Add commit "-o relaxed_permission" changes

3 files changed, 25 insertions, 2 deletions

diff --git a/src/opts.c b/src/opts.c
index e8189ab..a6fa82e 100644
--- a/src/opts.c
+++ b/src/opts.c
@@ -228,6 +228,8 @@ static void print_help(const char *progname) {
 	"    -o hide_meta_dir       \".unionfs\" is a secret directory not\n"
 	"                           print by readdir()\n"
 	"    -o max_files=number    Increase the maximum number of open files\n"
+	"    -o relaxed_permissions Disable permissions checks, but only if\n"
+	"                           running neither as UID=0 or GID=0\n"
 	"    -o statfs_omit_ro      do not count blocks of ro-branches\n"
 	"    -o stats               show statistics in the file 'stats' under the\n"
 	"\n",
@@ -314,6 +316,9 @@ int unionfs_opt_proc(void *data, const char *arg, int key, struct fuse_args *out
 		case KEY_STATFS_OMIT_RO:
 			uopt.statfs_omit_ro = true;
 			return 0;
+		case KEY_RELAXED_PERMISSIONS:
+			uopt.relaxed_permissions = true;
+			return 0;
 		case KEY_STATS:
 			uopt.stats_enabled = 1;
 			return 0;
diff --git a/src/opts.h b/src/opts.h
index 1edddc4..b5fa2f9 100644
--- a/src/opts.h
+++ b/src/opts.h
@@ -27,6 +27,7 @@ typedef struct {
 	int retval;
 	char *chroot; 		// chroot we might go into
 	bool hide_meta_dir;
+	bool relaxed_permissions;
 
 } uopt_t;
 
@@ -37,6 +38,7 @@ enum {
 	KEY_HIDE_METADIR,
 	KEY_MAX_FILES,
 	KEY_NOINITGROUPS,
+	KEY_RELAXED_PERMISSIONS,
 	KEY_STATFS_OMIT_RO,
 	KEY_STATS,
 	KEY_VERSION
diff --git a/src/unionfs.c b/src/unionfs.c
index de22d19..9101d7f 100644
--- a/src/unionfs.c
+++ b/src/unionfs.c
@@ -58,6 +58,7 @@ static struct fuse_opt unionfs_opts[] = {
 	FUSE_OPT_KEY("hide_meta_dir", KEY_HIDE_METADIR),
 	FUSE_OPT_KEY("max_files=%s", KEY_MAX_FILES),
 	FUSE_OPT_KEY("noinitgroups", KEY_NOINITGROUPS),
+	FUSE_OPT_KEY("relaxed_permissions", KEY_RELAXED_PERMISSIONS),
 	FUSE_OPT_KEY("statfs_omit_ro", KEY_STATFS_OMIT_RO),
 	FUSE_OPT_KEY("stats", KEY_STATS),
 	FUSE_OPT_KEY("--version", KEY_VERSION),
@@ -803,10 +804,25 @@ int main(int argc, char *argv[]) {
 
 	// enable fuse permission checks, we need to set this, even we we are
 	// not root, since we don't have our own access() function
-	if (fuse_opt_add_arg(&args, "-odefault_permissions")) {
-		fprintf(stderr, "Severe failure, can't enable permssion checks, aborting!\n");
+	int uid = getuid();
+	int gid = getgid();
+	bool default_permissions = true;
+	
+	if (uid != 0 && gid != 0 && uopt.relaxed_permissions) {
+		default_permissions = false;
+	} else if (uopt.relaxed_permissions) {
+		// protec the user of a very critical security issue
+		fprintf(stderr, "Relaxed permissions disallowed for root!\n");
 		exit(1);
 	}
+	
+	if (default_permissions) {
+		fprintf(stderr, "Enabling default permissions\n");
+		if (fuse_opt_add_arg(&args, "-odefault_permissions")) {
+			fprintf(stderr, "Severe failure, can't enable permssion checks, aborting!\n");
+			exit(1);
+		}
+	}
 	unionfs_post_opts();
 
 	umask(0);