The Design and Implementation of the FreeBSD Operating System, Second Edition
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

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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_capsicum.h"
   42 #include "opt_ktrace.h"
   43 #include "opt_kdtrace.h"
   44 
   45 __FBSDID("$FreeBSD: releng/9.0/sys/kern/subr_syscall.c 226248 2011-10-11 13:18:44Z kib $");
   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 static inline int
   56 syscallenter(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 
  161 static inline void
  162 syscallret(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 }

Cache object: e68736a4b761a451b0aec521d3075e56


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