xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ubfis: authentication: Authenticate master node

Browse Source 
The master node contains hashes over the root index node and the LPT.
This patch adds a HMAC to authenticate the master node itself.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Sascha Hauer
2018-09-07 14:36:40 +02:00
committed by Richard Weinberger
parent a1dc58140f
commit 625700ccb5
3 changed files with 61 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
fs/ubifs/master.c
View File

@@ -24,6 +24,42 @@
#include "ubifs.h"
/**
* ubifs_compare_master_node - compare two UBIFS master nodes
* @c: UBIFS file-system description object
* @m1: the first node
* @m2: the second node
*
* This function compares two UBIFS master nodes. Returns 0 if they are equal
* and nonzero if not.
*/
int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
{
int ret;
int behind;
int hmac_offs = offsetof(struct ubifs_mst_node, hmac);
/*
* Do not compare the common node header since the sequence number and
* hence the CRC are different.
*/
ret = memcmp(m1 + UBIFS_CH_SZ, m2 + UBIFS_CH_SZ,
hmac_offs - UBIFS_CH_SZ);
if (ret)
return ret;
/*
* Do not compare the embedded HMAC aswell which also must be different
* due to the different common node header.
*/
behind = hmac_offs + UBIFS_MAX_HMAC_LEN;
if (UBIFS_MST_NODE_SZ > behind)
return memcmp(m1 + behind, m2 + behind, UBIFS_MST_NODE_SZ - behind);
return 0;
}
/**
* scan_for_master - search the valid master node.
* @c: UBIFS file-system description object
@@ -37,7 +73,7 @@ static int scan_for_master(struct ubifs_info *c)
{
struct ubifs_scan_leb *sleb;
struct ubifs_scan_node *snod;
int lnum, offs = 0, nodes_cnt;
int lnum, offs = 0, nodes_cnt, err;
lnum = UBIFS_MST_LNUM;
@@ -69,12 +105,23 @@ static int scan_for_master(struct ubifs_info *c)
goto out_dump;
if (snod->offs != offs)
goto out;
if (memcmp((void *)c->mst_node + UBIFS_CH_SZ,
(void *)snod->node + UBIFS_CH_SZ,
UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))
if (ubifs_compare_master_node(c, c->mst_node, snod->node))
goto out;
c->mst_offs = offs;
ubifs_scan_destroy(sleb);
if (!ubifs_authenticated(c))
return 0;
err = ubifs_node_verify_hmac(c, c->mst_node,
sizeof(struct ubifs_mst_node),
offsetof(struct ubifs_mst_node, hmac));
if (err) {
ubifs_err(c, "Failed to verify master node HMAC");
return -EPERM;
}
return 0;
out:
@@ -381,7 +428,8 @@ int ubifs_write_master(struct ubifs_info *c)
c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);
ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);
err = ubifs_write_node(c, c->mst_node, len, lnum, offs);
err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
offsetof(struct ubifs_mst_node, hmac));
if (err)
return err;
@@ -392,7 +440,8 @@ int ubifs_write_master(struct ubifs_info *c)
if (err)
return err;
}
err = ubifs_write_node(c, c->mst_node, len, lnum, offs);
err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
offsetof(struct ubifs_mst_node, hmac));
return err;
}