From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: B Horn <b@horn.uk>
Date: Tue, 11 Feb 2025 13:44:25 -0600
Subject: [PATCH] kern/file: Implement filesystem reference counting

The grub_file_open() and grub_file_close() should be the only places
that allow a reference to a filesystem to stay open. So, add grub_dl_t
to grub_fs_t and set this in the GRUB_MOD_INIT() for each filesystem to
avoid issues when filesystems forget to do it themselves or do not track
their own references, e.g. squash4.

The fs_label(), fs_uuid(), fs_mtime() and fs_read() should all ref and
unref in the same function but it is essentially redundant in GRUB
single threaded model.

Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 grub-core/fs/affs.c     | 1 +
 grub-core/fs/bfs.c      | 1 +
 grub-core/fs/btrfs.c    | 1 +
 grub-core/fs/cbfs.c     | 1 +
 grub-core/fs/cpio.c     | 1 +
 grub-core/fs/cpio_be.c  | 1 +
 grub-core/fs/ext2.c     | 1 +
 grub-core/fs/f2fs.c     | 1 +
 grub-core/fs/fat.c      | 1 +
 grub-core/fs/hfs.c      | 1 +
 grub-core/fs/hfsplus.c  | 1 +
 grub-core/fs/iso9660.c  | 1 +
 grub-core/fs/jfs.c      | 1 +
 grub-core/fs/minix.c    | 1 +
 grub-core/fs/newc.c     | 1 +
 grub-core/fs/nilfs2.c   | 1 +
 grub-core/fs/ntfs.c     | 1 +
 grub-core/fs/odc.c      | 1 +
 grub-core/fs/proc.c     | 1 +
 grub-core/fs/reiserfs.c | 1 +
 grub-core/fs/romfs.c    | 1 +
 grub-core/fs/sfs.c      | 1 +
 grub-core/fs/squash4.c  | 1 +
 grub-core/fs/tar.c      | 1 +
 grub-core/fs/udf.c      | 1 +
 grub-core/fs/ufs.c      | 1 +
 grub-core/fs/xfs.c      | 1 +
 grub-core/fs/zfs/zfs.c  | 1 +
 grub-core/kern/file.c   | 7 +++++++
 include/grub/fs.h       | 4 ++++
 30 files changed, 39 insertions(+)

diff --git a/grub-core/fs/affs.c b/grub-core/fs/affs.c
index cafcd0fba..b1c64e77d 100644
--- a/grub-core/fs/affs.c
+++ b/grub-core/fs/affs.c
@@ -699,6 +699,7 @@ static struct grub_fs grub_affs_fs =
 
 GRUB_MOD_INIT(affs)
 {
+  grub_affs_fs.mod = mod;
   grub_fs_register (&grub_affs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/bfs.c b/grub-core/fs/bfs.c
index 47dbe2011..17705812d 100644
--- a/grub-core/fs/bfs.c
+++ b/grub-core/fs/bfs.c
@@ -1104,6 +1104,7 @@ GRUB_MOD_INIT (bfs)
 {
   COMPILE_TIME_ASSERT (1 << LOG_EXTENT_SIZE ==
 		       sizeof (struct grub_bfs_extent));
+  grub_bfs_fs.mod = mod;
   grub_fs_register (&grub_bfs_fs);
 }
 
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 47325f6ad..3ed37a4db 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -3365,6 +3365,7 @@ subvol_get_env (struct grub_env_var *var __attribute__ ((unused)),
 
 GRUB_MOD_INIT (btrfs)
 {
+  grub_btrfs_fs.mod = mod;
   grub_fs_register (&grub_btrfs_fs);
   cmd_info = grub_register_command("btrfs-info", grub_cmd_btrfs_info,
 				   "DEVICE",
diff --git a/grub-core/fs/cbfs.c b/grub-core/fs/cbfs.c
index 581215ef1..3e527cbf2 100644
--- a/grub-core/fs/cbfs.c
+++ b/grub-core/fs/cbfs.c
@@ -390,6 +390,7 @@ GRUB_MOD_INIT (cbfs)
 #if (defined (__i386__) || defined (__x86_64__)) && !defined (GRUB_UTIL) && !defined (GRUB_MACHINE_EMU) && !defined (GRUB_MACHINE_XEN)
   init_cbfsdisk ();
 #endif
+  grub_cbfs_fs.mod = mod;
   grub_fs_register (&grub_cbfs_fs);
 }
 
diff --git a/grub-core/fs/cpio.c b/grub-core/fs/cpio.c
index dab5f9898..1799f7ff5 100644
--- a/grub-core/fs/cpio.c
+++ b/grub-core/fs/cpio.c
@@ -52,6 +52,7 @@ read_number (const grub_uint16_t *arr, grub_size_t size)
 
 GRUB_MOD_INIT (cpio)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 
diff --git a/grub-core/fs/cpio_be.c b/grub-core/fs/cpio_be.c
index 846548892..7bed1b848 100644
--- a/grub-core/fs/cpio_be.c
+++ b/grub-core/fs/cpio_be.c
@@ -52,6 +52,7 @@ read_number (const grub_uint16_t *arr, grub_size_t size)
 
 GRUB_MOD_INIT (cpio_be)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 
diff --git a/grub-core/fs/ext2.c b/grub-core/fs/ext2.c
index eac639e36..0ee22e675 100644
--- a/grub-core/fs/ext2.c
+++ b/grub-core/fs/ext2.c
@@ -1113,6 +1113,7 @@ static struct grub_fs grub_ext2_fs =
 
 GRUB_MOD_INIT(ext2)
 {
+  grub_ext2_fs.mod = mod;
   grub_fs_register (&grub_ext2_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/f2fs.c b/grub-core/fs/f2fs.c
index f7daa9435..e5dcbc470 100644
--- a/grub-core/fs/f2fs.c
+++ b/grub-core/fs/f2fs.c
@@ -1353,6 +1353,7 @@ static struct grub_fs grub_f2fs_fs = {
 
 GRUB_MOD_INIT (f2fs)
 {
+  grub_f2fs_fs.mod = mod;
   grub_fs_register (&grub_f2fs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/fat.c b/grub-core/fs/fat.c
index ff6200c5b..1cf355af4 100644
--- a/grub-core/fs/fat.c
+++ b/grub-core/fs/fat.c
@@ -1312,6 +1312,7 @@ GRUB_MOD_INIT(fat)
 #endif
 {
   COMPILE_TIME_ASSERT (sizeof (struct grub_fat_dir_entry) == 32);
+  grub_fat_fs.mod = mod;
   grub_fs_register (&grub_fat_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/hfs.c b/grub-core/fs/hfs.c
index bb7af5f67..3a9894443 100644
--- a/grub-core/fs/hfs.c
+++ b/grub-core/fs/hfs.c
@@ -1434,6 +1434,7 @@ static struct grub_fs grub_hfs_fs =
 
 GRUB_MOD_INIT(hfs)
 {
+  grub_hfs_fs.mod = mod;
   if (!grub_is_lockdown ())
     grub_fs_register (&grub_hfs_fs);
   my_mod = mod;
diff --git a/grub-core/fs/hfsplus.c b/grub-core/fs/hfsplus.c
index e7fd98a07..d5f90007b 100644
--- a/grub-core/fs/hfsplus.c
+++ b/grub-core/fs/hfsplus.c
@@ -1150,6 +1150,7 @@ static struct grub_fs grub_hfsplus_fs =
 
 GRUB_MOD_INIT(hfsplus)
 {
+  grub_hfsplus_fs.mod = mod;
   grub_fs_register (&grub_hfsplus_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/iso9660.c b/grub-core/fs/iso9660.c
index 7a59a65a5..0c0aae597 100644
--- a/grub-core/fs/iso9660.c
+++ b/grub-core/fs/iso9660.c
@@ -1165,6 +1165,7 @@ static struct grub_fs grub_iso9660_fs =
 
 GRUB_MOD_INIT(iso9660)
 {
+  grub_iso9660_fs.mod = mod;
   grub_fs_register (&grub_iso9660_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/jfs.c b/grub-core/fs/jfs.c
index 70a2f4947..b0283ac00 100644
--- a/grub-core/fs/jfs.c
+++ b/grub-core/fs/jfs.c
@@ -1005,6 +1005,7 @@ static struct grub_fs grub_jfs_fs =
 
 GRUB_MOD_INIT(jfs)
 {
+  grub_jfs_fs.mod = mod;
   grub_fs_register (&grub_jfs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/minix.c b/grub-core/fs/minix.c
index 3cd18c85b..beb1a6378 100644
--- a/grub-core/fs/minix.c
+++ b/grub-core/fs/minix.c
@@ -732,6 +732,7 @@ GRUB_MOD_INIT(minix)
 #endif
 #endif
 {
+  grub_minix_fs.mod = mod;
   grub_fs_register (&grub_minix_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/newc.c b/grub-core/fs/newc.c
index 4fb8b2e3d..43b7f8b64 100644
--- a/grub-core/fs/newc.c
+++ b/grub-core/fs/newc.c
@@ -64,6 +64,7 @@ read_number (const char *str, grub_size_t size)
 
 GRUB_MOD_INIT (newc)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 
diff --git a/grub-core/fs/nilfs2.c b/grub-core/fs/nilfs2.c
index 3c248a910..c44583ee8 100644
--- a/grub-core/fs/nilfs2.c
+++ b/grub-core/fs/nilfs2.c
@@ -1231,6 +1231,7 @@ GRUB_MOD_INIT (nilfs2)
 				  grub_nilfs2_dat_entry));
   COMPILE_TIME_ASSERT (1 << LOG_INODE_SIZE
 		       == sizeof (struct grub_nilfs2_inode));
+  grub_nilfs2_fs.mod = mod;
   grub_fs_register (&grub_nilfs2_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/ntfs.c b/grub-core/fs/ntfs.c
index 8fdb8f2ff..03e3e5c6a 100644
--- a/grub-core/fs/ntfs.c
+++ b/grub-core/fs/ntfs.c
@@ -1537,6 +1537,7 @@ static struct grub_fs grub_ntfs_fs =
 
 GRUB_MOD_INIT (ntfs)
 {
+  grub_ntfs_fs.mod = mod;
   grub_fs_register (&grub_ntfs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/odc.c b/grub-core/fs/odc.c
index 790000622..8e4e8aeac 100644
--- a/grub-core/fs/odc.c
+++ b/grub-core/fs/odc.c
@@ -52,6 +52,7 @@ read_number (const char *str, grub_size_t size)
 
 GRUB_MOD_INIT (odc)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 
diff --git a/grub-core/fs/proc.c b/grub-core/fs/proc.c
index 5f516502d..bcde43349 100644
--- a/grub-core/fs/proc.c
+++ b/grub-core/fs/proc.c
@@ -192,6 +192,7 @@ static struct grub_fs grub_procfs_fs =
 
 GRUB_MOD_INIT (procfs)
 {
+  grub_procfs_fs.mod = mod;
   grub_disk_dev_register (&grub_procfs_dev);
   grub_fs_register (&grub_procfs_fs);
 }
diff --git a/grub-core/fs/reiserfs.c b/grub-core/fs/reiserfs.c
index b8253da7f..d9a8bf602 100644
--- a/grub-core/fs/reiserfs.c
+++ b/grub-core/fs/reiserfs.c
@@ -1407,6 +1407,7 @@ static struct grub_fs grub_reiserfs_fs =
 
 GRUB_MOD_INIT(reiserfs)
 {
+  grub_reiserfs_fs.mod = mod;
   grub_fs_register (&grub_reiserfs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/romfs.c b/grub-core/fs/romfs.c
index d97b8fbb8..a43546d95 100644
--- a/grub-core/fs/romfs.c
+++ b/grub-core/fs/romfs.c
@@ -475,6 +475,7 @@ static struct grub_fs grub_romfs_fs =
 
 GRUB_MOD_INIT(romfs)
 {
+  grub_romfs_fs.mod = mod;
   grub_fs_register (&grub_romfs_fs);
 }
 
diff --git a/grub-core/fs/sfs.c b/grub-core/fs/sfs.c
index 983e88008..f0d7cac43 100644
--- a/grub-core/fs/sfs.c
+++ b/grub-core/fs/sfs.c
@@ -779,6 +779,7 @@ static struct grub_fs grub_sfs_fs =
 
 GRUB_MOD_INIT(sfs)
 {
+  grub_sfs_fs.mod = mod;
   grub_fs_register (&grub_sfs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/squash4.c b/grub-core/fs/squash4.c
index 6dd731e23..ccfa3eea5 100644
--- a/grub-core/fs/squash4.c
+++ b/grub-core/fs/squash4.c
@@ -1032,6 +1032,7 @@ static struct grub_fs grub_squash_fs =
 
 GRUB_MOD_INIT(squash4)
 {
+  grub_squash_fs.mod = mod;
   grub_fs_register (&grub_squash_fs);
 }
 
diff --git a/grub-core/fs/tar.c b/grub-core/fs/tar.c
index 386c09022..fd2ec1f74 100644
--- a/grub-core/fs/tar.c
+++ b/grub-core/fs/tar.c
@@ -354,6 +354,7 @@ static struct grub_fs grub_cpio_fs = {
 
 GRUB_MOD_INIT (tar)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 
diff --git a/grub-core/fs/udf.c b/grub-core/fs/udf.c
index 2ac5c1d00..3d4b40263 100644
--- a/grub-core/fs/udf.c
+++ b/grub-core/fs/udf.c
@@ -1382,6 +1382,7 @@ static struct grub_fs grub_udf_fs = {
 
 GRUB_MOD_INIT (udf)
 {
+  grub_udf_fs.mod = mod;
   grub_fs_register (&grub_udf_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/ufs.c b/grub-core/fs/ufs.c
index 47272665e..7f72494cd 100644
--- a/grub-core/fs/ufs.c
+++ b/grub-core/fs/ufs.c
@@ -899,6 +899,7 @@ GRUB_MOD_INIT(ufs1)
 #endif
 #endif
 {
+  grub_ufs_fs.mod = mod;
   grub_fs_register (&grub_ufs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/xfs.c b/grub-core/fs/xfs.c
index 9d3420ece..7b0ea577e 100644
--- a/grub-core/fs/xfs.c
+++ b/grub-core/fs/xfs.c
@@ -1220,6 +1220,7 @@ static struct grub_fs grub_xfs_fs =
 
 GRUB_MOD_INIT(xfs)
 {
+  grub_xfs_fs.mod = mod;
   grub_fs_register (&grub_xfs_fs);
   my_mod = mod;
 }
diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
index cf4d2ab18..cbbd86730 100644
--- a/grub-core/fs/zfs/zfs.c
+++ b/grub-core/fs/zfs/zfs.c
@@ -4394,6 +4394,7 @@ static struct grub_fs grub_zfs_fs = {
 GRUB_MOD_INIT (zfs)
 {
   COMPILE_TIME_ASSERT (sizeof (zap_leaf_chunk_t) == ZAP_LEAF_CHUNKSIZE);
+  grub_zfs_fs.mod = mod;
   grub_fs_register (&grub_zfs_fs);
 #ifndef GRUB_UTIL
   my_mod = mod;
diff --git a/grub-core/kern/file.c b/grub-core/kern/file.c
index 1dc4339dc..58fae17ba 100644
--- a/grub-core/kern/file.c
+++ b/grub-core/kern/file.c
@@ -25,6 +25,7 @@
 #include <grub/fs.h>
 #include <grub/device.h>
 #include <grub/i18n.h>
+#include <grub/dl.h>
 
 void (*EXPORT_VAR (grub_grubnet_fini)) (void);
 
@@ -127,6 +128,9 @@ grub_file_open (const char *name, enum grub_file_type type)
   if (file->data == NULL)
     goto fail;
 
+  if (file->fs->mod)
+      grub_dl_ref (file->fs->mod);
+
   file->name = grub_strdup (name);
   grub_errno = GRUB_ERR_NONE;
 
@@ -215,6 +219,9 @@ grub_file_read (grub_file_t file, void *buf, grub_size_t len)
 grub_err_t
 grub_file_close (grub_file_t file)
 {
+  if (file->fs->mod)
+    grub_dl_unref (file->fs->mod);
+
   grub_dprintf ("file", "Closing `%s' ...\n", file->name);
   if (file->fs->fs_close)
     (file->fs->fs_close) (file);
diff --git a/include/grub/fs.h b/include/grub/fs.h
index 026bc3bb8..df4c93b16 100644
--- a/include/grub/fs.h
+++ b/include/grub/fs.h
@@ -23,6 +23,7 @@
 #include <grub/device.h>
 #include <grub/symbol.h>
 #include <grub/types.h>
+#include <grub/dl.h>
 
 #include <grub/list.h>
 /* For embedding types.  */
@@ -57,6 +58,9 @@ struct grub_fs
   /* My name.  */
   const char *name;
 
+  /* My module */
+  grub_dl_t mod;
+
   /* Call HOOK with each file under DIR.  */
   grub_err_t (*fs_dir) (grub_device_t device, const char *path,
 		     grub_fs_dir_hook_t hook, void *hook_data);