Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_syscall.c
Version:
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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_ktrace.h" 42 #include "opt_kdtrace.h" 43 44 __FBSDID("$FreeBSD$"); 45 46 #include <sys/ktr.h> 47 #ifdef KTRACE 48 #include <sys/uio.h> 49 #include <sys/ktrace.h> 50 #endif 51 #include <security/audit/audit.h> 52 53 static inline int 54 syscallenter(struct thread *td, struct syscall_args *sa) 55 { 56 struct proc *p; 57 int error, traced; 58 59 PCPU_INC(cnt.v_syscall); 60 p = td->td_proc; 61 td->td_syscalls++; 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 80 CTR6(KTR_SYSC, 81 "syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 82 td, td->td_proc->p_pid, syscallname(p, sa->code), 83 sa->args[0], sa->args[1], sa->args[2]); 84 85 if (error == 0) { 86 STOPEVENT(p, S_SCE, sa->narg); 87 PTRACESTOP_SC(p, td, S_PT_SCE); 88 if (td->td_dbgflags & TDB_USERWR) { 89 /* 90 * Reread syscall number and arguments if 91 * debugger modified registers or memory. 92 */ 93 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 94 #ifdef KTRACE 95 if (KTRPOINT(td, KTR_SYSCALL)) 96 ktrsyscall(sa->code, sa->narg, sa->args); 97 #endif 98 if (error != 0) 99 goto retval; 100 } 101 102 #ifdef KDTRACE_HOOKS 103 /* 104 * If the systrace module has registered it's probe 105 * callback and if there is a probe active for the 106 * syscall 'entry', process the probe. 107 */ 108 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 109 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 110 sa->callp, sa->args, 0); 111 #endif 112 113 AUDIT_SYSCALL_ENTER(sa->code, td); 114 error = (sa->callp->sy_call)(td, sa->args); 115 AUDIT_SYSCALL_EXIT(error, td); 116 117 /* Save the latest error return value. */ 118 if ((td->td_pflags & TDP_NERRNO) == 0) 119 td->td_errno = error; 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 'return', process the probe. 126 */ 127 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 128 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 129 sa->callp, NULL, (error) ? -1 : td->td_retval[0]); 130 #endif 131 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 132 p, error, td->td_retval[0], td->td_retval[1]); 133 } 134 retval: 135 if (traced) { 136 PROC_LOCK(p); 137 td->td_dbgflags &= ~TDB_SCE; 138 PROC_UNLOCK(p); 139 } 140 (p->p_sysent->sv_set_syscall_retval)(td, error); 141 return (error); 142 } 143 144 static inline void 145 syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 146 { 147 struct proc *p; 148 int traced; 149 150 p = td->td_proc; 151 152 /* 153 * Check for misbehavior. 154 */ 155 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 156 syscallname(p, sa->code)); 157 KASSERT(td->td_critnest == 0, 158 ("System call %s returning in a critical section", 159 syscallname(p, sa->code))); 160 KASSERT(td->td_locks == 0, 161 ("System call %s returning with %d locks held", 162 syscallname(p, sa->code), td->td_locks)); 163 164 /* 165 * Handle reschedule and other end-of-syscall issues 166 */ 167 userret(td, td->td_frame); 168 169 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 170 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 171 172 #ifdef KTRACE 173 if (KTRPOINT(td, KTR_SYSRET)) { 174 ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ? 175 error : td->td_errno, td->td_retval[0]); 176 } 177 #endif 178 td->td_pflags &= ~TDP_NERRNO; 179 180 if (p->p_flag & P_TRACED) { 181 traced = 1; 182 PROC_LOCK(p); 183 td->td_dbgflags |= TDB_SCX; 184 PROC_UNLOCK(p); 185 } else 186 traced = 0; 187 /* 188 * This works because errno is findable through the 189 * register set. If we ever support an emulation where this 190 * is not the case, this code will need to be revisited. 191 */ 192 STOPEVENT(p, S_SCX, sa->code); 193 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 194 PROC_LOCK(p); 195 /* 196 * If tracing the execed process, trap to the debugger 197 * so that breakpoints can be set before the program 198 * executes. If debugger requested tracing of syscall 199 * returns, do it now too. 200 */ 201 if (traced && 202 ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 || 203 (p->p_stops & S_PT_SCX) != 0)) 204 ptracestop(td, SIGTRAP); 205 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 206 PROC_UNLOCK(p); 207 } 208 }
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