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 error = (p->p_sysent->sv_fetch_syscall_args)(td); 78 se = sa->callp; 79 #ifdef KTRACE 80 if (KTRPOINT(td, KTR_SYSCALL)) 81 ktrsyscall(sa->code, se->sy_narg, sa->args); 82 #endif 83 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 84 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 85 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 86 87 if (__predict_false(error != 0)) { 88 td->td_errno = error; 89 goto retval; 90 } 91 92 if (__predict_false(traced)) { 93 PROC_LOCK(p); 94 if (p->p_ptevents & PTRACE_SCE) 95 ptracestop((td), SIGTRAP, NULL); 96 PROC_UNLOCK(p); 97 98 if ((td->td_dbgflags & TDB_USERWR) != 0) { 99 /* 100 * Reread syscall number and arguments if debugger 101 * modified registers or memory. 102 */ 103 error = (p->p_sysent->sv_fetch_syscall_args)(td); 104 se = sa->callp; 105 #ifdef KTRACE 106 if (KTRPOINT(td, KTR_SYSCALL)) 107 ktrsyscall(sa->code, se->sy_narg, sa->args); 108 #endif 109 if (error != 0) { 110 td->td_errno = error; 111 goto retval; 112 } 113 } 114 } 115 116 #ifdef CAPABILITY_MODE 117 /* 118 * In capability mode, we only allow access to system calls 119 * flagged with SYF_CAPENABLED. 120 */ 121 if ((se->sy_flags & SYF_CAPENABLED) == 0) { 122 if (CAP_TRACING(td)) 123 ktrcapfail(CAPFAIL_SYSCALL, NULL); 124 if (IN_CAPABILITY_MODE(td)) { 125 td->td_errno = error = ECAPMODE; 126 goto retval; 127 } 128 } 129 #endif 130 131 /* 132 * Fetch fast sigblock value at the time of syscall entry to 133 * handle sleepqueue primitives which might call cursig(). 134 */ 135 if (__predict_false(sigfastblock_fetch_always)) 136 (void)sigfastblock_fetch(td); 137 138 /* Let system calls set td_errno directly. */ 139 KASSERT((td->td_pflags & TDP_NERRNO) == 0, 140 ("%s: TDP_NERRNO set", __func__)); 141 142 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0; 143 144 if (__predict_false(SYSTRACE_ENABLED() || 145 AUDIT_SYSCALL_ENTER(sa->code, td) || 146 !sy_thr_static)) { 147 if (!sy_thr_static) { 148 error = syscall_thread_enter(td, &se); 149 sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0; 150 if (error != 0) { 151 td->td_errno = error; 152 goto retval; 153 } 154 } 155 156 #ifdef KDTRACE_HOOKS 157 /* Give the syscall:::entry DTrace probe a chance to fire. */ 158 if (__predict_false(se->sy_entry != 0)) 159 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 160 #endif 161 error = (se->sy_call)(td, sa->args); 162 /* Save the latest error return value. */ 163 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 164 td->td_pflags &= ~TDP_NERRNO; 165 else 166 td->td_errno = error; 167 168 /* 169 * Note that some syscall implementations (e.g., sys_execve) 170 * will commit the audit record just before their final return. 171 * These were done under the assumption that nothing of interest 172 * would happen between their return and here, where we would 173 * normally commit the audit record. These assumptions will 174 * need to be revisited should any substantial logic be added 175 * above. 176 */ 177 AUDIT_SYSCALL_EXIT(error, td); 178 179 #ifdef KDTRACE_HOOKS 180 /* Give the syscall:::return DTrace probe a chance to fire. */ 181 if (__predict_false(se->sy_return != 0)) 182 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 183 error ? -1 : td->td_retval[0]); 184 #endif 185 186 if (!sy_thr_static) 187 syscall_thread_exit(td, se); 188 } else { 189 error = (se->sy_call)(td, sa->args); 190 /* Save the latest error return value. */ 191 if (__predict_false((td->td_pflags & TDP_NERRNO) != 0)) 192 td->td_pflags &= ~TDP_NERRNO; 193 else 194 td->td_errno = error; 195 } 196 197 retval: 198 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 199 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 200 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 201 td->td_retval[1]); 202 if (__predict_false(traced)) { 203 PROC_LOCK(p); 204 td->td_dbgflags &= ~(TDB_SCE | TDB_BOUNDARY); 205 PROC_UNLOCK(p); 206 } 207 (p->p_sysent->sv_set_syscall_retval)(td, error); 208 } 209 210 static inline void 211 syscallret(struct thread *td) 212 { 213 struct proc *p; 214 struct syscall_args *sa; 215 ksiginfo_t ksi; 216 int traced; 217 218 KASSERT(td->td_errno != ERELOOKUP, 219 ("ERELOOKUP not consumed syscall %d", td->td_sa.code)); 220 221 p = td->td_proc; 222 sa = &td->td_sa; 223 if (__predict_false(td->td_errno == ENOTCAPABLE || 224 td->td_errno == ECAPMODE)) { 225 if ((trap_enotcap || 226 (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) { 227 ksiginfo_init_trap(&ksi); 228 ksi.ksi_signo = SIGTRAP; 229 ksi.ksi_errno = td->td_errno; 230 ksi.ksi_code = TRAP_CAP; 231 ksi.ksi_info.si_syscall = sa->original_code; 232 trapsignal(td, &ksi); 233 } 234 } 235 236 /* 237 * Handle reschedule and other end-of-syscall issues 238 */ 239 userret(td, td->td_frame); 240 241 #ifdef KTRACE 242 if (KTRPOINT(td, KTR_SYSRET)) { 243 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 244 } 245 #endif 246 247 traced = 0; 248 if (__predict_false(p->p_flag & P_TRACED)) { 249 traced = 1; 250 PROC_LOCK(p); 251 td->td_dbgflags |= TDB_SCX; 252 PROC_UNLOCK(p); 253 } 254 if (__predict_false(traced || 255 (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) { 256 PROC_LOCK(p); 257 /* 258 * Linux debuggers expect an additional stop for exec, 259 * between the usual syscall entry and exit. Raise 260 * the exec event now and then clear TDB_EXEC so that 261 * the next stop is reported as a syscall exit by 262 * linux_ptrace_status(). 263 * 264 * We are accessing p->p_pptr without any additional 265 * locks here: it cannot change while p is kept locked; 266 * while the debugger could in theory change its ABI 267 * while tracing another process, the outcome of such 268 * a race wouln't be deterministic anyway. 269 */ 270 if (traced && (td->td_dbgflags & TDB_EXEC) != 0 && 271 SV_PROC_ABI(p->p_pptr) == SV_ABI_LINUX) { 272 ptracestop(td, SIGTRAP, NULL); 273 td->td_dbgflags &= ~TDB_EXEC; 274 } 275 /* 276 * If tracing the execed process, trap to the debugger 277 * so that breakpoints can be set before the program 278 * executes. If debugger requested tracing of syscall 279 * returns, do it now too. 280 */ 281 if (traced && 282 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 283 (p->p_ptevents & PTRACE_SCX) != 0)) { 284 MPASS((td->td_dbgflags & TDB_BOUNDARY) == 0); 285 td->td_dbgflags |= TDB_BOUNDARY; 286 ptracestop(td, SIGTRAP, NULL); 287 } 288 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK | 289 TDB_BOUNDARY); 290 PROC_UNLOCK(p); 291 } 292 } 293