The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_process.c

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    1 /*-
    2  * Copyright (c) 1994, Sean Eric Fagan
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. All advertising materials mentioning features or use of this software
   14  *    must display the following acknowledgement:
   15  *      This product includes software developed by Sean Eric Fagan.
   16  * 4. The name of the author may not be used to endorse or promote products
   17  *    derived from this software without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/8.2/sys/kern/sys_process.c 214756 2010-11-03 21:24:21Z kib $");
   34 
   35 #include "opt_compat.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/lock.h>
   40 #include <sys/mutex.h>
   41 #include <sys/syscallsubr.h>
   42 #include <sys/sysent.h>
   43 #include <sys/sysproto.h>
   44 #include <sys/proc.h>
   45 #include <sys/vnode.h>
   46 #include <sys/ptrace.h>
   47 #include <sys/sx.h>
   48 #include <sys/malloc.h>
   49 #include <sys/signalvar.h>
   50 
   51 #include <machine/reg.h>
   52 
   53 #include <security/audit/audit.h>
   54 
   55 #include <vm/vm.h>
   56 #include <vm/pmap.h>
   57 #include <vm/vm_extern.h>
   58 #include <vm/vm_map.h>
   59 #include <vm/vm_kern.h>
   60 #include <vm/vm_object.h>
   61 #include <vm/vm_page.h>
   62 #include <vm/vm_param.h>
   63 
   64 #ifdef COMPAT_FREEBSD32
   65 #include <sys/procfs.h>
   66 #include <compat/freebsd32/freebsd32_signal.h>
   67 
   68 struct ptrace_io_desc32 {
   69         int             piod_op;
   70         u_int32_t       piod_offs;
   71         u_int32_t       piod_addr;
   72         u_int32_t       piod_len;
   73 };
   74 
   75 struct ptrace_vm_entry32 {
   76         int             pve_entry;
   77         int             pve_timestamp;
   78         uint32_t        pve_start;
   79         uint32_t        pve_end;
   80         uint32_t        pve_offset;
   81         u_int           pve_prot;
   82         u_int           pve_pathlen;
   83         int32_t         pve_fileid;
   84         u_int           pve_fsid;
   85         uint32_t        pve_path;
   86 };
   87 
   88 struct ptrace_lwpinfo32 {
   89         lwpid_t pl_lwpid;       /* LWP described. */
   90         int     pl_event;       /* Event that stopped the LWP. */
   91         int     pl_flags;       /* LWP flags. */
   92         sigset_t        pl_sigmask;     /* LWP signal mask */
   93         sigset_t        pl_siglist;     /* LWP pending signal */
   94         struct siginfo32 pl_siginfo;    /* siginfo for signal */
   95 };
   96 
   97 #endif
   98 
   99 /*
  100  * Functions implemented using PROC_ACTION():
  101  *
  102  * proc_read_regs(proc, regs)
  103  *      Get the current user-visible register set from the process
  104  *      and copy it into the regs structure (<machine/reg.h>).
  105  *      The process is stopped at the time read_regs is called.
  106  *
  107  * proc_write_regs(proc, regs)
  108  *      Update the current register set from the passed in regs
  109  *      structure.  Take care to avoid clobbering special CPU
  110  *      registers or privileged bits in the PSL.
  111  *      Depending on the architecture this may have fix-up work to do,
  112  *      especially if the IAR or PCW are modified.
  113  *      The process is stopped at the time write_regs is called.
  114  *
  115  * proc_read_fpregs, proc_write_fpregs
  116  *      deal with the floating point register set, otherwise as above.
  117  *
  118  * proc_read_dbregs, proc_write_dbregs
  119  *      deal with the processor debug register set, otherwise as above.
  120  *
  121  * proc_sstep(proc)
  122  *      Arrange for the process to trap after executing a single instruction.
  123  */
  124 
  125 #define PROC_ACTION(action) do {                                        \
  126         int error;                                                      \
  127                                                                         \
  128         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);                        \
  129         if ((td->td_proc->p_flag & P_INMEM) == 0)                       \
  130                 error = EIO;                                            \
  131         else                                                            \
  132                 error = (action);                                       \
  133         return (error);                                                 \
  134 } while(0)
  135 
  136 int
  137 proc_read_regs(struct thread *td, struct reg *regs)
  138 {
  139 
  140         PROC_ACTION(fill_regs(td, regs));
  141 }
  142 
  143 int
  144 proc_write_regs(struct thread *td, struct reg *regs)
  145 {
  146 
  147         PROC_ACTION(set_regs(td, regs));
  148 }
  149 
  150 int
  151 proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
  152 {
  153 
  154         PROC_ACTION(fill_dbregs(td, dbregs));
  155 }
  156 
  157 int
  158 proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
  159 {
  160 
  161         PROC_ACTION(set_dbregs(td, dbregs));
  162 }
  163 
  164 /*
  165  * Ptrace doesn't support fpregs at all, and there are no security holes
  166  * or translations for fpregs, so we can just copy them.
  167  */
  168 int
  169 proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
  170 {
  171 
  172         PROC_ACTION(fill_fpregs(td, fpregs));
  173 }
  174 
  175 int
  176 proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
  177 {
  178 
  179         PROC_ACTION(set_fpregs(td, fpregs));
  180 }
  181 
  182 #ifdef COMPAT_FREEBSD32
  183 /* For 32 bit binaries, we need to expose the 32 bit regs layouts. */
  184 int
  185 proc_read_regs32(struct thread *td, struct reg32 *regs32)
  186 {
  187 
  188         PROC_ACTION(fill_regs32(td, regs32));
  189 }
  190 
  191 int
  192 proc_write_regs32(struct thread *td, struct reg32 *regs32)
  193 {
  194 
  195         PROC_ACTION(set_regs32(td, regs32));
  196 }
  197 
  198 int
  199 proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
  200 {
  201 
  202         PROC_ACTION(fill_dbregs32(td, dbregs32));
  203 }
  204 
  205 int
  206 proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
  207 {
  208 
  209         PROC_ACTION(set_dbregs32(td, dbregs32));
  210 }
  211 
  212 int
  213 proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
  214 {
  215 
  216         PROC_ACTION(fill_fpregs32(td, fpregs32));
  217 }
  218 
  219 int
  220 proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
  221 {
  222 
  223         PROC_ACTION(set_fpregs32(td, fpregs32));
  224 }
  225 #endif
  226 
  227 int
  228 proc_sstep(struct thread *td)
  229 {
  230 
  231         PROC_ACTION(ptrace_single_step(td));
  232 }
  233 
  234 int
  235 proc_rwmem(struct proc *p, struct uio *uio)
  236 {
  237         vm_map_t map;
  238         vm_object_t backing_object, object = NULL;
  239         vm_offset_t pageno = 0;         /* page number */
  240         vm_prot_t reqprot;
  241         int error, fault_flags, writing;
  242 
  243         /*
  244          * Assert that someone has locked this vmspace.  (Should be
  245          * curthread but we can't assert that.)  This keeps the process
  246          * from exiting out from under us until this operation completes.
  247          */
  248         KASSERT(p->p_lock >= 1, ("%s: process %p (pid %d) not held", __func__,
  249             p, p->p_pid));
  250 
  251         /*
  252          * The map we want...
  253          */
  254         map = &p->p_vmspace->vm_map;
  255 
  256         writing = uio->uio_rw == UIO_WRITE;
  257         reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) :
  258             VM_PROT_READ;
  259         fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL; 
  260 
  261         /*
  262          * Only map in one page at a time.  We don't have to, but it
  263          * makes things easier.  This way is trivial - right?
  264          */
  265         do {
  266                 vm_map_t tmap;
  267                 vm_offset_t uva;
  268                 int page_offset;                /* offset into page */
  269                 vm_map_entry_t out_entry;
  270                 vm_prot_t out_prot;
  271                 boolean_t wired;
  272                 vm_pindex_t pindex;
  273                 u_int len;
  274                 vm_page_t m;
  275 
  276                 object = NULL;
  277 
  278                 uva = (vm_offset_t)uio->uio_offset;
  279 
  280                 /*
  281                  * Get the page number of this segment.
  282                  */
  283                 pageno = trunc_page(uva);
  284                 page_offset = uva - pageno;
  285 
  286                 /*
  287                  * How many bytes to copy
  288                  */
  289                 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
  290 
  291                 /*
  292                  * Fault the page on behalf of the process
  293                  */
  294                 error = vm_fault(map, pageno, reqprot, fault_flags);
  295                 if (error) {
  296                         if (error == KERN_RESOURCE_SHORTAGE)
  297                                 error = ENOMEM;
  298                         else
  299                                 error = EFAULT;
  300                         break;
  301                 }
  302 
  303                 /*
  304                  * Now we need to get the page.  out_entry, out_prot, wired,
  305                  * and single_use aren't used.  One would think the vm code
  306                  * would be a *bit* nicer...  We use tmap because
  307                  * vm_map_lookup() can change the map argument.
  308                  */
  309                 tmap = map;
  310                 error = vm_map_lookup(&tmap, pageno, reqprot, &out_entry,
  311                     &object, &pindex, &out_prot, &wired);
  312                 if (error) {
  313                         error = EFAULT;
  314                         break;
  315                 }
  316                 VM_OBJECT_LOCK(object);
  317                 while ((m = vm_page_lookup(object, pindex)) == NULL &&
  318                     !writing &&
  319                     (backing_object = object->backing_object) != NULL) {
  320                         /*
  321                          * Allow fallback to backing objects if we are reading.
  322                          */
  323                         VM_OBJECT_LOCK(backing_object);
  324                         pindex += OFF_TO_IDX(object->backing_object_offset);
  325                         VM_OBJECT_UNLOCK(object);
  326                         object = backing_object;
  327                 }
  328                 VM_OBJECT_UNLOCK(object);
  329                 if (m == NULL) {
  330                         vm_map_lookup_done(tmap, out_entry);
  331                         error = EFAULT;
  332                         break;
  333                 }
  334 
  335                 /*
  336                  * Hold the page in memory.
  337                  */
  338                 vm_page_lock_queues();
  339                 vm_page_hold(m);
  340                 vm_page_unlock_queues();
  341 
  342                 /*
  343                  * We're done with tmap now.
  344                  */
  345                 vm_map_lookup_done(tmap, out_entry);
  346 
  347                 /*
  348                  * Now do the i/o move.
  349                  */
  350                 error = uiomove_fromphys(&m, page_offset, len, uio);
  351 
  352                 /* Make the I-cache coherent for breakpoints. */
  353                 if (!error && writing && (out_prot & VM_PROT_EXECUTE))
  354                         vm_sync_icache(map, uva, len);
  355 
  356                 /*
  357                  * Release the page.
  358                  */
  359                 vm_page_lock_queues();
  360                 vm_page_unhold(m);
  361                 vm_page_unlock_queues();
  362 
  363         } while (error == 0 && uio->uio_resid > 0);
  364 
  365         return (error);
  366 }
  367 
  368 static int
  369 ptrace_vm_entry(struct thread *td, struct proc *p, struct ptrace_vm_entry *pve)
  370 {
  371         struct vattr vattr;
  372         vm_map_t map;
  373         vm_map_entry_t entry;
  374         vm_object_t obj, tobj, lobj;
  375         struct vmspace *vm;
  376         struct vnode *vp;
  377         char *freepath, *fullpath;
  378         u_int pathlen;
  379         int error, index, vfslocked;
  380 
  381         error = 0;
  382         obj = NULL;
  383 
  384         vm = vmspace_acquire_ref(p);
  385         map = &vm->vm_map;
  386         vm_map_lock_read(map);
  387 
  388         do {
  389                 entry = map->header.next;
  390                 index = 0;
  391                 while (index < pve->pve_entry && entry != &map->header) {
  392                         entry = entry->next;
  393                         index++;
  394                 }
  395                 if (index != pve->pve_entry) {
  396                         error = EINVAL;
  397                         break;
  398                 }
  399                 while (entry != &map->header &&
  400                     (entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) {
  401                         entry = entry->next;
  402                         index++;
  403                 }
  404                 if (entry == &map->header) {
  405                         error = ENOENT;
  406                         break;
  407                 }
  408 
  409                 /* We got an entry. */
  410                 pve->pve_entry = index + 1;
  411                 pve->pve_timestamp = map->timestamp;
  412                 pve->pve_start = entry->start;
  413                 pve->pve_end = entry->end - 1;
  414                 pve->pve_offset = entry->offset;
  415                 pve->pve_prot = entry->protection;
  416 
  417                 /* Backing object's path needed? */
  418                 if (pve->pve_pathlen == 0)
  419                         break;
  420 
  421                 pathlen = pve->pve_pathlen;
  422                 pve->pve_pathlen = 0;
  423 
  424                 obj = entry->object.vm_object;
  425                 if (obj != NULL)
  426                         VM_OBJECT_LOCK(obj);
  427         } while (0);
  428 
  429         vm_map_unlock_read(map);
  430         vmspace_free(vm);
  431 
  432         pve->pve_fsid = VNOVAL;
  433         pve->pve_fileid = VNOVAL;
  434 
  435         if (error == 0 && obj != NULL) {
  436                 lobj = obj;
  437                 for (tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
  438                         if (tobj != obj)
  439                                 VM_OBJECT_LOCK(tobj);
  440                         if (lobj != obj)
  441                                 VM_OBJECT_UNLOCK(lobj);
  442                         lobj = tobj;
  443                         pve->pve_offset += tobj->backing_object_offset;
  444                 }
  445                 vp = (lobj->type == OBJT_VNODE) ? lobj->handle : NULL;
  446                 if (vp != NULL)
  447                         vref(vp);
  448                 if (lobj != obj)
  449                         VM_OBJECT_UNLOCK(lobj);
  450                 VM_OBJECT_UNLOCK(obj);
  451 
  452                 if (vp != NULL) {
  453                         freepath = NULL;
  454                         fullpath = NULL;
  455                         vn_fullpath(td, vp, &fullpath, &freepath);
  456                         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  457                         vn_lock(vp, LK_SHARED | LK_RETRY);
  458                         if (VOP_GETATTR(vp, &vattr, td->td_ucred) == 0) {
  459                                 pve->pve_fileid = vattr.va_fileid;
  460                                 pve->pve_fsid = vattr.va_fsid;
  461                         }
  462                         vput(vp);
  463                         VFS_UNLOCK_GIANT(vfslocked);
  464 
  465                         if (fullpath != NULL) {
  466                                 pve->pve_pathlen = strlen(fullpath) + 1;
  467                                 if (pve->pve_pathlen <= pathlen) {
  468                                         error = copyout(fullpath, pve->pve_path,
  469                                             pve->pve_pathlen);
  470                                 } else
  471                                         error = ENAMETOOLONG;
  472                         }
  473                         if (freepath != NULL)
  474                                 free(freepath, M_TEMP);
  475                 }
  476         }
  477 
  478         return (error);
  479 }
  480 
  481 #ifdef COMPAT_FREEBSD32
  482 static int      
  483 ptrace_vm_entry32(struct thread *td, struct proc *p,
  484     struct ptrace_vm_entry32 *pve32)
  485 {
  486         struct ptrace_vm_entry pve;
  487         int error;
  488 
  489         pve.pve_entry = pve32->pve_entry;
  490         pve.pve_pathlen = pve32->pve_pathlen;
  491         pve.pve_path = (void *)(uintptr_t)pve32->pve_path;
  492 
  493         error = ptrace_vm_entry(td, p, &pve);
  494         if (error == 0) {
  495                 pve32->pve_entry = pve.pve_entry;
  496                 pve32->pve_timestamp = pve.pve_timestamp;
  497                 pve32->pve_start = pve.pve_start;
  498                 pve32->pve_end = pve.pve_end;
  499                 pve32->pve_offset = pve.pve_offset;
  500                 pve32->pve_prot = pve.pve_prot;
  501                 pve32->pve_fileid = pve.pve_fileid;
  502                 pve32->pve_fsid = pve.pve_fsid;
  503         }
  504 
  505         pve32->pve_pathlen = pve.pve_pathlen;
  506         return (error);
  507 }
  508 
  509 static void
  510 ptrace_lwpinfo_to32(const struct ptrace_lwpinfo *pl,
  511     struct ptrace_lwpinfo32 *pl32)
  512 {
  513 
  514         pl32->pl_lwpid = pl->pl_lwpid;
  515         pl32->pl_event = pl->pl_event;
  516         pl32->pl_flags = pl->pl_flags;
  517         pl32->pl_sigmask = pl->pl_sigmask;
  518         pl32->pl_siglist = pl->pl_siglist;
  519         siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
  520 }
  521 #endif /* COMPAT_FREEBSD32 */
  522 
  523 /*
  524  * Process debugging system call.
  525  */
  526 #ifndef _SYS_SYSPROTO_H_
  527 struct ptrace_args {
  528         int     req;
  529         pid_t   pid;
  530         caddr_t addr;
  531         int     data;
  532 };
  533 #endif
  534 
  535 #ifdef COMPAT_FREEBSD32
  536 /*
  537  * This CPP subterfuge is to try and reduce the number of ifdefs in
  538  * the body of the code.
  539  *   COPYIN(uap->addr, &r.reg, sizeof r.reg);
  540  * becomes either:
  541  *   copyin(uap->addr, &r.reg, sizeof r.reg);
  542  * or
  543  *   copyin(uap->addr, &r.reg32, sizeof r.reg32);
  544  * .. except this is done at runtime.
  545  */
  546 #define COPYIN(u, k, s)         wrap32 ? \
  547         copyin(u, k ## 32, s ## 32) : \
  548         copyin(u, k, s)
  549 #define COPYOUT(k, u, s)        wrap32 ? \
  550         copyout(k ## 32, u, s ## 32) : \
  551         copyout(k, u, s)
  552 #else
  553 #define COPYIN(u, k, s)         copyin(u, k, s)
  554 #define COPYOUT(k, u, s)        copyout(k, u, s)
  555 #endif
  556 int
  557 ptrace(struct thread *td, struct ptrace_args *uap)
  558 {
  559         /*
  560          * XXX this obfuscation is to reduce stack usage, but the register
  561          * structs may be too large to put on the stack anyway.
  562          */
  563         union {
  564                 struct ptrace_io_desc piod;
  565                 struct ptrace_lwpinfo pl;
  566                 struct ptrace_vm_entry pve;
  567                 struct dbreg dbreg;
  568                 struct fpreg fpreg;
  569                 struct reg reg;
  570 #ifdef COMPAT_FREEBSD32
  571                 struct dbreg32 dbreg32;
  572                 struct fpreg32 fpreg32;
  573                 struct reg32 reg32;
  574                 struct ptrace_io_desc32 piod32;
  575                 struct ptrace_lwpinfo32 pl32;
  576                 struct ptrace_vm_entry32 pve32;
  577 #endif
  578         } r;
  579         void *addr;
  580         int error = 0;
  581 #ifdef COMPAT_FREEBSD32
  582         int wrap32 = 0;
  583 
  584         if (SV_CURPROC_FLAG(SV_ILP32))
  585                 wrap32 = 1;
  586 #endif
  587         AUDIT_ARG_PID(uap->pid);
  588         AUDIT_ARG_CMD(uap->req);
  589         AUDIT_ARG_VALUE(uap->data);
  590         addr = &r;
  591         switch (uap->req) {
  592         case PT_GETREGS:
  593         case PT_GETFPREGS:
  594         case PT_GETDBREGS:
  595         case PT_LWPINFO:
  596                 break;
  597         case PT_SETREGS:
  598                 error = COPYIN(uap->addr, &r.reg, sizeof r.reg);
  599                 break;
  600         case PT_SETFPREGS:
  601                 error = COPYIN(uap->addr, &r.fpreg, sizeof r.fpreg);
  602                 break;
  603         case PT_SETDBREGS:
  604                 error = COPYIN(uap->addr, &r.dbreg, sizeof r.dbreg);
  605                 break;
  606         case PT_IO:
  607                 error = COPYIN(uap->addr, &r.piod, sizeof r.piod);
  608                 break;
  609         case PT_VM_ENTRY:
  610                 error = COPYIN(uap->addr, &r.pve, sizeof r.pve);
  611                 break;
  612         default:
  613                 addr = uap->addr;
  614                 break;
  615         }
  616         if (error)
  617                 return (error);
  618 
  619         error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
  620         if (error)
  621                 return (error);
  622 
  623         switch (uap->req) {
  624         case PT_VM_ENTRY:
  625                 error = COPYOUT(&r.pve, uap->addr, sizeof r.pve);
  626                 break;
  627         case PT_IO:
  628                 error = COPYOUT(&r.piod, uap->addr, sizeof r.piod);
  629                 break;
  630         case PT_GETREGS:
  631                 error = COPYOUT(&r.reg, uap->addr, sizeof r.reg);
  632                 break;
  633         case PT_GETFPREGS:
  634                 error = COPYOUT(&r.fpreg, uap->addr, sizeof r.fpreg);
  635                 break;
  636         case PT_GETDBREGS:
  637                 error = COPYOUT(&r.dbreg, uap->addr, sizeof r.dbreg);
  638                 break;
  639         case PT_LWPINFO:
  640                 error = copyout(&r.pl, uap->addr, uap->data);
  641                 break;
  642         }
  643 
  644         return (error);
  645 }
  646 #undef COPYIN
  647 #undef COPYOUT
  648 
  649 #ifdef COMPAT_FREEBSD32
  650 /*
  651  *   PROC_READ(regs, td2, addr);
  652  * becomes either:
  653  *   proc_read_regs(td2, addr);
  654  * or
  655  *   proc_read_regs32(td2, addr);
  656  * .. except this is done at runtime.  There is an additional
  657  * complication in that PROC_WRITE disallows 32 bit consumers
  658  * from writing to 64 bit address space targets.
  659  */
  660 #define PROC_READ(w, t, a)      wrap32 ? \
  661         proc_read_ ## w ## 32(t, a) : \
  662         proc_read_ ## w (t, a)
  663 #define PROC_WRITE(w, t, a)     wrap32 ? \
  664         (safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \
  665         proc_write_ ## w (t, a)
  666 #else
  667 #define PROC_READ(w, t, a)      proc_read_ ## w (t, a)
  668 #define PROC_WRITE(w, t, a)     proc_write_ ## w (t, a)
  669 #endif
  670 
  671 int
  672 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
  673 {
  674         struct iovec iov;
  675         struct uio uio;
  676         struct proc *curp, *p, *pp;
  677         struct thread *td2 = NULL;
  678         struct ptrace_io_desc *piod = NULL;
  679         struct ptrace_lwpinfo *pl;
  680         int error, write, tmp, num;
  681         int proctree_locked = 0;
  682         lwpid_t tid = 0, *buf;
  683 #ifdef COMPAT_FREEBSD32
  684         int wrap32 = 0, safe = 0;
  685         struct ptrace_io_desc32 *piod32 = NULL;
  686         struct ptrace_lwpinfo32 *pl32 = NULL;
  687         struct ptrace_lwpinfo plr;
  688 #endif
  689 
  690         curp = td->td_proc;
  691 
  692         /* Lock proctree before locking the process. */
  693         switch (req) {
  694         case PT_TRACE_ME:
  695         case PT_ATTACH:
  696         case PT_STEP:
  697         case PT_CONTINUE:
  698         case PT_TO_SCE:
  699         case PT_TO_SCX:
  700         case PT_SYSCALL:
  701         case PT_DETACH:
  702                 sx_xlock(&proctree_lock);
  703                 proctree_locked = 1;
  704                 break;
  705         default:
  706                 break;
  707         }
  708 
  709         write = 0;
  710         if (req == PT_TRACE_ME) {
  711                 p = td->td_proc;
  712                 PROC_LOCK(p);
  713         } else {
  714                 if (pid <= PID_MAX) {
  715                         if ((p = pfind(pid)) == NULL) {
  716                                 if (proctree_locked)
  717                                         sx_xunlock(&proctree_lock);
  718                                 return (ESRCH);
  719                         }
  720                 } else {
  721                         /* this is slow, should be optimized */
  722                         sx_slock(&allproc_lock);
  723                         FOREACH_PROC_IN_SYSTEM(p) {
  724                                 PROC_LOCK(p);
  725                                 FOREACH_THREAD_IN_PROC(p, td2) {
  726                                         if (td2->td_tid == pid)
  727                                                 break;
  728                                 }
  729                                 if (td2 != NULL)
  730                                         break; /* proc lock held */
  731                                 PROC_UNLOCK(p);
  732                         }
  733                         sx_sunlock(&allproc_lock);
  734                         if (p == NULL) {
  735                                 if (proctree_locked)
  736                                         sx_xunlock(&proctree_lock);
  737                                 return (ESRCH);
  738                         }
  739                         tid = pid;
  740                         pid = p->p_pid;
  741                 }
  742         }
  743         AUDIT_ARG_PROCESS(p);
  744 
  745         if ((p->p_flag & P_WEXIT) != 0) {
  746                 error = ESRCH;
  747                 goto fail;
  748         }
  749         if ((error = p_cansee(td, p)) != 0)
  750                 goto fail;
  751 
  752         if ((error = p_candebug(td, p)) != 0)
  753                 goto fail;
  754 
  755         /*
  756          * System processes can't be debugged.
  757          */
  758         if ((p->p_flag & P_SYSTEM) != 0) {
  759                 error = EINVAL;
  760                 goto fail;
  761         }
  762 
  763         if (tid == 0) {
  764                 if ((p->p_flag & P_STOPPED_TRACE) != 0) {
  765                         KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
  766                         td2 = p->p_xthread;
  767                 } else {
  768                         td2 = FIRST_THREAD_IN_PROC(p);
  769                 }
  770                 tid = td2->td_tid;
  771         }
  772 
  773 #ifdef COMPAT_FREEBSD32
  774         /*
  775          * Test if we're a 32 bit client and what the target is.
  776          * Set the wrap controls accordingly.
  777          */
  778         if (SV_CURPROC_FLAG(SV_ILP32)) {
  779                 if (td2->td_proc->p_sysent->sv_flags & SV_ILP32)
  780                         safe = 1;
  781                 wrap32 = 1;
  782         }
  783 #endif
  784         /*
  785          * Permissions check
  786          */
  787         switch (req) {
  788         case PT_TRACE_ME:
  789                 /* Always legal. */
  790                 break;
  791 
  792         case PT_ATTACH:
  793                 /* Self */
  794                 if (p->p_pid == td->td_proc->p_pid) {
  795                         error = EINVAL;
  796                         goto fail;
  797                 }
  798 
  799                 /* Already traced */
  800                 if (p->p_flag & P_TRACED) {
  801                         error = EBUSY;
  802                         goto fail;
  803                 }
  804 
  805                 /* Can't trace an ancestor if you're being traced. */
  806                 if (curp->p_flag & P_TRACED) {
  807                         for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
  808                                 if (pp == p) {
  809                                         error = EINVAL;
  810                                         goto fail;
  811                                 }
  812                         }
  813                 }
  814 
  815 
  816                 /* OK */
  817                 break;
  818 
  819         case PT_CLEARSTEP:
  820                 /* Allow thread to clear single step for itself */
  821                 if (td->td_tid == tid)
  822                         break;
  823 
  824                 /* FALLTHROUGH */
  825         default:
  826                 /* not being traced... */
  827                 if ((p->p_flag & P_TRACED) == 0) {
  828                         error = EPERM;
  829                         goto fail;
  830                 }
  831 
  832                 /* not being traced by YOU */
  833                 if (p->p_pptr != td->td_proc) {
  834                         error = EBUSY;
  835                         goto fail;
  836                 }
  837 
  838                 /* not currently stopped */
  839                 if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) == 0 ||
  840                     p->p_suspcount != p->p_numthreads  ||
  841                     (p->p_flag & P_WAITED) == 0) {
  842                         error = EBUSY;
  843                         goto fail;
  844                 }
  845 
  846                 if ((p->p_flag & P_STOPPED_TRACE) == 0) {
  847                         static int count = 0;
  848                         if (count++ == 0)
  849                                 printf("P_STOPPED_TRACE not set.\n");
  850                 }
  851 
  852                 /* OK */
  853                 break;
  854         }
  855 
  856         /* Keep this process around until we finish this request. */
  857         _PHOLD(p);
  858 
  859 #ifdef FIX_SSTEP
  860         /*
  861          * Single step fixup ala procfs
  862          */
  863         FIX_SSTEP(td2);
  864 #endif
  865 
  866         /*
  867          * Actually do the requests
  868          */
  869 
  870         td->td_retval[0] = 0;
  871 
  872         switch (req) {
  873         case PT_TRACE_ME:
  874                 /* set my trace flag and "owner" so it can read/write me */
  875                 p->p_flag |= P_TRACED;
  876                 p->p_oppid = p->p_pptr->p_pid;
  877                 break;
  878 
  879         case PT_ATTACH:
  880                 /* security check done above */
  881                 p->p_flag |= P_TRACED;
  882                 p->p_oppid = p->p_pptr->p_pid;
  883                 if (p->p_pptr != td->td_proc)
  884                         proc_reparent(p, td->td_proc);
  885                 data = SIGSTOP;
  886                 goto sendsig;   /* in PT_CONTINUE below */
  887 
  888         case PT_CLEARSTEP:
  889                 error = ptrace_clear_single_step(td2);
  890                 break;
  891 
  892         case PT_SETSTEP:
  893                 error = ptrace_single_step(td2);
  894                 break;
  895 
  896         case PT_SUSPEND:
  897                 td2->td_dbgflags |= TDB_SUSPEND;
  898                 thread_lock(td2);
  899                 td2->td_flags |= TDF_NEEDSUSPCHK;
  900                 thread_unlock(td2);
  901                 break;
  902 
  903         case PT_RESUME:
  904                 td2->td_dbgflags &= ~TDB_SUSPEND;
  905                 break;
  906 
  907         case PT_STEP:
  908         case PT_CONTINUE:
  909         case PT_TO_SCE:
  910         case PT_TO_SCX:
  911         case PT_SYSCALL:
  912         case PT_DETACH:
  913                 /* Zero means do not send any signal */
  914                 if (data < 0 || data > _SIG_MAXSIG) {
  915                         error = EINVAL;
  916                         break;
  917                 }
  918 
  919                 switch (req) {
  920                 case PT_STEP:
  921                         error = ptrace_single_step(td2);
  922                         if (error)
  923                                 goto out;
  924                         break;
  925                 case PT_CONTINUE:
  926                 case PT_TO_SCE:
  927                 case PT_TO_SCX:
  928                 case PT_SYSCALL:
  929                         if (addr != (void *)1) {
  930                                 error = ptrace_set_pc(td2,
  931                                     (u_long)(uintfptr_t)addr);
  932                                 if (error)
  933                                         goto out;
  934                         }
  935                         switch (req) {
  936                         case PT_TO_SCE:
  937                                 p->p_stops |= S_PT_SCE;
  938                                 break;
  939                         case PT_TO_SCX:
  940                                 p->p_stops |= S_PT_SCX;
  941                                 break;
  942                         case PT_SYSCALL:
  943                                 p->p_stops |= S_PT_SCE | S_PT_SCX;
  944                                 break;
  945                         }
  946                         break;
  947                 case PT_DETACH:
  948                         /* reset process parent */
  949                         if (p->p_oppid != p->p_pptr->p_pid) {
  950                                 struct proc *pp;
  951 
  952                                 PROC_LOCK(p->p_pptr);
  953                                 sigqueue_take(p->p_ksi);
  954                                 PROC_UNLOCK(p->p_pptr);
  955 
  956                                 PROC_UNLOCK(p);
  957                                 pp = pfind(p->p_oppid);
  958                                 if (pp == NULL)
  959                                         pp = initproc;
  960                                 else
  961                                         PROC_UNLOCK(pp);
  962                                 PROC_LOCK(p);
  963                                 proc_reparent(p, pp);
  964                                 if (pp == initproc)
  965                                         p->p_sigparent = SIGCHLD;
  966                         }
  967                         p->p_flag &= ~(P_TRACED | P_WAITED);
  968                         p->p_oppid = 0;
  969 
  970                         /* should we send SIGCHLD? */
  971                         /* childproc_continued(p); */
  972                         break;
  973                 }
  974 
  975         sendsig:
  976                 if (proctree_locked) {
  977                         sx_xunlock(&proctree_lock);
  978                         proctree_locked = 0;
  979                 }
  980                 p->p_xstat = data;
  981                 p->p_xthread = NULL;
  982                 if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) != 0) {
  983                         /* deliver or queue signal */
  984                         td2->td_dbgflags &= ~TDB_XSIG;
  985                         td2->td_xsig = data;
  986 
  987                         if (req == PT_DETACH) {
  988                                 struct thread *td3;
  989                                 FOREACH_THREAD_IN_PROC(p, td3) {
  990                                         td3->td_dbgflags &= ~TDB_SUSPEND; 
  991                                 }
  992                         }
  993                         /*
  994                          * unsuspend all threads, to not let a thread run,
  995                          * you should use PT_SUSPEND to suspend it before
  996                          * continuing process.
  997                          */
  998                         PROC_SLOCK(p);
  999                         p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
 1000                         thread_unsuspend(p);
 1001                         PROC_SUNLOCK(p);
 1002                 } else {
 1003                         if (data)
 1004                                 psignal(p, data);
 1005                 }
 1006                 break;
 1007 
 1008         case PT_WRITE_I:
 1009         case PT_WRITE_D:
 1010                 td2->td_dbgflags |= TDB_USERWR;
 1011                 write = 1;
 1012                 /* FALLTHROUGH */
 1013         case PT_READ_I:
 1014         case PT_READ_D:
 1015                 PROC_UNLOCK(p);
 1016                 tmp = 0;
 1017                 /* write = 0 set above */
 1018                 iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp;
 1019                 iov.iov_len = sizeof(int);
 1020                 uio.uio_iov = &iov;
 1021                 uio.uio_iovcnt = 1;
 1022                 uio.uio_offset = (off_t)(uintptr_t)addr;
 1023                 uio.uio_resid = sizeof(int);
 1024                 uio.uio_segflg = UIO_SYSSPACE;  /* i.e.: the uap */
 1025                 uio.uio_rw = write ? UIO_WRITE : UIO_READ;
 1026                 uio.uio_td = td;
 1027                 error = proc_rwmem(p, &uio);
 1028                 if (uio.uio_resid != 0) {
 1029                         /*
 1030                          * XXX proc_rwmem() doesn't currently return ENOSPC,
 1031                          * so I think write() can bogusly return 0.
 1032                          * XXX what happens for short writes?  We don't want
 1033                          * to write partial data.
 1034                          * XXX proc_rwmem() returns EPERM for other invalid
 1035                          * addresses.  Convert this to EINVAL.  Does this
 1036                          * clobber returns of EPERM for other reasons?
 1037                          */
 1038                         if (error == 0 || error == ENOSPC || error == EPERM)
 1039                                 error = EINVAL; /* EOF */
 1040                 }
 1041                 if (!write)
 1042                         td->td_retval[0] = tmp;
 1043                 PROC_LOCK(p);
 1044                 break;
 1045 
 1046         case PT_IO:
 1047 #ifdef COMPAT_FREEBSD32
 1048                 if (wrap32) {
 1049                         piod32 = addr;
 1050                         iov.iov_base = (void *)(uintptr_t)piod32->piod_addr;
 1051                         iov.iov_len = piod32->piod_len;
 1052                         uio.uio_offset = (off_t)(uintptr_t)piod32->piod_offs;
 1053                         uio.uio_resid = piod32->piod_len;
 1054                 } else
 1055 #endif
 1056                 {
 1057                         piod = addr;
 1058                         iov.iov_base = piod->piod_addr;
 1059                         iov.iov_len = piod->piod_len;
 1060                         uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
 1061                         uio.uio_resid = piod->piod_len;
 1062                 }
 1063                 uio.uio_iov = &iov;
 1064                 uio.uio_iovcnt = 1;
 1065                 uio.uio_segflg = UIO_USERSPACE;
 1066                 uio.uio_td = td;
 1067 #ifdef COMPAT_FREEBSD32
 1068                 tmp = wrap32 ? piod32->piod_op : piod->piod_op;
 1069 #else
 1070                 tmp = piod->piod_op;
 1071 #endif
 1072                 switch (tmp) {
 1073                 case PIOD_READ_D:
 1074                 case PIOD_READ_I:
 1075                         uio.uio_rw = UIO_READ;
 1076                         break;
 1077                 case PIOD_WRITE_D:
 1078                 case PIOD_WRITE_I:
 1079                         td2->td_dbgflags |= TDB_USERWR;
 1080                         uio.uio_rw = UIO_WRITE;
 1081                         break;
 1082                 default:
 1083                         error = EINVAL;
 1084                         goto out;
 1085                 }
 1086                 PROC_UNLOCK(p);
 1087                 error = proc_rwmem(p, &uio);
 1088 #ifdef COMPAT_FREEBSD32
 1089                 if (wrap32)
 1090                         piod32->piod_len -= uio.uio_resid;
 1091                 else
 1092 #endif
 1093                         piod->piod_len -= uio.uio_resid;
 1094                 PROC_LOCK(p);
 1095                 break;
 1096 
 1097         case PT_KILL:
 1098                 data = SIGKILL;
 1099                 goto sendsig;   /* in PT_CONTINUE above */
 1100 
 1101         case PT_SETREGS:
 1102                 td2->td_dbgflags |= TDB_USERWR;
 1103                 error = PROC_WRITE(regs, td2, addr);
 1104                 break;
 1105 
 1106         case PT_GETREGS:
 1107                 error = PROC_READ(regs, td2, addr);
 1108                 break;
 1109 
 1110         case PT_SETFPREGS:
 1111                 td2->td_dbgflags |= TDB_USERWR;
 1112                 error = PROC_WRITE(fpregs, td2, addr);
 1113                 break;
 1114 
 1115         case PT_GETFPREGS:
 1116                 error = PROC_READ(fpregs, td2, addr);
 1117                 break;
 1118 
 1119         case PT_SETDBREGS:
 1120                 td2->td_dbgflags |= TDB_USERWR;
 1121                 error = PROC_WRITE(dbregs, td2, addr);
 1122                 break;
 1123 
 1124         case PT_GETDBREGS:
 1125                 error = PROC_READ(dbregs, td2, addr);
 1126                 break;
 1127 
 1128         case PT_LWPINFO:
 1129                 if (data <= 0 ||
 1130 #ifdef COMPAT_FREEBSD32
 1131                     (!wrap32 && data > sizeof(*pl)) ||
 1132                     (wrap32 && data > sizeof(*pl32))) {
 1133 #else
 1134                     data > sizeof(*pl)) {
 1135 #endif
 1136                         error = EINVAL;
 1137                         break;
 1138                 }
 1139 #ifdef COMPAT_FREEBSD32
 1140                 if (wrap32) {
 1141                         pl = &plr;
 1142                         pl32 = addr;
 1143                 } else
 1144 #endif
 1145                 pl = addr;
 1146                 pl->pl_lwpid = td2->td_tid;
 1147                 pl->pl_flags = 0;
 1148                 if (td2->td_dbgflags & TDB_XSIG) {
 1149                         pl->pl_event = PL_EVENT_SIGNAL;
 1150                         if (td2->td_dbgksi.ksi_signo != 0 &&
 1151 #ifdef COMPAT_FREEBSD32
 1152                             ((!wrap32 && data >= offsetof(struct ptrace_lwpinfo,
 1153                             pl_siginfo) + sizeof(pl->pl_siginfo)) ||
 1154                             (wrap32 && data >= offsetof(struct ptrace_lwpinfo32,
 1155                             pl_siginfo) + sizeof(struct siginfo32)))
 1156 #else
 1157                             data >= offsetof(struct ptrace_lwpinfo, pl_siginfo)
 1158                             + sizeof(pl->pl_siginfo)
 1159 #endif
 1160                         ){
 1161                                 pl->pl_flags |= PL_FLAG_SI;
 1162                                 pl->pl_siginfo = td2->td_dbgksi.ksi_info;
 1163                         }
 1164                 }
 1165                 if ((pl->pl_flags & PL_FLAG_SI) == 0)
 1166                         bzero(&pl->pl_siginfo, sizeof(pl->pl_siginfo));
 1167                 if (td2->td_dbgflags & TDB_SCE)
 1168                         pl->pl_flags |= PL_FLAG_SCE;
 1169                 else if (td2->td_dbgflags & TDB_SCX)
 1170                         pl->pl_flags |= PL_FLAG_SCX;
 1171                 if (td2->td_dbgflags & TDB_EXEC)
 1172                         pl->pl_flags |= PL_FLAG_EXEC;
 1173                 pl->pl_sigmask = td2->td_sigmask;
 1174                 pl->pl_siglist = td2->td_siglist;
 1175 #ifdef COMPAT_FREEBSD32
 1176                 if (wrap32)
 1177                         ptrace_lwpinfo_to32(pl, pl32);
 1178 #endif
 1179                 break;
 1180 
 1181         case PT_GETNUMLWPS:
 1182                 td->td_retval[0] = p->p_numthreads;
 1183                 break;
 1184 
 1185         case PT_GETLWPLIST:
 1186                 if (data <= 0) {
 1187                         error = EINVAL;
 1188                         break;
 1189                 }
 1190                 num = imin(p->p_numthreads, data);
 1191                 PROC_UNLOCK(p);
 1192                 buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
 1193                 tmp = 0;
 1194                 PROC_LOCK(p);
 1195                 FOREACH_THREAD_IN_PROC(p, td2) {
 1196                         if (tmp >= num)
 1197                                 break;
 1198                         buf[tmp++] = td2->td_tid;
 1199                 }
 1200                 PROC_UNLOCK(p);
 1201                 error = copyout(buf, addr, tmp * sizeof(lwpid_t));
 1202                 free(buf, M_TEMP);
 1203                 if (!error)
 1204                         td->td_retval[0] = tmp;
 1205                 PROC_LOCK(p);
 1206                 break;
 1207 
 1208         case PT_VM_TIMESTAMP:
 1209                 td->td_retval[0] = p->p_vmspace->vm_map.timestamp;
 1210                 break;
 1211 
 1212         case PT_VM_ENTRY:
 1213                 PROC_UNLOCK(p);
 1214 #ifdef COMPAT_FREEBSD32
 1215                 if (wrap32)
 1216                         error = ptrace_vm_entry32(td, p, addr);
 1217                 else
 1218 #endif
 1219                 error = ptrace_vm_entry(td, p, addr);
 1220                 PROC_LOCK(p);
 1221                 break;
 1222 
 1223         default:
 1224 #ifdef __HAVE_PTRACE_MACHDEP
 1225                 if (req >= PT_FIRSTMACH) {
 1226                         PROC_UNLOCK(p);
 1227                         error = cpu_ptrace(td2, req, addr, data);
 1228                         PROC_LOCK(p);
 1229                 } else
 1230 #endif
 1231                         /* Unknown request. */
 1232                         error = EINVAL;
 1233                 break;
 1234         }
 1235 
 1236 out:
 1237         /* Drop our hold on this process now that the request has completed. */
 1238         _PRELE(p);
 1239 fail:
 1240         PROC_UNLOCK(p);
 1241         if (proctree_locked)
 1242                 sx_xunlock(&proctree_lock);
 1243         return (error);
 1244 }
 1245 #undef PROC_READ
 1246 #undef PROC_WRITE
 1247 
 1248 /*
 1249  * Stop a process because of a debugging event;
 1250  * stay stopped until p->p_step is cleared
 1251  * (cleared by PIOCCONT in procfs).
 1252  */
 1253 void
 1254 stopevent(struct proc *p, unsigned int event, unsigned int val)
 1255 {
 1256 
 1257         PROC_LOCK_ASSERT(p, MA_OWNED);
 1258         p->p_step = 1;
 1259         do {
 1260                 p->p_xstat = val;
 1261                 p->p_xthread = NULL;
 1262                 p->p_stype = event;     /* Which event caused the stop? */
 1263                 wakeup(&p->p_stype);    /* Wake up any PIOCWAIT'ing procs */
 1264                 msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0);
 1265         } while (p->p_step);
 1266 }

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