From: Mimi Zohar <zohar@linux.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: Roberto Sassu <roberto.sassu@huawei.com>,
Stefan Berger <stefanb@linux.ibm.com>,
Russell Coker <russell@coker.com.au>,
Mimi Zohar <zohar@linux.ibm.com>
Subject: [RFC PATCH 2/2] evm: output EVM digest calculation info needed for debugging
Date: Thu, 3 Jun 2021 11:18:19 -0400 [thread overview]
Message-ID: <20210603151819.242247-3-zohar@linux.ibm.com> (raw)
In-Reply-To: <20210603151819.242247-1-zohar@linux.ibm.com>
Convert and output the binary data used in calculating the EVM digest
to a hexadecimal string.
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
security/integrity/evm/evm.h | 1 +
security/integrity/evm/evm_crypto.c | 7 +++++++
security/integrity/evm/evm_main.c | 19 +++++++++++++++++++
3 files changed, 27 insertions(+)
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index 0d44f41d16f8..3d2d2da8fa97 100644
--- a/security/integrity/evm/evm.h
+++ b/security/integrity/evm/evm.h
@@ -64,5 +64,6 @@ int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
int evm_init_hmac(struct inode *inode, const struct xattr *xattr,
char *hmac_val);
int evm_init_secfs(void);
+void evm_bin2hex_print(const char *prefix, const void *src, size_t count);
#endif
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 1628e2ca9862..7601aa29c6d3 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -175,6 +175,8 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
type != EVM_XATTR_PORTABLE_DIGSIG)
crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
crypto_shash_final(desc, digest);
+
+ evm_bin2hex_print("hmac_misc", &hmac_misc, sizeof(struct h_misc));
}
/*
@@ -230,6 +232,9 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
req_xattr_value_len);
if (is_ima)
ima_present = true;
+
+ evm_bin2hex_print(req_xattr_name, req_xattr_value,
+ req_xattr_value_len);
continue;
}
size = vfs_getxattr_alloc(&init_user_ns, dentry, xattr->name,
@@ -246,6 +251,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
if (is_ima)
ima_present = true;
+
+ evm_bin2hex_print(xattr->name, xattr_value, xattr_size);
}
hmac_add_misc(desc, inode, type, data->digest);
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 2c226e634ae9..03d963fe2e67 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -155,6 +155,23 @@ static int evm_find_protected_xattrs(struct dentry *dentry)
return count;
}
+void evm_bin2hex_print(const char *prefix, const void *src, size_t count)
+{
+#ifdef DEBUG
+ char *asciihex, *p;
+
+ p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
+ if (!asciihex)
+ return;
+
+ p = bin2hex(p, src, count);
+ *p = 0;
+ printk("%s: (%lu) %.*s\n", prefix, count, (int) count * 2, asciihex);
+
+ kfree(asciihex);
+#endif
+}
+
/*
* evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
*
@@ -272,6 +289,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
else
evm_status = INTEGRITY_FAIL;
}
+
+ evm_bin2hex_print("evm digest", digest.digest, digest.hdr.length);
out:
if (iint)
iint->evm_status = evm_status;
--
2.27.0
next prev parent reply other threads:[~2021-06-03 15:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-03 15:18 [RFC PATCH 0/2] EVM: add some debugging info Mimi Zohar
2021-06-03 15:18 ` [RFC PATCH 1/2] ima: differentiate between EVM failures in the audit log Mimi Zohar
2021-06-04 6:37 ` Roberto Sassu
2021-06-03 15:18 ` Mimi Zohar [this message]
2021-06-03 16:34 ` [RFC PATCH 2/2] evm: output EVM digest calculation info needed for debugging nramas
2021-06-03 16:55 ` Mimi Zohar
2021-06-03 17:48 ` nramas
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