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 #include <sys/capsicum.h> 46 #include <sys/ktr.h> 47 #include <sys/vmmeter.h> 48 #ifdef KTRACE 49 #include <sys/uio.h> 50 #include <sys/ktrace.h> 51 #endif 52 #include <security/audit/audit.h> 53 54 static inline void 55 syscallenter(struct thread *td) 56 { 57 struct proc *p; 58 struct syscall_args *sa; 59 struct sysent *se; 60 int error, traced; 61 bool sy_thr_static; 62 63 VM_CNT_INC(v_syscall); 64 p = td->td_proc; 65 sa = &td->td_sa; 66 67 td->td_pticks = 0; 68 if (__predict_false(td->td_cowgen != atomic_load_int(&p->p_cowgen))) 69 thread_cow_update(td); 70 traced = (p->p_flag & P_TRACED) != 0; 71 if (__predict_false(traced || td->td_dbgflags & TDB_USERWR)) { 72 PROC_LOCK(p); 73 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0); 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 se = sa->callp; 81 #ifdef KTRACE 82 if (KTRPOINT(td, KTR_SYSCALL)) 83 ktrsyscall(sa->code, se->sy_narg, sa->args); 84 #endif 85 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 86 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 87 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 88 89 if (__predict_false(error != 0)) { 90 td->td_errno = error; 91 goto retval; 92 } 93 94 if (__predict_false(traced)) { 95 PROC_LOCK(p); 96 if (p->p_ptevents & PTRACE_SCE) 97 ptracestop((td), SIGTRAP, NULL); 98 PROC_UNLOCK(p); 99 100 if ((td->td_dbgflags & TDB_USERWR) != 0) { 101 /* 102 * Reread syscall number and arguments if debugger 103 * modified registers or memory. 104 */ 105 error = (p->p_sysent->sv_fetch_syscall_args)(td); 106 se = sa->callp; 107 #ifdef KTRACE 108 if (KTRPOINT(td, KTR_SYSCALL)) 109 ktrsyscall(sa->code, se->sy_narg, sa->args); 110 #endif 111 if (error != 0) { 112 td->td_errno = error; 113 goto retval; 114 } 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 /* 131 * Fetch fast sigblock value at the time of syscall entry to 132 * handle sleepqueue primitives which might call cursig(). 133 */ 134 if (__predict_false(sigfastblock_fetch_always)) 135 (void)sigfastblock_fetch(td); 136 137 /* Let system calls set td_errno directly. */ 138 KASSERT((td->td_pflags & TDP_NERRNO) == 0, 139 ("%s: TDP_NERRNO set", __func__)); 140 141 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0; 142 143 if (__predict_false(SYSTRACE_ENABLED() || 144 AUDIT_SYSCALL_ENTER(sa->code, td) || 145 !sy_thr_static)) { 146 if (!sy_thr_static) { 147 error = syscall_thread_enter(td, &se); 148 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0; 149 if (error != 0) { 150 td->td_errno = error; 151 goto retval; 152 } 153 } 154 155 #ifdef KDTRACE_HOOKS 156 /* Give the syscall:::entry DTrace probe a chance to fire. */ 157 if (__predict_false(se->sy_entry != 0)) 158 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 159 #endif 160 error = (se->sy_call)(td, sa->args); 161 /* Save the latest error return value. */ 162 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 163 td->td_pflags &= ~TDP_NERRNO; 164 else 165 td->td_errno = error; 166 167 /* 168 * Note that some syscall implementations (e.g., sys_execve) 169 * will commit the audit record just before their final return. 170 * These were done under the assumption that nothing of interest 171 * would happen between their return and here, where we would 172 * normally commit the audit record. These assumptions will 173 * need to be revisited should any substantial logic be added 174 * above. 175 */ 176 AUDIT_SYSCALL_EXIT(error, td); 177 178 #ifdef KDTRACE_HOOKS 179 /* Give the syscall:::return DTrace probe a chance to fire. */ 180 if (__predict_false(se->sy_return != 0)) 181 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 182 error ? -1 : td->td_retval[0]); 183 #endif 184 185 if (!sy_thr_static) 186 syscall_thread_exit(td, se); 187 } else { 188 error = (se->sy_call)(td, sa->args); 189 /* Save the latest error return value. */ 190 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 191 td->td_pflags &= ~TDP_NERRNO; 192 else 193 td->td_errno = error; 194 } 195 196 retval: 197 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 198 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 199 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 200 td->td_retval[1]); 201 if (__predict_false(traced)) { 202 PROC_LOCK(p); 203 td->td_dbgflags &= ~(TDB_SCE | TDB_BOUNDARY); 204 PROC_UNLOCK(p); 205 } 206 (p->p_sysent->sv_set_syscall_retval)(td, error); 207 } 208 209 static inline void 210 syscallret(struct thread *td) 211 { 212 struct proc *p; 213 struct syscall_args *sa; 214 ksiginfo_t ksi; 215 int traced; 216 217 KASSERT(td->td_errno != ERELOOKUP, 218 ("ERELOOKUP not consumed syscall %d", td->td_sa.code)); 219 220 p = td->td_proc; 221 sa = &td->td_sa; 222 if (__predict_false(td->td_errno == ENOTCAPABLE || 223 td->td_errno == ECAPMODE)) { 224 if ((trap_enotcap || 225 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) { 226 ksiginfo_init_trap(&ksi); 227 ksi.ksi_signo = SIGTRAP; 228 ksi.ksi_errno = td->td_errno; 229 ksi.ksi_code = TRAP_CAP; 230 ksi.ksi_info.si_syscall = sa->original_code; 231 trapsignal(td, &ksi); 232 } 233 } 234 235 /* 236 * Handle reschedule and other end-of-syscall issues 237 */ 238 userret(td, td->td_frame); 239 240 #ifdef KTRACE 241 if (KTRPOINT(td, KTR_SYSRET)) { 242 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 243 } 244 #endif 245 246 traced = 0; 247 if (__predict_false(p->p_flag & P_TRACED)) { 248 traced = 1; 249 PROC_LOCK(p); 250 td->td_dbgflags |= TDB_SCX; 251 PROC_UNLOCK(p); 252 } 253 if (__predict_false(traced || 254 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) { 255 PROC_LOCK(p); 256 /* 257 * Linux debuggers expect an additional stop for exec, 258 * between the usual syscall entry and exit. Raise 259 * the exec event now and then clear TDB_EXEC so that 260 * the next stop is reported as a syscall exit by 261 * linux_ptrace_status(). 262 * 263 * We are accessing p->p_pptr without any additional 264 * locks here: it cannot change while p is kept locked; 265 * while the debugger could in theory change its ABI 266 * while tracing another process, the outcome of such 267 * a race wouln't be deterministic anyway. 268 */ 269 if (traced && (td->td_dbgflags & TDB_EXEC) != 0 && 270 SV_PROC_ABI(p->p_pptr) == SV_ABI_LINUX) { 271 ptracestop(td, SIGTRAP, NULL); 272 td->td_dbgflags &= ~TDB_EXEC; 273 } 274 /* 275 * If tracing the execed process, trap to the debugger 276 * so that breakpoints can be set before the program 277 * executes. If debugger requested tracing of syscall 278 * returns, do it now too. 279 */ 280 if (traced && 281 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 282 (p->p_ptevents & PTRACE_SCX) != 0)) { 283 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0); 284 td->td_dbgflags |= TDB_BOUNDARY; 285 ptracestop(td, SIGTRAP, NULL); 286 } 287 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK | 288 TDB_BOUNDARY); 289 PROC_UNLOCK(p); 290 } 291 } 292