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/*-
* Copyright (C) 1994, David Greenman
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org>
*
* This code is derived from software contributed to Berkeley by
* the University of Utah, and William Jolitz.
*
* 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.
*
* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
*/
#include "opt_capsicum.h"
#include "opt_ktrace.h"
#include "opt_kdtrace.h"
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/subr_syscall.c 236648 2012-06-06 01:01:12Z kib $");
#include <sys/capability.h>
#include <sys/ktr.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.h>
static inline int
syscallenter(struct thread *td, struct syscall_args *sa)
{
struct proc *p;
int error, traced;
PCPU_INC(cnt.v_syscall);
p = td->td_proc;
td->td_pticks = 0;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (p->p_flag & P_TRACED) {
traced = 1;
PROC_LOCK(p);
td->td_dbgflags &= ~TDB_USERWR;
td->td_dbgflags |= TDB_SCE;
PROC_UNLOCK(p);
} else
traced = 0;
error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
#ifdef KTRACE
if (KTRPOINT(td, KTR_SYSCALL))
ktrsyscall(sa->code, sa->narg, sa->args);
#endif
CTR6(KTR_SYSC,
"syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)",
td, td->td_proc->p_pid, syscallname(p, sa->code),
sa->args[0], sa->args[1], sa->args[2]);
if (error == 0) {
STOPEVENT(p, S_SCE, sa->narg);
if (p->p_flag & P_TRACED && p->p_stops & S_PT_SCE) {
PROC_LOCK(p);
ptracestop((td), SIGTRAP);
PROC_UNLOCK(p);
}
if (td->td_dbgflags & TDB_USERWR) {
/*
* Reread syscall number and arguments if
* debugger modified registers or memory.
*/
error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
#ifdef KTRACE
if (KTRPOINT(td, KTR_SYSCALL))
ktrsyscall(sa->code, sa->narg, sa->args);
#endif
if (error != 0)
goto retval;
}
#ifdef CAPABILITY_MODE
/*
* In capability mode, we only allow access to system calls
* flagged with SYF_CAPENABLED.
*/
if (IN_CAPABILITY_MODE(td) &&
!(sa->callp->sy_flags & SYF_CAPENABLED)) {
error = ECAPMODE;
goto retval;
}
#endif
error = syscall_thread_enter(td, sa->callp);
if (error != 0)
goto retval;
#ifdef KDTRACE_HOOKS
/*
* If the systrace module has registered it's probe
* callback and if there is a probe active for the
* syscall 'entry', process the probe.
*/
if (systrace_probe_func != NULL && sa->callp->sy_entry != 0)
(*systrace_probe_func)(sa->callp->sy_entry, sa->code,
sa->callp, sa->args, 0);
#endif
AUDIT_SYSCALL_ENTER(sa->code, td);
error = (sa->callp->sy_call)(td, sa->args);
AUDIT_SYSCALL_EXIT(error, td);
/* Save the latest error return value. */
if ((td->td_pflags & TDP_NERRNO) == 0)
td->td_errno = error;
#ifdef KDTRACE_HOOKS
/*
* If the systrace module has registered it's probe
* callback and if there is a probe active for the
* syscall 'return', process the probe.
*/
if (systrace_probe_func != NULL && sa->callp->sy_return != 0)
(*systrace_probe_func)(sa->callp->sy_return, sa->code,
sa->callp, NULL, (error) ? -1 : td->td_retval[0]);
#endif
syscall_thread_exit(td, sa->callp);
CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx",
p, error, td->td_retval[0], td->td_retval[1]);
}
retval:
if (traced) {
PROC_LOCK(p);
td->td_dbgflags &= ~TDB_SCE;
PROC_UNLOCK(p);
}
(p->p_sysent->sv_set_syscall_retval)(td, error);
return (error);
}
static inline void
syscallret(struct thread *td, int error, struct syscall_args *sa __unused)
{
struct proc *p, *p2;
int traced;
p = td->td_proc;
/*
* Check for misbehavior.
*/
WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning",
syscallname(p, sa->code));
KASSERT(td->td_critnest == 0,
("System call %s returning in a critical section",
syscallname(p, sa->code)));
KASSERT(td->td_locks == 0,
("System call %s returning with %d locks held",
syscallname(p, sa->code), td->td_locks));
KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
("System call %s returning with pagefaults disabled",
syscallname(p, sa->code)));
KASSERT((td->td_pflags & TDP_NOSLEEPING) == 0,
("System call %s returning with sleep disabled",
syscallname(p, sa->code)));
/*
* Handle reschedule and other end-of-syscall issues
*/
userret(td, td->td_frame);
CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s",
syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name);
#ifdef KTRACE
if (KTRPOINT(td, KTR_SYSRET)) {
ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
error : td->td_errno, td->td_retval[0]);
}
#endif
td->td_pflags &= ~TDP_NERRNO;
if (p->p_flag & P_TRACED) {
traced = 1;
PROC_LOCK(p);
td->td_dbgflags |= TDB_SCX;
PROC_UNLOCK(p);
} else
traced = 0;
/*
* This works because errno is findable through the
* register set. If we ever support an emulation where this
* is not the case, this code will need to be revisited.
*/
STOPEVENT(p, S_SCX, sa->code);
if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
PROC_LOCK(p);
/*
* If tracing the execed process, trap to the debugger
* so that breakpoints can be set before the program
* executes. If debugger requested tracing of syscall
* returns, do it now too.
*/
if (traced &&
((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
(p->p_stops & S_PT_SCX) != 0))
ptracestop(td, SIGTRAP);
td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
PROC_UNLOCK(p);
}
if (td->td_pflags & TDP_RFPPWAIT) {
/*
* Preserve synchronization semantics of vfork. If
* waiting for child to exec or exit, fork set
* P_PPWAIT on child, and there we sleep on our proc
* (in case of exit).
*
* Do it after the ptracestop() above is finished, to
* not block our debugger until child execs or exits
* to finish vfork wait.
*/
td->td_pflags &= ~TDP_RFPPWAIT;
p2 = td->td_rfppwait_p;
PROC_LOCK(p2);
while (p2->p_flag & P_PPWAIT)
cv_wait(&p2->p_pwait, &p2->p_mtx);
PROC_UNLOCK(p2);
}
}