291 lines
8.7 KiB
C
291 lines
8.7 KiB
C
/*-
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* SPDX-License-Identifier: BSD-4-Clause
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*
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* Copyright (C) 1994, David Greenman
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org>
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*
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* This code is derived from software contributed to Berkeley by
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* the University of Utah, and William Jolitz.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
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*/
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#include "opt_capsicum.h"
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#include "opt_ktrace.h"
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#include <sys/capsicum.h>
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#include <sys/ktr.h>
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#include <sys/vmmeter.h>
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#ifdef KTRACE
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#endif
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#include <security/audit/audit.h>
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static inline void
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syscallenter(struct thread *td)
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{
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struct proc *p;
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struct syscall_args *sa;
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struct sysent *se;
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int error, traced;
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bool sy_thr_static;
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VM_CNT_INC(v_syscall);
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p = td->td_proc;
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sa = &td->td_sa;
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td->td_pticks = 0;
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if (__predict_false(td->td_cowgen != atomic_load_int(&p->p_cowgen)))
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thread_cow_update(td);
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traced = (p->p_flag & P_TRACED) != 0;
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if (__predict_false(traced || td->td_dbgflags & TDB_USERWR)) {
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PROC_LOCK(p);
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MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0);
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td->td_dbgflags &= ~TDB_USERWR;
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if (traced)
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td->td_dbgflags |= TDB_SCE;
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PROC_UNLOCK(p);
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}
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error = (p->p_sysent->sv_fetch_syscall_args)(td);
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se = sa->callp;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSCALL))
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ktrsyscall(sa->code, se->sy_narg, sa->args);
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#endif
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KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code),
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(uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
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"arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
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if (__predict_false(error != 0)) {
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td->td_errno = error;
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goto retval;
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}
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if (__predict_false(traced)) {
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PROC_LOCK(p);
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if (p->p_ptevents & PTRACE_SCE)
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ptracestop((td), SIGTRAP, NULL);
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PROC_UNLOCK(p);
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if ((td->td_dbgflags & TDB_USERWR) != 0) {
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/*
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* Reread syscall number and arguments if debugger
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* modified registers or memory.
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*/
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error = (p->p_sysent->sv_fetch_syscall_args)(td);
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se = sa->callp;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSCALL))
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ktrsyscall(sa->code, se->sy_narg, sa->args);
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#endif
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if (error != 0) {
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td->td_errno = error;
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goto retval;
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}
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}
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}
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#ifdef CAPABILITY_MODE
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/*
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* In capability mode, we only allow access to system calls
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* flagged with SYF_CAPENABLED.
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*/
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if (__predict_false(IN_CAPABILITY_MODE(td) &&
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(se->sy_flags & SYF_CAPENABLED) == 0)) {
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td->td_errno = error = ECAPMODE;
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goto retval;
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}
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#endif
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/*
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* Fetch fast sigblock value at the time of syscall entry to
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* handle sleepqueue primitives which might call cursig().
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*/
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if (__predict_false(sigfastblock_fetch_always))
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(void)sigfastblock_fetch(td);
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/* Let system calls set td_errno directly. */
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KASSERT((td->td_pflags & TDP_NERRNO) == 0,
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("%s: TDP_NERRNO set", __func__));
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sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0;
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if (__predict_false(SYSTRACE_ENABLED() ||
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AUDIT_SYSCALL_ENTER(sa->code, td) ||
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!sy_thr_static)) {
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if (!sy_thr_static) {
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error = syscall_thread_enter(td, se);
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if (error != 0) {
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td->td_errno = error;
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goto retval;
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}
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}
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#ifdef KDTRACE_HOOKS
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/* Give the syscall:::entry DTrace probe a chance to fire. */
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if (__predict_false(se->sy_entry != 0))
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(*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0);
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#endif
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error = (se->sy_call)(td, sa->args);
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/* Save the latest error return value. */
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if (__predict_false((td->td_pflags & TDP_NERRNO) != 0))
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td->td_pflags &= ~TDP_NERRNO;
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else
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td->td_errno = error;
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/*
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* Note that some syscall implementations (e.g., sys_execve)
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* will commit the audit record just before their final return.
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* These were done under the assumption that nothing of interest
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* would happen between their return and here, where we would
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* normally commit the audit record. These assumptions will
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* need to be revisited should any substantial logic be added
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* above.
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*/
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AUDIT_SYSCALL_EXIT(error, td);
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#ifdef KDTRACE_HOOKS
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/* Give the syscall:::return DTrace probe a chance to fire. */
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if (__predict_false(se->sy_return != 0))
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(*systrace_probe_func)(sa, SYSTRACE_RETURN,
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error ? -1 : td->td_retval[0]);
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#endif
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if (!sy_thr_static)
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syscall_thread_exit(td, se);
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} else {
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error = (se->sy_call)(td, sa->args);
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/* Save the latest error return value. */
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if (__predict_false((td->td_pflags & TDP_NERRNO) != 0))
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td->td_pflags &= ~TDP_NERRNO;
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else
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td->td_errno = error;
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}
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retval:
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KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code),
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(uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error,
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"retval0:%#lx", td->td_retval[0], "retval1:%#lx",
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td->td_retval[1]);
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if (__predict_false(traced)) {
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PROC_LOCK(p);
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td->td_dbgflags &= ~(TDB_SCE | TDB_BOUNDARY);
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PROC_UNLOCK(p);
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}
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(p->p_sysent->sv_set_syscall_retval)(td, error);
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}
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static inline void
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syscallret(struct thread *td)
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{
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struct proc *p;
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struct syscall_args *sa;
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ksiginfo_t ksi;
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int traced;
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KASSERT(td->td_errno != ERELOOKUP,
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("ERELOOKUP not consumed syscall %d", td->td_sa.code));
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p = td->td_proc;
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sa = &td->td_sa;
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if (__predict_false(td->td_errno == ENOTCAPABLE ||
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td->td_errno == ECAPMODE)) {
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if ((trap_enotcap ||
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(p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) {
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ksiginfo_init_trap(&ksi);
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ksi.ksi_signo = SIGTRAP;
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ksi.ksi_errno = td->td_errno;
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ksi.ksi_code = TRAP_CAP;
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ksi.ksi_info.si_syscall = sa->original_code;
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trapsignal(td, &ksi);
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}
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}
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/*
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* Handle reschedule and other end-of-syscall issues
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*/
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userret(td, td->td_frame);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSRET)) {
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ktrsysret(sa->code, td->td_errno, td->td_retval[0]);
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}
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#endif
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traced = 0;
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if (__predict_false(p->p_flag & P_TRACED)) {
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traced = 1;
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PROC_LOCK(p);
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td->td_dbgflags |= TDB_SCX;
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PROC_UNLOCK(p);
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}
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if (__predict_false(traced ||
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(td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) {
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PROC_LOCK(p);
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/*
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* Linux debuggers expect an additional stop for exec,
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* between the usual syscall entry and exit. Raise
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* the exec event now and then clear TDB_EXEC so that
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* the next stop is reported as a syscall exit by
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* linux_ptrace_status().
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*
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* We are accessing p->p_pptr without any additional
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* locks here: it cannot change while p is kept locked;
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* while the debugger could in theory change its ABI
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* while tracing another process, the outcome of such
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* a race wouln't be deterministic anyway.
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*/
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if (traced && (td->td_dbgflags & TDB_EXEC) != 0 &&
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SV_PROC_ABI(p->p_pptr) == SV_ABI_LINUX) {
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ptracestop(td, SIGTRAP, NULL);
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td->td_dbgflags &= ~TDB_EXEC;
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}
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/*
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* If tracing the execed process, trap to the debugger
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* so that breakpoints can be set before the program
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* executes. If debugger requested tracing of syscall
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* returns, do it now too.
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*/
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if (traced &&
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((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
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(p->p_ptevents & PTRACE_SCX) != 0)) {
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MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0);
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td->td_dbgflags |= TDB_BOUNDARY;
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ptracestop(td, SIGTRAP, NULL);
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}
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td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK |
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TDB_BOUNDARY);
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PROC_UNLOCK(p);
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}
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}
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