2 * SPDX-License-Identifier: BSD-4-Clause
4 * Copyright (C) 1994, David Greenman
5 * Copyright (c) 1990, 1993
6 * The Regents of the University of California. All rights reserved.
7 * Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org>
9 * This code is derived from software contributed to Berkeley by
10 * the University of Utah, and William Jolitz.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
43 #include "opt_capsicum.h"
44 #include "opt_ktrace.h"
46 __FBSDID("$FreeBSD$");
48 #include <sys/capsicum.h>
50 #include <sys/vmmeter.h>
53 #include <sys/ktrace.h>
55 #include <security/audit/audit.h>
58 syscallenter(struct thread *td)
61 struct syscall_args *sa;
65 VM_CNT_INC(v_syscall);
70 if (__predict_false(td->td_cowgen != p->p_cowgen))
71 thread_cow_update(td);
72 traced = (p->p_flag & P_TRACED) != 0;
73 if (__predict_false(traced || td->td_dbgflags & TDB_USERWR)) {
75 td->td_dbgflags &= ~TDB_USERWR;
77 td->td_dbgflags |= TDB_SCE;
80 error = (p->p_sysent->sv_fetch_syscall_args)(td);
83 if (KTRPOINT(td, KTR_SYSCALL))
84 ktrsyscall(sa->code, se->sy_narg, sa->args);
86 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code),
87 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
88 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
90 if (__predict_false(error != 0)) {
95 if (__predict_false(traced)) {
97 if (p->p_ptevents & PTRACE_SCE)
98 ptracestop((td), SIGTRAP, NULL);
101 if (__predict_false((td->td_dbgflags & TDB_USERWR) != 0)) {
103 * Reread syscall number and arguments if debugger
104 * modified registers or memory.
106 error = (p->p_sysent->sv_fetch_syscall_args)(td);
109 if (KTRPOINT(td, KTR_SYSCALL))
110 ktrsyscall(sa->code, se->sy_narg, sa->args);
113 td->td_errno = error;
118 #ifdef CAPABILITY_MODE
120 * In capability mode, we only allow access to system calls
121 * flagged with SYF_CAPENABLED.
123 if (__predict_false(IN_CAPABILITY_MODE(td) &&
124 (se->sy_flags & SYF_CAPENABLED) == 0)) {
125 td->td_errno = error = ECAPMODE;
130 error = syscall_thread_enter(td, se);
132 td->td_errno = error;
137 * Fetch fast sigblock value at the time of syscall entry to
138 * handle sleepqueue primitives which might call cursig().
140 if (__predict_false(sigfastblock_fetch_always))
141 (void)sigfastblock_fetch(td);
143 /* Let system calls set td_errno directly. */
144 KASSERT((td->td_pflags & TDP_NERRNO) == 0,
145 ("%s: TDP_NERRNO set", __func__));
147 if (__predict_false(SYSTRACE_ENABLED() ||
148 AUDIT_SYSCALL_ENTER(sa->code, td))) {
150 /* Give the syscall:::entry DTrace probe a chance to fire. */
151 if (__predict_false(se->sy_entry != 0))
152 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0);
154 error = (se->sy_call)(td, sa->args);
155 /* Save the latest error return value. */
156 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0))
157 td->td_pflags &= ~TDP_NERRNO;
159 td->td_errno = error;
162 * Note that some syscall implementations (e.g., sys_execve)
163 * will commit the audit record just before their final return.
164 * These were done under the assumption that nothing of interest
165 * would happen between their return and here, where we would
166 * normally commit the audit record. These assumptions will
167 * need to be revisited should any substantial logic be added
170 AUDIT_SYSCALL_EXIT(error, td);
173 /* Give the syscall:::return DTrace probe a chance to fire. */
174 if (__predict_false(se->sy_return != 0))
175 (*systrace_probe_func)(sa, SYSTRACE_RETURN,
176 error ? -1 : td->td_retval[0]);
179 error = (se->sy_call)(td, sa->args);
180 /* Save the latest error return value. */
181 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0))
182 td->td_pflags &= ~TDP_NERRNO;
184 td->td_errno = error;
186 syscall_thread_exit(td, se);
189 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code),
190 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error,
191 "retval0:%#lx", td->td_retval[0], "retval1:%#lx",
193 if (__predict_false(traced)) {
195 td->td_dbgflags &= ~TDB_SCE;
198 (p->p_sysent->sv_set_syscall_retval)(td, error);
202 syscallret(struct thread *td)
205 struct syscall_args *sa;
209 KASSERT((td->td_pflags & TDP_FORKING) == 0,
210 ("fork() did not clear TDP_FORKING upon completion"));
214 if (__predict_false(td->td_errno == ENOTCAPABLE ||
215 td->td_errno == ECAPMODE)) {
217 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) {
218 ksiginfo_init_trap(&ksi);
219 ksi.ksi_signo = SIGTRAP;
220 ksi.ksi_errno = td->td_errno;
221 ksi.ksi_code = TRAP_CAP;
222 trapsignal(td, &ksi);
227 * Handle reschedule and other end-of-syscall issues
229 userret(td, td->td_frame);
232 if (KTRPOINT(td, KTR_SYSRET)) {
233 ktrsysret(sa->code, td->td_errno, td->td_retval[0]);
238 if (__predict_false(p->p_flag & P_TRACED)) {
241 td->td_dbgflags |= TDB_SCX;
244 if (__predict_false(traced ||
245 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) {
248 * If tracing the execed process, trap to the debugger
249 * so that breakpoints can be set before the program
250 * executes. If debugger requested tracing of syscall
251 * returns, do it now too.
254 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
255 (p->p_ptevents & PTRACE_SCX) != 0))
256 ptracestop(td, SIGTRAP, NULL);
257 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
261 if (__predict_false(td->td_pflags & TDP_RFPPWAIT))