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Subject[PATCH 1/2] exfat: add dir-entry set checksum validation
Date
Add checksum validation for dir-entry set when getting it.
exfat_calc_dir_chksum_with_entry_set() also validates entry-type.

** This patch depends on:
'[PATCH v3] exfat: integrates dir-entry getting and validation'

Signed-off-by: Tetsuhiro Kohada <kohada.t2@gmail.com>
---
fs/exfat/dir.c | 34 ++++++++++++++++++++++------------
1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index c9715c7a55a1..2e79ac464f5f 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -563,18 +563,27 @@ int exfat_remove_entries(struct inode *inode, struct exfat_chain *p_dir,
return 0;
}

-void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
+static int exfat_calc_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es, u16 *chksum)
{
- int chksum_type = CS_DIR_ENTRY, i;
- unsigned short chksum = 0;
struct exfat_dentry *ep;
+ int i;

- for (i = 0; i < es->num_entries; i++) {
- ep = exfat_get_validated_dentry(es, i, TYPE_ALL);
- chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
- chksum_type);
- chksum_type = CS_DEFAULT;
+ ep = container_of(es->de_file, struct exfat_dentry, dentry.file);
+ *chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, 0, CS_DIR_ENTRY);
+ for (i = 0; i < es->de_file->num_ext; i++) {
+ ep = exfat_get_validated_dentry(es, 1 + i, TYPE_SECONDARY);
+ if (!ep)
+ return -EIO;
+ *chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, *chksum, CS_DEFAULT);
}
+ return 0;
+}
+
+void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
+{
+ u16 chksum;
+
+ exfat_calc_dir_chksum_with_entry_set(es, &chksum);
es->de_file->checksum = cpu_to_le16(chksum);
es->modified = true;
}
@@ -775,6 +784,7 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
struct exfat_entry_set_cache *es;
struct exfat_dentry *ep;
struct buffer_head *bh;
+ u16 chksum;

if (p_dir->dir == DIR_DELETED) {
exfat_err(sb, "access to deleted dentry");
@@ -839,10 +849,10 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
goto free_es;
es->de_stream = &ep->dentry.stream;

- for (i = 2; i < es->num_entries; i++) {
- if (!exfat_get_validated_dentry(es, i, TYPE_SECONDARY))
- goto free_es;
- }
+ if (max_entries == ES_ALL_ENTRIES &&
+ ((exfat_calc_dir_chksum_with_entry_set(es, &chksum) ||
+ chksum != le16_to_cpu(es->de_file->checksum))))
+ goto free_es;

return es;

--
2.25.1
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