d6e029adbe
while in kernel mode, and later changing signal mask to block the signal, was fixed for sigprocmask(2) and ptread_exit(3). The same race exists for sigreturn(2), setcontext(2) and swapcontext(2) syscalls. Use kern_sigprocmask() instead of direct manipulation of td_sigmask to reschedule newly blocked signals, closing the race. Reviewed by: davidxu Tested by: pho MFC after: 1 month
127 lines
3.4 KiB
C
127 lines
3.4 KiB
C
/*-
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* Copyright (c) 2002 Daniel M. Eischen <deischen@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/sysent.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/signalvar.h>
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#include <sys/ucontext.h>
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/*
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* The first two fields of a ucontext_t are the signal mask and the machine
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* context. The next field is uc_link; we want to avoid destroying the link
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* when copying out contexts.
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*/
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#define UC_COPY_SIZE offsetof(ucontext_t, uc_link)
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#ifndef _SYS_SYSPROTO_H_
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struct getcontext_args {
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struct __ucontext *ucp;
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}
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struct setcontext_args {
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const struct __ucontext_t *ucp;
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}
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struct swapcontext_args {
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struct __ucontext *oucp;
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const struct __ucontext_t *ucp;
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}
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#endif
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int
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getcontext(struct thread *td, struct getcontext_args *uap)
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{
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ucontext_t uc;
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int ret;
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if (uap->ucp == NULL)
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ret = EINVAL;
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else {
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get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
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PROC_LOCK(td->td_proc);
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uc.uc_sigmask = td->td_sigmask;
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PROC_UNLOCK(td->td_proc);
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ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
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}
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return (ret);
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}
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int
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setcontext(struct thread *td, struct setcontext_args *uap)
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{
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ucontext_t uc;
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int ret;
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if (uap->ucp == NULL)
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ret = EINVAL;
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else {
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ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
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if (ret == 0) {
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ret = set_mcontext(td, &uc.uc_mcontext);
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if (ret == 0) {
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kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask,
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NULL, 0);
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}
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}
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}
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return (ret == 0 ? EJUSTRETURN : ret);
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}
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int
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swapcontext(struct thread *td, struct swapcontext_args *uap)
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{
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ucontext_t uc;
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int ret;
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if (uap->oucp == NULL || uap->ucp == NULL)
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ret = EINVAL;
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else {
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get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
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PROC_LOCK(td->td_proc);
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uc.uc_sigmask = td->td_sigmask;
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PROC_UNLOCK(td->td_proc);
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ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
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if (ret == 0) {
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ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
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if (ret == 0) {
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ret = set_mcontext(td, &uc.uc_mcontext);
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if (ret == 0) {
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kern_sigprocmask(td, SIG_SETMASK,
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&uc.uc_sigmask, NULL, 0);
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}
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}
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}
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}
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return (ret == 0 ? EJUSTRETURN : ret);
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}
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