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/i386/linux/linux_ptrace.c

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    1 /*-
    2  * Copyright (c) 2001 Alexander Kabaev
    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  *    in this position and unchanged.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. The name of the author may not be used to endorse or promote products
   15  *    derived from this software without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: releng/11.2/sys/i386/linux/linux_ptrace.c 331722 2018-03-29 02:50:57Z eadler $");
   31 
   32 #include "opt_cpu.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/lock.h>
   36 #include <sys/mutex.h>
   37 #include <sys/proc.h>
   38 #include <sys/ptrace.h>
   39 #include <sys/syscallsubr.h>
   40 #include <sys/systm.h>
   41 
   42 #include <machine/md_var.h>
   43 #include <machine/pcb.h>
   44 #include <machine/reg.h>
   45 
   46 #include <i386/linux/linux.h>
   47 #include <i386/linux/linux_proto.h>
   48 #include <compat/linux/linux_signal.h>
   49 
   50 /*
   51  *   Linux ptrace requests numbers. Mostly identical to FreeBSD,
   52  *   except for MD ones and PT_ATTACH/PT_DETACH.
   53  */
   54 #define PTRACE_TRACEME          0
   55 #define PTRACE_PEEKTEXT         1
   56 #define PTRACE_PEEKDATA         2
   57 #define PTRACE_PEEKUSR          3
   58 #define PTRACE_POKETEXT         4
   59 #define PTRACE_POKEDATA         5
   60 #define PTRACE_POKEUSR          6
   61 #define PTRACE_CONT             7
   62 #define PTRACE_KILL             8
   63 #define PTRACE_SINGLESTEP       9
   64 
   65 #define PTRACE_ATTACH           16
   66 #define PTRACE_DETACH           17
   67 
   68 #define LINUX_PTRACE_SYSCALL    24
   69 
   70 #define PTRACE_GETREGS          12
   71 #define PTRACE_SETREGS          13
   72 #define PTRACE_GETFPREGS        14
   73 #define PTRACE_SETFPREGS        15
   74 #define PTRACE_GETFPXREGS       18
   75 #define PTRACE_SETFPXREGS       19
   76 
   77 #define PTRACE_SETOPTIONS       21
   78 
   79 /*
   80  * Linux keeps debug registers at the following
   81  * offset in the user struct
   82  */
   83 #define LINUX_DBREG_OFFSET      252
   84 #define LINUX_DBREG_SIZE        (8*sizeof(l_int))
   85 
   86 static __inline int
   87 map_signum(int signum)
   88 {
   89 
   90         signum = linux_to_bsd_signal(signum);
   91         return ((signum == SIGSTOP)? 0 : signum);
   92 }
   93 
   94 struct linux_pt_reg {
   95         l_long  ebx;
   96         l_long  ecx;
   97         l_long  edx;
   98         l_long  esi;
   99         l_long  edi;
  100         l_long  ebp;
  101         l_long  eax;
  102         l_int   xds;
  103         l_int   xes;
  104         l_int   xfs;
  105         l_int   xgs;
  106         l_long  orig_eax;
  107         l_long  eip;
  108         l_int   xcs;
  109         l_long  eflags;
  110         l_long  esp;
  111         l_int   xss;
  112 };
  113 
  114 /*
  115  *   Translate i386 ptrace registers between Linux and FreeBSD formats.
  116  *   The translation is pretty straighforward, for all registers, but
  117  *   orig_eax on Linux side and r_trapno and r_err in FreeBSD
  118  */
  119 static void
  120 map_regs_to_linux(struct reg *bsd_r, struct linux_pt_reg *linux_r)
  121 {
  122         linux_r->ebx = bsd_r->r_ebx;
  123         linux_r->ecx = bsd_r->r_ecx;
  124         linux_r->edx = bsd_r->r_edx;
  125         linux_r->esi = bsd_r->r_esi;
  126         linux_r->edi = bsd_r->r_edi;
  127         linux_r->ebp = bsd_r->r_ebp;
  128         linux_r->eax = bsd_r->r_eax;
  129         linux_r->xds = bsd_r->r_ds;
  130         linux_r->xes = bsd_r->r_es;
  131         linux_r->xfs = bsd_r->r_fs;
  132         linux_r->xgs = bsd_r->r_gs;
  133         linux_r->orig_eax = bsd_r->r_eax;
  134         linux_r->eip = bsd_r->r_eip;
  135         linux_r->xcs = bsd_r->r_cs;
  136         linux_r->eflags = bsd_r->r_eflags;
  137         linux_r->esp = bsd_r->r_esp;
  138         linux_r->xss = bsd_r->r_ss;
  139 }
  140 
  141 static void
  142 map_regs_from_linux(struct reg *bsd_r, struct linux_pt_reg *linux_r)
  143 {
  144         bsd_r->r_ebx = linux_r->ebx;
  145         bsd_r->r_ecx = linux_r->ecx;
  146         bsd_r->r_edx = linux_r->edx;
  147         bsd_r->r_esi = linux_r->esi;
  148         bsd_r->r_edi = linux_r->edi;
  149         bsd_r->r_ebp = linux_r->ebp;
  150         bsd_r->r_eax = linux_r->eax;
  151         bsd_r->r_ds  = linux_r->xds;
  152         bsd_r->r_es  = linux_r->xes;
  153         bsd_r->r_fs  = linux_r->xfs;
  154         bsd_r->r_gs  = linux_r->xgs;
  155         bsd_r->r_eip = linux_r->eip;
  156         bsd_r->r_cs  = linux_r->xcs;
  157         bsd_r->r_eflags = linux_r->eflags;
  158         bsd_r->r_esp = linux_r->esp;
  159         bsd_r->r_ss = linux_r->xss;
  160 }
  161 
  162 struct linux_pt_fpreg {
  163         l_long cwd;
  164         l_long swd;
  165         l_long twd;
  166         l_long fip;
  167         l_long fcs;
  168         l_long foo;
  169         l_long fos;
  170         l_long st_space[2*10];
  171 };
  172 
  173 static void
  174 map_fpregs_to_linux(struct fpreg *bsd_r, struct linux_pt_fpreg *linux_r)
  175 {
  176         linux_r->cwd = bsd_r->fpr_env[0];
  177         linux_r->swd = bsd_r->fpr_env[1];
  178         linux_r->twd = bsd_r->fpr_env[2];
  179         linux_r->fip = bsd_r->fpr_env[3];
  180         linux_r->fcs = bsd_r->fpr_env[4];
  181         linux_r->foo = bsd_r->fpr_env[5];
  182         linux_r->fos = bsd_r->fpr_env[6];
  183         bcopy(bsd_r->fpr_acc, linux_r->st_space, sizeof(linux_r->st_space));
  184 }
  185 
  186 static void
  187 map_fpregs_from_linux(struct fpreg *bsd_r, struct linux_pt_fpreg *linux_r)
  188 {
  189         bsd_r->fpr_env[0] = linux_r->cwd;
  190         bsd_r->fpr_env[1] = linux_r->swd;
  191         bsd_r->fpr_env[2] = linux_r->twd;
  192         bsd_r->fpr_env[3] = linux_r->fip;
  193         bsd_r->fpr_env[4] = linux_r->fcs;
  194         bsd_r->fpr_env[5] = linux_r->foo;
  195         bsd_r->fpr_env[6] = linux_r->fos;
  196         bcopy(bsd_r->fpr_acc, linux_r->st_space, sizeof(bsd_r->fpr_acc));
  197 }
  198 
  199 struct linux_pt_fpxreg {
  200         l_ushort        cwd;
  201         l_ushort        swd;
  202         l_ushort        twd;
  203         l_ushort        fop;
  204         l_long          fip;
  205         l_long          fcs;
  206         l_long          foo;
  207         l_long          fos;
  208         l_long          mxcsr;
  209         l_long          reserved;
  210         l_long          st_space[32];
  211         l_long          xmm_space[32];
  212         l_long          padding[56];
  213 };
  214 
  215 static int
  216 linux_proc_read_fpxregs(struct thread *td, struct linux_pt_fpxreg *fpxregs)
  217 {
  218 
  219         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
  220         if (cpu_fxsr == 0 || (td->td_proc->p_flag & P_INMEM) == 0)
  221                 return (EIO);
  222         bcopy(&get_pcb_user_save_td(td)->sv_xmm, fpxregs, sizeof(*fpxregs));
  223         return (0);
  224 }
  225 
  226 static int
  227 linux_proc_write_fpxregs(struct thread *td, struct linux_pt_fpxreg *fpxregs)
  228 {
  229 
  230         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
  231         if (cpu_fxsr == 0 || (td->td_proc->p_flag & P_INMEM) == 0)
  232                 return (EIO);
  233         bcopy(fpxregs, &get_pcb_user_save_td(td)->sv_xmm, sizeof(*fpxregs));
  234         return (0);
  235 }
  236 
  237 int
  238 linux_ptrace(struct thread *td, struct linux_ptrace_args *uap)
  239 {
  240         union {
  241                 struct linux_pt_reg     reg;
  242                 struct linux_pt_fpreg   fpreg;
  243                 struct linux_pt_fpxreg  fpxreg;
  244         } r;
  245         union {
  246                 struct reg              bsd_reg;
  247                 struct fpreg            bsd_fpreg;
  248                 struct dbreg            bsd_dbreg;
  249         } u;
  250         void *addr;
  251         pid_t pid;
  252         int error, req;
  253 
  254         error = 0;
  255 
  256         /* by default, just copy data intact */
  257         req  = uap->req;
  258         pid  = (pid_t)uap->pid;
  259         addr = (void *)uap->addr;
  260 
  261         switch (req) {
  262         case PTRACE_TRACEME:
  263         case PTRACE_POKETEXT:
  264         case PTRACE_POKEDATA:
  265         case PTRACE_KILL:
  266                 error = kern_ptrace(td, req, pid, addr, uap->data);
  267                 break;
  268         case PTRACE_PEEKTEXT:
  269         case PTRACE_PEEKDATA: {
  270                 /* need to preserve return value */
  271                 int rval = td->td_retval[0];
  272                 error = kern_ptrace(td, req, pid, addr, 0);
  273                 if (error == 0)
  274                         error = copyout(td->td_retval, (void *)uap->data,
  275                             sizeof(l_int));
  276                 td->td_retval[0] = rval;
  277                 break;
  278         }
  279         case PTRACE_DETACH:
  280                 error = kern_ptrace(td, PT_DETACH, pid, (void *)1,
  281                      map_signum(uap->data));
  282                 break;
  283         case PTRACE_SINGLESTEP:
  284         case PTRACE_CONT:
  285                 error = kern_ptrace(td, req, pid, (void *)1,
  286                      map_signum(uap->data));
  287                 break;
  288         case PTRACE_ATTACH:
  289                 error = kern_ptrace(td, PT_ATTACH, pid, addr, uap->data);
  290                 break;
  291         case PTRACE_GETREGS:
  292                 /* Linux is using data where FreeBSD is using addr */
  293                 error = kern_ptrace(td, PT_GETREGS, pid, &u.bsd_reg, 0);
  294                 if (error == 0) {
  295                         map_regs_to_linux(&u.bsd_reg, &r.reg);
  296                         error = copyout(&r.reg, (void *)uap->data,
  297                             sizeof(r.reg));
  298                 }
  299                 break;
  300         case PTRACE_SETREGS:
  301                 /* Linux is using data where FreeBSD is using addr */
  302                 error = copyin((void *)uap->data, &r.reg, sizeof(r.reg));
  303                 if (error == 0) {
  304                         map_regs_from_linux(&u.bsd_reg, &r.reg);
  305                         error = kern_ptrace(td, PT_SETREGS, pid, &u.bsd_reg, 0);
  306                 }
  307                 break;
  308         case PTRACE_GETFPREGS:
  309                 /* Linux is using data where FreeBSD is using addr */
  310                 error = kern_ptrace(td, PT_GETFPREGS, pid, &u.bsd_fpreg, 0);
  311                 if (error == 0) {
  312                         map_fpregs_to_linux(&u.bsd_fpreg, &r.fpreg);
  313                         error = copyout(&r.fpreg, (void *)uap->data,
  314                             sizeof(r.fpreg));
  315                 }
  316                 break;
  317         case PTRACE_SETFPREGS:
  318                 /* Linux is using data where FreeBSD is using addr */
  319                 error = copyin((void *)uap->data, &r.fpreg, sizeof(r.fpreg));
  320                 if (error == 0) {
  321                         map_fpregs_from_linux(&u.bsd_fpreg, &r.fpreg);
  322                         error = kern_ptrace(td, PT_SETFPREGS, pid,
  323                             &u.bsd_fpreg, 0);
  324                 }
  325                 break;
  326         case PTRACE_SETFPXREGS:
  327                 error = copyin((void *)uap->data, &r.fpxreg, sizeof(r.fpxreg));
  328                 if (error)
  329                         break;
  330                 /* FALL THROUGH */
  331         case PTRACE_GETFPXREGS: {
  332                 struct proc *p;
  333                 struct thread *td2;
  334 
  335                 if (sizeof(struct linux_pt_fpxreg) != sizeof(struct savexmm)) {
  336                         static int once = 0;
  337                         if (!once) {
  338                                 printf("linux: savexmm != linux_pt_fpxreg\n");
  339                                 once = 1;
  340                         }
  341                         error = EIO;
  342                         break;
  343                 }
  344 
  345                 if ((p = pfind(uap->pid)) == NULL) {
  346                         error = ESRCH;
  347                         break;
  348                 }
  349 
  350                 /* Exiting processes can't be debugged. */
  351                 if ((p->p_flag & P_WEXIT) != 0) {
  352                         error = ESRCH;
  353                         goto fail;
  354                 }
  355 
  356                 if ((error = p_candebug(td, p)) != 0)
  357                         goto fail;
  358 
  359                 /* System processes can't be debugged. */
  360                 if ((p->p_flag & P_SYSTEM) != 0) {
  361                         error = EINVAL;
  362                         goto fail;
  363                 }
  364 
  365                 /* not being traced... */
  366                 if ((p->p_flag & P_TRACED) == 0) {
  367                         error = EPERM;
  368                         goto fail;
  369                 }
  370 
  371                 /* not being traced by YOU */
  372                 if (p->p_pptr != td->td_proc) {
  373                         error = EBUSY;
  374                         goto fail;
  375                 }
  376 
  377                 /* not currently stopped */
  378                 if (!P_SHOULDSTOP(p) || (p->p_flag & P_WAITED) == 0) {
  379                         error = EBUSY;
  380                         goto fail;
  381                 }
  382 
  383                 if (req == PTRACE_GETFPXREGS) {
  384                         _PHOLD(p);      /* may block */
  385                         td2 = FIRST_THREAD_IN_PROC(p);
  386                         error = linux_proc_read_fpxregs(td2, &r.fpxreg);
  387                         _PRELE(p);
  388                         PROC_UNLOCK(p);
  389                         if (error == 0)
  390                                 error = copyout(&r.fpxreg, (void *)uap->data,
  391                                     sizeof(r.fpxreg));
  392                 } else {
  393                         /* clear dangerous bits exactly as Linux does*/
  394                         r.fpxreg.mxcsr &= 0xffbf;
  395                         _PHOLD(p);      /* may block */
  396                         td2 = FIRST_THREAD_IN_PROC(p);
  397                         error = linux_proc_write_fpxregs(td2, &r.fpxreg);
  398                         _PRELE(p);
  399                         PROC_UNLOCK(p);
  400                 }
  401                 break;
  402 
  403         fail:
  404                 PROC_UNLOCK(p);
  405                 break;
  406         }
  407         case PTRACE_PEEKUSR:
  408         case PTRACE_POKEUSR: {
  409                 error = EIO;
  410 
  411                 /* check addr for alignment */
  412                 if (uap->addr < 0 || uap->addr & (sizeof(l_int) - 1))
  413                         break;
  414                 /*
  415                  * Allow linux programs to access register values in
  416                  * user struct. We simulate this through PT_GET/SETREGS
  417                  * as necessary.
  418                  */
  419                 if (uap->addr < sizeof(struct linux_pt_reg)) {
  420                         error = kern_ptrace(td, PT_GETREGS, pid, &u.bsd_reg, 0);
  421                         if (error != 0)
  422                                 break;
  423 
  424                         map_regs_to_linux(&u.bsd_reg, &r.reg);
  425                         if (req == PTRACE_PEEKUSR) {
  426                                 error = copyout((char *)&r.reg + uap->addr,
  427                                     (void *)uap->data, sizeof(l_int));
  428                                 break;
  429                         }
  430 
  431                         *(l_int *)((char *)&r.reg + uap->addr) =
  432                             (l_int)uap->data;
  433 
  434                         map_regs_from_linux(&u.bsd_reg, &r.reg);
  435                         error = kern_ptrace(td, PT_SETREGS, pid, &u.bsd_reg, 0);
  436                 }
  437 
  438                 /*
  439                  * Simulate debug registers access
  440                  */
  441                 if (uap->addr >= LINUX_DBREG_OFFSET &&
  442                     uap->addr <= LINUX_DBREG_OFFSET + LINUX_DBREG_SIZE) {
  443                         error = kern_ptrace(td, PT_GETDBREGS, pid, &u.bsd_dbreg,
  444                             0);
  445                         if (error != 0)
  446                                 break;
  447 
  448                         uap->addr -= LINUX_DBREG_OFFSET;
  449                         if (req == PTRACE_PEEKUSR) {
  450                                 error = copyout((char *)&u.bsd_dbreg +
  451                                     uap->addr, (void *)uap->data,
  452                                     sizeof(l_int));
  453                                 break;
  454                         }
  455 
  456                         *(l_int *)((char *)&u.bsd_dbreg + uap->addr) =
  457                              uap->data;
  458                         error = kern_ptrace(td, PT_SETDBREGS, pid,
  459                             &u.bsd_dbreg, 0);
  460                 }
  461 
  462                 break;
  463         }
  464         case LINUX_PTRACE_SYSCALL:
  465                 /* fall through */
  466         default:
  467                 printf("linux: ptrace(%u, ...) not implemented\n",
  468                     (unsigned int)uap->req);
  469                 error = EINVAL;
  470                 break;
  471         }
  472 
  473         return (error);
  474 }

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