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 struct sysent *se; 63 int error, traced; 64 65 VM_CNT_INC(v_syscall); 66 p = td->td_proc; 67 sa = &td->td_sa; 68 69 td->td_pticks = 0; 70 if (__predict_false(td->td_cowgen != p->p_cowgen)) 71 thread_cow_update(td); 72 traced = (p->p_flag & P_TRACED) != 0; 73 if (__predict_false(traced || td->td_dbgflags & TDB_USERWR)) { 74 PROC_LOCK(p); 75 td->td_dbgflags &= ~TDB_USERWR; 76 if (traced) 77 td->td_dbgflags |= TDB_SCE; 78 PROC_UNLOCK(p); 79 } 80 error = (p->p_sysent->sv_fetch_syscall_args)(td); 81 se = sa->callp; 82 #ifdef KTRACE 83 if (KTRPOINT(td, KTR_SYSCALL)) 84 ktrsyscall(sa->code, se->sy_narg, sa->args); 85 #endif 86 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 87 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 88 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 89 90 if (__predict_false(error != 0)) { 91 td->td_errno = error; 92 goto retval; 93 } 94 95 if (__predict_false(traced)) { 96 PROC_LOCK(p); 97 if (p->p_ptevents & PTRACE_SCE) 98 ptracestop((td), SIGTRAP, NULL); 99 PROC_UNLOCK(p); 100 } 101 if (__predict_false((td->td_dbgflags & TDB_USERWR) != 0)) { 102 /* 103 * Reread syscall number and arguments if debugger 104 * modified registers or memory. 105 */ 106 error = (p->p_sysent->sv_fetch_syscall_args)(td); 107 se = sa->callp; 108 #ifdef KTRACE 109 if (KTRPOINT(td, KTR_SYSCALL)) 110 ktrsyscall(sa->code, se->sy_narg, sa->args); 111 #endif 112 if (error != 0) { 113 td->td_errno = error; 114 goto retval; 115 } 116 } 117 118 #ifdef CAPABILITY_MODE 119 /* 120 * In capability mode, we only allow access to system calls 121 * flagged with SYF_CAPENABLED. 122 */ 123 if (__predict_false(IN_CAPABILITY_MODE(td) && 124 (se->sy_flags & SYF_CAPENABLED) == 0)) { 125 td->td_errno = error = ECAPMODE; 126 goto retval; 127 } 128 #endif 129 130 error = syscall_thread_enter(td, se); 131 if (error != 0) { 132 td->td_errno = error; 133 goto retval; 134 } 135 136 /* 137 * Fetch fast sigblock value at the time of syscall entry to 138 * handle sleepqueue primitives which might call cursig(). 139 */ 140 if (__predict_false(sigfastblock_fetch_always)) 141 (void)sigfastblock_fetch(td); 142 143 /* Let system calls set td_errno directly. */ 144 KASSERT((td->td_pflags & TDP_NERRNO) == 0, 145 ("%s: TDP_NERRNO set", __func__)); 146 147 if (__predict_false(SYSTRACE_ENABLED() || 148 AUDIT_SYSCALL_ENTER(sa->code, td))) { 149 #ifdef KDTRACE_HOOKS 150 /* Give the syscall:::entry DTrace probe a chance to fire. */ 151 if (__predict_false(se->sy_entry != 0)) 152 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 153 #endif 154 error = (se->sy_call)(td, sa->args); 155 /* Save the latest error return value. */ 156 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 157 td->td_pflags &= ~TDP_NERRNO; 158 else 159 td->td_errno = error; 160 161 /* 162 * Note that some syscall implementations (e.g., sys_execve) 163 * will commit the audit record just before their final return. 164 * These were done under the assumption that nothing of interest 165 * would happen between their return and here, where we would 166 * normally commit the audit record. These assumptions will 167 * need to be revisited should any substantial logic be added 168 * above. 169 */ 170 AUDIT_SYSCALL_EXIT(error, td); 171 172 #ifdef KDTRACE_HOOKS 173 /* Give the syscall:::return DTrace probe a chance to fire. */ 174 if (__predict_false(se->sy_return != 0)) 175 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 176 error ? -1 : td->td_retval[0]); 177 #endif 178 } else { 179 error = (se->sy_call)(td, sa->args); 180 /* Save the latest error return value. */ 181 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 182 td->td_pflags &= ~TDP_NERRNO; 183 else 184 td->td_errno = error; 185 } 186 syscall_thread_exit(td, se); 187 188 retval: 189 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 190 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 191 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 192 td->td_retval[1]); 193 if (__predict_false(traced)) { 194 PROC_LOCK(p); 195 td->td_dbgflags &= ~TDB_SCE; 196 PROC_UNLOCK(p); 197 } 198 (p->p_sysent->sv_set_syscall_retval)(td, error); 199 } 200 201 static inline void 202 syscallret(struct thread *td) 203 { 204 struct proc *p; 205 struct syscall_args *sa; 206 ksiginfo_t ksi; 207 int traced; 208 209 KASSERT((td->td_pflags & TDP_FORKING) == 0, 210 ("fork() did not clear TDP_FORKING upon completion")); 211 212 p = td->td_proc; 213 sa = &td->td_sa; 214 if (__predict_false(td->td_errno == ENOTCAPABLE || 215 td->td_errno == ECAPMODE)) { 216 if ((trap_enotcap || 217 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) { 218 ksiginfo_init_trap(&ksi); 219 ksi.ksi_signo = SIGTRAP; 220 ksi.ksi_errno = td->td_errno; 221 ksi.ksi_code = TRAP_CAP; 222 trapsignal(td, &ksi); 223 } 224 } 225 226 /* 227 * Handle reschedule and other end-of-syscall issues 228 */ 229 userret(td, td->td_frame); 230 231 #ifdef KTRACE 232 if (KTRPOINT(td, KTR_SYSRET)) { 233 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 234 } 235 #endif 236 237 traced = 0; 238 if (__predict_false(p->p_flag & P_TRACED)) { 239 traced = 1; 240 PROC_LOCK(p); 241 td->td_dbgflags |= TDB_SCX; 242 PROC_UNLOCK(p); 243 } 244 if (__predict_false(traced || 245 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) { 246 PROC_LOCK(p); 247 /* 248 * If tracing the execed process, trap to the debugger 249 * so that breakpoints can be set before the program 250 * executes. If debugger requested tracing of syscall 251 * returns, do it now too. 252 */ 253 if (traced && 254 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 255 (p->p_ptevents & PTRACE_SCX) != 0)) 256 ptracestop(td, SIGTRAP, NULL); 257 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 258 PROC_UNLOCK(p); 259 } 260 261 if (__predict_false(td->td_pflags & TDP_RFPPWAIT)) 262 fork_rfppwait(td); 263 } 264