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: releng/9.0/sys/kern/subr_syscall.c 226248 2011-10-11 13:18:44Z kib $");
46
47 #include <sys/capability.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 if (p->p_flag & P_TRACED) {
68 traced = 1;
69 PROC_LOCK(p);
70 td->td_dbgflags &= ~TDB_USERWR;
71 td->td_dbgflags |= TDB_SCE;
72 PROC_UNLOCK(p);
73 } else
74 traced = 0;
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
81 CTR6(KTR_SYSC,
82 "syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)",
83 td, td->td_proc->p_pid, syscallname(p, sa->code),
84 sa->args[0], sa->args[1], sa->args[2]);
85
86 if (error == 0) {
87 STOPEVENT(p, S_SCE, sa->narg);
88 PTRACESTOP_SC(p, td, S_PT_SCE);
89 if (td->td_dbgflags & TDB_USERWR) {
90 /*
91 * Reread syscall number and arguments if
92 * debugger modified registers or memory.
93 */
94 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
95 #ifdef KTRACE
96 if (KTRPOINT(td, KTR_SYSCALL))
97 ktrsyscall(sa->code, sa->narg, sa->args);
98 #endif
99 if (error != 0)
100 goto retval;
101 }
102
103 #ifdef CAPABILITY_MODE
104 /*
105 * In capability mode, we only allow access to system calls
106 * flagged with SYF_CAPENABLED.
107 */
108 if (IN_CAPABILITY_MODE(td) &&
109 !(sa->callp->sy_flags & SYF_CAPENABLED)) {
110 error = ECAPMODE;
111 goto retval;
112 }
113 #endif
114
115 error = syscall_thread_enter(td, sa->callp);
116 if (error != 0)
117 goto retval;
118
119 #ifdef KDTRACE_HOOKS
120 /*
121 * If the systrace module has registered it's probe
122 * callback and if there is a probe active for the
123 * syscall 'entry', process the probe.
124 */
125 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0)
126 (*systrace_probe_func)(sa->callp->sy_entry, sa->code,
127 sa->callp, sa->args, 0);
128 #endif
129
130 AUDIT_SYSCALL_ENTER(sa->code, td);
131 error = (sa->callp->sy_call)(td, sa->args);
132 AUDIT_SYSCALL_EXIT(error, td);
133
134 /* Save the latest error return value. */
135 td->td_errno = error;
136
137 #ifdef KDTRACE_HOOKS
138 /*
139 * If the systrace module has registered it's probe
140 * callback and if there is a probe active for the
141 * syscall 'return', process the probe.
142 */
143 if (systrace_probe_func != NULL && sa->callp->sy_return != 0)
144 (*systrace_probe_func)(sa->callp->sy_return, sa->code,
145 sa->callp, NULL, (error) ? -1 : td->td_retval[0]);
146 #endif
147 syscall_thread_exit(td, sa->callp);
148 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx",
149 p, error, td->td_retval[0], td->td_retval[1]);
150 }
151 retval:
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, struct syscall_args *sa __unused)
163 {
164 struct proc *p;
165 int traced;
166
167 p = td->td_proc;
168
169 /*
170 * Check for misbehavior.
171 */
172 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning",
173 syscallname(p, sa->code));
174 KASSERT(td->td_critnest == 0,
175 ("System call %s returning in a critical section",
176 syscallname(p, sa->code)));
177 KASSERT(td->td_locks == 0,
178 ("System call %s returning with %d locks held",
179 syscallname(p, sa->code), td->td_locks));
180
181 /*
182 * Handle reschedule and other end-of-syscall issues
183 */
184 userret(td, td->td_frame);
185
186 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s",
187 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name);
188
189 #ifdef KTRACE
190 if (KTRPOINT(td, KTR_SYSRET))
191 ktrsysret(sa->code, error, td->td_retval[0]);
192 #endif
193
194 if (p->p_flag & P_TRACED) {
195 traced = 1;
196 PROC_LOCK(p);
197 td->td_dbgflags |= TDB_SCX;
198 PROC_UNLOCK(p);
199 } else
200 traced = 0;
201 /*
202 * This works because errno is findable through the
203 * register set. If we ever support an emulation where this
204 * is not the case, this code will need to be revisited.
205 */
206 STOPEVENT(p, S_SCX, sa->code);
207 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
208 PROC_LOCK(p);
209 /*
210 * If tracing the execed process, trap to the debugger
211 * so that breakpoints can be set before the program
212 * executes. If debugger requested tracing of syscall
213 * returns, do it now too.
214 */
215 if (traced && ((td->td_dbgflags & TDB_EXEC) != 0 ||
216 (p->p_stops & S_PT_SCX) != 0))
217 ptracestop(td, SIGTRAP);
218 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
219 PROC_UNLOCK(p);
220 }
221 }
Cache object: e68736a4b761a451b0aec521d3075e56
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