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
44 __FBSDID("$FreeBSD$");
45
46 #include <sys/capsicum.h>
47 #include <sys/ktr.h>
48 #include <sys/vmmeter.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)
57 {
58 struct proc *p;
59 struct syscall_args *sa;
60 int error, traced;
61
62 PCPU_INC(cnt.v_syscall);
63 p = td->td_proc;
64 sa = &td->td_sa;
65
66 td->td_pticks = 0;
67 if (td->td_cowgen != p->p_cowgen)
68 thread_cow_update(td);
69 traced = (p->p_flag & P_TRACED) != 0;
70 if (traced || td->td_dbgflags & TDB_USERWR) {
71 PROC_LOCK(p);
72 td->td_dbgflags &= ~TDB_USERWR;
73 if (traced)
74 td->td_dbgflags |= TDB_SCE;
75 PROC_UNLOCK(p);
76 }
77 error = (p->p_sysent->sv_fetch_syscall_args)(td);
78 #ifdef KTRACE
79 if (KTRPOINT(td, KTR_SYSCALL))
80 ktrsyscall(sa->code, sa->narg, sa->args);
81 #endif
82 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code),
83 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
84 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
85
86 if (error == 0) {
87
88 STOPEVENT(p, S_SCE, sa->narg);
89 if (p->p_flag & P_TRACED) {
90 PROC_LOCK(p);
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);
101 #ifdef KTRACE
102 if (KTRPOINT(td, KTR_SYSCALL))
103 ktrsyscall(sa->code, sa->narg, sa->args);
104 #endif
105 if (error != 0)
106 goto retval;
107 }
108
109 #ifdef CAPABILITY_MODE
110 /*
111 * In capability mode, we only allow access to system calls
112 * flagged with SYF_CAPENABLED.
113 */
114 if (IN_CAPABILITY_MODE(td) &&
115 !(sa->callp->sy_flags & SYF_CAPENABLED)) {
116 error = ECAPMODE;
117 goto retval;
118 }
119 #endif
120
121 error = syscall_thread_enter(td, sa->callp);
122 if (error != 0)
123 goto retval;
124
125 #ifdef KDTRACE_HOOKS
126 /* Give the syscall:::entry DTrace probe a chance to fire. */
127 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0)
128 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0);
129 #endif
130
131 AUDIT_SYSCALL_ENTER(sa->code, td);
132 error = (sa->callp->sy_call)(td, sa->args);
133 AUDIT_SYSCALL_EXIT(error, td);
134
135 /* Save the latest error return value. */
136 if ((td->td_pflags & TDP_NERRNO) == 0)
137 td->td_errno = error;
138
139 #ifdef KDTRACE_HOOKS
140 /* Give the syscall:::return DTrace probe a chance to fire. */
141 if (systrace_probe_func != NULL && sa->callp->sy_return != 0)
142 (*systrace_probe_func)(sa, SYSTRACE_RETURN,
143 error ? -1 : td->td_retval[0]);
144 #endif
145 syscall_thread_exit(td, sa->callp);
146 }
147 retval:
148 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code),
149 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error,
150 "retval0:%#lx", td->td_retval[0], "retval1:%#lx",
151 td->td_retval[1]);
152 if (traced) {
153 PROC_LOCK(p);
154 td->td_dbgflags &= ~TDB_SCE;
155 PROC_UNLOCK(p);
156 }
157 (p->p_sysent->sv_set_syscall_retval)(td, error);
158 return (error);
159 }
160
161 static inline void
162 syscallret(struct thread *td, int error)
163 {
164 struct proc *p, *p2;
165 struct syscall_args *sa;
166 ksiginfo_t ksi;
167 int traced, error1;
168
169 KASSERT((td->td_pflags & TDP_FORKING) == 0,
170 ("fork() did not clear TDP_FORKING upon completion"));
171
172 p = td->td_proc;
173 sa = &td->td_sa;
174 if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) &&
175 IN_CAPABILITY_MODE(td)) {
176 error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error :
177 td->td_errno;
178 if (error1 == ENOTCAPABLE || error1 == ECAPMODE) {
179 ksiginfo_init_trap(&ksi);
180 ksi.ksi_signo = SIGTRAP;
181 ksi.ksi_errno = error1;
182 ksi.ksi_code = TRAP_CAP;
183 trapsignal(td, &ksi);
184 }
185 }
186
187 /*
188 * Handle reschedule and other end-of-syscall issues
189 */
190 userret(td, td->td_frame);
191
192 #ifdef KTRACE
193 if (KTRPOINT(td, KTR_SYSRET)) {
194 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
195 error : td->td_errno, td->td_retval[0]);
196 }
197 #endif
198 td->td_pflags &= ~TDP_NERRNO;
199
200 if (p->p_flag & P_TRACED) {
201 traced = 1;
202 PROC_LOCK(p);
203 td->td_dbgflags |= TDB_SCX;
204 PROC_UNLOCK(p);
205 } else
206 traced = 0;
207 /*
208 * This works because errno is findable through the
209 * register set. If we ever support an emulation where this
210 * is not the case, this code will need to be revisited.
211 */
212 STOPEVENT(p, S_SCX, sa->code);
213 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
214 PROC_LOCK(p);
215 /*
216 * If tracing the execed process, trap to the debugger
217 * so that breakpoints can be set before the program
218 * executes. If debugger requested tracing of syscall
219 * returns, do it now too.
220 */
221 if (traced &&
222 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
223 (p->p_ptevents & PTRACE_SCX) != 0))
224 ptracestop(td, SIGTRAP, NULL);
225 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
226 PROC_UNLOCK(p);
227 }
228
229 if (td->td_pflags & TDP_RFPPWAIT) {
230 /*
231 * Preserve synchronization semantics of vfork. If
232 * waiting for child to exec or exit, fork set
233 * P_PPWAIT on child, and there we sleep on our proc
234 * (in case of exit).
235 *
236 * Do it after the ptracestop() above is finished, to
237 * not block our debugger until child execs or exits
238 * to finish vfork wait.
239 */
240 td->td_pflags &= ~TDP_RFPPWAIT;
241 p2 = td->td_rfppwait_p;
242 again:
243 PROC_LOCK(p2);
244 while (p2->p_flag & P_PPWAIT) {
245 PROC_LOCK(p);
246 if (thread_suspend_check_needed()) {
247 PROC_UNLOCK(p2);
248 thread_suspend_check(0);
249 PROC_UNLOCK(p);
250 goto again;
251 } else {
252 PROC_UNLOCK(p);
253 }
254 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
255 }
256 PROC_UNLOCK(p2);
257
258 if (td->td_dbgflags & TDB_VFORK) {
259 PROC_LOCK(p);
260 if (p->p_ptevents & PTRACE_VFORK)
261 ptracestop(td, SIGTRAP, NULL);
262 td->td_dbgflags &= ~TDB_VFORK;
263 PROC_UNLOCK(p);
264 }
265 }
266 }
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