skb_put(skb, slen + 2); /* don't include null terminator */
}
+/**
+ * audit_string_contains_control - does a string need to be logged in hex
+ * @string - string to be checked
+ * @len - max length of the string to check
+ */
+int audit_string_contains_control(const char *string, size_t len)
+{
+ const unsigned char *p;
+ for (p = string; p < (const unsigned char *)string + len && *p; p++) {
+ if (*p == '"' || *p < 0x21 || *p > 0x7f)
+ return 1;
+ }
+ return 0;
+}
+
/**
* audit_log_n_untrustedstring - log a string that may contain random characters
* @ab: audit_buffer
* The caller specifies the number of characters in the string to log, which may
* or may not be the entire string.
*/
-const char *audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
- const char *string)
+void audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
+ const char *string)
{
- const unsigned char *p;
-
- for (p = string; p < (const unsigned char *)string + len && *p; p++) {
- if (*p == '"' || *p < 0x21 || *p > 0x7f) {
- audit_log_hex(ab, string, len);
- return string + len + 1;
- }
- }
- audit_log_n_string(ab, len, string);
- return p + 1;
+ if (audit_string_contains_control(string, len))
+ audit_log_hex(ab, string, len);
+ else
+ audit_log_n_string(ab, len, string);
}
/**
* Same as audit_log_n_untrustedstring(), except that strlen is used to
* determine string length.
*/
-const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
+void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
{
- return audit_log_n_untrustedstring(ab, strlen(string), string);
+ audit_log_n_untrustedstring(ab, strlen(string), string);
}
/* This is a helper-function to print the escaped d_path */
/* Indicates that audit should log the full pathname. */
#define AUDIT_NAME_FULL -1
+/* no execve audit message should be longer than this (userspace limits) */
+#define MAX_EXECVE_AUDIT_LEN 7500
+
/* number of audit rules */
int audit_n_rules;
return rc;
}
-static void audit_log_execve_info(struct audit_buffer *ab,
- struct audit_aux_data_execve *axi)
+/*
+ * 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 boundry)
+ *
+ * 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)
{
- int i;
- long len, ret;
- 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? 3 is the length of a=\n */
+ size_t arg_num_len = snprintf(arg_num_len_buf, 12, "%d", arg_num) + 3;
+ 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;
- if (axi->mm != current->mm)
- return; /* execve failed, no additional info */
-
- p = (const char __user *)axi->mm->arg_start;
+ /*
+ * 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);
+ }
- for (i = 0; i < axi->argc; i++, p += len) {
- len = strnlen_user(p, MAX_ARG_STRLEN);
+ /* 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);
/*
- * 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.
+ * 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 (!len || len > MAX_ARG_STRLEN) {
+ if (ret) {
WARN_ON(1);
send_sig(SIGKILL, current, 0);
}
-
- buf = kmalloc(len, GFP_KERNEL);
- if (!buf) {
- audit_panic("out of memory for argv string\n");
+ 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;
+ }
- ret = copy_from_user(buf, p, len);
/*
- * 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.
+ * 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=%ld ", 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);
}
+ 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_hex(*ab, buf, to_send);
+ else
+ audit_log_format(*ab, "\"%s\"", buf);
+ audit_log_format(*ab, "\n");
+
+ 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;
+}
+
+static void audit_log_execve_info(struct audit_context *context,
+ struct audit_buffer **ab,
+ struct audit_aux_data_execve *axi)
+{
+ int i;
+ size_t len, len_sent = 0;
+ const char __user *p;
+ char *buf;
- audit_log_format(ab, "a%d=", i);
- audit_log_untrustedstring(ab, buf);
- audit_log_format(ab, "\n");
+ if (axi->mm != current->mm)
+ return; /* execve failed, no additional info */
+
+ p = (const char __user *)axi->mm->arg_start;
- kfree(buf);
+ audit_log_format(*ab, "argc=%d ", axi->argc);
+
+ /*
+ * we need some kernel buffer to hold the userspace args. Just
+ * allocate one big one rather than allocating one of the right size
+ * for every single argument inside audit_log_single_execve_arg()
+ * should be <8k allocation so should be pretty safe.
+ */
+ buf = kmalloc(MAX_EXECVE_AUDIT_LEN + 1, GFP_KERNEL);
+ if (!buf) {
+ audit_panic("out of memory for argv string\n");
+ return;
}
+
+ for (i = 0; i < axi->argc; i++) {
+ len = audit_log_single_execve_arg(context, ab, i,
+ &len_sent, p, buf);
+ if (len <= 0)
+ break;
+ p += len;
+ }
+ kfree(buf);
}
static void audit_log_exit(struct audit_context *context, struct task_struct *tsk)
case AUDIT_EXECVE: {
struct audit_aux_data_execve *axi = (void *)aux;
- audit_log_execve_info(ab, axi);
+ audit_log_execve_info(context, &ab, axi);
break; }
case AUDIT_SOCKETCALL: {
return 0;
}
-int audit_argv_kb = 32;
-
int audit_bprm(struct linux_binprm *bprm)
{
struct audit_aux_data_execve *ax;
if (likely(!audit_enabled || !context || context->dummy))
return 0;
- /*
- * Even though the stack code doesn't limit the arg+env size any more,
- * the audit code requires that _all_ arguments be logged in a single
- * netlink skb. Hence cap it :-(
- */
- if (bprm->argv_len > (audit_argv_kb << 10))
- return -E2BIG;
-
ax = kmalloc(sizeof(*ax), GFP_KERNEL);
if (!ax)
return -ENOMEM;
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff