freebsd-dev/sys/kern/kern_thr.c
Eric Badger 82a4538f31 Defer ptracestop() signals that cannot be delivered immediately
When a thread is stopped in ptracestop(), the ptrace(2) user may request
a signal be delivered upon resumption of the thread. Heretofore, those signals
were discarded unless ptracestop()'s caller was issignal(). Fix this by
modifying ptracestop() to queue up signals requested by the ptrace user that
will be delivered when possible. Take special care when the signal is SIGKILL
(usually generated from a PT_KILL request); no new stop events should be
triggered after a PT_KILL.

Add a number of tests for the new functionality. Several tests were authored
by jhb.

PR:		212607
Reviewed by:	kib
Approved by:	kib (mentor)
MFC after:	2 weeks
Sponsored by:	Dell EMC
In collaboration with:	jhb
Differential Revision:	https://reviews.freebsd.org/D9260
2017-02-20 15:53:16 +00:00

617 lines
14 KiB
C

/*-
* Copyright (c) 2003, Jeffrey Roberson <jeff@freebsd.org>
* 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 unmodified, 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#include "opt_posix.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/posix4.h>
#include <sys/ptrace.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#include <sys/smp.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/ucontext.h>
#include <sys/thr.h>
#include <sys/rtprio.h>
#include <sys/umtx.h>
#include <sys/limits.h>
#include <vm/vm_domain.h>
#include <machine/frame.h>
#include <security/audit/audit.h>
static SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0,
"thread allocation");
static int max_threads_per_proc = 1500;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW,
&max_threads_per_proc, 0, "Limit on threads per proc");
static int max_threads_hits;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
&max_threads_hits, 0, "kern.threads.max_threads_per_proc hit count");
#ifdef COMPAT_FREEBSD32
static inline int
suword_lwpid(void *addr, lwpid_t lwpid)
{
int error;
if (SV_CURPROC_FLAG(SV_LP64))
error = suword(addr, lwpid);
else
error = suword32(addr, lwpid);
return (error);
}
#else
#define suword_lwpid suword
#endif
/*
* System call interface.
*/
struct thr_create_initthr_args {
ucontext_t ctx;
long *tid;
};
static int
thr_create_initthr(struct thread *td, void *thunk)
{
struct thr_create_initthr_args *args;
/* Copy out the child tid. */
args = thunk;
if (args->tid != NULL && suword_lwpid(args->tid, td->td_tid))
return (EFAULT);
return (set_mcontext(td, &args->ctx.uc_mcontext));
}
int
sys_thr_create(struct thread *td, struct thr_create_args *uap)
/* ucontext_t *ctx, long *id, int flags */
{
struct thr_create_initthr_args args;
int error;
if ((error = copyin(uap->ctx, &args.ctx, sizeof(args.ctx))))
return (error);
args.tid = uap->id;
return (thread_create(td, NULL, thr_create_initthr, &args));
}
int
sys_thr_new(struct thread *td, struct thr_new_args *uap)
/* struct thr_param * */
{
struct thr_param param;
int error;
if (uap->param_size < 0 || uap->param_size > sizeof(param))
return (EINVAL);
bzero(&param, sizeof(param));
if ((error = copyin(uap->param, &param, uap->param_size)))
return (error);
return (kern_thr_new(td, &param));
}
static int
thr_new_initthr(struct thread *td, void *thunk)
{
stack_t stack;
struct thr_param *param;
/*
* Here we copy out tid to two places, one for child and one
* for parent, because pthread can create a detached thread,
* if parent wants to safely access child tid, it has to provide
* its storage, because child thread may exit quickly and
* memory is freed before parent thread can access it.
*/
param = thunk;
if ((param->child_tid != NULL &&
suword_lwpid(param->child_tid, td->td_tid)) ||
(param->parent_tid != NULL &&
suword_lwpid(param->parent_tid, td->td_tid)))
return (EFAULT);
/* Set up our machine context. */
stack.ss_sp = param->stack_base;
stack.ss_size = param->stack_size;
/* Set upcall address to user thread entry function. */
cpu_set_upcall(td, param->start_func, param->arg, &stack);
/* Setup user TLS address and TLS pointer register. */
return (cpu_set_user_tls(td, param->tls_base));
}
int
kern_thr_new(struct thread *td, struct thr_param *param)
{
struct rtprio rtp, *rtpp;
int error;
rtpp = NULL;
if (param->rtp != 0) {
error = copyin(param->rtp, &rtp, sizeof(struct rtprio));
if (error)
return (error);
rtpp = &rtp;
}
return (thread_create(td, rtpp, thr_new_initthr, param));
}
int
thread_create(struct thread *td, struct rtprio *rtp,
int (*initialize_thread)(struct thread *, void *), void *thunk)
{
struct thread *newtd;
struct proc *p;
int error;
p = td->td_proc;
if (rtp != NULL) {
switch(rtp->type) {
case RTP_PRIO_REALTIME:
case RTP_PRIO_FIFO:
/* Only root can set scheduler policy */
if (priv_check(td, PRIV_SCHED_SETPOLICY) != 0)
return (EPERM);
if (rtp->prio > RTP_PRIO_MAX)
return (EINVAL);
break;
case RTP_PRIO_NORMAL:
rtp->prio = 0;
break;
default:
return (EINVAL);
}
}
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(p);
error = racct_add(p, RACCT_NTHR, 1);
PROC_UNLOCK(p);
if (error != 0)
return (EPROCLIM);
}
#endif
/* Initialize our td */
error = kern_thr_alloc(p, 0, &newtd);
if (error)
goto fail;
cpu_copy_thread(newtd, td);
bzero(&newtd->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
bcopy(&td->td_startcopy, &newtd->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
newtd->td_proc = td->td_proc;
newtd->td_rb_list = newtd->td_rbp_list = newtd->td_rb_inact = 0;
thread_cow_get(newtd, td);
error = initialize_thread(newtd, thunk);
if (error != 0) {
thread_cow_free(newtd);
thread_free(newtd);
goto fail;
}
PROC_LOCK(p);
p->p_flag |= P_HADTHREADS;
thread_link(newtd, p);
bcopy(p->p_comm, newtd->td_name, sizeof(newtd->td_name));
thread_lock(td);
/* let the scheduler know about these things. */
sched_fork_thread(td, newtd);
thread_unlock(td);
if (P_SHOULDSTOP(p))
newtd->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
if (p->p_ptevents & PTRACE_LWP)
newtd->td_dbgflags |= TDB_BORN;
/*
* Copy the existing thread VM policy into the new thread.
*/
vm_domain_policy_localcopy(&newtd->td_vm_dom_policy,
&td->td_vm_dom_policy);
PROC_UNLOCK(p);
tidhash_add(newtd);
thread_lock(newtd);
if (rtp != NULL) {
if (!(td->td_pri_class == PRI_TIMESHARE &&
rtp->type == RTP_PRIO_NORMAL)) {
rtp_to_pri(rtp, newtd);
sched_prio(newtd, newtd->td_user_pri);
} /* ignore timesharing class */
}
TD_SET_CAN_RUN(newtd);
sched_add(newtd, SRQ_BORING);
thread_unlock(newtd);
return (0);
fail:
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(p);
racct_sub(p, RACCT_NTHR, 1);
PROC_UNLOCK(p);
}
#endif
return (error);
}
int
sys_thr_self(struct thread *td, struct thr_self_args *uap)
/* long *id */
{
int error;
error = suword_lwpid(uap->id, (unsigned)td->td_tid);
if (error == -1)
return (EFAULT);
return (0);
}
int
sys_thr_exit(struct thread *td, struct thr_exit_args *uap)
/* long *state */
{
umtx_thread_exit(td);
/* Signal userland that it can free the stack. */
if ((void *)uap->state != NULL) {
suword_lwpid(uap->state, 1);
kern_umtx_wake(td, uap->state, INT_MAX, 0);
}
return (kern_thr_exit(td));
}
int
kern_thr_exit(struct thread *td)
{
struct proc *p;
p = td->td_proc;
/*
* If all of the threads in a process call this routine to
* exit (e.g. all threads call pthread_exit()), exactly one
* thread should return to the caller to terminate the process
* instead of the thread.
*
* Checking p_numthreads alone is not sufficient since threads
* might be committed to terminating while the PROC_LOCK is
* dropped in either ptracestop() or while removing this thread
* from the tidhash. Instead, the p_pendingexits field holds
* the count of threads in either of those states and a thread
* is considered the "last" thread if all of the other threads
* in a process are already terminating.
*/
PROC_LOCK(p);
if (p->p_numthreads == p->p_pendingexits + 1) {
/*
* Ignore attempts to shut down last thread in the
* proc. This will actually call _exit(2) in the
* usermode trampoline when it returns.
*/
PROC_UNLOCK(p);
return (0);
}
p->p_pendingexits++;
td->td_dbgflags |= TDB_EXIT;
if (p->p_ptevents & PTRACE_LWP)
ptracestop(td, SIGTRAP, NULL);
PROC_UNLOCK(p);
tidhash_remove(td);
PROC_LOCK(p);
p->p_pendingexits--;
/*
* The check above should prevent all other threads from this
* process from exiting while the PROC_LOCK is dropped, so
* there must be at least one other thread other than the
* current thread.
*/
KASSERT(p->p_numthreads > 1, ("too few threads"));
racct_sub(p, RACCT_NTHR, 1);
tdsigcleanup(td);
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();
/* NOTREACHED */
}
int
sys_thr_kill(struct thread *td, struct thr_kill_args *uap)
/* long id, int sig */
{
ksiginfo_t ksi;
struct thread *ttd;
struct proc *p;
int error;
p = td->td_proc;
ksiginfo_init(&ksi);
ksi.ksi_signo = uap->sig;
ksi.ksi_code = SI_LWP;
ksi.ksi_pid = p->p_pid;
ksi.ksi_uid = td->td_ucred->cr_ruid;
if (uap->id == -1) {
if (uap->sig != 0 && !_SIG_VALID(uap->sig)) {
error = EINVAL;
} else {
error = ESRCH;
PROC_LOCK(p);
FOREACH_THREAD_IN_PROC(p, ttd) {
if (ttd != td) {
error = 0;
if (uap->sig == 0)
break;
tdksignal(ttd, uap->sig, &ksi);
}
}
PROC_UNLOCK(p);
}
} else {
error = 0;
ttd = tdfind((lwpid_t)uap->id, p->p_pid);
if (ttd == NULL)
return (ESRCH);
if (uap->sig == 0)
;
else if (!_SIG_VALID(uap->sig))
error = EINVAL;
else
tdksignal(ttd, uap->sig, &ksi);
PROC_UNLOCK(ttd->td_proc);
}
return (error);
}
int
sys_thr_kill2(struct thread *td, struct thr_kill2_args *uap)
/* pid_t pid, long id, int sig */
{
ksiginfo_t ksi;
struct thread *ttd;
struct proc *p;
int error;
AUDIT_ARG_SIGNUM(uap->sig);
ksiginfo_init(&ksi);
ksi.ksi_signo = uap->sig;
ksi.ksi_code = SI_LWP;
ksi.ksi_pid = td->td_proc->p_pid;
ksi.ksi_uid = td->td_ucred->cr_ruid;
if (uap->id == -1) {
if ((p = pfind(uap->pid)) == NULL)
return (ESRCH);
AUDIT_ARG_PROCESS(p);
error = p_cansignal(td, p, uap->sig);
if (error) {
PROC_UNLOCK(p);
return (error);
}
if (uap->sig != 0 && !_SIG_VALID(uap->sig)) {
error = EINVAL;
} else {
error = ESRCH;
FOREACH_THREAD_IN_PROC(p, ttd) {
if (ttd != td) {
error = 0;
if (uap->sig == 0)
break;
tdksignal(ttd, uap->sig, &ksi);
}
}
}
PROC_UNLOCK(p);
} else {
ttd = tdfind((lwpid_t)uap->id, uap->pid);
if (ttd == NULL)
return (ESRCH);
p = ttd->td_proc;
AUDIT_ARG_PROCESS(p);
error = p_cansignal(td, p, uap->sig);
if (uap->sig == 0)
;
else if (!_SIG_VALID(uap->sig))
error = EINVAL;
else
tdksignal(ttd, uap->sig, &ksi);
PROC_UNLOCK(p);
}
return (error);
}
int
sys_thr_suspend(struct thread *td, struct thr_suspend_args *uap)
/* const struct timespec *timeout */
{
struct timespec ts, *tsp;
int error;
tsp = NULL;
if (uap->timeout != NULL) {
error = umtx_copyin_timeout(uap->timeout, &ts);
if (error != 0)
return (error);
tsp = &ts;
}
return (kern_thr_suspend(td, tsp));
}
int
kern_thr_suspend(struct thread *td, struct timespec *tsp)
{
struct proc *p = td->td_proc;
struct timeval tv;
int error = 0;
int timo = 0;
if (td->td_pflags & TDP_WAKEUP) {
td->td_pflags &= ~TDP_WAKEUP;
return (0);
}
if (tsp != NULL) {
if (tsp->tv_sec == 0 && tsp->tv_nsec == 0)
error = EWOULDBLOCK;
else {
TIMESPEC_TO_TIMEVAL(&tv, tsp);
timo = tvtohz(&tv);
}
}
PROC_LOCK(p);
if (error == 0 && (td->td_flags & TDF_THRWAKEUP) == 0)
error = msleep((void *)td, &p->p_mtx,
PCATCH, "lthr", timo);
if (td->td_flags & TDF_THRWAKEUP) {
thread_lock(td);
td->td_flags &= ~TDF_THRWAKEUP;
thread_unlock(td);
PROC_UNLOCK(p);
return (0);
}
PROC_UNLOCK(p);
if (error == EWOULDBLOCK)
error = ETIMEDOUT;
else if (error == ERESTART) {
if (timo != 0)
error = EINTR;
}
return (error);
}
int
sys_thr_wake(struct thread *td, struct thr_wake_args *uap)
/* long id */
{
struct proc *p;
struct thread *ttd;
if (uap->id == td->td_tid) {
td->td_pflags |= TDP_WAKEUP;
return (0);
}
p = td->td_proc;
ttd = tdfind((lwpid_t)uap->id, p->p_pid);
if (ttd == NULL)
return (ESRCH);
thread_lock(ttd);
ttd->td_flags |= TDF_THRWAKEUP;
thread_unlock(ttd);
wakeup((void *)ttd);
PROC_UNLOCK(p);
return (0);
}
int
sys_thr_set_name(struct thread *td, struct thr_set_name_args *uap)
{
struct proc *p;
char name[MAXCOMLEN + 1];
struct thread *ttd;
int error;
error = 0;
name[0] = '\0';
if (uap->name != NULL) {
error = copyinstr(uap->name, name, sizeof(name), NULL);
if (error == ENAMETOOLONG) {
error = copyin(uap->name, name, sizeof(name) - 1);
name[sizeof(name) - 1] = '\0';
}
if (error)
return (error);
}
p = td->td_proc;
ttd = tdfind((lwpid_t)uap->id, p->p_pid);
if (ttd == NULL)
return (ESRCH);
strcpy(ttd->td_name, name);
#ifdef KTR
sched_clear_tdname(ttd);
#endif
PROC_UNLOCK(p);
return (error);
}
int
kern_thr_alloc(struct proc *p, int pages, struct thread **ntd)
{
/* Have race condition but it is cheap. */
if (p->p_numthreads >= max_threads_per_proc) {
++max_threads_hits;
return (EPROCLIM);
}
*ntd = thread_alloc(pages);
if (*ntd == NULL)
return (ENOMEM);
return (0);
}