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;
66 VM_CNT_INC(v_syscall);
71 if (__predict_false(td->td_cowgen != p->p_cowgen))
72 thread_cow_update(td);
73 traced = (p->p_flag & P_TRACED) != 0;
74 if (__predict_false(traced || td->td_dbgflags & TDB_USERWR)) {
76 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0);
77 td->td_dbgflags &= ~TDB_USERWR;
79 td->td_dbgflags |= TDB_SCE;
82 error = (p->p_sysent->sv_fetch_syscall_args)(td);
85 if (KTRPOINT(td, KTR_SYSCALL))
86 ktrsyscall(sa->code, se->sy_narg, sa->args);
88 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code),
89 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
90 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
92 if (__predict_false(error != 0)) {
97 if (__predict_false(traced)) {
99 if (p->p_ptevents & PTRACE_SCE)
100 ptracestop((td), SIGTRAP, NULL);
103 if ((td->td_dbgflags & TDB_USERWR) != 0) {
105 * Reread syscall number and arguments if debugger
106 * modified registers or memory.
108 error = (p->p_sysent->sv_fetch_syscall_args)(td);
111 if (KTRPOINT(td, KTR_SYSCALL))
112 ktrsyscall(sa->code, se->sy_narg, sa->args);
115 td->td_errno = error;
121 #ifdef CAPABILITY_MODE
123 * In capability mode, we only allow access to system calls
124 * flagged with SYF_CAPENABLED.
126 if (__predict_false(IN_CAPABILITY_MODE(td) &&
127 (se->sy_flags & SYF_CAPENABLED) == 0)) {
128 td->td_errno = error = ECAPMODE;
134 * Fetch fast sigblock value at the time of syscall entry to
135 * handle sleepqueue primitives which might call cursig().
137 if (__predict_false(sigfastblock_fetch_always))
138 (void)sigfastblock_fetch(td);
140 /* Let system calls set td_errno directly. */
141 KASSERT((td->td_pflags & TDP_NERRNO) == 0,
142 ("%s: TDP_NERRNO set", __func__));
144 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0;
146 if (__predict_false(SYSTRACE_ENABLED() ||
147 AUDIT_SYSCALL_ENTER(sa->code, td) ||
149 if (!sy_thr_static) {
150 error = syscall_thread_enter(td, se);
152 td->td_errno = error;
158 /* Give the syscall:::entry DTrace probe a chance to fire. */
159 if (__predict_false(se->sy_entry != 0))
160 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0);
162 error = (se->sy_call)(td, sa->args);
163 /* Save the latest error return value. */
164 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0))
165 td->td_pflags &= ~TDP_NERRNO;
167 td->td_errno = error;
170 * Note that some syscall implementations (e.g., sys_execve)
171 * will commit the audit record just before their final return.
172 * These were done under the assumption that nothing of interest
173 * would happen between their return and here, where we would
174 * normally commit the audit record. These assumptions will
175 * need to be revisited should any substantial logic be added
178 AUDIT_SYSCALL_EXIT(error, td);
181 /* Give the syscall:::return DTrace probe a chance to fire. */
182 if (__predict_false(se->sy_return != 0))
183 (*systrace_probe_func)(sa, SYSTRACE_RETURN,
184 error ? -1 : td->td_retval[0]);
188 syscall_thread_exit(td, se);
190 error = (se->sy_call)(td, sa->args);
191 /* Save the latest error return value. */
192 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0))
193 td->td_pflags &= ~TDP_NERRNO;
195 td->td_errno = error;
199 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code),
200 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error,
201 "retval0:%#lx", td->td_retval[0], "retval1:%#lx",
203 if (__predict_false(traced)) {
205 td->td_dbgflags &= ~(TDB_SCE | TDB_BOUNDARY);
208 (p->p_sysent->sv_set_syscall_retval)(td, error);
212 syscallret(struct thread *td)
215 struct syscall_args *sa;
219 KASSERT((td->td_pflags & TDP_FORKING) == 0,
220 ("fork() did not clear TDP_FORKING upon completion"));
221 KASSERT(td->td_errno != ERELOOKUP,
222 ("ERELOOKUP not consumed syscall %d", td->td_sa.code));
226 if (__predict_false(td->td_errno == ENOTCAPABLE ||
227 td->td_errno == ECAPMODE)) {
229 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) {
230 ksiginfo_init_trap(&ksi);
231 ksi.ksi_signo = SIGTRAP;
232 ksi.ksi_errno = td->td_errno;
233 ksi.ksi_code = TRAP_CAP;
234 trapsignal(td, &ksi);
239 * Handle reschedule and other end-of-syscall issues
241 userret(td, td->td_frame);
244 if (KTRPOINT(td, KTR_SYSRET)) {
245 ktrsysret(sa->code, td->td_errno, td->td_retval[0]);
250 if (__predict_false(p->p_flag & P_TRACED)) {
253 td->td_dbgflags |= TDB_SCX;
256 if (__predict_false(traced ||
257 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) {
260 * Linux debuggers expect an additional stop for exec,
261 * between the usual syscall entry and exit. Raise
262 * the exec event now and then clear TDB_EXEC so that
263 * the next stop is reported as a syscall exit by
264 * linux_ptrace_status().
266 * We are accessing p->p_pptr without any additional
267 * locks here: it cannot change while p is kept locked;
268 * while the debugger could in theory change its ABI
269 * while tracing another process, the outcome of such
270 * a race wouln't be deterministic anyway.
272 if (traced && (td->td_dbgflags & TDB_EXEC) != 0 &&
273 SV_PROC_ABI(p->p_pptr) == SV_ABI_LINUX) {
274 ptracestop(td, SIGTRAP, NULL);
275 td->td_dbgflags &= ~TDB_EXEC;
278 * If tracing the execed process, trap to the debugger
279 * so that breakpoints can be set before the program
280 * executes. If debugger requested tracing of syscall
281 * returns, do it now too.
284 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
285 (p->p_ptevents & PTRACE_SCX) != 0)) {
286 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0);
287 td->td_dbgflags |= TDB_BOUNDARY;
288 ptracestop(td, SIGTRAP, NULL);
290 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK |
295 if (__predict_false(td->td_pflags & TDP_RFPPWAIT))