3 files changed, 134 insertions, 0 deletions

diff --git a/fs/ubifs/lpt.c b/fs/ubifs/lpt.c
index 5f57af224b8f..ee18305a6152 100644
--- a/fs/ubifs/lpt.c
+++ b/fs/ubifs/lpt.c
@@ -1636,6 +1636,131 @@ struct ubifs_lprops *ubifs_lpt_lookup_dirty(struct ubifs_info *c, int lnum)
 }
 
 /**
+ * ubifs_lpt_calc_hash - Calculate hash of the LPT pnodes
+ * @c: UBIFS file-system description object
+ * @hash: the returned hash of the LPT pnodes
+ *
+ * This function iterates over the LPT pnodes and creates a hash over them.
+ * Returns 0 for success or a negative error code otherwise.
+ */
+int ubifs_lpt_calc_hash(struct ubifs_info *c, u8 *hash)
+{
+        struct ubifs_nnode *nnode, *nn;
+        struct ubifs_cnode *cnode;
+        struct shash_desc *desc;
+        int iip = 0, i;
+        int bufsiz = max_t(int, c->nnode_sz, c->pnode_sz);
+        void *buf;
+        int err;
+
+        if (!ubifs_authenticated(c))
+                return 0;
+
+        desc = ubifs_hash_get_desc(c);
+        if (IS_ERR(desc))
+                return PTR_ERR(desc);
+
+        buf = kmalloc(bufsiz, GFP_NOFS);
+        if (!buf) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        if (!c->nroot) {
+                err = ubifs_read_nnode(c, NULL, 0);
+                if (err)
+                        return err;
+        }
+
+        cnode = (struct ubifs_cnode *)c->nroot;
+
+        while (cnode) {
+                nnode = cnode->parent;
+                nn = (struct ubifs_nnode *)cnode;
+                if (cnode->level > 1) {
+                        while (iip < UBIFS_LPT_FANOUT) {
+                                if (nn->nbranch[iip].lnum == 0) {
+                                        /* Go right */
+                                        iip++;
+                                        continue;
+                                }
+
+                                nnode = ubifs_get_nnode(c, nn, iip);
+                                if (IS_ERR(nnode)) {
+                                        err = PTR_ERR(nnode);
+                                        goto out;
+                                }
+
+                                /* Go down */
+                                iip = 0;
+                                cnode = (struct ubifs_cnode *)nnode;
+                                break;
+                        }
+                        if (iip < UBIFS_LPT_FANOUT)
+                                continue;
+                } else {
+                        struct ubifs_pnode *pnode;
+
+                        for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
+                                if (nn->nbranch[i].lnum == 0)
+                                        continue;
+                                pnode = ubifs_get_pnode(c, nn, i);
+                                if (IS_ERR(pnode)) {
+                                        err = PTR_ERR(pnode);
+                                        goto out;
+                                }
+
+                                ubifs_pack_pnode(c, buf, pnode);
+                                err = ubifs_shash_update(c, desc, buf,
+                                                         c->pnode_sz);
+                                if (err)
+                                        goto out;
+                        }
+                }
+                /* Go up and to the right */
+                iip = cnode->iip + 1;
+                cnode = (struct ubifs_cnode *)nnode;
+        }
+
+        err = ubifs_shash_final(c, desc, hash);
+out:
+        kfree(desc);
+        kfree(buf);
+
+        return err;
+}
+
+/**
+ * lpt_check_hash - check the hash of the LPT.
+ * @c: UBIFS file-system description object
+ *
+ * This function calculates a hash over all pnodes in the LPT and compares it with
+ * the hash stored in the master node. Returns %0 on success and a negative error
+ * code on failure.
+ */
+static int lpt_check_hash(struct ubifs_info *c)
+{
+        int err;
+        u8 hash[UBIFS_HASH_ARR_SZ];
+
+        if (!ubifs_authenticated(c))
+                return 0;
+
+        err = ubifs_lpt_calc_hash(c, hash);
+        if (err)
+                return err;
+
+        if (ubifs_check_hash(c, c->mst_node->hash_lpt, hash)) {
+                err = -EPERM;
+                ubifs_err(c, "Failed to authenticate LPT");
+        } else {
+                err = 0;
+        }
+
+        return err;
+}
+
+/**
  * lpt_init_rd - initialize the LPT for reading.
  * @c: UBIFS file-system description object
  *
@@ -1676,6 +1801,10 @@ static int lpt_init_rd(struct ubifs_info *c)
         if (err)
                 return err;
 
+        err = lpt_check_hash(c);
+        if (err)
+                return err;
+
         dbg_lp("space_bits %d", c->space_bits);
         dbg_lp("lpt_lnum_bits %d", c->lpt_lnum_bits);
         dbg_lp("lpt_offs_bits %d", c->lpt_offs_bits);
diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
index 62d6a87d4f5d..1f88caffdf2a 100644
--- a/fs/ubifs/lpt_commit.c
+++ b/fs/ubifs/lpt_commit.c
@@ -1247,6 +1247,10 @@ int ubifs_lpt_start_commit(struct ubifs_info *c)
         if (err)
                 goto out;
 
+        err = ubifs_lpt_calc_hash(c, c->mst_node->hash_lpt);
+        if (err)
+                goto out;
+
         /* Copy the LPT's own lprops for end commit to write */
         memcpy(c->ltab_cmt, c->ltab,
                sizeof(struct ubifs_lpt_lprops) * c->lpt_lebs);
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 600a25b93a80..7e519a4885a8 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1961,6 +1961,7 @@ struct ubifs_nnode *ubifs_first_nnode(struct ubifs_info *c, int *hght);
 /* Needed only in debugging code in lpt_commit.c */
 int ubifs_unpack_nnode(const struct ubifs_info *c, void *buf,
                        struct ubifs_nnode *nnode);
+int ubifs_lpt_calc_hash(struct ubifs_info *c, u8 *hash);
 
 /* lpt_commit.c */
 int ubifs_lpt_start_commit(struct ubifs_info *c);