freebsd-dev/sys/kern/subr_trap.c
Robert Watson fc94e4476b Continue introducing Capsicum capability mode support:
If a system call wasn't listed in capabilities.conf, return ECAPMODE at
syscall entry.

Reviewed by:	anderson
Discussed with:	benl, kris, pjd
Sponsored by:	Google, Inc.
Obtained from:	Capsicum Project
MFC after:	3 months
2011-03-01 13:32:07 +00:00

428 lines
11 KiB
C

/*-
* Copyright (C) 1994, David Greenman
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (c) 2007 The FreeBSD Foundation
*
* This code is derived from software contributed to Berkeley by
* the University of Utah, and William Jolitz.
*
* Portions of this software were developed by A. Joseph Koshy under
* sponsorship from the FreeBSD Foundation and Google, Inc.
*
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_capabilities.h"
#include "opt_ktrace.h"
#include "opt_kdtrace.h"
#include "opt_sched.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/capability.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/pmckern.h>
#include <sys/proc.h>
#include <sys/ktr.h>
#include <sys/pioctl.h>
#include <sys/ptrace.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/syscall.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/vmmeter.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.h>
#include <machine/cpu.h>
#ifdef VIMAGE
#include <net/vnet.h>
#endif
#ifdef XEN
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#endif
#include <security/mac/mac_framework.h>
/*
* Define the code needed before returning to user mode, for trap and
* syscall.
*/
void
userret(struct thread *td, struct trapframe *frame)
{
struct proc *p = td->td_proc;
CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
td->td_name);
#if 0
#ifdef DIAGNOSTIC
/* Check that we called signotify() enough. */
PROC_LOCK(p);
thread_lock(td);
if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
(td->td_flags & TDF_ASTPENDING) == 0))
printf("failed to set signal flags properly for ast()\n");
thread_unlock(td);
PROC_UNLOCK(p);
#endif
#endif
#ifdef KTRACE
KTRUSERRET(td);
#endif
/*
* If this thread tickled GEOM, we need to wait for the giggling to
* stop before we return to userland
*/
if (td->td_pflags & TDP_GEOM)
g_waitidle();
/*
* Charge system time if profiling.
*/
if (p->p_flag & P_PROFIL)
addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
/*
* Let the scheduler adjust our priority etc.
*/
sched_userret(td);
KASSERT(td->td_locks == 0,
("userret: Returning with %d locks held.", td->td_locks));
#ifdef VIMAGE
/* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
VNET_ASSERT(curvnet == NULL,
("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
__func__, td, p->p_pid, td->td_name, curvnet,
(td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
#endif
#ifdef XEN
PT_UPDATES_FLUSH();
#endif
}
/*
* Process an asynchronous software trap.
* This is relatively easy.
* This function will return with preemption disabled.
*/
void
ast(struct trapframe *framep)
{
struct thread *td;
struct proc *p;
int flags;
int sig;
td = curthread;
p = td->td_proc;
CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
p->p_comm);
KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
mtx_assert(&Giant, MA_NOTOWNED);
THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
td->td_frame = framep;
td->td_pticks = 0;
/*
* This updates the td_flag's for the checks below in one
* "atomic" operation with turning off the astpending flag.
* If another AST is triggered while we are handling the
* AST's saved in flags, the astpending flag will be set and
* ast() will be called again.
*/
thread_lock(td);
flags = td->td_flags;
td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
thread_unlock(td);
PCPU_INC(cnt.v_trap);
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
td->td_profil_ticks = 0;
td->td_pflags &= ~TDP_OWEUPC;
}
if (flags & TDF_ALRMPEND) {
PROC_LOCK(p);
psignal(p, SIGVTALRM);
PROC_UNLOCK(p);
}
if (flags & TDF_PROFPEND) {
PROC_LOCK(p);
psignal(p, SIGPROF);
PROC_UNLOCK(p);
}
#ifdef MAC
if (flags & TDF_MACPEND)
mac_thread_userret(td);
#endif
if (flags & TDF_NEEDRESCHED) {
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(1, 1);
#endif
thread_lock(td);
sched_prio(td, td->td_user_pri);
mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
thread_unlock(td);
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(0, 1);
#endif
}
/*
* Check for signals. Unlocked reads of p_pendingcnt or
* p_siglist might cause process-directed signal to be handled
* later.
*/
if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
!SIGISEMPTY(p->p_siglist)) {
PROC_LOCK(p);
mtx_lock(&p->p_sigacts->ps_mtx);
while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
postsig(sig);
mtx_unlock(&p->p_sigacts->ps_mtx);
PROC_UNLOCK(p);
}
/*
* We need to check to see if we have to exit or wait due to a
* single threading requirement or some other STOP condition.
*/
if (flags & TDF_NEEDSUSPCHK) {
PROC_LOCK(p);
thread_suspend_check(0);
PROC_UNLOCK(p);
}
if (td->td_pflags & TDP_OLDMASK) {
td->td_pflags &= ~TDP_OLDMASK;
kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
}
userret(td, framep);
mtx_assert(&Giant, MA_NOTOWNED);
}
#ifdef HAVE_SYSCALL_ARGS_DEF
const char *
syscallname(struct proc *p, u_int code)
{
static const char unknown[] = "unknown";
struct sysentvec *sv;
sv = p->p_sysent;
if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
return (unknown);
return (sv->sv_syscallnames[code]);
}
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);
PTRACESTOP_SC(p, td, S_PT_SCE);
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 CAPABILITIES
/*
* 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. */
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);
}
void
syscallret(struct thread *td, int error, struct syscall_args *sa __unused)
{
struct proc *p;
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));
/*
* 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, error, td->td_retval[0]);
#endif
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);
PTRACESTOP_SC(p, td, S_PT_SCX);
if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
PROC_LOCK(p);
td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
PROC_UNLOCK(p);
}
}
#endif /* HAVE_SYSCALL_ARGS_DEF */