bsd/security/audit/audit_mac.c

   1 /*-
   2  * Copyright (c) 1999-2008 Apple Inc.
   3  * All rights reserved.
   4  *
   5  * @APPLE_BSD_LICENSE_HEADER_START@
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1.  Redistributions of source code must retain the above copyright
  11  *     notice, this list of conditions and the following disclaimer.
  12  * 2.  Redistributions in binary form must reproduce the above copyright
  13  *     notice, this list of conditions and the following disclaimer in the
  14  *     documentation and/or other materials provided with the distribution.
  15  * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
  16  *     its contributors may be used to endorse or promote products derived
  17  *     from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS 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 APPLE OR ITS CONTRIBUTORS BE LIABLE FOR
  23  * 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,
  27  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  28  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  *
  31  * @APPLE_BSD_LICENSE_HEADER_END@
  32  */
  33 /*
  34  * NOTICE: This file was modified by McAfee Research in 2004 to introduce
  35  * support for mandatory and extensible security protections.  This notice
  36  * is included in support of clause 2.2 (b) of the Apple Public License,
  37  * Version 2.0.
  38  */
  39
  40 #include <sys/kernel.h>
  41 #include <sys/proc.h>
  42 #include <sys/kauth.h>
  43 #include <sys/queue.h>
  44 #include <sys/systm.h>
  45
  46 #include <bsm/audit.h>
  47 #include <bsm/audit_internal.h>
  48 #include <bsm/audit_kevents.h>
  49
  50 #include <security/audit/audit.h>
  51 #include <security/audit/audit_private.h>
  52
  53 #include <mach/host_priv.h>
  54 #include <mach/host_special_ports.h>
  55 #include <mach/audit_triggers_server.h>
  56
  57 #include <kern/host.h>
  58 #include <kern/kalloc.h>
  59 #include <kern/zalloc.h>
  60 #include <kern/sched_prim.h>
  61
  62 #if CONFIG_AUDIT
  63
  64 #if CONFIG_MACF
  65 #include <bsm/audit_record.h>
  66 #include <security/mac.h>
  67 #include <security/mac_framework.h>
  68 #include <security/mac_policy.h>
  69 #define MAC_ARG_PREFIX "arg: "
  70 #define MAC_ARG_PREFIX_LEN 5
  71
  72 zone_t          audit_mac_label_zone;
  73 extern zone_t   mac_audit_data_zone;
  74
  75 void
  76 audit_mac_init(void)
  77 {
  78         /* Assume 3 MAC labels for each audit record: two for vnodes,
  79          * one for creds.
  80          */
  81         audit_mac_label_zone = zinit(MAC_AUDIT_LABEL_LEN,
  82             AQ_HIWATER * 3*MAC_AUDIT_LABEL_LEN, 8192, "audit_mac_label_zone");
  83 }
  84
  85 int
  86 audit_mac_new(proc_t p, struct kaudit_record *ar)
  87 {
  88         struct mac mac;
  89
  90         /*
  91          * Retrieve the MAC labels for the process.
  92          */
  93         ar->k_ar.ar_cred_mac_labels = (char *)zalloc(audit_mac_label_zone);
  94         if (ar->k_ar.ar_cred_mac_labels == NULL)
  95                 return (1);
  96         mac.m_buflen = MAC_AUDIT_LABEL_LEN;
  97         mac.m_string = ar->k_ar.ar_cred_mac_labels;
  98         mac_cred_label_externalize_audit(p, &mac);
  99
 100         /*
 101          * grab space for the reconds.
 102          */
 103         ar->k_ar.ar_mac_records = (struct mac_audit_record_list_t *)
 104             kalloc(sizeof(*ar->k_ar.ar_mac_records));
 105         if (ar->k_ar.ar_mac_records == NULL) {
 106                 zfree(audit_mac_label_zone, ar->k_ar.ar_cred_mac_labels);
 107                 return (1);
 108         }
 109         LIST_INIT(ar->k_ar.ar_mac_records);
 110         ar->k_ar.ar_forced_by_mac = 0;
 111
 112         return (0);
 113 }
 114
 115 void
 116 audit_mac_free(struct kaudit_record *ar)
 117 {
 118         struct mac_audit_record *head, *next;
 119
 120         if (ar->k_ar.ar_vnode1_mac_labels != NULL)
 121                 zfree(audit_mac_label_zone, ar->k_ar.ar_vnode1_mac_labels);
 122         if (ar->k_ar.ar_vnode2_mac_labels != NULL)
 123                 zfree(audit_mac_label_zone, ar->k_ar.ar_vnode2_mac_labels);
 124         if (ar->k_ar.ar_cred_mac_labels != NULL)
 125                 zfree(audit_mac_label_zone, ar->k_ar.ar_cred_mac_labels);
 126         if (ar->k_ar.ar_arg_mac_string != NULL)
 127                 kfree(ar->k_ar.ar_arg_mac_string,
 128                     MAC_MAX_LABEL_BUF_LEN + MAC_ARG_PREFIX_LEN);
 129
 130         /*
 131          * Free the audit data from the MAC policies.
 132          */
 133         head = LIST_FIRST(ar->k_ar.ar_mac_records);
 134         while (head != NULL) {
 135                 next = LIST_NEXT(head, records);
 136                 zfree(mac_audit_data_zone, head->data);
 137                 kfree(head, sizeof(*head));
 138                 head = next;
 139         }
 140         kfree(ar->k_ar.ar_mac_records, sizeof(*ar->k_ar.ar_mac_records));
 141 }
 142
 143 int
 144 audit_mac_syscall_enter(unsigned short code, proc_t p, struct uthread *uthread,
 145     kauth_cred_t my_cred, au_event_t event)
 146 {
 147         int error;
 148
 149         error = mac_audit_check_preselect(my_cred, code,
 150              (void *)uthread->uu_arg);
 151         if (error == MAC_AUDIT_YES) {
 152                 uthread->uu_ar = audit_new(event, p, uthread);
 153                 uthread->uu_ar->k_ar.ar_forced_by_mac = 1;
 154                 au_to_text("Forced by a MAC policy");
 155                 return (1);
 156         } else if (error == MAC_AUDIT_NO) {
 157                 return (0);
 158         } else if (error == MAC_AUDIT_DEFAULT) {
 159                 return (1);
 160         }
 161
 162         return (0);
 163 }
 164
 165 int
 166 audit_mac_syscall_exit(unsigned short code, struct uthread *uthread, int error,
 167     int retval)
 168 {
 169         int mac_error;
 170
 171         if (uthread->uu_ar == NULL)  /* syscall wasn't audited */
 172                 return (1);
 173
 174         /*
 175          * Note, no other postselect mechanism exists.  If
 176          * mac_audit_check_postselect returns MAC_AUDIT_NO, the record will be
 177          * suppressed.  Other values at this point result in the audit record
 178          * being committed.  This suppression behavior will probably go away in
 179          * the port to 10.3.4.
 180          */
 181         mac_error = mac_audit_check_postselect(kauth_cred_get(), code,
 182             (void *) uthread->uu_arg, error, retval,
 183             uthread->uu_ar->k_ar.ar_forced_by_mac);
 184
 185         if (mac_error == MAC_AUDIT_YES)
 186                 uthread->uu_ar->k_ar_commit |= AR_COMMIT_KERNEL;
 187         else if (mac_error == MAC_AUDIT_NO) {
 188                 audit_free(uthread->uu_ar);
 189                 return (1);
 190         }
 191         return (0);
 192 }
 193
 194 /*
 195  * This function is called by the MAC Framework to add audit data
 196  * from a policy to the current audit record.
 197  */
 198 int
 199 audit_mac_data(int type, int len, u_char *data) {
 200         struct kaudit_record *cur;
 201         struct mac_audit_record *record;
 202
 203         if (audit_enabled == 0) {
 204                 kfree(data, len);
 205                 return (ENOTSUP);
 206         }
 207
 208         cur = currecord();
 209         if (cur == NULL) {
 210                 kfree(data, len);
 211                 return (ENOTSUP);
 212         }
 213
 214         /*
 215          * XXX: Note that we silently drop the audit data if this
 216          * allocation fails - this is consistent with the rest of the
 217          * audit implementation.
 218          */
 219         record = kalloc(sizeof(*record));
 220         if (record == NULL) {
 221                 kfree(data, len);
 222                 return (0);
 223         }
 224
 225         record->type = type;
 226         record->length = len;
 227         record->data = data;
 228         LIST_INSERT_HEAD(cur->k_ar.ar_mac_records, record, records);
 229
 230         return (0);
 231 }
 232
 233 void
 234 audit_arg_mac_string(struct kaudit_record *ar, char *string)
 235 {
 236
 237         if (ar->k_ar.ar_arg_mac_string == NULL)
 238                 ar->k_ar.ar_arg_mac_string =
 239                         kalloc(MAC_MAX_LABEL_BUF_LEN + MAC_ARG_PREFIX_LEN);
 240
 241         /*
 242          * XXX This should be a rare event. If kalloc() returns NULL,
 243          * the system is low on kernel virtual memory. To be
 244          * consistent with the rest of audit, just return
 245          * (may need to panic if required to for audit).
 246          */
 247         if (ar->k_ar.ar_arg_mac_string == NULL)
 248                 if (ar->k_ar.ar_arg_mac_string == NULL)
 249                         return;
 250
 251         strncpy(ar->k_ar.ar_arg_mac_string, MAC_ARG_PREFIX,
 252             MAC_ARG_PREFIX_LEN);
 253         strncpy(ar->k_ar.ar_arg_mac_string + MAC_ARG_PREFIX_LEN, string,
 254             MAC_MAX_LABEL_BUF_LEN);
 255         ARG_SET_VALID(ar, ARG_MAC_STRING);
 256 }
 257 #endif  /* MAC */
 258
 259 #endif /* CONFIG_AUDIT */