1 /*

     2  * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include <limits.h>

    26 #include <stdio.h>

    27 #include <stdlib.h>

    28 #include <string.h>

    29 #include <errno.h>

    30 #include <sys/types.h>

    31 #include <sys/wait.h>

    32 #include <sys/ptrace.h>

    33 #include <sys/param.h>

    34 #include <sys/user.h>

    35 #include <elf.h>

    36 #include <sys/elf_common.h>

    37 #include <sys/link_elf.h>

    38 #include <libutil.h>

    39 #include "libproc_impl.h"

    40 #include "elfmacros.h"

    41 

    42 // This file has the libproc implementation specific to live process

    43 // For core files, refer to ps_core.c

    44 

    45 static inline uintptr_t align(uintptr_t ptr, size_t size) {

    46   return (ptr & ~(size - 1));

    47 }

    48 

    49 // ---------------------------------------------

    50 // ptrace functions

    51 // ---------------------------------------------

    52 

    53 // read "size" bytes of data from "addr" within the target process.

    54 // unlike the standard ptrace() function, process_read_data() can handle

    55 // unaligned address - alignment check, if required, should be done

    56 // before calling process_read_data.

    57 

    58 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {

    59   int rslt;

    60   size_t i, words;

    61   uintptr_t end_addr = addr + size;

    62   uintptr_t aligned_addr = align(addr, sizeof(int));

    63 

    64   if (aligned_addr != addr) {

    65     char *ptr = (char *)&rslt;

    66     errno = 0;

    67     rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);

    68     if (errno) {

    69       print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);

    70       return false;

    71     }

    72     for (; aligned_addr != addr; aligned_addr++, ptr++);

    73     for (; ((intptr_t)aligned_addr % sizeof(int)) && aligned_addr < end_addr;

    74         aligned_addr++)

    75        *(buf++) = *(ptr++);

    76   }

    77 

    78   words = (end_addr - aligned_addr) / sizeof(int);

    79 

    80   // assert((intptr_t)aligned_addr % sizeof(int) == 0);

    81   for (i = 0; i < words; i++) {

    82     errno = 0;

    83     rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);

    84     if (errno) {

    85       print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);

    86       return false;

    87     }

    88     *(int *)buf = rslt;

    89     buf += sizeof(int);

    90     aligned_addr += sizeof(int);

    91   }

    92 

    93   if (aligned_addr != end_addr) {

    94     char *ptr = (char *)&rslt;

    95     errno = 0;

    96     rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);

    97     if (errno) {

    98       print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);

    99       return false;

   100     }

   101     for (; aligned_addr != end_addr; aligned_addr++)

   102        *(buf++) = *(ptr++);

   103   }

   104   return true;

   105 }

   106 

   107 // null implementation for write

   108 static bool process_write_data(struct ps_prochandle* ph,

   109                              uintptr_t addr, const char *buf , size_t size) {

   110   return false;

   111 }

   112 

   113 // "user" should be a pointer to a reg

   114 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct reg *user) {

   115   // we have already attached to all thread 'pid's, just use ptrace call

   116   // to get regset now. Note that we don't cache regset upfront for processes.

   117  if (ptrace(PT_GETREGS, pid, (caddr_t) user, 0) < 0) {

   118    print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);

   119    return false;

   120  }

   121  return true;

   122 }

   123 

   124 // fill in ptrace_lwpinfo for lid

   125 static bool process_get_lwp_info(struct ps_prochandle *ph, lwpid_t lwp_id, void *linfo) {

   126   errno = 0;

   127   ptrace(PT_LWPINFO, lwp_id, linfo, sizeof(struct ptrace_lwpinfo));

   128 

   129   return (errno == 0)? true: false;

   130 }

   131 

   132 static bool ptrace_continue(pid_t pid, int signal) {

   133   // pass the signal to the process so we don't swallow it

   134   if (ptrace(PT_CONTINUE, pid, NULL, signal) < 0) {

   135     print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);

   136     return false;

   137   }

   138   return true;

   139 }

   140 

   141 // waits until the ATTACH has stopped the process

   142 // by signal SIGSTOP

   143 static bool ptrace_waitpid(pid_t pid) {

   144   int ret;

   145   int status;

   146   do {

   147     // Wait for debuggee to stop.

   148     ret = waitpid(pid, &status, 0);

   149     if (ret >= 0) {

   150       if (WIFSTOPPED(status)) {

   151         // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP

   152         // will still be pending and delivered when the process is DETACHED and the process

   153         // will go to sleep.

   154         if (WSTOPSIG(status) == SIGSTOP) {

   155           // Debuggee stopped by SIGSTOP.

   156           return true;

   157         }

   158         if (!ptrace_continue(pid, WSTOPSIG(status))) {

   159           print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));

   160           return false;

   161         }

   162       } else {

   163         print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);

   164         return false;

   165       }

   166     } else {

   167       switch (errno) {

   168         case EINTR:

   169           continue;

   170           break;

   171         case ECHILD:

   172           print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);

   173           break;

   174         case EINVAL:

   175           print_debug("waitpid() failed. Invalid options argument.\n");

   176           break;

   177         default:

   178           print_debug("waitpid() failed. Unexpected error %d\n",errno);

   179       }

   180       return false;

   181     }

   182   } while(true);

   183 }

   184 

   185 // attach to a process/thread specified by "pid"

   186 static bool ptrace_attach(pid_t pid) {

   187   if (ptrace(PT_ATTACH, pid, NULL, 0) < 0) {

   188     print_debug("ptrace(PTRACE_ATTACH, ..) failed for %d\n", pid);

   189     return false;

   190   } else {

   191     return ptrace_waitpid(pid);

   192   }

   193 }

   194 

   195 // -------------------------------------------------------

   196 // functions for obtaining library information

   197 // -------------------------------------------------------

   198 

   199 // callback for read_thread_info

   200 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {

   201   return add_thread_info(ph, pthread_id, lwp_id) != NULL;

   202 }

   203 

   204 #if defined(__FreeBSD__) && __FreeBSD_version < 701000

   205 /*

   206  * TEXT_START_ADDR from binutils/ld/emulparams/<arch_spec>.sh

   207  * Not the most robust but good enough.

   208  */

   209 

   210 #if defined(amd64) || defined(x86_64)

   211 #define TEXT_START_ADDR 0x400000

   212 #elif defined(i386)

   213 #define TEXT_START_ADDR 0x8048000

   214 #else

   215 #error TEXT_START_ADDR not defined

   216 #endif

   217 

   218 #define BUF_SIZE (PATH_MAX + NAME_MAX + 1)

   219 

   220 uintptr_t linkmap_addr(struct ps_prochandle *ph) {

   221   uintptr_t ehdr_addr, phdr_addr, dyn_addr, dmap_addr, lmap_addr;

   222   ELF_EHDR ehdr;

   223   ELF_PHDR *phdrs, *phdr;

   224   ELF_DYN *dyns, *dyn;

   225   struct r_debug dmap;

   226   unsigned long hdrs_size;

   227   unsigned int i;

   228 

   229   /* read ELF_EHDR at TEXT_START_ADDR and validate */

   230 

   231   ehdr_addr = (uintptr_t)TEXT_START_ADDR;

   232 

   233   if (process_read_data(ph, ehdr_addr, (char *)&ehdr, sizeof(ehdr)) != true) {

   234     print_debug("process_read_data failed for ehdr_addr %p\n", ehdr_addr);

   235     return (0);

   236   }

   237 

   238   if (!IS_ELF(ehdr) ||

   239         ehdr.e_ident[EI_CLASS] != ELF_TARG_CLASS ||

   240         ehdr.e_ident[EI_DATA] != ELF_TARG_DATA ||

   241         ehdr.e_ident[EI_VERSION] != EV_CURRENT ||

   242         ehdr.e_phentsize != sizeof(ELF_PHDR) ||

   243         ehdr.e_version != ELF_TARG_VER ||

   244         ehdr.e_machine != ELF_TARG_MACH) {

   245     print_debug("not an ELF_EHDR at %p\n", ehdr_addr);

   246     return (0);

   247   }

   248 

   249   /* allocate space for all ELF_PHDR's and read */

   250 

   251   phdr_addr = ehdr_addr + ehdr.e_phoff;

   252   hdrs_size = ehdr.e_phnum * sizeof(ELF_PHDR);

   253 

   254   if ((phdrs = malloc(hdrs_size)) == NULL)

   255     return (0);

   256 

   257   if (process_read_data(ph, phdr_addr, (char *)phdrs, hdrs_size) != true) {

   258     print_debug("process_read_data failed for phdr_addr %p\n", phdr_addr);

   259     return (0);

   260   }

   261 

   262   /* find PT_DYNAMIC section */

   263 

   264   for (i = 0, phdr = phdrs; i < ehdr.e_phnum; i++, phdr++) {

   265     if (phdr->p_type == PT_DYNAMIC)

   266       break;

   267   }

   268 

   269   if (i >= ehdr.e_phnum) {

   270     print_debug("PT_DYNAMIC section not found!\n");

   271     free(phdrs);

   272     return (0);

   273   }

   274 

   275   /* allocate space and read in ELF_DYN headers */

   276 

   277   dyn_addr = phdr->p_vaddr;

   278   hdrs_size = phdr->p_memsz;

   279   free(phdrs);

   280 

   281   if ((dyns = malloc(hdrs_size)) == NULL)

   282     return (0);

   283 

   284   if (process_read_data(ph, dyn_addr, (char *)dyns, hdrs_size) != true) {

   285     print_debug("process_read_data failed for dyn_addr %p\n", dyn_addr);

   286     free(dyns);

   287     return (0);

   288   }

   289 

   290   /* find DT_DEBUG */

   291 

   292   dyn = dyns;

   293   while (dyn->d_tag != DT_DEBUG && dyn->d_tag != DT_NULL) {

   294     dyn++;

   295   }

   296 

   297   if (dyn->d_tag != DT_DEBUG) {

   298     print_debug("failed to find DT_DEBUG\n");

   299     free(dyns);

   300     return (0);

   301   }

   302 

   303   /* read struct r_debug into dmap */

   304 

   305   dmap_addr = (uintptr_t)dyn->d_un.d_ptr;

   306   free(dyns);

   307 

   308   if (process_read_data(ph, dmap_addr, (char *)&dmap, sizeof(dmap)) != true) {

   309     print_debug("process_read_data failed for dmap_addr %p\n", dmap_addr);

   310     return (0);

   311   }

   312 

   313   lmap_addr = (uintptr_t)dmap.r_map;

   314 

   315   return (lmap_addr);

   316 }

   317 #endif // __FreeBSD__ && __FreeBSD_version < 701000

   318 

   319 static bool read_lib_info(struct ps_prochandle* ph) {

   320 #if defined(__FreeBSD__) && __FreeBSD_version >= 701000

   321   struct kinfo_vmentry *freep, *kve;

   322   int i, cnt;

   323 

   324   freep = kinfo_getvmmap(ph->pid, &cnt);

   325   if (freep == NULL) {

   326       print_debug("can't get vm map for pid\n", ph->pid);

   327       return false;

   328   }

   329 

   330   for (i = 0; i < cnt; i++) {

   331     kve = &freep[i];

   332     if ((kve->kve_flags & KVME_FLAG_COW) &&

   333         kve->kve_path != NULL &&

   334         strlen(kve->kve_path) > 0) {

   335 

   336       if (find_lib(ph, kve->kve_path) == false) {

   337         lib_info* lib;

   338         if ((lib = add_lib_info(ph, kve->kve_path,

   339                                 (uintptr_t) kve->kve_start)) == NULL)

   340           continue; // ignore, add_lib_info prints error

   341 

   342         // we don't need to keep the library open, symtab is already

   343         // built. Only for core dump we need to keep the fd open.

   344         close(lib->fd);

   345         lib->fd = -1;

   346       }

   347     }

   348   }

   349 

   350   free(freep);

   351 

   352   return true;

   353 #else

   354   char *l_name;

   355   struct link_map *lmap;

   356   uintptr_t lmap_addr;

   357 

   358   if ((l_name = malloc(BUF_SIZE)) == NULL)

   359     return false;

   360 

   361   if ((lmap = malloc(sizeof(*lmap))) == NULL) {

   362     free(l_name);

   363     return false;

   364   }

   365 

   366   lmap_addr = linkmap_addr(ph);

   367 

   368   if (lmap_addr == 0) {

   369     free(l_name);

   370     free(lmap);

   371     return false;

   372   }

   373 

   374   do {

   375     if (process_read_data(ph, lmap_addr, (char *)lmap, sizeof(*lmap)) != true) {

   376       print_debug("process_read_data failed for lmap_addr %p\n", lmap_addr);

   377       free (l_name);

   378       free (lmap);

   379       return false;

   380     }

   381 

   382     if (process_read_data(ph, (uintptr_t)lmap->l_name, l_name,

   383         BUF_SIZE) != true) {

   384       print_debug("process_read_data failed for lmap->l_name %p\n",

   385           lmap->l_name);

   386       free (l_name);

   387       free (lmap);

   388       return false;

   389     }

   390 

   391     if (find_lib(ph, l_name) == false) {

   392       lib_info* lib;

   393       if ((lib = add_lib_info(ph, l_name,

   394                               (uintptr_t) lmap->l_addr)) == NULL)

   395         continue; // ignore, add_lib_info prints error

   396 

   397       // we don't need to keep the library open, symtab is already

   398       // built. Only for core dump we need to keep the fd open.

   399       close(lib->fd);

   400       lib->fd = -1;

   401     }

   402     lmap_addr = (uintptr_t)lmap->l_next;

   403   } while (lmap->l_next != NULL);

   404 

   405   free (l_name);

   406   free (lmap);

   407 

   408   return true;

   409 #endif

   410 }

   411 

   412 // detach a given pid

   413 static bool ptrace_detach(pid_t pid) {

   414   if (pid && ptrace(PT_DETACH, pid, (caddr_t)1, 0) < 0) {

   415     print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);

   416     return false;

   417   } else {

   418     return true;

   419   }

   420 }

   421 

   422 static void process_cleanup(struct ps_prochandle* ph) {

   423   ptrace_detach(ph->pid);

   424 }

   425 

   426 static ps_prochandle_ops process_ops = {

   427   .release=  process_cleanup,

   428   .p_pread=  process_read_data,

   429   .p_pwrite= process_write_data,

   430   .get_lwp_regs= process_get_lwp_regs,

   431   .get_lwp_info= process_get_lwp_info

   432 };

   433 

   434 // attach to the process. One and only one exposed stuff

   435 struct ps_prochandle* Pgrab(pid_t pid) {

   436   struct ps_prochandle* ph = NULL;

   437 

   438   if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {

   439      print_debug("can't allocate memory for ps_prochandle\n");

   440      return NULL;

   441   }

   442 

   443   if (ptrace_attach(pid) != true) {

   444      free(ph);

   445      return NULL;

   446   }

   447 

   448   // initialize ps_prochandle

   449   ph->pid = pid;

   450 

   451   // initialize vtable

   452   ph->ops = &process_ops;

   453 

   454   // read library info and symbol tables, must do this before attaching threads,

   455   // as the symbols in the pthread library will be used to figure out

   456   // the list of threads within the same process.

   457   if (read_lib_info(ph) != true) {

   458      ptrace_detach(pid);

   459      free(ph);

   460      return NULL;

   461   }

   462 

   463   // read thread info

   464   read_thread_info(ph, add_new_thread);

   465 

   466   return ph;

   467 }