1 /*-
2 * Copyright (C) 1994, David Greenman
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 * Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org>
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the University of Utah, and William Jolitz.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
39 */
40
41 #include "opt_capsicum.h"
42 #include "opt_ktrace.h"
43 #include "opt_kdtrace.h"
44
45 __FBSDID("$FreeBSD$");
46
47 #include <sys/capsicum.h>
48 #include <sys/ktr.h>
49 #ifdef KTRACE
50 #include <sys/uio.h>
51 #include <sys/ktrace.h>
52 #endif
53 #include <security/audit/audit.h>
54
55 static inline int
56 syscallenter(struct thread *td, struct syscall_args *sa)
57 {
58 struct proc *p;
59 int error, traced;
60
61 PCPU_INC(cnt.v_syscall);
62 p = td->td_proc;
63
64 td->td_pticks = 0;
65 if (td->td_ucred != p->p_ucred)
66 cred_update_thread(td);
67 traced = (p->p_flag & P_TRACED) != 0;
68 if (traced || td->td_dbgflags & TDB_USERWR) {
69 PROC_LOCK(p);
70 td->td_dbgflags &= ~TDB_USERWR;
71 if (traced)
72 td->td_dbgflags |= TDB_SCE;
73 PROC_UNLOCK(p);
74 }
75 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
76 #ifdef KTRACE
77 if (KTRPOINT(td, KTR_SYSCALL))
78 ktrsyscall(sa->code, sa->narg, sa->args);
79 #endif
80 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code),
81 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
82 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
83
84 if (error == 0) {
85
86 STOPEVENT(p, S_SCE, sa->narg);
87 if (p->p_flag & P_TRACED) {
88 PROC_LOCK(p);
89 td->td_dbg_sc_code = sa->code;
90 td->td_dbg_sc_narg = sa->narg;
91 if (p->p_ptevents & PTRACE_SCE)
92 ptracestop((td), SIGTRAP, NULL);
93 PROC_UNLOCK(p);
94 }
95 if (td->td_dbgflags & TDB_USERWR) {
96 /*
97 * Reread syscall number and arguments if
98 * debugger modified registers or memory.
99 */
100 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
101 PROC_LOCK(p);
102 td->td_dbg_sc_code = sa->code;
103 td->td_dbg_sc_narg = sa->narg;
104 PROC_UNLOCK(p);
105 #ifdef KTRACE
106 if (KTRPOINT(td, KTR_SYSCALL))
107 ktrsyscall(sa->code, sa->narg, sa->args);
108 #endif
109 if (error != 0)
110 goto retval;
111 }
112
113 #ifdef CAPABILITY_MODE
114 /*
115 * In capability mode, we only allow access to system calls
116 * flagged with SYF_CAPENABLED.
117 */
118 if (IN_CAPABILITY_MODE(td) &&
119 !(sa->callp->sy_flags & SYF_CAPENABLED)) {
120 error = ECAPMODE;
121 goto retval;
122 }
123 #endif
124
125 error = syscall_thread_enter(td, sa->callp);
126 if (error != 0)
127 goto retval;
128
129 #ifdef KDTRACE_HOOKS
130 /*
131 * If the systrace module has registered it's probe
132 * callback and if there is a probe active for the
133 * syscall 'entry', process the probe.
134 */
135 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0)
136 (*systrace_probe_func)(sa->callp->sy_entry, sa->code,
137 sa->callp, sa->args, 0);
138 #endif
139
140 AUDIT_SYSCALL_ENTER(sa->code, td);
141 error = (sa->callp->sy_call)(td, sa->args);
142 AUDIT_SYSCALL_EXIT(error, td);
143
144 /* Save the latest error return value. */
145 if ((td->td_pflags & TDP_NERRNO) == 0)
146 td->td_errno = error;
147
148 #ifdef KDTRACE_HOOKS
149 /*
150 * If the systrace module has registered it's probe
151 * callback and if there is a probe active for the
152 * syscall 'return', process the probe.
153 */
154 if (systrace_probe_func != NULL && sa->callp->sy_return != 0)
155 (*systrace_probe_func)(sa->callp->sy_return, sa->code,
156 sa->callp, NULL, (error) ? -1 : td->td_retval[0]);
157 #endif
158 syscall_thread_exit(td, sa->callp);
159 }
160 retval:
161 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code),
162 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error,
163 "retval0:%#lx", td->td_retval[0], "retval1:%#lx",
164 td->td_retval[1]);
165 if (traced) {
166 PROC_LOCK(p);
167 td->td_dbgflags &= ~TDB_SCE;
168 PROC_UNLOCK(p);
169 }
170 (p->p_sysent->sv_set_syscall_retval)(td, error);
171 return (error);
172 }
173
174 static inline void
175 syscallret(struct thread *td, int error, struct syscall_args *sa __unused)
176 {
177 struct proc *p, *p2;
178 int traced;
179
180 p = td->td_proc;
181
182 /*
183 * Handle reschedule and other end-of-syscall issues
184 */
185 userret(td, td->td_frame);
186
187 #ifdef KTRACE
188 if (KTRPOINT(td, KTR_SYSRET)) {
189 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
190 error : td->td_errno, td->td_retval[0]);
191 }
192 #endif
193 td->td_pflags &= ~TDP_NERRNO;
194
195 if (p->p_flag & P_TRACED) {
196 traced = 1;
197 PROC_LOCK(p);
198 td->td_dbgflags |= TDB_SCX;
199 PROC_UNLOCK(p);
200 } else
201 traced = 0;
202 /*
203 * This works because errno is findable through the
204 * register set. If we ever support an emulation where this
205 * is not the case, this code will need to be revisited.
206 */
207 STOPEVENT(p, S_SCX, sa->code);
208 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
209 PROC_LOCK(p);
210 /*
211 * If tracing the execed process, trap to the debugger
212 * so that breakpoints can be set before the program
213 * executes. If debugger requested tracing of syscall
214 * returns, do it now too.
215 */
216 if (traced &&
217 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
218 (p->p_ptevents & PTRACE_SCX) != 0))
219 ptracestop(td, SIGTRAP, NULL);
220 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
221 PROC_UNLOCK(p);
222 }
223
224 if (td->td_pflags & TDP_RFPPWAIT) {
225 /*
226 * Preserve synchronization semantics of vfork. If
227 * waiting for child to exec or exit, fork set
228 * P_PPWAIT on child, and there we sleep on our proc
229 * (in case of exit).
230 *
231 * Do it after the ptracestop() above is finished, to
232 * not block our debugger until child execs or exits
233 * to finish vfork wait.
234 */
235 td->td_pflags &= ~TDP_RFPPWAIT;
236 p2 = td->td_rfppwait_p;
237 again:
238 PROC_LOCK(p2);
239 while (p2->p_flag & P_PPWAIT) {
240 PROC_LOCK(p);
241 if (thread_suspend_check_needed()) {
242 PROC_UNLOCK(p2);
243 thread_suspend_check(0);
244 PROC_UNLOCK(p);
245 goto again;
246 } else {
247 PROC_UNLOCK(p);
248 }
249 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
250 }
251 PROC_UNLOCK(p2);
252
253 if (td->td_dbgflags & TDB_VFORK) {
254 PROC_LOCK(p);
255 if (p->p_ptevents & PTRACE_VFORK)
256 ptracestop(td, SIGTRAP, NULL);
257 td->td_dbgflags &= ~TDB_VFORK;
258 PROC_UNLOCK(p);
259 }
260 }
261 }
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