From: Mimi Zohar <zohar@linux.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: Mimi Zohar <zohar@linux.ibm.com>,
Roberto Sassu <roberto.sassu@huawei.com>,
Stefan Berger <stefanb@linux.ibm.com>,
Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
kernel test robot <lkp@intel.com>
Subject: [PATCH v2] evm: output EVM digest calculation info
Date: Sun, 20 Jun 2021 21:03:27 -0400 [thread overview]
Message-ID: <20210621010327.467523-1-zohar@linux.ibm.com> (raw)
Output the data used in calculating the EVM digest and the resulting
digest as ascii hexadecimal strings.
Suggested-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> (CONFIG_DYNAMIC_DEBUG)
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Reported-by: kernel test robot <lkp@intel.com> (Use %zu for size_t)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
Changelog v1:
- Use %zu for size_t
security/integrity/evm/evm_crypto.c | 43 +++++++++++++++++++++++++++++
security/integrity/evm/evm_main.c | 4 +++
2 files changed, 47 insertions(+)
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 1628e2ca9862..bebe160c57b9 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -10,6 +10,8 @@
* Using root's kernel master key (kmk), calculate the HMAC
*/
+#define pr_fmt(fmt) "EVM: "fmt
+
#include <linux/export.h>
#include <linux/crypto.h>
#include <linux/xattr.h>
@@ -175,6 +177,30 @@ 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);
+
+ pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
+ (int)sizeof(struct h_misc), &hmac_misc);
+}
+
+/*
+ * Dump large security xattr values as a continuous ascii hexademical string.
+ * (pr_debug is limited to 64 bytes.)
+ */
+static void dump_security_xattr(const char *prefix, const void *src,
+ size_t count)
+{
+#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
+ char *asciihex, *p;
+
+ p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
+ if (!asciihex)
+ return;
+
+ p = bin2hex(p, src, count);
+ *p = 0;
+ pr_debug("%s: (%zu) %.*s\n", prefix, count, (int)count * 2, asciihex);
+ kfree(asciihex);
+#endif
}
/*
@@ -230,6 +256,16 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
req_xattr_value_len);
if (is_ima)
ima_present = true;
+
+ if (req_xattr_value_len < 64)
+ pr_debug("%s: (%zu) [%*phN]\n", req_xattr_name,
+ req_xattr_value_len,
+ (int)req_xattr_value_len,
+ req_xattr_value);
+ else
+ dump_security_xattr(req_xattr_name,
+ req_xattr_value,
+ req_xattr_value_len);
continue;
}
size = vfs_getxattr_alloc(&init_user_ns, dentry, xattr->name,
@@ -246,6 +282,13 @@ 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;
+
+ if (xattr_size < 64)
+ pr_debug("%s: (%zu) [%*phN]", xattr->name, xattr_size,
+ (int)xattr_size, xattr_value);
+ else
+ dump_security_xattr(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 977208aecd06..1c8435dfabee 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -11,6 +11,8 @@
* evm_inode_removexattr, and evm_verifyxattr
*/
+#define pr_fmt(fmt) "EVM: "fmt
+
#include <linux/init.h>
#include <linux/crypto.h>
#include <linux/audit.h>
@@ -272,6 +274,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
else
evm_status = INTEGRITY_FAIL;
}
+ pr_debug("digest: (%d) [%*phN]\n", digest.hdr.length, digest.hdr.length,
+ digest.digest);
out:
if (iint)
iint->evm_status = evm_status;
--
2.27.0
next reply other threads:[~2021-06-21 1:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-21 1:03 Mimi Zohar [this message]
2021-06-21 15:58 ` [PATCH v2] evm: output EVM digest calculation info nramas
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