subr_syscall.c revision 304188
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#include "opt_kdtrace.h" 44 45__FBSDID("$FreeBSD: stable/10/sys/kern/subr_syscall.c 304188 2016-08-15 21:10:41Z jhb $"); 46 47#include <sys/capsicum.h> 48#include <sys/ktr.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, struct syscall_args *sa) 57{ 58 struct proc *p; 59 int error, traced; 60 61 PCPU_INC(cnt.v_syscall); 62 p = td->td_proc; 63 64 td->td_pticks = 0; 65 if (td->td_ucred != p->p_ucred) 66 cred_update_thread(td); 67 traced = (p->p_flag & P_TRACED) != 0; 68 if (traced || td->td_dbgflags & TDB_USERWR) { 69 PROC_LOCK(p); 70 td->td_dbgflags &= ~TDB_USERWR; 71 if (traced) 72 td->td_dbgflags |= TDB_SCE; 73 PROC_UNLOCK(p); 74 } 75 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 76#ifdef KTRACE 77 if (KTRPOINT(td, KTR_SYSCALL)) 78 ktrsyscall(sa->code, sa->narg, sa->args); 79#endif 80 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 81 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 82 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 83 84 if (error == 0) { 85 86 STOPEVENT(p, S_SCE, sa->narg); 87 if (p->p_flag & P_TRACED) { 88 PROC_LOCK(p); 89 td->td_dbg_sc_code = sa->code; 90 td->td_dbg_sc_narg = sa->narg; 91 if (p->p_ptevents & PTRACE_SCE) 92 ptracestop((td), SIGTRAP); 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, sa); 101 PROC_LOCK(p); 102 td->td_dbg_sc_code = sa->code; 103 td->td_dbg_sc_narg = sa->narg; 104 PROC_UNLOCK(p); 105#ifdef KTRACE 106 if (KTRPOINT(td, KTR_SYSCALL)) 107 ktrsyscall(sa->code, sa->narg, sa->args); 108#endif 109 if (error != 0) 110 goto retval; 111 } 112 113#ifdef CAPABILITY_MODE 114 /* 115 * In capability mode, we only allow access to system calls 116 * flagged with SYF_CAPENABLED. 117 */ 118 if (IN_CAPABILITY_MODE(td) && 119 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 120 error = ECAPMODE; 121 goto retval; 122 } 123#endif 124 125 error = syscall_thread_enter(td, sa->callp); 126 if (error != 0) 127 goto retval; 128 129#ifdef KDTRACE_HOOKS 130 /* 131 * If the systrace module has registered it's probe 132 * callback and if there is a probe active for the 133 * syscall 'entry', process the probe. 134 */ 135 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 136 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 137 sa->callp, sa->args, 0); 138#endif 139 140 AUDIT_SYSCALL_ENTER(sa->code, td); 141 error = (sa->callp->sy_call)(td, sa->args); 142 AUDIT_SYSCALL_EXIT(error, td); 143 144 /* Save the latest error return value. */ 145 if ((td->td_pflags & TDP_NERRNO) == 0) 146 td->td_errno = error; 147 148#ifdef KDTRACE_HOOKS 149 /* 150 * If the systrace module has registered it's probe 151 * callback and if there is a probe active for the 152 * syscall 'return', process the probe. 153 */ 154 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 155 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 156 sa->callp, NULL, (error) ? -1 : td->td_retval[0]); 157#endif 158 syscall_thread_exit(td, sa->callp); 159 } 160 retval: 161 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 162 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 163 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 164 td->td_retval[1]); 165 if (traced) { 166 PROC_LOCK(p); 167 td->td_dbgflags &= ~TDB_SCE; 168 PROC_UNLOCK(p); 169 } 170 (p->p_sysent->sv_set_syscall_retval)(td, error); 171 return (error); 172} 173 174static inline void 175syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 176{ 177 struct proc *p, *p2; 178 int traced; 179 180 p = td->td_proc; 181 182 /* 183 * Handle reschedule and other end-of-syscall issues 184 */ 185 userret(td, td->td_frame); 186 187#ifdef KTRACE 188 if (KTRPOINT(td, KTR_SYSRET)) { 189 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ? 190 error : td->td_errno, td->td_retval[0]); 191 } 192#endif 193 td->td_pflags &= ~TDP_NERRNO; 194 195 if (p->p_flag & P_TRACED) { 196 traced = 1; 197 PROC_LOCK(p); 198 td->td_dbgflags |= TDB_SCX; 199 PROC_UNLOCK(p); 200 } else 201 traced = 0; 202 /* 203 * This works because errno is findable through the 204 * register set. If we ever support an emulation where this 205 * is not the case, this code will need to be revisited. 206 */ 207 STOPEVENT(p, S_SCX, sa->code); 208 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 209 PROC_LOCK(p); 210 /* 211 * If tracing the execed process, trap to the debugger 212 * so that breakpoints can be set before the program 213 * executes. If debugger requested tracing of syscall 214 * returns, do it now too. 215 */ 216 if (traced && 217 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 218 (p->p_ptevents & PTRACE_SCX) != 0)) 219 ptracestop(td, SIGTRAP); 220 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 221 PROC_UNLOCK(p); 222 } 223 224 if (td->td_pflags & TDP_RFPPWAIT) { 225 /* 226 * Preserve synchronization semantics of vfork. If 227 * waiting for child to exec or exit, fork set 228 * P_PPWAIT on child, and there we sleep on our proc 229 * (in case of exit). 230 * 231 * Do it after the ptracestop() above is finished, to 232 * not block our debugger until child execs or exits 233 * to finish vfork wait. 234 */ 235 td->td_pflags &= ~TDP_RFPPWAIT; 236 p2 = td->td_rfppwait_p; 237again: 238 PROC_LOCK(p2); 239 while (p2->p_flag & P_PPWAIT) { 240 PROC_LOCK(p); 241 if (thread_suspend_check_needed()) { 242 PROC_UNLOCK(p2); 243 thread_suspend_check(0); 244 PROC_UNLOCK(p); 245 goto again; 246 } else { 247 PROC_UNLOCK(p); 248 } 249 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz); 250 } 251 PROC_UNLOCK(p2); 252 } 253} 254