Merge pull request #4009 from Tomin1/protocol_list_improvements

Allow changing protocol list after initial set

3 files changed, 151 insertions, 18 deletions

diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index 36340ff2c..c8080f778 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -451,6 +451,9 @@ int profile_check_line(char *ptr, int lineno, const char *fname);
 // add a profile entry in cfg.profile list; use str to populate the list
 void profile_add(char *str);
 void profile_add_ignore(const char *str);
+char *profile_list_normalize(char *list);
+char *profile_list_compress(char *list);
+void profile_list_augment(char **list, const char *items);
 
 // list.c
 void list(void);
diff --git a/src/firejail/main.c b/src/firejail/main.c
index 3c8667829..9b4f2bc60 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -1285,15 +1285,10 @@ int main(int argc, char **argv, char **envp) {
 #endif
                 else if (strncmp(argv[i], "--protocol=", 11) == 0) {
                         if (checkcfg(CFG_SECCOMP)) {
-                                if (cfg.protocol) {
-                                        fwarning("more than one protocol list is present, \"%s\" will be installed\n", cfg.protocol);
-                                }
-                                else {
-                                        // store list
-                                        cfg.protocol = strdup(argv[i] + 11);
-                                        if (!cfg.protocol)
-                                                errExit("strdup");
-                                }
+                                const char *add = argv[i] + 11;
+                                profile_list_augment(&cfg.protocol, add);
+                                if (arg_debug)
+                                        fprintf(stderr, "[option] combined protocol list: \"%s\"\n", cfg.protocol);
                         }
                         else
                                 exit_err_feature("seccomp");
diff --git a/src/firejail/profile.c b/src/firejail/profile.c
index 9339228f4..f3266c23e 100644
--- a/src/firejail/profile.c
+++ b/src/firejail/profile.c
@@ -911,15 +911,10 @@ int profile_check_line(char *ptr, int lineno, const char *fname) {
 
         if (strncmp(ptr, "protocol ", 9) == 0) {
                 if (checkcfg(CFG_SECCOMP)) {
-                        if (cfg.protocol) {
-                                fwarning("more than one protocol list is present, \"%s\" will be installed\n", cfg.protocol);
-                                return 0;
-                        }
-
-                        // store list
-                        cfg.protocol = strdup(ptr + 9);
-                        if (!cfg.protocol)
-                                errExit("strdup");
+                        const char *add = ptr + 9;
+                        profile_list_augment(&cfg.protocol, add);
+                        if (arg_debug)
+                                fprintf(stderr, "[profile] combined protocol list: \"%s\"\n", cfg.protocol);
                 }
                 else
                         warning_feature_disabled("seccomp");
@@ -1773,3 +1768,143 @@ void profile_read(const char *fname) {
         }
         fclose(fp);
 }
+
+char *profile_list_normalize(char *list)
+{
+        /* Remove redundant commas.
+         *
+         * As result is always shorter than original,
+         * in-place copying can be used.
+         */
+        size_t i = 0;
+        size_t j = 0;
+        int c;
+        while (list[i] == ',')
+                ++i;
+        while ((c = list[i++])) {
+                if (c == ',') {
+                        while (list[i] == ',')
+                                ++i;
+                        if (list[i] == 0)
+                                break;
+                }
+                list[j++] = c;
+        }
+        list[j] = 0;
+        return list;
+}
+
+char *profile_list_compress(char *list)
+{
+        size_t i;
+
+        /* Comma separated list is processed so that:
+         * "item"  -> adds item to list
+         * "-item" -> removes item from list
+         * "+item" -> adds item to list
+         * "=item" -> clear list, add item
+         *
+         * For example:
+         * ,a,,,b,,,c, -> a,b,c
+         * a,,b,,,c,a  -> a,b,c
+         * a,b,c,-a    -> b,c
+         * a,b,c,-a,a  -> b,c,a
+         * a,+b,c      -> a,b,c
+         * a,b,=c,d    -> c,d
+         * a,b,c,=     ->
+         */
+        profile_list_normalize(list);
+
+        /* Count items: comma count + 1 */
+        size_t count = 1;
+        for (i = 0; list[i]; ++i) {
+                if (list[i] == ',')
+                        ++count;
+        }
+
+        /* Collect items in an array */
+        char *in[count];
+        count = 0;
+        in[count++] = list;
+        for (i = 0; list[i]; ++i) {
+                if (list[i] != ',')
+                        continue;
+                list[i] = 0;
+                in[count++] = list + i + 1;
+        }
+
+        /* Filter array: add, remove, reset, filter out duplicates */
+        for (i = 0; i < count; ++i) {
+                char *item = in[i];
+                assert(item);
+
+                size_t k;
+                switch (*item) {
+                case '-':
+                        ++item;
+                        /* Do not include this item */
+                        in[i] = 0;
+                        /* Remove if already included */
+                        for (k = 0; k < i; ++k) {
+                                if (in[k] && !strcmp(in[k], item)) {
+                                        in[k] = 0;
+                                        break;
+                                }
+                        }
+                        break;
+                case '+':
+                        /* Allow +/- symmetry */
+                        in[i] = ++item;
+                        /* FALLTHRU */
+                default:
+                        /* Adding empty item is a NOP */
+                        if (!*item) {
+                                in[i] = 0;
+                                break;
+                        }
+                        /* Include item unless it is already included */
+                        for (k = 0; k < i; ++k) {
+                                if (in[k] && !strcmp(in[k], item)) {
+                                        in[i] = 0;
+                                        break;
+                                }
+                        }
+                        break;
+                case '=':
+                        in[i] = ++item;
+                        /* Include non-empty item */
+                        if (!*item)
+                                in[i] = 0;
+                        /* Remove all allready included items */
+                        for (k = 0; k < i; ++k)
+                                in[k] = 0;
+                        break;
+                }
+        }
+
+        /* Copying back using in-place data works because the
+         * original order is retained and no item gets longer
+         * than what it used to be.
+         */
+        char *pos = list;
+        for (i = 0; i < count; ++i) {
+                char *item = in[i];
+                if (!item)
+                        continue;
+                if (pos > list)
+                        *pos++ = ',';
+                while (*item)
+                        *pos++ = *item++;
+        }
+        *pos = 0;
+        return list;
+}
+
+void profile_list_augment(char **list, const char *items)
+{
+        char *tmp = 0;
+        if (asprintf(&tmp, "%s,%s", *list ?: "", items ?: "") < 0)
+                errExit("asprintf");
+        free(*list);
+        *list = profile_list_compress(tmp);
+}