1/*- 2 * Copyright (C) 1994, David Greenman 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org> 6 * 7 * This code is derived from software contributed to Berkeley by 8 * the University of Utah, and William Jolitz. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 39 */ 40 41#include "opt_capsicum.h" 42#include "opt_ktrace.h" 43 44__FBSDID("$FreeBSD: stable/11/sys/kern/subr_syscall.c 331722 2018-03-29 02:50:57Z eadler $"); 45 46#include <sys/capsicum.h> 47#include <sys/ktr.h> 48#include <sys/vmmeter.h> 49#ifdef KTRACE 50#include <sys/uio.h> 51#include <sys/ktrace.h> 52#endif 53#include <security/audit/audit.h> 54 55static inline int 56syscallenter(struct thread *td) 57{ 58 struct proc *p; 59 struct syscall_args *sa; 60 int error, traced; 61 62 PCPU_INC(cnt.v_syscall); 63 p = td->td_proc; 64 sa = &td->td_sa; 65 66 td->td_pticks = 0; 67 if (td->td_cowgen != p->p_cowgen) 68 thread_cow_update(td); 69 traced = (p->p_flag & P_TRACED) != 0; 70 if (traced || td->td_dbgflags & TDB_USERWR) { 71 PROC_LOCK(p); 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#ifdef KTRACE 79 if (KTRPOINT(td, KTR_SYSCALL)) 80 ktrsyscall(sa->code, sa->narg, sa->args); 81#endif 82 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 83 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 84 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 85 86 if (error == 0) { 87 88 STOPEVENT(p, S_SCE, sa->narg); 89 if (p->p_flag & P_TRACED) { 90 PROC_LOCK(p); 91 if (p->p_ptevents & PTRACE_SCE) 92 ptracestop((td), SIGTRAP, NULL); 93 PROC_UNLOCK(p); 94 } 95 if (td->td_dbgflags & TDB_USERWR) { 96 /* 97 * Reread syscall number and arguments if 98 * debugger modified registers or memory. 99 */ 100 error = (p->p_sysent->sv_fetch_syscall_args)(td); 101#ifdef KTRACE 102 if (KTRPOINT(td, KTR_SYSCALL)) 103 ktrsyscall(sa->code, sa->narg, sa->args); 104#endif 105 if (error != 0) 106 goto retval; 107 } 108 109#ifdef CAPABILITY_MODE 110 /* 111 * In capability mode, we only allow access to system calls 112 * flagged with SYF_CAPENABLED. 113 */ 114 if (IN_CAPABILITY_MODE(td) && 115 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 116 error = ECAPMODE; 117 goto retval; 118 } 119#endif 120 121 error = syscall_thread_enter(td, sa->callp); 122 if (error != 0) 123 goto retval; 124 125#ifdef KDTRACE_HOOKS 126 /* Give the syscall:::entry DTrace probe a chance to fire. */ 127 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 128 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 129#endif 130 131 AUDIT_SYSCALL_ENTER(sa->code, td); 132 error = (sa->callp->sy_call)(td, sa->args); 133 AUDIT_SYSCALL_EXIT(error, td); 134 135 /* Save the latest error return value. */ 136 if ((td->td_pflags & TDP_NERRNO) == 0) 137 td->td_errno = error; 138 139#ifdef KDTRACE_HOOKS 140 /* Give the syscall:::return DTrace probe a chance to fire. */ 141 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 142 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 143 error ? -1 : td->td_retval[0]); 144#endif 145 syscall_thread_exit(td, sa->callp); 146 } 147 retval: 148 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 149 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 150 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 151 td->td_retval[1]); 152 if (traced) { 153 PROC_LOCK(p); 154 td->td_dbgflags &= ~TDB_SCE; 155 PROC_UNLOCK(p); 156 } 157 (p->p_sysent->sv_set_syscall_retval)(td, error); 158 return (error); 159} 160 161static inline void 162syscallret(struct thread *td, int error) 163{ 164 struct proc *p, *p2; 165 struct syscall_args *sa; 166 ksiginfo_t ksi; 167 int traced, error1; 168 169 KASSERT((td->td_pflags & TDP_FORKING) == 0, 170 ("fork() did not clear TDP_FORKING upon completion")); 171 172 p = td->td_proc; 173 sa = &td->td_sa; 174 if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) && 175 IN_CAPABILITY_MODE(td)) { 176 error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error : 177 td->td_errno; 178 if (error1 == ENOTCAPABLE || error1 == ECAPMODE) { 179 ksiginfo_init_trap(&ksi); 180 ksi.ksi_signo = SIGTRAP; 181 ksi.ksi_errno = error1; 182 ksi.ksi_code = TRAP_CAP; 183 trapsignal(td, &ksi); 184 } 185 } 186 187 /* 188 * Handle reschedule and other end-of-syscall issues 189 */ 190 userret(td, td->td_frame); 191 192#ifdef KTRACE 193 if (KTRPOINT(td, KTR_SYSRET)) { 194 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ? 195 error : td->td_errno, td->td_retval[0]); 196 } 197#endif 198 td->td_pflags &= ~TDP_NERRNO; 199 200 if (p->p_flag & P_TRACED) { 201 traced = 1; 202 PROC_LOCK(p); 203 td->td_dbgflags |= TDB_SCX; 204 PROC_UNLOCK(p); 205 } else 206 traced = 0; 207 /* 208 * This works because errno is findable through the 209 * register set. If we ever support an emulation where this 210 * is not the case, this code will need to be revisited. 211 */ 212 STOPEVENT(p, S_SCX, sa->code); 213 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 214 PROC_LOCK(p); 215 /* 216 * If tracing the execed process, trap to the debugger 217 * so that breakpoints can be set before the program 218 * executes. If debugger requested tracing of syscall 219 * returns, do it now too. 220 */ 221 if (traced && 222 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 223 (p->p_ptevents & PTRACE_SCX) != 0)) 224 ptracestop(td, SIGTRAP, NULL); 225 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 226 PROC_UNLOCK(p); 227 } 228 229 if (td->td_pflags & TDP_RFPPWAIT) { 230 /* 231 * Preserve synchronization semantics of vfork. If 232 * waiting for child to exec or exit, fork set 233 * P_PPWAIT on child, and there we sleep on our proc 234 * (in case of exit). 235 * 236 * Do it after the ptracestop() above is finished, to 237 * not block our debugger until child execs or exits 238 * to finish vfork wait. 239 */ 240 td->td_pflags &= ~TDP_RFPPWAIT; 241 p2 = td->td_rfppwait_p; 242again: 243 PROC_LOCK(p2); 244 while (p2->p_flag & P_PPWAIT) { 245 PROC_LOCK(p); 246 if (thread_suspend_check_needed()) { 247 PROC_UNLOCK(p2); 248 thread_suspend_check(0); 249 PROC_UNLOCK(p); 250 goto again; 251 } else { 252 PROC_UNLOCK(p); 253 } 254 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz); 255 } 256 PROC_UNLOCK(p2); 257 258 if (td->td_dbgflags & TDB_VFORK) { 259 PROC_LOCK(p); 260 if (p->p_ptevents & PTRACE_VFORK) 261 ptracestop(td, SIGTRAP, NULL); 262 td->td_dbgflags &= ~TDB_VFORK; 263 PROC_UNLOCK(p); 264 } 265 } 266} 267