Provide a freebsd32 implementation of sigqueue()
The previous misuse of sys_sigqueue() was sending random register or stack garbage to 64-bit targets. The freebsd32 implementation preserves the sival_int member of value when signaling a 64-bit process. Document the mixed ABI implementation of union sigval and the incompability of sival_ptr with pointer integrity schemes. Reviewed by: kib, wblock MFC after: 1 week Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D10605
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2020-12-20 02:59:44 +00:00
svn path=/head/; revision=317845
@ -27,7 +27,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 10, 2012
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.Dd May 5, 2017
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.Dt SIGQUEUE 2
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.Os
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.Sh NAME
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@ -129,7 +129,6 @@ does not exist.
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.Xr kill 2 ,
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.Xr sigaction 2 ,
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.Xr sigpending 2 ,
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.Xr sigqueue 2 ,
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.Xr sigsuspend 2 ,
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.Xr sigtimedwait 2 ,
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.Xr sigwait 2 ,
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@ -147,3 +146,18 @@ Support for
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.Tn POSIX
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realtime signal queue first appeared in
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.Fx 7.0 .
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.Sh CAVEATS
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When using
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.Nm
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to send signals to a process which might have a different ABI
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(for instance, one is 32-bit and the other 64-bit),
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the
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.Va sival_int
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member of
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.Fa value
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can be delivered reliably, but the
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.Va sival_ptr
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may be truncated in endian dependent ways and must not be relied on.
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Further, many pointer integrity schemes disallow sending pointers to other
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processes, and this technique should not be used in programs intended to
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be portable.
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@ -2477,6 +2477,32 @@ siginfo_to_siginfo32(const siginfo_t *src, struct siginfo32 *dst)
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dst->si_overrun = src->si_overrun;
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}
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#ifndef _FREEBSD32_SYSPROTO_H_
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struct freebsd32_sigqueue_args {
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pid_t pid;
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int signum;
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/* union sigval32 */ int value;
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};
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#endif
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int
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freebsd32_sigqueue(struct thread *td, struct freebsd32_sigqueue_args *uap)
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{
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union sigval sv;
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/*
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* On 32-bit ABIs, sival_int and sival_ptr are the same.
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* On 64-bit little-endian ABIs, the low bits are the same.
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* In 64-bit big-endian ABIs, sival_int overlaps with
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* sival_ptr's HIGH bits. We choose to support sival_int
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* rather than sival_ptr in this case as it seems to be
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* more common.
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*/
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bzero(&sv, sizeof(sv));
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sv.sival_int = uap->value;
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return (kern_sigqueue(td, uap->pid, uap->signum, &sv));
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}
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int
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freebsd32_sigtimedwait(struct thread *td, struct freebsd32_sigtimedwait_args *uap)
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{
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@ -819,8 +819,8 @@
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455 AUE_THR_NEW STD { int freebsd32_thr_new( \
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struct thr_param32 *param, \
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int param_size); }
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456 AUE_NULL NOPROTO { int sigqueue(pid_t pid, int signum, \
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void *value); }
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456 AUE_NULL STD { int freebsd32_sigqueue(pid_t pid, \
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int signum, int value); }
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457 AUE_MQ_OPEN NOSTD { int freebsd32_kmq_open( \
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const char *path, int flags, mode_t mode, \
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const struct mq_attr32 *attr); }
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@ -1843,34 +1843,44 @@ struct sigqueue_args {
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#endif
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int
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sys_sigqueue(struct thread *td, struct sigqueue_args *uap)
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{
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union sigval sv;
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sv.sival_ptr = uap->value;
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return (kern_sigqueue(td, uap->pid, uap->signum, &sv));
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}
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int
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kern_sigqueue(struct thread *td, pid_t pid, int signum, union sigval *value)
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{
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ksiginfo_t ksi;
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struct proc *p;
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int error;
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if ((u_int)uap->signum > _SIG_MAXSIG)
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if ((u_int)signum > _SIG_MAXSIG)
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return (EINVAL);
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/*
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* Specification says sigqueue can only send signal to
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* single process.
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*/
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if (uap->pid <= 0)
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if (pid <= 0)
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return (EINVAL);
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if ((p = pfind(uap->pid)) == NULL) {
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if ((p = zpfind(uap->pid)) == NULL)
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if ((p = pfind(pid)) == NULL) {
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if ((p = zpfind(pid)) == NULL)
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return (ESRCH);
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}
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error = p_cansignal(td, p, uap->signum);
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if (error == 0 && uap->signum != 0) {
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error = p_cansignal(td, p, signum);
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if (error == 0 && signum != 0) {
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ksiginfo_init(&ksi);
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ksi.ksi_flags = KSI_SIGQ;
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ksi.ksi_signo = uap->signum;
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ksi.ksi_signo = signum;
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ksi.ksi_code = SI_QUEUE;
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ksi.ksi_pid = td->td_proc->p_pid;
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ksi.ksi_uid = td->td_ucred->cr_ruid;
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ksi.ksi_value.sival_ptr = uap->value;
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ksi.ksi_value = *value;
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error = pksignal(p, ksi.ksi_signo, &ksi);
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}
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PROC_UNLOCK(p);
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@ -249,6 +249,8 @@ int kern_sigprocmask(struct thread *td, int how,
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int kern_sigsuspend(struct thread *td, sigset_t mask);
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int kern_sigtimedwait(struct thread *td, sigset_t waitset,
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struct ksiginfo *ksi, struct timespec *timeout);
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int kern_sigqueue(struct thread *td, pid_t pid, int signum,
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union sigval *value);
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int kern_socket(struct thread *td, int domain, int type, int protocol);
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int kern_statat(struct thread *td, int flag, int fd, char *path,
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enum uio_seg pathseg, struct stat *sbp,
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