gensquashfs: Add options to globally override UID/GID values

A common use case for mksquashfs is to simply pack a directory and set
a magic option to force all user/group IDs to root.

This commit adds similar options to gensquashfs to maek it better
suited as a direct replacement for packing an input directory.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

4 files changed, 63 insertions, 1 deletions

diff --git a/bin/gensquashfs/mkfs.c b/bin/gensquashfs/mkfs.c
index 9ffbb94..b1542d1 100644
--- a/bin/gensquashfs/mkfs.c
+++ b/bin/gensquashfs/mkfs.c
@@ -171,6 +171,20 @@ static int read_fstree(fstree_t *fs, options_t *opt, sqfs_xattr_writer_t *xwr,
 	return ret;
 }
 
+static void override_owner_dfs(const options_t *opt, tree_node_t *n)
+{
+	if (opt->force_uid)
+		n->uid = opt->force_uid_value;
+
+	if (opt->force_gid)
+		n->gid = opt->force_gid_value;
+
+	if (S_ISDIR(n->mode)) {
+		for (n = n->data.dir.children; n != NULL; n = n->next)
+			override_owner_dfs(opt, n);
+	}
+}
+
 int main(int argc, char **argv)
 {
 	int status = EXIT_FAILURE;
@@ -195,6 +209,9 @@ int main(int argc, char **argv)
 		goto out;
 	}
 
+	if (opt.force_uid || opt.force_gid)
+		override_owner_dfs(&opt, sqfs.fs.root);
+
 	if (sehnd != NULL) {
 		selinux_close_context_file(sehnd);
 		sehnd = NULL;
diff --git a/bin/gensquashfs/mkfs.h b/bin/gensquashfs/mkfs.h
index 1b767aa..9a36d8c 100644
--- a/bin/gensquashfs/mkfs.h
+++ b/bin/gensquashfs/mkfs.h
@@ -46,6 +46,11 @@ typedef struct {
 	const char *packdir;
 	const char *selinux;
 	bool no_tail_packing;
+
+	unsigned int force_uid_value;
+	unsigned int force_gid_value;
+	bool force_uid;
+	bool force_gid;
 } options_t;
 
 enum {
diff --git a/bin/gensquashfs/options.c b/bin/gensquashfs/options.c
index 2369787..d029c09 100644
--- a/bin/gensquashfs/options.c
+++ b/bin/gensquashfs/options.c
@@ -6,7 +6,14 @@
  */
 #include "mkfs.h"
 
+enum {
+	ALL_ROOT_OPTION = 1,
+};
+
 static struct option long_opts[] = {
+	{ "all-root", required_argument, NULL, ALL_ROOT_OPTION },
+	{ "set-uid", required_argument, NULL, 'u' },
+	{ "set-gid", required_argument, NULL, 'g' },
 	{ "compressor", required_argument, NULL, 'c' },
 	{ "block-size", required_argument, NULL, 'b' },
 	{ "dev-block-size", required_argument, NULL, 'B' },
@@ -33,7 +40,7 @@ static struct option long_opts[] = {
 	{ NULL, 0, NULL, 0 },
 };
 
-static const char *short_opts = "F:D:X:c:b:B:d:j:Q:kxoefqThV"
+static const char *short_opts = "F:D:X:c:b:B:d:u:g:j:Q:kxoefqThV"
 #ifdef WITH_SELINUX
 "s:"
 #endif
@@ -83,6 +90,14 @@ static const char *help_string =
 "                                 mode=<value>   0755 if not set.\n"
 "                                 mtime=<value>  0 if not set.\n"
 "\n"
+"  --set-uid, -u <number>      Force the owners user ID for ALL inodes to\n"
+"                              this value, no matter what the pack file or\n"
+"                              directory entries actually specify.\n"
+"  --set-gid, -g <number>      Force the owners group ID for ALL inodes to\n"
+"                              this value, no matter what the pack file or\n"
+"                              directory entries actually specify.\n"
+"  --all-root                  A short hand for `--set-uid 0 --set-gid 0`.\n"
+"\n"
 #ifdef WITH_SELINUX
 "  --selinux, -s <file>        Specify an SELinux label file to get context\n"
 "                              attributes from.\n"
@@ -162,6 +177,20 @@ void process_command_line(options_t *opt, int argc, char **argv)
 			break;
 
 		switch (i) {
+		case ALL_ROOT_OPTION:
+			opt->force_uid_value = 0;
+			opt->force_gid_value = 0;
+			opt->force_uid = true;
+			opt->force_gid = true;
+			break;
+		case 'u':
+			opt->force_uid_value = strtol(optarg, NULL, 0);
+			opt->force_uid = true;
+			break;
+		case 'g':
+			opt->force_gid_value = strtol(optarg, NULL, 0);
+			opt->force_gid = true;
+			break;
 		case 'T':
 			opt->no_tail_packing = true;
 			break;
diff --git a/doc/gensquashfs.1 b/doc/gensquashfs.1
index 0de39bf..6214741 100644
--- a/doc/gensquashfs.1
+++ b/doc/gensquashfs.1
@@ -76,6 +76,17 @@ mtime=<value>;\fB$SOURCE\_DATE\_EPOCH\fR if set, 0 otherwise
 .TE
 .TP
 .TP
+\fB\-\-set\-uid\fR, \fB\-u\fR <number>
+Force the owners user ID for ALL inodes to this value, no matter what the pack
+file or directory entries actually specify.
+.TP
+\fB\-\-set\-gid\fR, \fB\-g\fR <number>
+Force the owners group ID for ALL inodes to this value, no matter what the pack
+file or directory entries actually specify.
+.TP
+\fB\-\-all\-root\fR
+A short hand for `\-\-set\-uid 0 \-\-set\-gid 0`.
+.TP
 \fB\-\-selinux\fR, \fB\-s\fR <file>
 If built with SELinux support, use the given SELinux label file to add context
 labels to the elements packed into the SquashFS image.