ubifs: authentication: Add hashes to index nodes

With this patch the hashes over the index nodes stored in the tree node
cache are written to flash and are checked when read back from flash.
The hash of the root index node is stored in the master node.

During journal replay the hashes are regenerated from the read nodes
and stored in the tree node cache. This means the nodes must previously
be authenticated by other means. This is done in a later patch.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 27 insertions, 0 deletions

diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
index dba87d09b989..dbcd2c350b65 100644
--- a/fs/ubifs/tnc_commit.c
+++ b/fs/ubifs/tnc_commit.c
@@ -38,6 +38,7 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
                          struct ubifs_znode *znode, int lnum, int offs, int len)
 {
         struct ubifs_znode *zp;
+        u8 hash[UBIFS_HASH_ARR_SZ];
         int i, err;
 
         /* Make index node */
@@ -52,6 +53,7 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
                 br->lnum = cpu_to_le32(zbr->lnum);
                 br->offs = cpu_to_le32(zbr->offs);
                 br->len = cpu_to_le32(zbr->len);
+                ubifs_copy_hash(c, zbr->hash, ubifs_branch_hash(c, br));
                 if (!zbr->lnum || !zbr->len) {
                         ubifs_err(c, "bad ref in znode");
                         ubifs_dump_znode(c, znode);
@@ -62,6 +64,7 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
                 }
         }
         ubifs_prepare_node(c, idx, len, 0);
+        ubifs_node_calc_hash(c, idx, hash);
 
         znode->lnum = lnum;
         znode->offs = offs;
@@ -78,10 +81,12 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
                 zbr->lnum = lnum;
                 zbr->offs = offs;
                 zbr->len = len;
+                ubifs_copy_hash(c, hash, zbr->hash);
         } else {
                 c->zroot.lnum = lnum;
                 c->zroot.offs = offs;
                 c->zroot.len = len;
+                ubifs_copy_hash(c, hash, c->zroot.hash);
         }
         c->calc_idx_sz += ALIGN(len, 8);
 
@@ -647,6 +652,8 @@ static int get_znodes_to_commit(struct ubifs_info *c)
                         znode->cnext = c->cnext;
                         break;
                 }
+                znode->cparent = znode->parent;
+                znode->ciip = znode->iip;
                 znode->cnext = cnext;
                 znode = cnext;
                 cnt += 1;
@@ -840,6 +847,8 @@ static int write_index(struct ubifs_info *c)
         }
 
         while (1) {
+                u8 hash[UBIFS_HASH_ARR_SZ];
+
                 cond_resched();
 
                 znode = cnext;
@@ -857,6 +866,7 @@ static int write_index(struct ubifs_info *c)
                         br->lnum = cpu_to_le32(zbr->lnum);
                         br->offs = cpu_to_le32(zbr->offs);
                         br->len = cpu_to_le32(zbr->len);
+                        ubifs_copy_hash(c, zbr->hash, ubifs_branch_hash(c, br));
                         if (!zbr->lnum || !zbr->len) {
                                 ubifs_err(c, "bad ref in znode");
                                 ubifs_dump_znode(c, znode);
@@ -868,6 +878,23 @@ static int write_index(struct ubifs_info *c)
                 }
                 len = ubifs_idx_node_sz(c, znode->child_cnt);
                 ubifs_prepare_node(c, idx, len, 0);
+                ubifs_node_calc_hash(c, idx, hash);
+
+                mutex_lock(&c->tnc_mutex);
+
+                if (znode->cparent)
+                        ubifs_copy_hash(c, hash,
+                                        znode->cparent->zbranch[znode->ciip].hash);
+
+                if (znode->parent) {
+                        if (!ubifs_zn_obsolete(znode))
+                                ubifs_copy_hash(c, hash,
+                                        znode->parent->zbranch[znode->iip].hash);
+                } else {
+                        ubifs_copy_hash(c, hash, c->zroot.hash);
+                }
+
+                mutex_unlock(&c->tnc_mutex);
 
                 /* Determine the index node position */
                 if (lnum == -1) {