subr_syscall.c revision 226893
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: head/sys/kern/subr_syscall.c 226893 2011-10-29 01:26:36Z marcel $"); 46 47#include <sys/capability.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 55#ifdef KDTRACE_HOOKS 56/* 57 * This is a hook which is initialised by the systrace module 58 * when it is loaded. This keeps the DTrace syscall provider 59 * implementation opaque. 60 */ 61systrace_probe_func_t systrace_probe_func; 62#endif 63 64static inline int 65syscallenter(struct thread *td, struct syscall_args *sa) 66{ 67 struct proc *p; 68 int error, traced; 69 70 PCPU_INC(cnt.v_syscall); 71 p = td->td_proc; 72 73 td->td_pticks = 0; 74 if (td->td_ucred != p->p_ucred) 75 cred_update_thread(td); 76 if (p->p_flag & P_TRACED) { 77 traced = 1; 78 PROC_LOCK(p); 79 td->td_dbgflags &= ~TDB_USERWR; 80 td->td_dbgflags |= TDB_SCE; 81 PROC_UNLOCK(p); 82 } else 83 traced = 0; 84 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 85#ifdef KTRACE 86 if (KTRPOINT(td, KTR_SYSCALL)) 87 ktrsyscall(sa->code, sa->narg, sa->args); 88#endif 89 90 CTR6(KTR_SYSC, 91"syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 92 td, td->td_proc->p_pid, syscallname(p, sa->code), 93 sa->args[0], sa->args[1], sa->args[2]); 94 95 if (error == 0) { 96 STOPEVENT(p, S_SCE, sa->narg); 97 PTRACESTOP_SC(p, td, S_PT_SCE); 98 if (td->td_dbgflags & TDB_USERWR) { 99 /* 100 * Reread syscall number and arguments if 101 * debugger modified registers or memory. 102 */ 103 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 104#ifdef KTRACE 105 if (KTRPOINT(td, KTR_SYSCALL)) 106 ktrsyscall(sa->code, sa->narg, sa->args); 107#endif 108 if (error != 0) 109 goto retval; 110 } 111 112#ifdef CAPABILITY_MODE 113 /* 114 * In capability mode, we only allow access to system calls 115 * flagged with SYF_CAPENABLED. 116 */ 117 if (IN_CAPABILITY_MODE(td) && 118 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 119 error = ECAPMODE; 120 goto retval; 121 } 122#endif 123 124 error = syscall_thread_enter(td, sa->callp); 125 if (error != 0) 126 goto retval; 127 128#ifdef KDTRACE_HOOKS 129 /* 130 * If the systrace module has registered it's probe 131 * callback and if there is a probe active for the 132 * syscall 'entry', process the probe. 133 */ 134 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 135 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 136 sa->callp, sa->args, 0); 137#endif 138 139 AUDIT_SYSCALL_ENTER(sa->code, td); 140 error = (sa->callp->sy_call)(td, sa->args); 141 AUDIT_SYSCALL_EXIT(error, td); 142 143 /* Save the latest error return value. */ 144 td->td_errno = error; 145 146#ifdef KDTRACE_HOOKS 147 /* 148 * If the systrace module has registered it's probe 149 * callback and if there is a probe active for the 150 * syscall 'return', process the probe. 151 */ 152 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 153 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 154 sa->callp, NULL, (error) ? -1 : td->td_retval[0]); 155#endif 156 syscall_thread_exit(td, sa->callp); 157 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 158 p, error, td->td_retval[0], td->td_retval[1]); 159 } 160 retval: 161 if (traced) { 162 PROC_LOCK(p); 163 td->td_dbgflags &= ~TDB_SCE; 164 PROC_UNLOCK(p); 165 } 166 (p->p_sysent->sv_set_syscall_retval)(td, error); 167 return (error); 168} 169 170static inline void 171syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 172{ 173 struct proc *p; 174 int traced; 175 176 p = td->td_proc; 177 178 /* 179 * Check for misbehavior. 180 */ 181 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 182 syscallname(p, sa->code)); 183 KASSERT(td->td_critnest == 0, 184 ("System call %s returning in a critical section", 185 syscallname(p, sa->code))); 186 KASSERT(td->td_locks == 0, 187 ("System call %s returning with %d locks held", 188 syscallname(p, sa->code), td->td_locks)); 189 190 /* 191 * Handle reschedule and other end-of-syscall issues 192 */ 193 userret(td, td->td_frame); 194 195 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 196 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 197 198#ifdef KTRACE 199 if (KTRPOINT(td, KTR_SYSRET)) 200 ktrsysret(sa->code, error, td->td_retval[0]); 201#endif 202 203 if (p->p_flag & P_TRACED) { 204 traced = 1; 205 PROC_LOCK(p); 206 td->td_dbgflags |= TDB_SCX; 207 PROC_UNLOCK(p); 208 } else 209 traced = 0; 210 /* 211 * This works because errno is findable through the 212 * register set. If we ever support an emulation where this 213 * is not the case, this code will need to be revisited. 214 */ 215 STOPEVENT(p, S_SCX, sa->code); 216 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 217 PROC_LOCK(p); 218 /* 219 * If tracing the execed process, trap to the debugger 220 * so that breakpoints can be set before the program 221 * executes. If debugger requested tracing of syscall 222 * returns, do it now too. 223 */ 224 if (traced && ((td->td_dbgflags & TDB_EXEC) != 0 || 225 (p->p_stops & S_PT_SCX) != 0)) 226 ptracestop(td, SIGTRAP); 227 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 228 PROC_UNLOCK(p); 229 } 230} 231