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 int error, traced; 63 64 VM_CNT_INC(v_syscall); 65 p = td->td_proc; 66 sa = &td->td_sa; 67 68 td->td_pticks = 0; 69 if (__predict_false(td->td_cowgen != p->p_cowgen)) 70 thread_cow_update(td); 71 traced = (p->p_flag & P_TRACED) != 0; 72 if (traced || td->td_dbgflags & TDB_USERWR) { 73 PROC_LOCK(p); 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 #ifdef KTRACE 81 if (KTRPOINT(td, KTR_SYSCALL)) 82 ktrsyscall(sa->code, sa->narg, sa->args); 83 #endif 84 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 85 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 86 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 87 88 if (error != 0) { 89 td->td_errno = error; 90 goto retval; 91 } 92 93 STOPEVENT(p, S_SCE, sa->narg); 94 if ((p->p_flag & P_TRACED) != 0) { 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 #ifdef KTRACE 107 if (KTRPOINT(td, KTR_SYSCALL)) 108 ktrsyscall(sa->code, sa->narg, sa->args); 109 #endif 110 if (error != 0) { 111 td->td_errno = error; 112 goto retval; 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 (IN_CAPABILITY_MODE(td) && 122 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 123 td->td_errno = error = ECAPMODE; 124 goto retval; 125 } 126 #endif 127 128 error = syscall_thread_enter(td, sa->callp); 129 if (error != 0) { 130 td->td_errno = error; 131 goto retval; 132 } 133 134 #ifdef KDTRACE_HOOKS 135 /* Give the syscall:::entry DTrace probe a chance to fire. */ 136 if (__predict_false(systrace_enabled && sa->callp->sy_entry != 0)) 137 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 138 #endif 139 140 /* Let system calls set td_errno directly. */ 141 td->td_pflags &= ~TDP_NERRNO; 142 143 /* 144 * Fetch fast sigblock value at the time of syscall 145 * entry because sleepqueue primitives might call 146 * cursig(). 147 */ 148 fetch_sigfastblock(td); 149 150 AUDIT_SYSCALL_ENTER(sa->code, td); 151 error = (sa->callp->sy_call)(td, sa->args); 152 AUDIT_SYSCALL_EXIT(error, td); 153 154 /* Save the latest error return value. */ 155 if ((td->td_pflags & TDP_NERRNO) == 0) 156 td->td_errno = error; 157 158 #ifdef KDTRACE_HOOKS 159 /* Give the syscall:::return DTrace probe a chance to fire. */ 160 if (__predict_false(systrace_enabled && sa->callp->sy_return != 0)) 161 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 162 error ? -1 : td->td_retval[0]); 163 #endif 164 syscall_thread_exit(td, sa->callp); 165 166 retval: 167 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 168 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 169 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 170 td->td_retval[1]); 171 if (traced) { 172 PROC_LOCK(p); 173 td->td_dbgflags &= ~TDB_SCE; 174 PROC_UNLOCK(p); 175 } 176 (p->p_sysent->sv_set_syscall_retval)(td, error); 177 } 178 179 static inline void 180 syscallret(struct thread *td) 181 { 182 struct proc *p; 183 struct syscall_args *sa; 184 ksiginfo_t ksi; 185 int traced; 186 187 KASSERT((td->td_pflags & TDP_FORKING) == 0, 188 ("fork() did not clear TDP_FORKING upon completion")); 189 190 p = td->td_proc; 191 sa = &td->td_sa; 192 if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) && 193 IN_CAPABILITY_MODE(td)) { 194 if (td->td_errno == ENOTCAPABLE || td->td_errno == ECAPMODE) { 195 ksiginfo_init_trap(&ksi); 196 ksi.ksi_signo = SIGTRAP; 197 ksi.ksi_errno = td->td_errno; 198 ksi.ksi_code = TRAP_CAP; 199 trapsignal(td, &ksi); 200 } 201 } 202 203 /* 204 * Handle reschedule and other end-of-syscall issues 205 */ 206 userret(td, td->td_frame); 207 208 #ifdef KTRACE 209 if (KTRPOINT(td, KTR_SYSRET)) { 210 ktrsysret(sa->code, td->td_errno, td->td_retval[0]); 211 } 212 #endif 213 214 if (p->p_flag & P_TRACED) { 215 traced = 1; 216 PROC_LOCK(p); 217 td->td_dbgflags |= TDB_SCX; 218 PROC_UNLOCK(p); 219 } else 220 traced = 0; 221 /* 222 * This works because errno is findable through the 223 * register set. If we ever support an emulation where this 224 * is not the case, this code will need to be revisited. 225 */ 226 STOPEVENT(p, S_SCX, sa->code); 227 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 228 PROC_LOCK(p); 229 /* 230 * If tracing the execed process, trap to the debugger 231 * so that breakpoints can be set before the program 232 * executes. If debugger requested tracing of syscall 233 * returns, do it now too. 234 */ 235 if (traced && 236 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 237 (p->p_ptevents & PTRACE_SCX) != 0)) 238 ptracestop(td, SIGTRAP, NULL); 239 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 240 PROC_UNLOCK(p); 241 } 242 243 if (__predict_false(td->td_pflags & TDP_RFPPWAIT)) 244 fork_rfppwait(td); 245 } 246