-/*
- * to_send and len_sent accounting are very loose estimates. We aren't
- * really worried about a hard cap to MAX_EXECVE_AUDIT_LEN so much as being
- * within about 500 bytes (next page boundary)
- *
- * why snprintf? an int is up to 12 digits long. if we just assumed when
- * logging that a[%d]= was going to be 16 characters long we would be wasting
- * space in every audit message. In one 7500 byte message we can log up to
- * about 1000 min size arguments. That comes down to about 50% waste of space
- * if we didn't do the snprintf to find out how long arg_num_len was.
- */
-static int audit_log_single_execve_arg(struct audit_context *context,
- struct audit_buffer **ab,
- int arg_num,
- size_t *len_sent,
- const char __user *p,
- char *buf)
-{
- char arg_num_len_buf[12];
- const char __user *tmp_p = p;
- /* how many digits are in arg_num? 5 is the length of ' a=""' */
- size_t arg_num_len = snprintf(arg_num_len_buf, 12, "%d", arg_num) + 5;
- size_t len, len_left, to_send;
- size_t max_execve_audit_len = MAX_EXECVE_AUDIT_LEN;
- unsigned int i, has_cntl = 0, too_long = 0;
- int ret;
-
- /* strnlen_user includes the null we don't want to send */
- len_left = len = strnlen_user(p, MAX_ARG_STRLEN) - 1;
-
- /*
- * We just created this mm, if we can't find the strings
- * we just copied into it something is _very_ wrong. Similar
- * for strings that are too long, we should not have created
- * any.
- */
- if (unlikely((len == -1) || len > MAX_ARG_STRLEN - 1)) {
- WARN_ON(1);
- send_sig(SIGKILL, current, 0);
- return -1;
- }
-
- /* walk the whole argument looking for non-ascii chars */
- do {
- if (len_left > MAX_EXECVE_AUDIT_LEN)
- to_send = MAX_EXECVE_AUDIT_LEN;
- else
- to_send = len_left;
- ret = copy_from_user(buf, tmp_p, to_send);
- /*
- * There is no reason for this copy to be short. We just
- * copied them here, and the mm hasn't been exposed to user-
- * space yet.
- */
- if (ret) {
- WARN_ON(1);
- send_sig(SIGKILL, current, 0);
- return -1;
- }
- buf[to_send] = '\0';
- has_cntl = audit_string_contains_control(buf, to_send);
- if (has_cntl) {
- /*
- * hex messages get logged as 2 bytes, so we can only
- * send half as much in each message
- */
- max_execve_audit_len = MAX_EXECVE_AUDIT_LEN / 2;
- break;
- }
- len_left -= to_send;
- tmp_p += to_send;
- } while (len_left > 0);
-
- len_left = len;
-
- if (len > max_execve_audit_len)
- too_long = 1;
-
- /* rewalk the argument actually logging the message */
- for (i = 0; len_left > 0; i++) {
- int room_left;
-
- if (len_left > max_execve_audit_len)
- to_send = max_execve_audit_len;
- else
- to_send = len_left;
-
- /* do we have space left to send this argument in this ab? */
- room_left = MAX_EXECVE_AUDIT_LEN - arg_num_len - *len_sent;
- if (has_cntl)
- room_left -= (to_send * 2);
- else
- room_left -= to_send;
- if (room_left < 0) {
- *len_sent = 0;
- audit_log_end(*ab);
- *ab = audit_log_start(context, GFP_KERNEL, AUDIT_EXECVE);
- if (!*ab)
- return 0;
- }
-
- /*
- * first record needs to say how long the original string was
- * so we can be sure nothing was lost.
- */
- if ((i == 0) && (too_long))
- audit_log_format(*ab, " a%d_len=%zu", arg_num,
- has_cntl ? 2*len : len);
-
- /*
- * normally arguments are small enough to fit and we already
- * filled buf above when we checked for control characters
- * so don't bother with another copy_from_user
- */
- if (len >= max_execve_audit_len)
- ret = copy_from_user(buf, p, to_send);
- else
- ret = 0;
- if (ret) {
- WARN_ON(1);
- send_sig(SIGKILL, current, 0);
- return -1;
- }
- buf[to_send] = '\0';
-
- /* actually log it */
- audit_log_format(*ab, " a%d", arg_num);
- if (too_long)
- audit_log_format(*ab, "[%d]", i);
- audit_log_format(*ab, "=");
- if (has_cntl)
- audit_log_n_hex(*ab, buf, to_send);
- else
- audit_log_string(*ab, buf);
-
- p += to_send;
- len_left -= to_send;
- *len_sent += arg_num_len;
- if (has_cntl)
- *len_sent += to_send * 2;
- else
- *len_sent += to_send;
- }
- /* include the null we didn't log */
- return len + 1;
-}
-