400 /* Special file times changed */
#define NTRUNCDELAYED 0x1000 /* Should be truncated later */
#define NREMOVED 0x2000 /* Has been removed */
#define NUSEOPENCRED 0x4000 /* Try open cred first rather than owner's */
/*
* Convert between nfsnode pointers and vnode pointers