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 ((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 } 118 119 #ifdef CAPABILITY_MODE 120 /* 121 * In capability mode, we only allow access to system calls 122 * flagged with SYF_CAPENABLED. 123 */ 124 if (__predict_false(IN_CAPABILITY_MODE(td) && 125 (se->sy_flags & SYF_CAPENABLED) == 0)) { 126 td->td_errno = error = ECAPMODE; 127 goto retval; 128 } 129 #endif 130 131 error = syscall_thread_enter(td, se); 132 if (error != 0) { 133 td->td_errno = error; 134 goto retval; 135 } 136 137 /* 138 * Fetch fast sigblock value at the time of syscall entry to 139 * handle sleepqueue primitives which might call cursig(). 140 */ 141 if (__predict_false(sigfastblock_fetch_always)) 142 (void)sigfastblock_fetch(td); 143 144 /* Let system calls set td_errno directly. */ 145 KASSERT((td->td_pflags & TDP_NERRNO) == 0, 146 ("%s: TDP_NERRNO set", __func__)); 147 148 if (__predict_false(SYSTRACE_ENABLED() || 149 AUDIT_SYSCALL_ENTER(sa->code, td))) { 150 #ifdef KDTRACE_HOOKS 151 /* Give the syscall:::entry DTrace probe a chance to fire. */ 152 if (__predict_false(se->sy_entry != 0)) 153 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 154 #endif 155 error = (se->sy_call)(td, sa->args); 156 /* Save the latest error return value. */ 157 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 158 td->td_pflags &= ~TDP_NERRNO; 159 else 160 td->td_errno = error; 161 162 /* 163 * Note that some syscall implementations (e.g., sys_execve) 164 * will commit the audit record just before their final return. 165 * These were done under the assumption that nothing of interest 166 * would happen between their return and here, where we would 167 * normally commit the audit record. These assumptions will 168 * need to be revisited should any substantial logic be added 169 * above. 170 */ 171 AUDIT_SYSCALL_EXIT(error, td); 172 173 #ifdef KDTRACE_HOOKS 174 /* Give the syscall:::return DTrace probe a chance to fire. */ 175 if (__predict_false(se->sy_return != 0)) 176 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 177 error ? -1 : td->td_retval[0]); 178 #endif 179 } else { 180 error = (se->sy_call)(td, sa->args); 181 /* Save the latest error return value. */ 182 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 183 td->td_pflags &= ~TDP_NERRNO; 184 else 185 td->td_errno = error; 186 } 187 syscall_thread_exit(td, se); 188 189 retval: 190 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 191 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 192 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 193 td->td_retval[1]); 194 if (__predict_false(traced)) { 195 PROC_LOCK(p); 196 td->td_dbgflags &= ~TDB_SCE; 197 PROC_UNLOCK(p); 198 } 199 (p->p_sysent->sv_set_syscall_retval)(td, error); 200 } 201 202 static inline void 203 syscallret(struct thread *td) 204 { 205 struct proc *p; 206 struct syscall_args *sa; 207 ksiginfo_t ksi; 208 int traced; 209 210 KASSERT((td->td_pflags & TDP_FORKING) == 0, 211 ("fork() did not clear TDP_FORKING upon completion")); 212 213 p = td->td_proc; 214 sa = &td->td_sa; 215 if (__predict_false(td->td_errno == ENOTCAPABLE || 216 td->td_errno == ECAPMODE)) { 217 if ((trap_enotcap || 218 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) { 219 ksiginfo_init_trap(&ksi); 220 ksi.ksi_signo = SIGTRAP; 221 ksi.ksi_errno = td->td_errno; 222 ksi.ksi_code = TRAP_CAP; 223 trapsignal(td, &ksi); 224 } 225 } 226 227 /* 228 * Handle reschedule and other end-of-syscall issues 229 */ 230 userret(td, td->td_frame); 231 232 #ifdef KTRACE 233 if (KTRPOINT(td, KTR_SYSRET)) { 234 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 235 } 236 #endif 237 238 traced = 0; 239 if (__predict_false(p->p_flag & P_TRACED)) { 240 traced = 1; 241 PROC_LOCK(p); 242 td->td_dbgflags |= TDB_SCX; 243 PROC_UNLOCK(p); 244 } 245 if (__predict_false(traced || 246 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) { 247 PROC_LOCK(p); 248 /* 249 * If tracing the execed process, trap to the debugger 250 * so that breakpoints can be set before the program 251 * executes. If debugger requested tracing of syscall 252 * returns, do it now too. 253 */ 254 if (traced && 255 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 256 (p->p_ptevents & PTRACE_SCX) != 0)) 257 ptracestop(td, SIGTRAP, NULL); 258 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 259 PROC_UNLOCK(p); 260 } 261 262 if (__predict_false(td->td_pflags & TDP_RFPPWAIT)) 263 fork_rfppwait(td); 264 } 265