Date: Fri, 5 May 2017 18:49:39 +0000 (UTC) From: Brooks Davis <brooks@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r317845 - in head: lib/libc/sys sys/compat/freebsd32 sys/kern sys/sys Message-ID: <201705051849.v45IndZM002719@repo.freebsd.org>
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Author: brooks Date: Fri May 5 18:49:39 2017 New Revision: 317845 URL: https://svnweb.freebsd.org/changeset/base/317845 Log: 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 Modified: head/lib/libc/sys/sigqueue.2 head/sys/compat/freebsd32/freebsd32_misc.c head/sys/compat/freebsd32/syscalls.master head/sys/kern/kern_sig.c head/sys/sys/syscallsubr.h Modified: head/lib/libc/sys/sigqueue.2 ============================================================================== --- head/lib/libc/sys/sigqueue.2 Fri May 5 18:36:41 2017 (r317844) +++ head/lib/libc/sys/sigqueue.2 Fri May 5 18:49:39 2017 (r317845) @@ -27,7 +27,7 @@ .\" .\" $FreeBSD$ .\" -.Dd March 10, 2012 +.Dd May 5, 2017 .Dt SIGQUEUE 2 .Os .Sh NAME @@ -129,7 +129,6 @@ does not exist. .Xr kill 2 , .Xr sigaction 2 , .Xr sigpending 2 , -.Xr sigqueue 2 , .Xr sigsuspend 2 , .Xr sigtimedwait 2 , .Xr sigwait 2 , @@ -147,3 +146,18 @@ Support for .Tn POSIX realtime signal queue first appeared in .Fx 7.0 . +.Sh CAVEATS +When using +.Nm +to send signals to a process which might have a different ABI +(for instance, one is 32-bit and the other 64-bit), +the +.Va sival_int +member of +.Fa value +can be delivered reliably, but the +.Va sival_ptr +may be truncated in endian dependent ways and must not be relied on. +Further, many pointer integrity schemes disallow sending pointers to other +processes, and this technique should not be used in programs intended to +be portable. Modified: head/sys/compat/freebsd32/freebsd32_misc.c ============================================================================== --- head/sys/compat/freebsd32/freebsd32_misc.c Fri May 5 18:36:41 2017 (r317844) +++ head/sys/compat/freebsd32/freebsd32_misc.c Fri May 5 18:49:39 2017 (r317845) @@ -2477,6 +2477,32 @@ siginfo_to_siginfo32(const siginfo_t *sr dst->si_overrun = src->si_overrun; } +#ifndef _FREEBSD32_SYSPROTO_H_ +struct freebsd32_sigqueue_args { + pid_t pid; + int signum; + /* union sigval32 */ int value; +}; +#endif +int +freebsd32_sigqueue(struct thread *td, struct freebsd32_sigqueue_args *uap) +{ + union sigval sv; + + /* + * On 32-bit ABIs, sival_int and sival_ptr are the same. + * On 64-bit little-endian ABIs, the low bits are the same. + * In 64-bit big-endian ABIs, sival_int overlaps with + * sival_ptr's HIGH bits. We choose to support sival_int + * rather than sival_ptr in this case as it seems to be + * more common. + */ + bzero(&sv, sizeof(sv)); + sv.sival_int = uap->value; + + return (kern_sigqueue(td, uap->pid, uap->signum, &sv)); +} + int freebsd32_sigtimedwait(struct thread *td, struct freebsd32_sigtimedwait_args *uap) { Modified: head/sys/compat/freebsd32/syscalls.master ============================================================================== --- head/sys/compat/freebsd32/syscalls.master Fri May 5 18:36:41 2017 (r317844) +++ head/sys/compat/freebsd32/syscalls.master Fri May 5 18:49:39 2017 (r317845) @@ -819,8 +819,8 @@ 455 AUE_THR_NEW STD { int freebsd32_thr_new( \ struct thr_param32 *param, \ int param_size); } -456 AUE_NULL NOPROTO { int sigqueue(pid_t pid, int signum, \ - void *value); } +456 AUE_NULL STD { int freebsd32_sigqueue(pid_t pid, \ + int signum, int value); } 457 AUE_MQ_OPEN NOSTD { int freebsd32_kmq_open( \ const char *path, int flags, mode_t mode, \ const struct mq_attr32 *attr); } Modified: head/sys/kern/kern_sig.c ============================================================================== --- head/sys/kern/kern_sig.c Fri May 5 18:36:41 2017 (r317844) +++ head/sys/kern/kern_sig.c Fri May 5 18:49:39 2017 (r317845) @@ -1844,33 +1844,43 @@ struct sigqueue_args { int sys_sigqueue(struct thread *td, struct sigqueue_args *uap) { + union sigval sv; + + sv.sival_ptr = uap->value; + + return (kern_sigqueue(td, uap->pid, uap->signum, &sv)); +} + +int +kern_sigqueue(struct thread *td, pid_t pid, int signum, union sigval *value) +{ ksiginfo_t ksi; struct proc *p; int error; - if ((u_int)uap->signum > _SIG_MAXSIG) + if ((u_int)signum > _SIG_MAXSIG) return (EINVAL); /* * Specification says sigqueue can only send signal to * single process. */ - if (uap->pid <= 0) + if (pid <= 0) return (EINVAL); - if ((p = pfind(uap->pid)) == NULL) { - if ((p = zpfind(uap->pid)) == NULL) + if ((p = pfind(pid)) == NULL) { + if ((p = zpfind(pid)) == NULL) return (ESRCH); } - error = p_cansignal(td, p, uap->signum); - if (error == 0 && uap->signum != 0) { + error = p_cansignal(td, p, signum); + if (error == 0 && signum != 0) { ksiginfo_init(&ksi); ksi.ksi_flags = KSI_SIGQ; - ksi.ksi_signo = uap->signum; + ksi.ksi_signo = signum; ksi.ksi_code = SI_QUEUE; ksi.ksi_pid = td->td_proc->p_pid; ksi.ksi_uid = td->td_ucred->cr_ruid; - ksi.ksi_value.sival_ptr = uap->value; + ksi.ksi_value = *value; error = pksignal(p, ksi.ksi_signo, &ksi); } PROC_UNLOCK(p); Modified: head/sys/sys/syscallsubr.h ============================================================================== --- head/sys/sys/syscallsubr.h Fri May 5 18:36:41 2017 (r317844) +++ head/sys/sys/syscallsubr.h Fri May 5 18:49:39 2017 (r317845) @@ -249,6 +249,8 @@ int kern_sigprocmask(struct thread *td, int kern_sigsuspend(struct thread *td, sigset_t mask); int kern_sigtimedwait(struct thread *td, sigset_t waitset, struct ksiginfo *ksi, struct timespec *timeout); +int kern_sigqueue(struct thread *td, pid_t pid, int signum, + union sigval *value); int kern_socket(struct thread *td, int domain, int type, int protocol); int kern_statat(struct thread *td, int flag, int fd, char *path, enum uio_seg pathseg, struct stat *sbp,
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