subr_syscall.c revision 226925
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 226925 2011-10-30 02:19:39Z 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 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 if (p->p_flag & P_TRACED) { 68 traced = 1; 69 PROC_LOCK(p); 70 td->td_dbgflags &= ~TDB_USERWR; 71 td->td_dbgflags |= TDB_SCE; 72 PROC_UNLOCK(p); 73 } else 74 traced = 0; 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 81 CTR6(KTR_SYSC, 82"syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 83 td, td->td_proc->p_pid, syscallname(p, sa->code), 84 sa->args[0], sa->args[1], sa->args[2]); 85 86 if (error == 0) { 87 STOPEVENT(p, S_SCE, sa->narg); 88 PTRACESTOP_SC(p, td, S_PT_SCE); 89 if (td->td_dbgflags & TDB_USERWR) { 90 /* 91 * Reread syscall number and arguments if 92 * debugger modified registers or memory. 93 */ 94 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 95#ifdef KTRACE 96 if (KTRPOINT(td, KTR_SYSCALL)) 97 ktrsyscall(sa->code, sa->narg, sa->args); 98#endif 99 if (error != 0) 100 goto retval; 101 } 102 103#ifdef CAPABILITY_MODE 104 /* 105 * In capability mode, we only allow access to system calls 106 * flagged with SYF_CAPENABLED. 107 */ 108 if (IN_CAPABILITY_MODE(td) && 109 !(sa->callp->sy_flags & SYF_CAPENABLED)) { 110 error = ECAPMODE; 111 goto retval; 112 } 113#endif 114 115 error = syscall_thread_enter(td, sa->callp); 116 if (error != 0) 117 goto retval; 118 119#ifdef KDTRACE_HOOKS 120 /* 121 * If the systrace module has registered it's probe 122 * callback and if there is a probe active for the 123 * syscall 'entry', process the probe. 124 */ 125 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 126 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 127 sa->callp, sa->args, 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 td->td_errno = error; 136 137#ifdef KDTRACE_HOOKS 138 /* 139 * If the systrace module has registered it's probe 140 * callback and if there is a probe active for the 141 * syscall 'return', process the probe. 142 */ 143 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 144 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 145 sa->callp, NULL, (error) ? -1 : td->td_retval[0]); 146#endif 147 syscall_thread_exit(td, sa->callp); 148 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 149 p, error, td->td_retval[0], td->td_retval[1]); 150 } 151 retval: 152 if (traced) { 153 PROC_LOCK(p); 154 td->td_dbgflags &= ~TDB_SCE; 155 PROC_UNLOCK(p); 156 } 157 (p->p_sysent->sv_set_syscall_retval)(td, error); 158 return (error); 159} 160 161static inline void 162syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 163{ 164 struct proc *p; 165 int traced; 166 167 p = td->td_proc; 168 169 /* 170 * Check for misbehavior. 171 */ 172 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 173 syscallname(p, sa->code)); 174 KASSERT(td->td_critnest == 0, 175 ("System call %s returning in a critical section", 176 syscallname(p, sa->code))); 177 KASSERT(td->td_locks == 0, 178 ("System call %s returning with %d locks held", 179 syscallname(p, sa->code), td->td_locks)); 180 181 /* 182 * Handle reschedule and other end-of-syscall issues 183 */ 184 userret(td, td->td_frame); 185 186 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 187 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 188 189#ifdef KTRACE 190 if (KTRPOINT(td, KTR_SYSRET)) 191 ktrsysret(sa->code, error, td->td_retval[0]); 192#endif 193 194 if (p->p_flag & P_TRACED) { 195 traced = 1; 196 PROC_LOCK(p); 197 td->td_dbgflags |= TDB_SCX; 198 PROC_UNLOCK(p); 199 } else 200 traced = 0; 201 /* 202 * This works because errno is findable through the 203 * register set. If we ever support an emulation where this 204 * is not the case, this code will need to be revisited. 205 */ 206 STOPEVENT(p, S_SCX, sa->code); 207 if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) { 208 PROC_LOCK(p); 209 /* 210 * If tracing the execed process, trap to the debugger 211 * so that breakpoints can be set before the program 212 * executes. If debugger requested tracing of syscall 213 * returns, do it now too. 214 */ 215 if (traced && ((td->td_dbgflags & TDB_EXEC) != 0 || 216 (p->p_stops & S_PT_SCX) != 0)) 217 ptracestop(td, SIGTRAP); 218 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); 219 PROC_UNLOCK(p); 220 } 221} 222