subr_syscall.c revision 321343
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 321343 2017-07-21 18:06:57Z kib $"); 45 46#include <sys/capsicum.h> 47#include <sys/ktr.h> 48#ifdef KTRACE 49#include <sys/uio.h> 50#include <sys/ktrace.h> 51#endif 52#include <security/audit/audit.h> 53 54static inline int 55syscallenter(struct thread *td) 56{ 57 struct proc *p; 58 struct syscall_args *sa; 59 int error, traced; 60 61 PCPU_INC(cnt.v_syscall); 62 p = td->td_proc; 63 sa = &td->td_sa; 64 65 td->td_pticks = 0; 66 if (td->td_cowgen != p->p_cowgen) 67 thread_cow_update(td); 68 traced = (p->p_flag & P_TRACED) != 0; 69 if (traced || td->td_dbgflags & TDB_USERWR) { 70 PROC_LOCK(p); 71 td->td_dbgflags &= ~TDB_USERWR; 72 if (traced) 73 td->td_dbgflags |= TDB_SCE; 74 PROC_UNLOCK(p); 75 } 76 error = (p->p_sysent->sv_fetch_syscall_args)(td); 77#ifdef KTRACE 78 if (KTRPOINT(td, KTR_SYSCALL)) 79 ktrsyscall(sa->code, sa->narg, sa->args); 80#endif 81 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 82 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 83 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 84 85 if (error == 0) { 86 87 STOPEVENT(p, S_SCE, sa->narg); 88 if (p->p_flag & P_TRACED) { 89 PROC_LOCK(p); 90 if (p->p_ptevents & PTRACE_SCE) 91 ptracestop((td), SIGTRAP, NULL); 92 PROC_UNLOCK(p); 93 } 94 if (td->td_dbgflags & TDB_USERWR) { 95 /* 96 * Reread syscall number and arguments if 97 * debugger modified registers or memory. 98 */ 99 error = (p->p_sysent->sv_fetch_syscall_args)(td); 100#ifdef KTRACE 101 if (KTRPOINT(td, KTR_SYSCALL)) 102 ktrsyscall(sa->code, sa->narg, sa->args); 103#endif 104 if (error != 0) 105 goto retval; 106 } 107 108#ifdef CAPABILITY_MODE 109 /* 110 * In capability mode, we only allow access to system calls 111 * flagged with SYF_CAPENABLED. 112 */ 113 if (IN_CAPABILITY_MODE(td) && 114 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 115 error = ECAPMODE; 116 goto retval; 117 } 118#endif 119 120 error = syscall_thread_enter(td, sa->callp); 121 if (error != 0) 122 goto retval; 123 124#ifdef KDTRACE_HOOKS 125 /* Give the syscall:::entry DTrace probe a chance to fire. */ 126 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 127 (*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0); 128#endif 129 130 AUDIT_SYSCALL_ENTER(sa->code, td); 131 error = (sa->callp->sy_call)(td, sa->args); 132 AUDIT_SYSCALL_EXIT(error, td); 133 134 /* Save the latest error return value. */ 135 if ((td->td_pflags & TDP_NERRNO) == 0) 136 td->td_errno = error; 137 138#ifdef KDTRACE_HOOKS 139 /* Give the syscall:::return DTrace probe a chance to fire. */ 140 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 141 (*systrace_probe_func)(sa, SYSTRACE_RETURN, 142 error ? -1 : td->td_retval[0]); 143#endif 144 syscall_thread_exit(td, sa->callp); 145 } 146 retval: 147 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 148 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 149 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 150 td->td_retval[1]); 151 if (traced) { 152 PROC_LOCK(p); 153 td->td_dbgflags &= ~TDB_SCE; 154 PROC_UNLOCK(p); 155 } 156 (p->p_sysent->sv_set_syscall_retval)(td, error); 157 return (error); 158} 159 160static inline void 161syscallret(struct thread *td, int error) 162{ 163 struct proc *p, *p2; 164 struct syscall_args *sa; 165 ksiginfo_t ksi; 166 int traced, error1; 167 168 KASSERT((td->td_pflags & TDP_FORKING) == 0, 169 ("fork() did not clear TDP_FORKING upon completion")); 170 171 p = td->td_proc; 172 sa = &td->td_sa; 173 if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) && 174 IN_CAPABILITY_MODE(td)) { 175 error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error : 176 td->td_errno; 177 if (error1 == ENOTCAPABLE || error1 == ECAPMODE) { 178 ksiginfo_init_trap(&ksi); 179 ksi.ksi_signo = SIGTRAP; 180 ksi.ksi_errno = error1; 181 ksi.ksi_code = TRAP_CAP; 182 trapsignal(td, &ksi); 183 } 184 } 185 186 /* 187 * Handle reschedule and other end-of-syscall issues 188 */ 189 userret(td, td->td_frame); 190 191#ifdef KTRACE 192 if (KTRPOINT(td, KTR_SYSRET)) { 193 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ? 194 error : td->td_errno, td->td_retval[0]); 195 } 196#endif 197 td->td_pflags &= ~TDP_NERRNO; 198 199 if (p->p_flag & P_TRACED) { 200 traced = 1; 201 PROC_LOCK(p); 202 td->td_dbgflags |= TDB_SCX; 203 PROC_UNLOCK(p); 204 } else 205 traced = 0; 206 /* 207 * This works because errno is findable through the 208 * register set. If we ever support an emulation where this 209 * is not the case, this code will need to be revisited. 210 */ 211 STOPEVENT(p, S_SCX, sa->code); 212 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 213 PROC_LOCK(p); 214 /* 215 * If tracing the execed process, trap to the debugger 216 * so that breakpoints can be set before the program 217 * executes. If debugger requested tracing of syscall 218 * returns, do it now too. 219 */ 220 if (traced && 221 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 222 (p->p_ptevents & PTRACE_SCX) != 0)) 223 ptracestop(td, SIGTRAP, NULL); 224 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 225 PROC_UNLOCK(p); 226 } 227 228 if (td->td_pflags & TDP_RFPPWAIT) { 229 /* 230 * Preserve synchronization semantics of vfork. If 231 * waiting for child to exec or exit, fork set 232 * P_PPWAIT on child, and there we sleep on our proc 233 * (in case of exit). 234 * 235 * Do it after the ptracestop() above is finished, to 236 * not block our debugger until child execs or exits 237 * to finish vfork wait. 238 */ 239 td->td_pflags &= ~TDP_RFPPWAIT; 240 p2 = td->td_rfppwait_p; 241again: 242 PROC_LOCK(p2); 243 while (p2->p_flag & P_PPWAIT) { 244 PROC_LOCK(p); 245 if (thread_suspend_check_needed()) { 246 PROC_UNLOCK(p2); 247 thread_suspend_check(0); 248 PROC_UNLOCK(p); 249 goto again; 250 } else { 251 PROC_UNLOCK(p); 252 } 253 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz); 254 } 255 PROC_UNLOCK(p2); 256 257 if (td->td_dbgflags & TDB_VFORK) { 258 PROC_LOCK(p); 259 if (p->p_ptevents & PTRACE_VFORK) 260 ptracestop(td, SIGTRAP, NULL); 261 td->td_dbgflags &= ~TDB_VFORK; 262 PROC_UNLOCK(p); 263 } 264 } 265} 266