chsmack: add option to remove labels

Adding that option allow chsmack to remove the smack labels.
It is really important to have it.

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

diff --git a/utils/chsmack.c b/utils/chsmack.c
index 4ae7bc9..11ea2f6 100644 (file)
--- a/utils/chsmack.c
+++ b/utils/chsmack.c
@@ -22,6 +22,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/xattr.h>
+#include <attr/xattr.h>
 #include <linux/xattr.h>
 #include <sys/smack.h>
 #include <unistd.h>
@@ -39,6 +40,7 @@ static const char usage[] =
        " -e --exec          set/remove "XATTR_NAME_SMACKEXEC"\n"  
        " -m --mmap          set/remove "XATTR_NAME_SMACKMMAP"\n"  
        " -t --transmute     set/remove "XATTR_NAME_SMACKTRANSMUTE"\n"
+       " -d --remove        tell to remove the attribute\n"
        " -L --dereference   tell to follow the symbolic links\n"
 ;
 
@@ -94,13 +96,29 @@ static int smack_set_label_for_path(const char *path,
        return ret;
 }
 
+/*!
+  * Remove the SMACK label in an extended attribute.
+  *
+  * @param path path of the file
+  * @param xattr the extended attribute containing the SMACK label
+  * @param follow whether or not to follow symbolic link
+  * @return Returns 0 on success and negative on failure.
+  */
+static int smack_remove_label_for_path(const char *path,
+                                 const char *xattr,
+                                 int follow)
+{
+       return follow ? removexattr(path, xattr) : lremovexattr(path, xattr);
+}
+
+/* main */
 int main(int argc, char *argv[])
 {
-       static const char shortoptions[] = "a:e:m:tL";
+       static const char shortoptions[] = "a::e::m::tdL";
        static struct option options[] = {
-               {"access", required_argument, 0, 'a'},
-               {"exec", required_argument, 0, 'e'},
-               {"mmap", required_argument, 0, 'm'},
+               {"access", optional_argument, 0, 'a'},
+               {"exec", optional_argument, 0, 'e'},
+               {"mmap", optional_argument, 0, 'm'},
                {"transmute", no_argument, 0, 't'},
                {"dereference", no_argument, 0, 'L'},
                {NULL, 0, 0, 0}
@@ -124,6 +142,7 @@ int main(int argc, char *argv[])
        struct stat st;
        char *label;
 
+       int delete_flag = 0;
        int follow_flag = 0;
        int transmute_flag = 0;
        int option_flag = 0;
@@ -141,6 +160,11 @@ int main(int argc, char *argv[])
                        case 'a':
                        case 'e':
                        case 'm':
+                               /* greedy on optional arguments */
+                               if (optarg == NULL && argv[optind] != NULL 
+                                               && argv[optind][0] != '-') {
+                                       optind++;
+                               }
                                break;
                        case 't':
                                if (transmute_flag)
@@ -149,6 +173,12 @@ int main(int argc, char *argv[])
                                transmute_flag = 1;
                                option_flag = 1;
                                break;
+                       case 'd':
+                               if (delete_flag)
+                                       fprintf(stderr, "%s: %s: option set many times.\n",
+                                                       basename(argv[0]), options[options_map[c]].name);
+                               delete_flag = 1;
+                               break;
                        case 'L':
                                if (follow_flag)
                                        fprintf(stderr, "%s: %s: option set many times.\n",
@@ -161,7 +191,7 @@ int main(int argc, char *argv[])
                }
        }
 
-       /* scan options with argument */
+       /* scan options with argument (possibly) */
        optind = 1;
        while ((c = getopt_long(argc, argv, shortoptions, options, NULL)) != -1) {
 
@@ -179,7 +209,23 @@ int main(int argc, char *argv[])
                                continue;
                }
 
-               if (strnlen(optarg, SMACK_LABEL_LEN + 1) == SMACK_LABEL_LEN + 1) {
+               /* greedy on optional arguments */
+               if (optarg == NULL && argv[optind] != NULL && argv[optind][0] != '-') {
+                       optarg = argv[optind++];
+               }
+               if (optarg == NULL) {
+                       if (!delete_flag) {
+                               fprintf(stderr, "%s: %s: requires a label when setting.\n",
+                                       basename(argv[0]), options[options_map[c]].name);
+                               exit(1);
+                       }
+               }
+               else if (delete_flag) {
+                       fprintf(stderr, "%s: %s: requires no label when deleting.\n",
+                               basename(argv[0]), options[options_map[c]].name);
+                       exit(1);
+               }
+               else 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);
@@ -195,8 +241,47 @@ int main(int argc, char *argv[])
                option_flag = 1;
        }
 
+       /* deleting labels */
+       if (delete_flag) {
+               if (!option_flag) {
+                       access_set.isset = 1;
+                       exec_set.isset = 1;
+                       mmap_set.isset = 1;
+                       transmute_flag = 1;
+               }
+               for (i = optind; i < argc; i++) {
+                       if (access_set.isset) {
+                               rc = smack_remove_label_for_path(argv[i],
+                                                       XATTR_NAME_SMACK, follow_flag);
+                               if (rc < 0 && (option_flag || errno != ENOATTR))
+                                       perror(argv[i]);
+                       }
+
+                       if (exec_set.isset) {
+                               rc = smack_remove_label_for_path(argv[i],
+                                                       XATTR_NAME_SMACKEXEC, follow_flag);
+                               if (rc < 0 && (option_flag || errno != ENOATTR))
+                                       perror(argv[i]);
+                       }
+
+                       if (mmap_set.isset) {
+                               rc = smack_remove_label_for_path(argv[i],
+                                                       XATTR_NAME_SMACKMMAP, follow_flag);
+                               if (rc < 0 && (option_flag || errno != ENOATTR))
+                                       perror(argv[i]);
+                       }
+
+                       if (transmute_flag) {
+                               rc = smack_remove_label_for_path(argv[i],
+                                                       XATTR_NAME_SMACKTRANSMUTE, follow_flag);
+                               if (rc < 0 && (option_flag || errno != ENOATTR))
+                                       perror(argv[i]);
+                       }
+               }
+       }
+
        /* setting labels */
-       if (option_flag) {
+       else if (option_flag) {
                for (i = optind; i < argc; i++) {
                        if (access_set.isset) {
                                rc = smack_set_label_for_path(argv[i],