Stephen Smalley | f074036 | 2012-01-04 12:30:47 -0500 | [diff] [blame] | 1 | /* |
| 2 | * Callbacks for user-supplied memory allocation, supplemental |
| 3 | * auditing, and locking routines. |
| 4 | * |
| 5 | * Author : Eamon Walsh <ewalsh@epoch.ncsc.mil> |
| 6 | * |
| 7 | * Netlink code derived in part from sample code by |
| 8 | * James Morris <jmorris@redhat.com>. |
| 9 | */ |
| 10 | |
| 11 | #include <errno.h> |
| 12 | #include <stdio.h> |
| 13 | #include <stdlib.h> |
| 14 | #include <stdint.h> |
| 15 | #include <unistd.h> |
| 16 | #include <fcntl.h> |
| 17 | #include <string.h> |
| 18 | #include <poll.h> |
| 19 | #include <sys/types.h> |
| 20 | #include <sys/socket.h> |
| 21 | #include <linux/types.h> |
| 22 | #include <linux/netlink.h> |
| 23 | #include "callbacks.h" |
| 24 | #include "selinux_netlink.h" |
| 25 | #include "avc_internal.h" |
| 26 | |
| 27 | #ifndef NETLINK_SELINUX |
| 28 | #define NETLINK_SELINUX 7 |
| 29 | #endif |
| 30 | |
| 31 | /* callback pointers */ |
| 32 | void *(*avc_func_malloc) (size_t) = NULL; |
| 33 | void (*avc_func_free) (void *) = NULL; |
| 34 | |
| 35 | void (*avc_func_log) (const char *, ...) = NULL; |
| 36 | void (*avc_func_audit) (void *, security_class_t, char *, size_t) = NULL; |
| 37 | |
| 38 | int avc_using_threads = 0; |
| 39 | int avc_app_main_loop = 0; |
| 40 | void *(*avc_func_create_thread) (void (*)(void)) = NULL; |
| 41 | void (*avc_func_stop_thread) (void *) = NULL; |
| 42 | |
| 43 | void *(*avc_func_alloc_lock) (void) = NULL; |
| 44 | void (*avc_func_get_lock) (void *) = NULL; |
| 45 | void (*avc_func_release_lock) (void *) = NULL; |
| 46 | void (*avc_func_free_lock) (void *) = NULL; |
| 47 | |
| 48 | /* message prefix string and avc enforcing mode */ |
| 49 | char avc_prefix[AVC_PREFIX_SIZE] = "uavc"; |
| 50 | int avc_running = 0; |
| 51 | int avc_enforcing = 1; |
| 52 | int avc_setenforce = 0; |
| 53 | int avc_netlink_trouble = 0; |
| 54 | |
| 55 | /* netlink socket code */ |
| 56 | static int fd; |
| 57 | |
| 58 | int avc_netlink_open(int blocking) |
| 59 | { |
| 60 | int len, rc = 0; |
| 61 | struct sockaddr_nl addr; |
| 62 | |
| 63 | fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_SELINUX); |
| 64 | if (fd < 0) { |
| 65 | rc = fd; |
| 66 | goto out; |
| 67 | } |
| 68 | |
| 69 | fcntl(fd, F_SETFD, FD_CLOEXEC); |
| 70 | if (!blocking && fcntl(fd, F_SETFL, O_NONBLOCK)) { |
| 71 | close(fd); |
| 72 | rc = -1; |
| 73 | goto out; |
| 74 | } |
| 75 | |
| 76 | len = sizeof(addr); |
| 77 | |
| 78 | memset(&addr, 0, len); |
| 79 | addr.nl_family = AF_NETLINK; |
| 80 | addr.nl_groups = SELNL_GRP_AVC; |
| 81 | |
| 82 | if (bind(fd, (struct sockaddr *)&addr, len) < 0) { |
| 83 | close(fd); |
| 84 | rc = -1; |
| 85 | goto out; |
| 86 | } |
| 87 | out: |
| 88 | return rc; |
| 89 | } |
| 90 | |
| 91 | void avc_netlink_close(void) |
| 92 | { |
| 93 | close(fd); |
| 94 | } |
| 95 | |
| 96 | static int avc_netlink_receive(char *buf, unsigned buflen, int blocking) |
| 97 | { |
| 98 | int rc; |
| 99 | struct pollfd pfd = { fd, POLLIN | POLLPRI, 0 }; |
| 100 | struct sockaddr_nl nladdr; |
| 101 | socklen_t nladdrlen = sizeof nladdr; |
| 102 | struct nlmsghdr *nlh = (struct nlmsghdr *)buf; |
| 103 | |
| 104 | rc = poll(&pfd, 1, (blocking ? -1 : 0)); |
| 105 | |
| 106 | if (rc == 0 && !blocking) { |
| 107 | errno = EWOULDBLOCK; |
| 108 | return -1; |
| 109 | } |
| 110 | else if (rc < 1) { |
| 111 | avc_log(SELINUX_ERROR, "%s: netlink poll: error %d\n", |
| 112 | avc_prefix, errno); |
| 113 | return rc; |
| 114 | } |
| 115 | |
| 116 | rc = recvfrom(fd, buf, buflen, 0, (struct sockaddr *)&nladdr, |
| 117 | &nladdrlen); |
| 118 | if (rc < 0) |
| 119 | return rc; |
| 120 | |
| 121 | if (nladdrlen != sizeof nladdr) { |
| 122 | avc_log(SELINUX_WARNING, |
| 123 | "%s: warning: netlink address truncated, len %d?\n", |
| 124 | avc_prefix, nladdrlen); |
| 125 | return -1; |
| 126 | } |
| 127 | |
| 128 | if (nladdr.nl_pid) { |
| 129 | avc_log(SELINUX_WARNING, |
| 130 | "%s: warning: received spoofed netlink packet from: %d\n", |
| 131 | avc_prefix, nladdr.nl_pid); |
| 132 | return -1; |
| 133 | } |
| 134 | |
| 135 | if (rc == 0) { |
| 136 | avc_log(SELINUX_WARNING, |
| 137 | "%s: warning: received EOF on netlink socket\n", |
| 138 | avc_prefix); |
| 139 | errno = EBADFD; |
| 140 | return -1; |
| 141 | } |
| 142 | |
| 143 | if (nlh->nlmsg_flags & MSG_TRUNC || nlh->nlmsg_len > (unsigned)rc) { |
| 144 | avc_log(SELINUX_WARNING, |
| 145 | "%s: warning: incomplete netlink message\n", |
| 146 | avc_prefix); |
| 147 | return -1; |
| 148 | } |
| 149 | |
| 150 | return 0; |
| 151 | } |
| 152 | |
| 153 | static int avc_netlink_process(char *buf) |
| 154 | { |
| 155 | int rc; |
| 156 | struct nlmsghdr *nlh = (struct nlmsghdr *)buf; |
| 157 | |
| 158 | switch (nlh->nlmsg_type) { |
| 159 | case NLMSG_ERROR:{ |
| 160 | struct nlmsgerr *err = NLMSG_DATA(nlh); |
| 161 | |
| 162 | /* Netlink ack */ |
| 163 | if (err->error == 0) |
| 164 | break; |
| 165 | |
| 166 | errno = -err->error; |
| 167 | avc_log(SELINUX_ERROR, |
| 168 | "%s: netlink error: %d\n", avc_prefix, errno); |
| 169 | return -1; |
| 170 | } |
| 171 | |
| 172 | case SELNL_MSG_SETENFORCE:{ |
| 173 | struct selnl_msg_setenforce *msg = NLMSG_DATA(nlh); |
| 174 | avc_log(SELINUX_INFO, |
| 175 | "%s: received setenforce notice (enforcing=%d)\n", |
| 176 | avc_prefix, msg->val); |
| 177 | if (avc_setenforce) |
| 178 | break; |
| 179 | avc_enforcing = msg->val; |
| 180 | if (avc_enforcing && (rc = avc_ss_reset(0)) < 0) { |
| 181 | avc_log(SELINUX_ERROR, |
| 182 | "%s: cache reset returned %d (errno %d)\n", |
| 183 | avc_prefix, rc, errno); |
| 184 | return rc; |
| 185 | } |
| 186 | rc = selinux_netlink_setenforce(msg->val); |
| 187 | if (rc < 0) |
| 188 | return rc; |
| 189 | break; |
| 190 | } |
| 191 | |
| 192 | case SELNL_MSG_POLICYLOAD:{ |
| 193 | struct selnl_msg_policyload *msg = NLMSG_DATA(nlh); |
| 194 | avc_log(SELINUX_INFO, |
| 195 | "%s: received policyload notice (seqno=%d)\n", |
| 196 | avc_prefix, msg->seqno); |
| 197 | rc = avc_ss_reset(msg->seqno); |
| 198 | if (rc < 0) { |
| 199 | avc_log(SELINUX_ERROR, |
| 200 | "%s: cache reset returned %d (errno %d)\n", |
| 201 | avc_prefix, rc, errno); |
| 202 | return rc; |
| 203 | } |
| 204 | rc = selinux_netlink_policyload(msg->seqno); |
| 205 | if (rc < 0) |
| 206 | return rc; |
| 207 | break; |
| 208 | } |
| 209 | |
| 210 | default: |
| 211 | avc_log(SELINUX_WARNING, |
| 212 | "%s: warning: unknown netlink message %d\n", |
| 213 | avc_prefix, nlh->nlmsg_type); |
| 214 | } |
| 215 | return 0; |
| 216 | } |
| 217 | |
| 218 | int avc_netlink_check_nb(void) |
| 219 | { |
| 220 | int rc; |
| 221 | char buf[1024] __attribute__ ((aligned)); |
| 222 | |
| 223 | while (1) { |
| 224 | errno = 0; |
| 225 | rc = avc_netlink_receive(buf, sizeof(buf), 0); |
| 226 | if (rc < 0) { |
| 227 | if (errno == EWOULDBLOCK) |
| 228 | return 0; |
| 229 | if (errno == 0 || errno == EINTR) |
| 230 | continue; |
| 231 | else { |
| 232 | avc_log(SELINUX_ERROR, |
| 233 | "%s: netlink recvfrom: error %d\n", |
| 234 | avc_prefix, errno); |
| 235 | return rc; |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | (void)avc_netlink_process(buf); |
| 240 | } |
| 241 | return 0; |
| 242 | } |
| 243 | |
| 244 | /* run routine for the netlink listening thread */ |
| 245 | void avc_netlink_loop(void) |
| 246 | { |
| 247 | int rc; |
| 248 | char buf[1024] __attribute__ ((aligned)); |
| 249 | |
| 250 | while (1) { |
| 251 | errno = 0; |
| 252 | rc = avc_netlink_receive(buf, sizeof(buf), 1); |
| 253 | if (rc < 0) { |
| 254 | if (errno == 0 || errno == EINTR) |
| 255 | continue; |
| 256 | else { |
| 257 | avc_log(SELINUX_ERROR, |
| 258 | "%s: netlink recvfrom: error %d\n", |
| 259 | avc_prefix, errno); |
| 260 | break; |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | rc = avc_netlink_process(buf); |
| 265 | if (rc < 0) |
| 266 | break; |
| 267 | } |
| 268 | |
| 269 | close(fd); |
| 270 | avc_netlink_trouble = 1; |
| 271 | avc_log(SELINUX_ERROR, |
| 272 | "%s: netlink thread: errors encountered, terminating\n", |
| 273 | avc_prefix); |
| 274 | } |
| 275 | |
| 276 | int avc_netlink_acquire_fd(void) |
| 277 | { |
| 278 | avc_app_main_loop = 1; |
| 279 | |
| 280 | return fd; |
| 281 | } |
| 282 | |
| 283 | void avc_netlink_release_fd(void) |
| 284 | { |
| 285 | avc_app_main_loop = 0; |
| 286 | } |