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Add two new options to the nfssvc(2) syscall that allow

Browse Source 
processes running as root to suspend/resume execution
of the kernel nfsd threads. An earlier version of this
patch was tested by Vincent Hoffman (vince at unsane.co.uk)
and John Hickey (jh at deterlab.net).

Reviewed by:	kib
MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2012-10-14 22:33:17 +00:00
parent 8e7393944d
commit 6001db296e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=241561
4 changed files with 47 additions and 2 deletions
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20
sys/fs/nfsserver/nfs_nfsdkrpc.c
View File

@ -45,6 +45,8 @@ __FBSDID("$FreeBSD$");
#include <security/mac/mac_framework.h>
NFSDLOCKMUTEX;
NFSV4ROOTLOCKMUTEX;
struct nfsv4lock nfsd_suspend_lock;
/*
* Mapping of old NFS Version 2 RPC numbers to generic numbers.
@ -221,9 +223,24 @@ nfssvc_program(struct svc_req *rqst, SVCXPRT *xprt)
#ifdef MAC
mac_cred_associate_nfsd(nd.nd_cred);
#endif
/*
* Get a refcnt (shared lock) on nfsd_suspend_lock.
* NFSSVC_SUSPENDNFSD will take an exclusive lock on
* nfsd_suspend_lock to suspend these threads.
* This must be done here, before the check of
* nfsv4root exports by nfsvno_v4rootexport().
*/
NFSLOCKV4ROOTMUTEX();
nfsv4_getref(&nfsd_suspend_lock, NULL, NFSV4ROOTLOCKMUTEXPTR,
NULL);
NFSUNLOCKV4ROOTMUTEX();
if ((nd.nd_flag & ND_NFSV4) != 0) {
nd.nd_repstat = nfsvno_v4rootexport(&nd);
if (nd.nd_repstat != 0) {
NFSLOCKV4ROOTMUTEX();
nfsv4_relref(&nfsd_suspend_lock);
NFSUNLOCKV4ROOTMUTEX();
svcerr_weakauth(rqst);
svc_freereq(rqst);
m_freem(nd.nd_mrep);
@ -233,6 +250,9 @@ nfssvc_program(struct svc_req *rqst, SVCXPRT *xprt)
cacherep = nfs_proc(&nd, rqst->rq_xid, xprt->xp_socket,
xprt->xp_sockref, &rp);
NFSLOCKV4ROOTMUTEX();
nfsv4_relref(&nfsd_suspend_lock);
NFSUNLOCKV4ROOTMUTEX();
} else {
NFSMGET(nd.nd_mreq);
nd.nd_mreq->m_len = 0;

24
sys/fs/nfsserver/nfs_nfsdport.c
View File

@ -57,6 +57,7 @@ extern struct mount nfsv4root_mnt;
extern struct nfsrv_stablefirst nfsrv_stablefirst;
extern void (*nfsd_call_servertimer)(void);
extern SVCPOOL *nfsrvd_pool;
extern struct nfsv4lock nfsd_suspend_lock;
struct vfsoptlist nfsv4root_opt, nfsv4root_newopt;
NFSDLOCKMUTEX;
struct mtx nfs_cache_mutex;
@ -3095,8 +3096,9 @@ nfssvc_srvcall(struct thread *p, struct nfssvc_args *uap, struct ucred *cred)
struct nfsd_dumplocks *dumplocks;
struct nameidata nd;
vnode_t vp;
int error = EINVAL;
int error = EINVAL, igotlock;
struct proc *procp;
static int suspend_nfsd = 0;
if (uap->flag & NFSSVC_PUBLICFH) {
NFSBZERO((caddr_t)&nfs_pubfh.nfsrvfh_data,
@ -3175,6 +3177,26 @@ nfssvc_srvcall(struct thread *p, struct nfssvc_args *uap, struct ucred *cred)
nfsd_master_start = procp->p_stats->p_start;
nfsd_master_proc = procp;
PROC_UNLOCK(procp);
} else if ((uap->flag & NFSSVC_SUSPENDNFSD) != 0) {
NFSLOCKV4ROOTMUTEX();
if (suspend_nfsd == 0) {
/* Lock out all nfsd threads */
do {
igotlock = nfsv4_lock(&nfsd_suspend_lock, 1,
NULL, NFSV4ROOTLOCKMUTEXPTR, NULL);
} while (igotlock == 0 && suspend_nfsd == 0);
suspend_nfsd = 1;
}
NFSUNLOCKV4ROOTMUTEX();
error = 0;
} else if ((uap->flag & NFSSVC_RESUMENFSD) != 0) {
NFSLOCKV4ROOTMUTEX();
if (suspend_nfsd != 0) {
nfsv4_unlock(&nfsd_suspend_lock, 0);
suspend_nfsd = 0;
}
NFSUNLOCKV4ROOTMUTEX();
error = 0;
}
NFSEXITCODE(error);

3
sys/nfs/nfs_nfssvc.c
View File

@ -102,7 +102,8 @@ sys_nfssvc(struct thread *td, struct nfssvc_args *uap)
else if ((uap->flag & (NFSSVC_NFSDNFSD | NFSSVC_NFSDADDSOCK |
NFSSVC_PUBLICFH | NFSSVC_V4ROOTEXPORT | NFSSVC_NOPUBLICFH |
NFSSVC_STABLERESTART | NFSSVC_ADMINREVOKE |
NFSSVC_DUMPCLIENTS | NFSSVC_DUMPLOCKS | NFSSVC_BACKUPSTABLE)) &&
NFSSVC_DUMPCLIENTS | NFSSVC_DUMPLOCKS | NFSSVC_BACKUPSTABLE |
NFSSVC_SUSPENDNFSD | NFSSVC_RESUMENFSD)) &&
nfsd_call_nfsd != NULL)
error = (*nfsd_call_nfsd)(td, uap);
if (error == EINTR || error == ERESTART)

2
sys/nfs/nfssvc.h
View File

@ -66,5 +66,7 @@
#define NFSSVC_BACKUPSTABLE 0x00800000
#define NFSSVC_ZEROCLTSTATS 0x01000000 /* modifier for GETSTATS */
#define NFSSVC_ZEROSRVSTATS 0x02000000 /* modifier for GETSTATS */
#define NFSSVC_SUSPENDNFSD 0x04000000
#define NFSSVC_RESUMENFSD 0x08000000
#endif /* _NFS_NFSSVC_H */