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 41 #include "opt_capsicum.h" 42 #include "opt_ktrace.h" 43 #include <sys/capsicum.h> 44 #include <sys/ktr.h> 45 #include <sys/vmmeter.h> 46 #ifdef KTRACE 47 #include <sys/uio.h> 48 #include <sys/ktrace.h> 49 #endif 50 #include <security/audit/audit.h> 51 52 static inline void 53 syscallenter(struct thread *td) 54 { 55 struct proc *p; 56 struct syscall_args *sa; 57 struct sysent *se; 58 int error, traced; 59 bool sy_thr_static; 60 61 VM_CNT_INC(v_syscall); 62 p = td->td_proc; 63 sa = &td->td_sa; 64 65 td->td_pticks = 0; 66 if (__predict_false(td->td_cowgen != atomic_load_int(&p->p_cowgen))) 67 thread_cow_update(td); 68 traced = (p->p_flag & P_TRACED) != 0; 69 if (__predict_false(traced || td->td_dbgflags & TDB_USERWR)) { 70 PROC_LOCK(p); 71 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0); 72 td->td_dbgflags &= ~TDB_USERWR; 73 if (traced) 74 td->td_dbgflags |= TDB_SCE; 75 PROC_UNLOCK(p); 76 } 77 if ((td->td_pflags2 & TDP2_UEXTERR) != 0) 78 td->td_pflags2 &= ~TDP2_EXTERR; 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 ((se->sy_flags & SYF_CAPENABLED) == 0) { 124 if (CAP_TRACING(td)) 125 ktrcapfail(CAPFAIL_SYSCALL, NULL); 126 if (IN_CAPABILITY_MODE(td)) { 127 td->td_errno = error = ECAPMODE; 128 goto retval; 129 } 130 } 131 #endif 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 KASSERT((td->td_pflags & TDP_NERRNO) == 0, 142 ("%s: TDP_NERRNO set", __func__)); 143 144 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0; 145 146 if (__predict_false(AUDIT_SYSCALL_ENABLED() || 147 SYSTRACE_ENABLED() || !sy_thr_static)) { 148 if (!sy_thr_static) { 149 error = syscall_thread_enter(td, &se); 150 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0; 151 if (error != 0) { 152 td->td_errno = error; 153 goto retval; 154 } 155 } 156 157 #ifdef KDTRACE_HOOKS 158 /* Give the syscall:::entry DTrace probe a chance to fire. */ 159 if (__predict_false(se->sy_entry != 0)) 160 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 161 #endif 162 163 AUDIT_SYSCALL_ENTER(sa->code, td); 164 165 error = (se->sy_call)(td, sa->args); 166 /* Save the latest error return value. */ 167 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 168 td->td_pflags &= ~TDP_NERRNO; 169 else 170 td->td_errno = error; 171 172 /* 173 * Note that some syscall implementations (e.g., sys_execve) 174 * will commit the audit record just before their final return. 175 * These were done under the assumption that nothing of interest 176 * would happen between their return and here, where we would 177 * normally commit the audit record. These assumptions will 178 * need to be revisited should any substantial logic be added 179 * above. 180 */ 181 AUDIT_SYSCALL_EXIT(error, td); 182 183 #ifdef KDTRACE_HOOKS 184 /* Give the syscall:::return DTrace probe a chance to fire. */ 185 if (__predict_false(se->sy_return != 0)) 186 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 187 error ? -1 : td->td_retval[0]); 188 #endif 189 190 if (!sy_thr_static) 191 syscall_thread_exit(td, se); 192 } else { 193 error = (se->sy_call)(td, sa->args); 194 /* Save the latest error return value. */ 195 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 196 td->td_pflags &= ~TDP_NERRNO; 197 else 198 td->td_errno = error; 199 } 200 201 retval: 202 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 203 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 204 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 205 td->td_retval[1]); 206 if (__predict_false(traced)) { 207 PROC_LOCK(p); 208 td->td_dbgflags &= ~(TDB_SCE | TDB_BOUNDARY); 209 PROC_UNLOCK(p); 210 } 211 (p->p_sysent->sv_set_syscall_retval)(td, error); 212 if (error != 0 && (td->td_pflags2 & TDP2_UEXTERR) != 0) 213 exterr_copyout(td); 214 } 215 216 static inline void 217 syscallret(struct thread *td) 218 { 219 struct proc *p; 220 struct syscall_args *sa; 221 ksiginfo_t ksi; 222 int traced; 223 224 KASSERT(td->td_errno != ERELOOKUP, 225 ("ERELOOKUP not consumed syscall %d", td->td_sa.code)); 226 227 p = td->td_proc; 228 sa = &td->td_sa; 229 if (__predict_false(td->td_errno == ENOTCAPABLE || 230 td->td_errno == ECAPMODE)) { 231 if ((trap_enotcap || 232 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) { 233 ksiginfo_init_trap(&ksi); 234 ksi.ksi_signo = SIGTRAP; 235 ksi.ksi_errno = td->td_errno; 236 ksi.ksi_code = TRAP_CAP; 237 ksi.ksi_info.si_syscall = sa->original_code; 238 trapsignal(td, &ksi); 239 } 240 } 241 242 /* 243 * Handle reschedule and other end-of-syscall issues 244 */ 245 userret(td, td->td_frame); 246 247 #ifdef KTRACE 248 if (KTRPOINT(td, KTR_SYSRET)) { 249 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 250 } 251 #endif 252 253 traced = 0; 254 if (__predict_false(p->p_flag & P_TRACED)) { 255 traced = 1; 256 PROC_LOCK(p); 257 td->td_dbgflags |= TDB_SCX; 258 PROC_UNLOCK(p); 259 } 260 if (__predict_false(traced || 261 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) { 262 PROC_LOCK(p); 263 /* 264 * Linux debuggers expect an additional stop for exec, 265 * between the usual syscall entry and exit. Raise 266 * the exec event now and then clear TDB_EXEC so that 267 * the next stop is reported as a syscall exit by 268 * linux_ptrace_status(). 269 * 270 * We are accessing p->p_pptr without any additional 271 * locks here: it cannot change while p is kept locked; 272 * while the debugger could in theory change its ABI 273 * while tracing another process, the outcome of such 274 * a race wouln't be deterministic anyway. 275 */ 276 if (traced && (td->td_dbgflags & TDB_EXEC) != 0 && 277 SV_PROC_ABI(p->p_pptr) == SV_ABI_LINUX) { 278 ptracestop(td, SIGTRAP, NULL); 279 td->td_dbgflags &= ~TDB_EXEC; 280 } 281 /* 282 * If tracing the execed process, trap to the debugger 283 * so that breakpoints can be set before the program 284 * executes. If debugger requested tracing of syscall 285 * returns, do it now too. 286 */ 287 if (traced && 288 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 289 (p->p_ptevents & PTRACE_SCX) != 0)) { 290 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0); 291 td->td_dbgflags |= TDB_BOUNDARY; 292 ptracestop(td, SIGTRAP, NULL); 293 } 294 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK | 295 TDB_BOUNDARY); 296 PROC_UNLOCK(p); 297 } 298 } 299