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, struct syscall_args *sa) 57 { 58 struct proc *p; 59 int error, traced; 60 61 VM_CNT_INC(v_syscall); 62 p = td->td_proc; 63 64 td->td_pticks = 0; 65 if (td->td_cowgen != p->p_cowgen) 66 thread_cow_update(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 /* Give the syscall:::entry DTrace probe a chance to fire. */ 131 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 132 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 133 #endif 134 135 AUDIT_SYSCALL_ENTER(sa->code, td); 136 error = (sa->callp->sy_call)(td, sa->args); 137 AUDIT_SYSCALL_EXIT(error, td); 138 139 /* Save the latest error return value. */ 140 if ((td->td_pflags & TDP_NERRNO) == 0) 141 td->td_errno = error; 142 143 #ifdef KDTRACE_HOOKS 144 /* Give the syscall:::return DTrace probe a chance to fire. */ 145 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 146 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 147 error ? -1 : td->td_retval[0]); 148 #endif 149 syscall_thread_exit(td, sa->callp); 150 } 151 retval: 152 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 153 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 154 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 155 td->td_retval[1]); 156 if (traced) { 157 PROC_LOCK(p); 158 td->td_dbgflags &= ~TDB_SCE; 159 PROC_UNLOCK(p); 160 } 161 (p->p_sysent->sv_set_syscall_retval)(td, error); 162 return (error); 163 } 164 165 static inline void 166 syscallret(struct thread *td, int error, struct syscall_args *sa) 167 { 168 struct proc *p, *p2; 169 ksiginfo_t ksi; 170 int traced, error1; 171 172 KASSERT((td->td_pflags & TDP_FORKING) == 0, 173 ("fork() did not clear TDP_FORKING upon completion")); 174 175 p = td->td_proc; 176 if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) && 177 IN_CAPABILITY_MODE(td)) { 178 error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error : 179 td->td_errno; 180 if (error1 == ENOTCAPABLE || error1 == ECAPMODE) { 181 ksiginfo_init_trap(&ksi); 182 ksi.ksi_signo = SIGTRAP; 183 ksi.ksi_errno = error1; 184 ksi.ksi_code = TRAP_CAP; 185 trapsignal(td, &ksi); 186 } 187 } 188 189 /* 190 * Handle reschedule and other end-of-syscall issues 191 */ 192 userret(td, td->td_frame); 193 194 #ifdef KTRACE 195 if (KTRPOINT(td, KTR_SYSRET)) { 196 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ? 197 error : td->td_errno, td->td_retval[0]); 198 } 199 #endif 200 td->td_pflags &= ~TDP_NERRNO; 201 202 if (p->p_flag & P_TRACED) { 203 traced = 1; 204 PROC_LOCK(p); 205 td->td_dbgflags |= TDB_SCX; 206 PROC_UNLOCK(p); 207 } else 208 traced = 0; 209 /* 210 * This works because errno is findable through the 211 * register set. If we ever support an emulation where this 212 * is not the case, this code will need to be revisited. 213 */ 214 STOPEVENT(p, S_SCX, sa->code); 215 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 216 PROC_LOCK(p); 217 /* 218 * If tracing the execed process, trap to the debugger 219 * so that breakpoints can be set before the program 220 * executes. If debugger requested tracing of syscall 221 * returns, do it now too. 222 */ 223 if (traced && 224 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 225 (p->p_ptevents & PTRACE_SCX) != 0)) 226 ptracestop(td, SIGTRAP, NULL); 227 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 228 PROC_UNLOCK(p); 229 } 230 231 if (td->td_pflags & TDP_RFPPWAIT) { 232 /* 233 * Preserve synchronization semantics of vfork. If 234 * waiting for child to exec or exit, fork set 235 * P_PPWAIT on child, and there we sleep on our proc 236 * (in case of exit). 237 * 238 * Do it after the ptracestop() above is finished, to 239 * not block our debugger until child execs or exits 240 * to finish vfork wait. 241 */ 242 td->td_pflags &= ~TDP_RFPPWAIT; 243 p2 = td->td_rfppwait_p; 244 again: 245 PROC_LOCK(p2); 246 while (p2->p_flag & P_PPWAIT) { 247 PROC_LOCK(p); 248 if (thread_suspend_check_needed()) { 249 PROC_UNLOCK(p2); 250 thread_suspend_check(0); 251 PROC_UNLOCK(p); 252 goto again; 253 } else { 254 PROC_UNLOCK(p); 255 } 256 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz); 257 } 258 PROC_UNLOCK(p2); 259 260 if (td->td_dbgflags & TDB_VFORK) { 261 PROC_LOCK(p); 262 if (p->p_ptevents & PTRACE_VFORK) 263 ptracestop(td, SIGTRAP, NULL); 264 td->td_dbgflags &= ~TDB_VFORK; 265 PROC_UNLOCK(p); 266 } 267 } 268 } 269