[AUDIT] break large execve argument logging into smaller messages

execve arguments can be quite large.  There is no limit on the number of
arguments and a 4G limit on the size of an argument.

this patch prints those aruguments in bite sized pieces.  a userspace size
limitation of 8k was discovered so this keeps messages around 7.5k

single arguments larger than 7.5k in length are split into multiple records
and can be identified as aX[Y]=

Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 23 insertions, 14 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index cf66982..26ff925 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1350,6 +1350,21 @@ static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
 }
 
 /**
+ * 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
  * @len: lenth of string (not including trailing null)
@@ -1363,19 +1378,13 @@ static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
  * 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);
 }
 
 /**
@@ -1386,9 +1395,9 @@ const char *audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
  * 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 */