usr/src/lib/libdtrace/common/dlink_common.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*
  28  * Copyright (c) 2012 by Delphix. All rights reserved.
  29  */
  30
  31 /*
  32  * Common functions for helper provider loading both compiled into the
  33  * executable via drti.o and dtrace(1M) -G, and the libdaudit.so library.
  34  */
  35
  36 #include <errno.h>
  37 #include <fcntl.h>
  38 #include <stdarg.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43
  44 #include <dlink.h>
  45
  46 /*
  47  * In Solaris 10 GA, the only mechanism for communicating helper information
  48  * is through the DTrace helper pseudo-device node in /devices; there is
  49  * no /dev link. Because of this, USDT providers and helper actions don't
  50  * work inside of non-global zones. This issue was addressed by adding
  51  * the /dev and having this initialization code use that /dev link. If the
  52  * /dev link doesn't exist it falls back to looking for the /devices node
  53  * as this code may be embedded in a binary which runs on Solaris 10 GA.
  54  */
  55 const char *devname = "/dev/dtrace/helper";
  56 static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
  57
  58 static boolean_t dof_init_debug = B_FALSE;
  59
  60 void
  61 dprintf(int debug, const char *fmt, ...)
  62 {
  63         va_list ap;
  64
  65         if (debug && !dof_init_debug)
  66                 return;
  67
  68         va_start(ap, fmt);
  69
  70         (void) fprintf(stderr, "dtrace DOF: ");
  71
  72         (void) vfprintf(stderr, fmt, ap);
  73
  74         if (fmt[strlen(fmt) - 1] != '\n')
  75                 (void) fprintf(stderr, ": %s\n", strerror(errno));
  76
  77         va_end(ap);
  78 }
  79
  80 /*
  81  * Users may set the following environment variable to affect the way
  82  * helper initialization takes place:
  83  *
  84  *      DTRACE_DOF_INIT_DEBUG           enable debugging output
  85  *      DTRACE_DOF_INIT_DISABLE         disable helper loading
  86  *      DTRACE_DOF_INIT_DEVNAME         set the path to the helper node
  87  */
  88 void
  89 dtrace_link_init(void)
  90 {
  91         if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
  92                 dof_init_debug = B_TRUE;
  93 }
  94
  95 void
  96 dtrace_link_dof(dof_hdr_t *dof, Lmid_t lmid, const char *name, uintptr_t addr)
  97 {
  98         const char *modname;
  99         const char *p;
 100 #ifdef _LP64
 101         Elf64_Ehdr *elf;
 102 #else
 103         Elf32_Ehdr *elf;
 104 #endif
 105         dof_helper_t dh;
 106         int fd;
 107
 108         if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
 109                 return;
 110
 111         if ((modname = strrchr(name, '/')) == NULL)
 112                 modname = name;
 113         else
 114                 modname++;
 115
 116         if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
 117             dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
 118             dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
 119             dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
 120                 dprintf(0, ".SUNW_dof section corrupt for %s\n", modname);
 121                 return;
 122         }
 123
 124         elf = (void *)addr;
 125
 126         dh.dofhp_dof = (uintptr_t)dof;
 127         dh.dofhp_addr = elf->e_type == ET_DYN ? addr : 0;
 128
 129         if (lmid == LM_ID_BASE) {
 130                 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
 131                     "%s", modname);
 132         } else {
 133                 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
 134                     "LM%lu`%s", lmid, modname);
 135         }
 136
 137         if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
 138                 devname = p;
 139
 140         if ((fd = open64(devname, O_RDWR)) < 0) {
 141                 dprintf(1, "failed to open helper device %s", devname);
 142
 143                 /*
 144                  * If the device path wasn't explicitly set, try again with
 145                  * the old device path.
 146                  */
 147                 if (p != NULL)
 148                         return;
 149
 150                 devname = olddevname;
 151
 152                 if ((fd = open64(devname, O_RDWR)) < 0) {
 153                         dprintf(1, "failed to open helper device %s", devname);
 154                         return;
 155                 }
 156         }
 157
 158         if (ioctl(fd, DTRACEHIOC_ADDDOF, &dh) == -1) {
 159                 dprintf(1, "DTrace ioctl failed for DOF at %p in %s", dof,
 160                     name);
 161         } else {
 162                 dprintf(1, "DTrace ioctl succeeded for DOF at %p in %s\n", dof,
 163                     name);
 164         }
 165         (void) close(fd);
 166 }