freebsd-skq/sys/kern/kern_proc.c
Alfred Perlstein c636255150 fix races in the uidinfo subsystem, several problems existed:
1) while allocating a uidinfo struct malloc is called with M_WAITOK,
   it's possible that while asleep another process by the same user
   could have woken up earlier and inserted an entry into the uid
   hash table.  Having redundant entries causes inconsistancies that
   we can't handle.

   fix: do a non-waiting malloc, and if that fails then do a blocking
   malloc, after waking up check that no one else has inserted an entry
   for us already.

2) Because many checks for sbsize were done as "test then set" in a non
   atomic manner it was possible to exceed the limits put up via races.

   fix: instead of querying the count then setting, we just attempt to
   set the count and leave it up to the function to return success or
   failure.

3) The uidinfo code was inlining and repeating, lookups and insertions
   and deletions needed to be in their own functions for clarity.

Reviewed by: green
2000-06-22 22:27:16 +00:00

726 lines
17 KiB
C

/*
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_proc.c 8.7 (Berkeley) 2/14/95
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/filedesc.h>
#include <sys/tty.h>
#include <sys/signalvar.h>
#include <vm/vm.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <sys/user.h>
#include <vm/vm_zone.h>
static MALLOC_DEFINE(M_PGRP, "pgrp", "process group header");
MALLOC_DEFINE(M_SESSION, "session", "session header");
static MALLOC_DEFINE(M_PROC, "proc", "Proc structures");
MALLOC_DEFINE(M_SUBPROC, "subproc", "Proc sub-structures");
static void pgdelete __P((struct pgrp *));
/*
* Structure associated with user cacheing.
*/
struct uidinfo {
LIST_ENTRY(uidinfo) ui_hash;
uid_t ui_uid;
long ui_proccnt;
rlim_t ui_sbsize;
};
#define UIHASH(uid) (&uihashtbl[(uid) & uihash])
static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash; /* size of hash table - 1 */
static void orphanpg __P((struct pgrp *pg));
static struct uidinfo *uifind(uid_t uid);
static struct uidinfo *uicreate(uid_t uid);
static int uifree(struct uidinfo *uip);
/*
* Other process lists
*/
struct pidhashhead *pidhashtbl;
u_long pidhash;
struct pgrphashhead *pgrphashtbl;
u_long pgrphash;
struct proclist allproc;
struct proclist zombproc;
vm_zone_t proc_zone;
/*
* Initialize global process hashing structures.
*/
void
procinit()
{
LIST_INIT(&allproc);
LIST_INIT(&zombproc);
pidhashtbl = hashinit(maxproc / 4, M_PROC, &pidhash);
pgrphashtbl = hashinit(maxproc / 4, M_PROC, &pgrphash);
uihashtbl = hashinit(maxproc / 16, M_PROC, &uihash);
proc_zone = zinit("PROC", sizeof (struct proc), 0, 0, 5);
}
/*
* find/create a uidinfo struct for the uid passed in
*/
static struct uidinfo *
uifind(uid)
uid_t uid;
{
struct uihashhead *uipp;
struct uidinfo *uip;
uipp = UIHASH(uid);
LIST_FOREACH(uip, uipp, ui_hash)
if (uip->ui_uid == uid)
break;
return (uip);
}
static struct uidinfo *
uicreate(uid)
uid_t uid;
{
struct uidinfo *uip, *norace;
MALLOC(uip, struct uidinfo *, sizeof(*uip), M_PROC, M_NOWAIT);
if (uip == NULL) {
MALLOC(uip, struct uidinfo *, sizeof(*uip), M_PROC, M_WAITOK);
/*
* if we M_WAITOK we must look afterwards or risk
* redundant entries
*/
norace = uifind(uid);
if (norace != NULL) {
FREE(uip, M_PROC);
return (norace);
}
}
LIST_INSERT_HEAD(UIHASH(uid), uip, ui_hash);
uip->ui_uid = uid;
uip->ui_proccnt = 0;
uip->ui_sbsize = 0;
return (uip);
}
static int
uifree(uip)
struct uidinfo *uip;
{
if (uip->ui_sbsize == 0 && uip->ui_proccnt == 0) {
LIST_REMOVE(uip, ui_hash);
FREE(uip, M_PROC);
return (1);
}
return (0);
}
/*
* Change the count associated with number of processes
* a given user is using. When 'max' is 0, don't enforce a limit
*/
int
chgproccnt(uid, diff, max)
uid_t uid;
int diff;
int max;
{
struct uidinfo *uip;
uip = uifind(uid);
if (diff < 0)
KASSERT(uip != NULL, ("reducing proccnt: lost count, uid = %d", uid));
if (uip == NULL)
uip = uicreate(uid);
/* don't allow them to exceed max, but allow subtraction */
if (diff > 0 && uip->ui_proccnt + diff > max && max != 0) {
(void)uifree(uip);
return (0);
}
uip->ui_proccnt += diff;
(void)uifree(uip);
return (1);
}
/*
* Change the total socket buffer size a user has used.
*/
int
chgsbsize(uid, diff, max)
uid_t uid;
rlim_t diff;
rlim_t max;
{
struct uidinfo *uip;
uip = uifind(uid);
if (diff < 0)
KASSERT(uip != NULL, ("reducing sbsize: lost count, uid = %d", uid));
if (uip == NULL)
uip = uicreate(uid);
/* don't allow them to exceed max, but allow subtraction */
if (diff > 0 && uip->ui_sbsize + diff > max) {
(void)uifree(uip);
return (0);
}
uip->ui_sbsize += diff;
(void)uifree(uip);
return (1);
}
/*
* Is p an inferior of the current process?
*/
inT
inferior(p)
register struct proc *p;
{
for (; p != curproc; p = p->p_pptr)
if (p->p_pid == 0)
return (0);
return (1);
}
/*
* Locate a process by number
*/
struct proc *
pfind(pid)
register pid_t pid;
{
register struct proc *p;
LIST_FOREACH(p, PIDHASH(pid), p_hash)
if (p->p_pid == pid)
return (p);
return (NULL);
}
/*
* Locate a process group by number
*/
struct pgrp *
pgfind(pgid)
register pid_t pgid;
{
register struct pgrp *pgrp;
LIST_FOREACH(pgrp, PGRPHASH(pgid), pg_hash)
if (pgrp->pg_id == pgid)
return (pgrp);
return (NULL);
}
/*
* Move p to a new or existing process group (and session)
*/
int
enterpgrp(p, pgid, mksess)
register struct proc *p;
pid_t pgid;
int mksess;
{
register struct pgrp *pgrp = pgfind(pgid);
KASSERT(pgrp == NULL || !mksess,
("enterpgrp: setsid into non-empty pgrp"));
KASSERT(!SESS_LEADER(p),
("enterpgrp: session leader attempted setpgrp"));
if (pgrp == NULL) {
pid_t savepid = p->p_pid;
struct proc *np;
/*
* new process group
*/
KASSERT(p->p_pid == pgid,
("enterpgrp: new pgrp and pid != pgid"));
MALLOC(pgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP,
M_WAITOK);
if ((np = pfind(savepid)) == NULL || np != p)
return (ESRCH);
if (mksess) {
register struct session *sess;
/*
* new session
*/
MALLOC(sess, struct session *, sizeof(struct session),
M_SESSION, M_WAITOK);
sess->s_leader = p;
sess->s_sid = p->p_pid;
sess->s_count = 1;
sess->s_ttyvp = NULL;
sess->s_ttyp = NULL;
bcopy(p->p_session->s_login, sess->s_login,
sizeof(sess->s_login));
p->p_flag &= ~P_CONTROLT;
pgrp->pg_session = sess;
KASSERT(p == curproc,
("enterpgrp: mksession and p != curproc"));
} else {
pgrp->pg_session = p->p_session;
pgrp->pg_session->s_count++;
}
pgrp->pg_id = pgid;
LIST_INIT(&pgrp->pg_members);
LIST_INSERT_HEAD(PGRPHASH(pgid), pgrp, pg_hash);
pgrp->pg_jobc = 0;
SLIST_INIT(&pgrp->pg_sigiolst);
} else if (pgrp == p->p_pgrp)
return (0);
/*
* Adjust eligibility of affected pgrps to participate in job control.
* Increment eligibility counts before decrementing, otherwise we
* could reach 0 spuriously during the first call.
*/
fixjobc(p, pgrp, 1);
fixjobc(p, p->p_pgrp, 0);
LIST_REMOVE(p, p_pglist);
if (LIST_EMPTY(&p->p_pgrp->pg_members))
pgdelete(p->p_pgrp);
p->p_pgrp = pgrp;
LIST_INSERT_HEAD(&pgrp->pg_members, p, p_pglist);
return (0);
}
/*
* remove process from process group
*/
int
leavepgrp(p)
register struct proc *p;
{
LIST_REMOVE(p, p_pglist);
if (LIST_EMPTY(&p->p_pgrp->pg_members))
pgdelete(p->p_pgrp);
p->p_pgrp = 0;
return (0);
}
/*
* delete a process group
*/
static void
pgdelete(pgrp)
register struct pgrp *pgrp;
{
/*
* Reset any sigio structures pointing to us as a result of
* F_SETOWN with our pgid.
*/
funsetownlst(&pgrp->pg_sigiolst);
if (pgrp->pg_session->s_ttyp != NULL &&
pgrp->pg_session->s_ttyp->t_pgrp == pgrp)
pgrp->pg_session->s_ttyp->t_pgrp = NULL;
LIST_REMOVE(pgrp, pg_hash);
if (--pgrp->pg_session->s_count == 0)
FREE(pgrp->pg_session, M_SESSION);
FREE(pgrp, M_PGRP);
}
/*
* Adjust pgrp jobc counters when specified process changes process group.
* We count the number of processes in each process group that "qualify"
* the group for terminal job control (those with a parent in a different
* process group of the same session). If that count reaches zero, the
* process group becomes orphaned. Check both the specified process'
* process group and that of its children.
* entering == 0 => p is leaving specified group.
* entering == 1 => p is entering specified group.
*/
void
fixjobc(p, pgrp, entering)
register struct proc *p;
register struct pgrp *pgrp;
int entering;
{
register struct pgrp *hispgrp;
register struct session *mysession = pgrp->pg_session;
/*
* Check p's parent to see whether p qualifies its own process
* group; if so, adjust count for p's process group.
*/
if ((hispgrp = p->p_pptr->p_pgrp) != pgrp &&
hispgrp->pg_session == mysession) {
if (entering)
pgrp->pg_jobc++;
else if (--pgrp->pg_jobc == 0)
orphanpg(pgrp);
}
/*
* Check this process' children to see whether they qualify
* their process groups; if so, adjust counts for children's
* process groups.
*/
LIST_FOREACH(p, &p->p_children, p_sibling)
if ((hispgrp = p->p_pgrp) != pgrp &&
hispgrp->pg_session == mysession &&
p->p_stat != SZOMB) {
if (entering)
hispgrp->pg_jobc++;
else if (--hispgrp->pg_jobc == 0)
orphanpg(hispgrp);
}
}
/*
* A process group has become orphaned;
* if there are any stopped processes in the group,
* hang-up all process in that group.
*/
static void
orphanpg(pg)
struct pgrp *pg;
{
register struct proc *p;
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
if (p->p_stat == SSTOP) {
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
psignal(p, SIGHUP);
psignal(p, SIGCONT);
}
return;
}
}
}
#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>
DB_SHOW_COMMAND(pgrpdump, pgrpdump)
{
register struct pgrp *pgrp;
register struct proc *p;
register int i;
for (i = 0; i <= pgrphash; i++) {
if (!LIST_EMPTY(&pgrphashtbl[i])) {
printf("\tindx %d\n", i);
LIST_FOREACH(pgrp, &pgrphashtbl[i], pg_hash) {
printf(
"\tpgrp %p, pgid %ld, sess %p, sesscnt %d, mem %p\n",
(void *)pgrp, (long)pgrp->pg_id,
(void *)pgrp->pg_session,
pgrp->pg_session->s_count,
(void *)LIST_FIRST(&pgrp->pg_members));
LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
printf("\t\tpid %ld addr %p pgrp %p\n",
(long)p->p_pid, (void *)p,
(void *)p->p_pgrp);
}
}
}
}
}
#endif /* DDB */
/*
* Fill in an eproc structure for the specified process.
*/
void
fill_eproc(p, ep)
register struct proc *p;
register struct eproc *ep;
{
register struct tty *tp;
bzero(ep, sizeof(*ep));
ep->e_paddr = p;
if (p->p_cred) {
ep->e_pcred = *p->p_cred;
if (p->p_ucred)
ep->e_ucred = *p->p_ucred;
}
if (p->p_procsig) {
ep->e_procsig = *p->p_procsig;
}
if (p->p_stat != SIDL && p->p_stat != SZOMB && p->p_vmspace != NULL) {
register struct vmspace *vm = p->p_vmspace;
ep->e_vm = *vm;
ep->e_vm.vm_rssize = vmspace_resident_count(vm); /*XXX*/
}
if ((p->p_flag & P_INMEM) && p->p_stats)
ep->e_stats = *p->p_stats;
if (p->p_pptr)
ep->e_ppid = p->p_pptr->p_pid;
if (p->p_pgrp) {
ep->e_pgid = p->p_pgrp->pg_id;
ep->e_jobc = p->p_pgrp->pg_jobc;
ep->e_sess = p->p_pgrp->pg_session;
if (ep->e_sess) {
bcopy(ep->e_sess->s_login, ep->e_login, sizeof(ep->e_login));
if (ep->e_sess->s_ttyvp)
ep->e_flag = EPROC_CTTY;
if (p->p_session && SESS_LEADER(p))
ep->e_flag |= EPROC_SLEADER;
}
}
if ((p->p_flag & P_CONTROLT) &&
(ep->e_sess != NULL) &&
((tp = ep->e_sess->s_ttyp) != NULL)) {
ep->e_tdev = dev2udev(tp->t_dev);
ep->e_tpgid = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PID;
ep->e_tsess = tp->t_session;
} else
ep->e_tdev = NOUDEV;
if (p->p_wmesg) {
strncpy(ep->e_wmesg, p->p_wmesg, WMESGLEN);
ep->e_wmesg[WMESGLEN] = 0;
}
}
static struct proc *
zpfind(pid_t pid)
{
struct proc *p;
LIST_FOREACH(p, &zombproc, p_list)
if (p->p_pid == pid)
return (p);
return (NULL);
}
static int
sysctl_out_proc(struct proc *p, struct sysctl_req *req, int doingzomb)
{
struct eproc eproc;
int error;
pid_t pid = p->p_pid;
fill_eproc(p, &eproc);
error = SYSCTL_OUT(req,(caddr_t)p, sizeof(struct proc));
if (error)
return (error);
error = SYSCTL_OUT(req,(caddr_t)&eproc, sizeof(eproc));
if (error)
return (error);
if (!doingzomb && pid && (pfind(pid) != p))
return EAGAIN;
if (doingzomb && zpfind(pid) != p)
return EAGAIN;
return (0);
}
static int
sysctl_kern_proc SYSCTL_HANDLER_ARGS
{
int *name = (int*) arg1;
u_int namelen = arg2;
struct proc *p;
int doingzomb;
int error = 0;
if (oidp->oid_number == KERN_PROC_PID) {
if (namelen != 1)
return (EINVAL);
p = pfind((pid_t)name[0]);
if (!p)
return (0);
if (!PRISON_CHECK(curproc, p))
return (0);
error = sysctl_out_proc(p, req, 0);
return (error);
}
if (oidp->oid_number == KERN_PROC_ALL && !namelen)
;
else if (oidp->oid_number != KERN_PROC_ALL && namelen == 1)
;
else
return (EINVAL);
if (!req->oldptr) {
/* overestimate by 5 procs */
error = SYSCTL_OUT(req, 0, sizeof (struct kinfo_proc) * 5);
if (error)
return (error);
}
for (doingzomb=0 ; doingzomb < 2 ; doingzomb++) {
if (!doingzomb)
p = LIST_FIRST(&allproc);
else
p = LIST_FIRST(&zombproc);
for (; p != 0; p = LIST_NEXT(p, p_list)) {
/*
* Skip embryonic processes.
*/
if (p->p_stat == SIDL)
continue;
/*
* TODO - make more efficient (see notes below).
* do by session.
*/
switch (oidp->oid_number) {
case KERN_PROC_PGRP:
/* could do this by traversing pgrp */
if (p->p_pgrp == NULL ||
p->p_pgrp->pg_id != (pid_t)name[0])
continue;
break;
case KERN_PROC_TTY:
if ((p->p_flag & P_CONTROLT) == 0 ||
p->p_session == NULL ||
p->p_session->s_ttyp == NULL ||
dev2udev(p->p_session->s_ttyp->t_dev) !=
(udev_t)name[0])
continue;
break;
case KERN_PROC_UID:
if (p->p_ucred == NULL ||
p->p_ucred->cr_uid != (uid_t)name[0])
continue;
break;
case KERN_PROC_RUID:
if (p->p_ucred == NULL ||
p->p_cred->p_ruid != (uid_t)name[0])
continue;
break;
}
if (!PRISON_CHECK(curproc, p))
continue;
error = sysctl_out_proc(p, req, doingzomb);
if (error)
return (error);
}
}
return (0);
}
/*
* This sysctl allows a process to retrieve the argument list or process
* title for another process without groping around in the address space
* of the other process. It also allow a process to set its own "process
* title to a string of its own choice.
*/
static int
sysctl_kern_proc_args SYSCTL_HANDLER_ARGS
{
int *name = (int*) arg1;
u_int namelen = arg2;
struct proc *p;
struct pargs *pa;
int error = 0;
if (namelen != 1)
return (EINVAL);
p = pfind((pid_t)name[0]);
if (!p)
return (0);
if ((!ps_argsopen) && p_trespass(curproc, p))
return (0);
if (req->newptr && curproc != p)
return (EPERM);
if (req->oldptr && p->p_args != NULL)
error = SYSCTL_OUT(req, p->p_args->ar_args, p->p_args->ar_length);
if (req->newptr == NULL)
return (error);
if (p->p_args && --p->p_args->ar_ref == 0)
FREE(p->p_args, M_PARGS);
p->p_args = NULL;
if (req->newlen + sizeof(struct pargs) > ps_arg_cache_limit)
return (error);
MALLOC(pa, struct pargs *, sizeof(struct pargs) + req->newlen,
M_PARGS, M_WAITOK);
pa->ar_ref = 1;
pa->ar_length = req->newlen;
error = SYSCTL_IN(req, pa->ar_args, req->newlen);
if (!error)
p->p_args = pa;
else
FREE(pa, M_PARGS);
return (error);
}
SYSCTL_NODE(_kern, KERN_PROC, proc, CTLFLAG_RD, 0, "Process table");
SYSCTL_PROC(_kern_proc, KERN_PROC_ALL, all, CTLFLAG_RD|CTLTYPE_STRUCT,
0, 0, sysctl_kern_proc, "S,proc", "Return entire process table");
SYSCTL_NODE(_kern_proc, KERN_PROC_PGRP, pgrp, CTLFLAG_RD,
sysctl_kern_proc, "Process table");
SYSCTL_NODE(_kern_proc, KERN_PROC_TTY, tty, CTLFLAG_RD,
sysctl_kern_proc, "Process table");
SYSCTL_NODE(_kern_proc, KERN_PROC_UID, uid, CTLFLAG_RD,
sysctl_kern_proc, "Process table");
SYSCTL_NODE(_kern_proc, KERN_PROC_RUID, ruid, CTLFLAG_RD,
sysctl_kern_proc, "Process table");
SYSCTL_NODE(_kern_proc, KERN_PROC_PID, pid, CTLFLAG_RD,
sysctl_kern_proc, "Process table");
SYSCTL_NODE(_kern_proc, KERN_PROC_ARGS, args, CTLFLAG_RW | CTLFLAG_ANYBODY,
sysctl_kern_proc_args, "Process argument list");