subr_syscall.c revision 258541
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: head/sys/kern/subr_syscall.c 258541 2013-11-25 07:38:45Z attilio $"); 45 46#include <sys/capability.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, struct syscall_args *sa) 56{ 57 struct proc *p; 58 int error, traced; 59 60 PCPU_INC(cnt.v_syscall); 61 p = td->td_proc; 62 63 td->td_pticks = 0; 64 if (td->td_ucred != p->p_ucred) 65 cred_update_thread(td); 66 if (p->p_flag & P_TRACED) { 67 traced = 1; 68 PROC_LOCK(p); 69 td->td_dbgflags &= ~TDB_USERWR; 70 td->td_dbgflags |= TDB_SCE; 71 PROC_UNLOCK(p); 72 } else 73 traced = 0; 74 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 75#ifdef KTRACE 76 if (KTRPOINT(td, KTR_SYSCALL)) 77 ktrsyscall(sa->code, sa->narg, sa->args); 78#endif 79 KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code), 80 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0], 81 "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]); 82 83 if (error == 0) { 84 85 STOPEVENT(p, S_SCE, sa->narg); 86 if (p->p_flag & P_TRACED && p->p_stops & S_PT_SCE) { 87 PROC_LOCK(p); 88 ptracestop((td), SIGTRAP); 89 PROC_UNLOCK(p); 90 } 91 if (td->td_dbgflags & TDB_USERWR) { 92 /* 93 * Reread syscall number and arguments if 94 * debugger modified registers or memory. 95 */ 96 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 97#ifdef KTRACE 98 if (KTRPOINT(td, KTR_SYSCALL)) 99 ktrsyscall(sa->code, sa->narg, sa->args); 100#endif 101 if (error != 0) 102 goto retval; 103 } 104 105#ifdef CAPABILITY_MODE 106 /* 107 * In capability mode, we only allow access to system calls 108 * flagged with SYF_CAPENABLED. 109 */ 110 if (IN_CAPABILITY_MODE(td) && 111 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 112 error = ECAPMODE; 113 goto retval; 114 } 115#endif 116 117 error = syscall_thread_enter(td, sa->callp); 118 if (error != 0) 119 goto retval; 120 121#ifdef KDTRACE_HOOKS 122 /* 123 * If the systrace module has registered it's probe 124 * callback and if there is a probe active for the 125 * syscall 'entry', process the probe. 126 */ 127 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 128 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 129 sa->callp, sa->args, 0); 130#endif 131 132 AUDIT_SYSCALL_ENTER(sa->code, td); 133 error = (sa->callp->sy_call)(td, sa->args); 134 AUDIT_SYSCALL_EXIT(error, td); 135 136 /* Save the latest error return value. */ 137 if ((td->td_pflags & TDP_NERRNO) == 0) 138 td->td_errno = error; 139 140#ifdef KDTRACE_HOOKS 141 /* 142 * If the systrace module has registered it's probe 143 * callback and if there is a probe active for the 144 * syscall 'return', process the probe. 145 */ 146 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 147 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 148 sa->callp, NULL, (error) ? -1 : td->td_retval[0]); 149#endif 150 syscall_thread_exit(td, sa->callp); 151 } 152 retval: 153 KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code), 154 (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error, 155 "retval0:%#lx", td->td_retval[0], "retval1:%#lx", 156 td->td_retval[1]); 157 if (traced) { 158 PROC_LOCK(p); 159 td->td_dbgflags &= ~TDB_SCE; 160 PROC_UNLOCK(p); 161 } 162 (p->p_sysent->sv_set_syscall_retval)(td, error); 163 return (error); 164} 165 166static inline void 167syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 168{ 169 struct proc *p, *p2; 170 int traced; 171 172 p = td->td_proc; 173 174 /* 175 * Handle reschedule and other end-of-syscall issues 176 */ 177 userret(td, td->td_frame); 178 179#ifdef KTRACE 180 if (KTRPOINT(td, KTR_SYSRET)) { 181 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ? 182 error : td->td_errno, td->td_retval[0]); 183 } 184#endif 185 td->td_pflags &= ~TDP_NERRNO; 186 187 if (p->p_flag & P_TRACED) { 188 traced = 1; 189 PROC_LOCK(p); 190 td->td_dbgflags |= TDB_SCX; 191 PROC_UNLOCK(p); 192 } else 193 traced = 0; 194 /* 195 * This works because errno is findable through the 196 * register set. If we ever support an emulation where this 197 * is not the case, this code will need to be revisited. 198 */ 199 STOPEVENT(p, S_SCX, sa->code); 200 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 201 PROC_LOCK(p); 202 /* 203 * If tracing the execed process, trap to the debugger 204 * so that breakpoints can be set before the program 205 * executes. If debugger requested tracing of syscall 206 * returns, do it now too. 207 */ 208 if (traced && 209 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 210 (p->p_stops & S_PT_SCX) != 0)) 211 ptracestop(td, SIGTRAP); 212 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 213 PROC_UNLOCK(p); 214 } 215 216 if (td->td_pflags & TDP_RFPPWAIT) { 217 /* 218 * Preserve synchronization semantics of vfork. If 219 * waiting for child to exec or exit, fork set 220 * P_PPWAIT on child, and there we sleep on our proc 221 * (in case of exit). 222 * 223 * Do it after the ptracestop() above is finished, to 224 * not block our debugger until child execs or exits 225 * to finish vfork wait. 226 */ 227 td->td_pflags &= ~TDP_RFPPWAIT; 228 p2 = td->td_rfppwait_p; 229 PROC_LOCK(p2); 230 while (p2->p_flag & P_PPWAIT) 231 cv_wait(&p2->p_pwait, &p2->p_mtx); 232 PROC_UNLOCK(p2); 233 } 234} 235