chsmack: validation of labels

To prepare to the future of libsmack (that will include the
validation function 'smack_label_length'), the validation
of the smack labels is separated from the main function.

Signed-off-by: José Bollo <jose.bollo@open.eurogiciel.org>

diff --git a/utils/chsmack.c b/utils/chsmack.c
index b7d90b0..7069174 100644 (file)
--- a/utils/chsmack.c
+++ b/utils/chsmack.c
@@ -40,6 +40,30 @@ static const char usage[] =
        " -t --transmute     set/remove "XATTR_NAME_SMACKTRANSMUTE"\n"
 ;
 
+/*!
+ * Validate a SMACK label and calculate its length.
+ *
+ * @param label label to verify
+ * @return Returns length of the label on success and negative on failure.
+ */
+static ssize_t smack_label_length(const char *label)
+{
+       int i;
+
+       if (!label || !*label || *label=='-')
+               return -1;
+
+       for (i = 0 ; i <= SMACK_LABEL_LEN ; i++) {
+               if (label[i] == '\0')
+                               return (ssize_t) i;
+               if (label[i] > '~' || label[i] <= ' ' || label[i] == '/' ||
+                   label[i] == '"' || label[i] == '\\' || label[i] == '\'')
+                               return -1;
+       }
+
+       return -1;
+}
+
 int main(int argc, char *argv[])
 {
        static struct option options[] = {
@@ -69,14 +93,18 @@ int main(int argc, char *argv[])
 
        while ((c = getopt_long(argc, argv, "a:e:m:t", options,
                                NULL)) != -1) {
-               if ((c == 'a' || c == 'e' || c == 'm')
-                   && strnlen(optarg, SMACK_LABEL_LEN + 1)
-                      == (SMACK_LABEL_LEN + 1)) {
-                       fprintf(stderr, "%s: %s: \"%s\" " \
-                                       "exceeds %d characters.\n",
-                               basename(argv[0]), options[options_map[c]].name, optarg,
-                                        SMACK_LABEL_LEN);
-                       exit(1);
+               if ((c == 'a' || c == 'e' || c == 'm')) {
+                       if (strnlen(optarg, SMACK_LABEL_LEN + 1) == (SMACK_LABEL_LEN + 1)) {
+                               fprintf(stderr, "%s: %s: \"%s\" exceeds %d characters.\n",
+                                               basename(argv[0]), options[options_map[c]].name, 
+                                               optarg, SMACK_LABEL_LEN);
+                               exit(1);
+                       }
+                       if (smack_label_length(optarg) < 0) {
+                               fprintf(stderr, "%s: %s: \"%s\" is an invalid Smack label.\n",
+                                       basename(argv[0]), options[options_map[c]].name, optarg);
+                               exit(1);
+                       }
                }
 
                switch (c) {