1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 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> 8 * 9 * This code is derived from software contributed to Berkeley by 10 * the University of Utah, and William Jolitz. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 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. 27 * 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 38 * SUCH DAMAGE. 39 * 40 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 41 */ 42 43 #include "opt_capsicum.h" 44 #include "opt_ktrace.h" 45 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/capsicum.h> 49 #include <sys/ktr.h> 50 #include <sys/vmmeter.h> 51 #ifdef KTRACE 52 #include <sys/uio.h> 53 #include <sys/ktrace.h> 54 #endif 55 #include <security/audit/audit.h> 56 57 static inline int 58 syscallenter(struct thread *td) 59 { 60 struct proc *p; 61 struct syscall_args *sa; 62 int error, traced; 63 64 VM_CNT_INC(v_syscall); 65 p = td->td_proc; 66 sa = &td->td_sa; 67 68 td->td_pticks = 0; 69 if (td->td_cowgen != p->p_cowgen) 70 thread_cow_update(td); 71 traced = (p->p_flag & P_TRACED) != 0; 72 if (traced || td->td_dbgflags & TDB_USERWR) { 73 PROC_LOCK(p); 74 td->td_dbgflags &= ~TDB_USERWR; 75 if (traced) 76 td->td_dbgflags |= TDB_SCE; 77 PROC_UNLOCK(p); 78 } 79 error = (p->p_sysent->sv_fetch_syscall_args)(td); 80 #ifdef KTRACE 81 if (KTRPOINT(td, KTR_SYSCALL)) 82 ktrsyscall(sa->code, sa->narg, sa->args); 83 #endif 84 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 85 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 86 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 87 88 if (error == 0) { 89 90 STOPEVENT(p, S_SCE, sa->narg); 91 if (p->p_flag & P_TRACED) { 92 PROC_LOCK(p); 93 if (p->p_ptevents & PTRACE_SCE) 94 ptracestop((td), SIGTRAP, NULL); 95 PROC_UNLOCK(p); 96 } 97 if (td->td_dbgflags & TDB_USERWR) { 98 /* 99 * Reread syscall number and arguments if 100 * debugger modified registers or memory. 101 */ 102 error = (p->p_sysent->sv_fetch_syscall_args)(td); 103 #ifdef KTRACE 104 if (KTRPOINT(td, KTR_SYSCALL)) 105 ktrsyscall(sa->code, sa->narg, sa->args); 106 #endif 107 if (error != 0) 108 goto retval; 109 } 110 111 #ifdef CAPABILITY_MODE 112 /* 113 * In capability mode, we only allow access to system calls 114 * flagged with SYF_CAPENABLED. 115 */ 116 if (IN_CAPABILITY_MODE(td) && 117 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 118 error = ECAPMODE; 119 goto retval; 120 } 121 #endif 122 123 error = syscall_thread_enter(td, sa->callp); 124 if (error != 0) 125 goto retval; 126 127 #ifdef KDTRACE_HOOKS 128 /* Give the syscall:::entry DTrace probe a chance to fire. */ 129 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 130 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 131 #endif 132 133 AUDIT_SYSCALL_ENTER(sa->code, td); 134 error = (sa->callp->sy_call)(td, sa->args); 135 AUDIT_SYSCALL_EXIT(error, td); 136 137 /* Save the latest error return value. */ 138 if ((td->td_pflags & TDP_NERRNO) == 0) 139 td->td_errno = error; 140 141 #ifdef KDTRACE_HOOKS 142 /* Give the syscall:::return DTrace probe a chance to fire. */ 143 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 144 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 145 error ? -1 : td->td_retval[0]); 146 #endif 147 syscall_thread_exit(td, sa->callp); 148 } 149 retval: 150 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 151 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 152 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 153 td->td_retval[1]); 154 if (traced) { 155 PROC_LOCK(p); 156 td->td_dbgflags &= ~TDB_SCE; 157 PROC_UNLOCK(p); 158 } 159 (p->p_sysent->sv_set_syscall_retval)(td, error); 160 return (error); 161 } 162 163 static inline void 164 syscallret(struct thread *td, int error) 165 { 166 struct proc *p, *p2; 167 struct syscall_args *sa; 168 ksiginfo_t ksi; 169 int traced, error1; 170 171 KASSERT((td->td_pflags & TDP_FORKING) == 0, 172 ("fork() did not clear TDP_FORKING upon completion")); 173 174 p = td->td_proc; 175 sa = &td->td_sa; 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