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 void 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 (__predict_false(td->td_cowgen != p->p_cowgen)) 70 thread_cow_update(td); 71 traced = (p->p_flag & P_TRACED) != 0; 72 if (__predict_false(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 (__predict_false(error != 0)) { 89 td->td_errno = error; 90 goto retval; 91 } 92 93 if (__predict_false((p->p_flag & P_TRACED) != 0)) { 94 PROC_LOCK(p); 95 if (p->p_ptevents & PTRACE_SCE) 96 ptracestop((td), SIGTRAP, NULL); 97 PROC_UNLOCK(p); 98 } 99 if (__predict_false((td->td_dbgflags & TDB_USERWR) != 0)) { 100 /* 101 * Reread syscall number and arguments if debugger 102 * modified registers or memory. 103 */ 104 error = (p->p_sysent->sv_fetch_syscall_args)(td); 105 #ifdef KTRACE 106 if (KTRPOINT(td, KTR_SYSCALL)) 107 ktrsyscall(sa->code, sa->narg, sa->args); 108 #endif 109 if (error != 0) { 110 td->td_errno = error; 111 goto retval; 112 } 113 } 114 115 #ifdef CAPABILITY_MODE 116 /* 117 * In capability mode, we only allow access to system calls 118 * flagged with SYF_CAPENABLED. 119 */ 120 if (__predict_false(IN_CAPABILITY_MODE(td) && 121 !(sa->callp->sy_flags & SYF_CAPENABLED))) { 122 td->td_errno = error = ECAPMODE; 123 goto retval; 124 } 125 #endif 126 127 error = syscall_thread_enter(td, sa->callp); 128 if (error != 0) { 129 td->td_errno = error; 130 goto retval; 131 } 132 133 /* 134 * Fetch fast sigblock value at the time of syscall entry to 135 * handle sleepqueue primitives which might call cursig(). 136 */ 137 if (__predict_false(sigfastblock_fetch_always)) 138 (void)sigfastblock_fetch(td); 139 140 /* Let system calls set td_errno directly. */ 141 td->td_pflags &= ~TDP_NERRNO; 142 143 if (__predict_false(SYSTRACE_ENABLED() || 144 AUDIT_SYSCALL_ENTER(sa->code, td))) { 145 #ifdef KDTRACE_HOOKS 146 /* Give the syscall:::entry DTrace probe a chance to fire. */ 147 if (__predict_false(sa->callp->sy_entry != 0)) 148 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 149 #endif 150 error = (sa->callp->sy_call)(td, sa->args); 151 /* Save the latest error return value. */ 152 if (__predict_false((td->td_pflags & TDP_NERRNO) == 0)) 153 td->td_errno = error; 154 AUDIT_SYSCALL_EXIT(error, td); 155 #ifdef KDTRACE_HOOKS 156 /* Give the syscall:::return DTrace probe a chance to fire. */ 157 if (__predict_false(sa->callp->sy_return != 0)) 158 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 159 error ? -1 : td->td_retval[0]); 160 #endif 161 } else { 162 error = (sa->callp->sy_call)(td, sa->args); 163 /* Save the latest error return value. */ 164 if (__predict_false((td->td_pflags & TDP_NERRNO) == 0)) 165 td->td_errno = error; 166 } 167 syscall_thread_exit(td, sa->callp); 168 169 retval: 170 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 171 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 172 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 173 td->td_retval[1]); 174 if (__predict_false(traced)) { 175 PROC_LOCK(p); 176 td->td_dbgflags &= ~TDB_SCE; 177 PROC_UNLOCK(p); 178 } 179 (p->p_sysent->sv_set_syscall_retval)(td, error); 180 } 181 182 static inline void 183 syscallret(struct thread *td) 184 { 185 struct proc *p; 186 struct syscall_args *sa; 187 ksiginfo_t ksi; 188 int traced; 189 190 KASSERT((td->td_pflags & TDP_FORKING) == 0, 191 ("fork() did not clear TDP_FORKING upon completion")); 192 193 p = td->td_proc; 194 sa = &td->td_sa; 195 if (__predict_false(td->td_errno == ENOTCAPABLE || 196 td->td_errno == ECAPMODE)) { 197 if ((trap_enotcap || 198 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) { 199 ksiginfo_init_trap(&ksi); 200 ksi.ksi_signo = SIGTRAP; 201 ksi.ksi_errno = td->td_errno; 202 ksi.ksi_code = TRAP_CAP; 203 trapsignal(td, &ksi); 204 } 205 } 206 207 /* 208 * Handle reschedule and other end-of-syscall issues 209 */ 210 userret(td, td->td_frame); 211 212 #ifdef KTRACE 213 if (KTRPOINT(td, KTR_SYSRET)) { 214 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 215 } 216 #endif 217 218 traced = 0; 219 if (__predict_false(p->p_flag & P_TRACED)) { 220 traced = 1; 221 PROC_LOCK(p); 222 td->td_dbgflags |= TDB_SCX; 223 PROC_UNLOCK(p); 224 } 225 if (__predict_false(traced || 226 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) { 227 PROC_LOCK(p); 228 /* 229 * If tracing the execed process, trap to the debugger 230 * so that breakpoints can be set before the program 231 * executes. If debugger requested tracing of syscall 232 * returns, do it now too. 233 */ 234 if (traced && 235 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 236 (p->p_ptevents & PTRACE_SCX) != 0)) 237 ptracestop(td, SIGTRAP, NULL); 238 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 239 PROC_UNLOCK(p); 240 } 241 242 if (__predict_false(td->td_pflags & TDP_RFPPWAIT)) 243 fork_rfppwait(td); 244 } 245