Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity updates from Mimi Zohar:
 "The major feature in this time is IMA support for measuring and
  appraising appended file signatures. In addition are a couple of bug
  fixes and code cleanup to use struct_size().

  In addition to the PE/COFF and IMA xattr signatures, the kexec kernel
  image may be signed with an appended signature, using the same
  scripts/sign-file tool that is used to sign kernel modules.

  Similarly, the initramfs may contain an appended signature.

  This contained a lot of refactoring of the existing appended signature
  verification code, so that IMA could retain the existing framework of
  calculating the file hash once, storing it in the IMA measurement list
  and extending the TPM, verifying the file's integrity based on a file
  hash or signature (eg. xattrs), and adding an audit record containing
  the file hash, all based on policy. (The IMA support for appended
  signatures patch set was posted and reviewed 11 times.)

  The support for appended signature paves the way for adding other
  signature verification methods, such as fs-verity, based on a single
  system-wide policy. The file hash used for verifying the signature and
  the signature, itself, can be included in the IMA measurement list"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: ima_api: Use struct_size() in kzalloc()
  ima: use struct_size() in kzalloc()
  sefltest/ima: support appended signatures (modsig)
  ima: Fix use after free in ima_read_modsig()
  MODSIGN: make new include file self contained
  ima: fix freeing ongoing ahash_request
  ima: always return negative code for error
  ima: Store the measurement again when appraising a modsig
  ima: Define ima-modsig template
  ima: Collect modsig
  ima: Implement support for module-style appended signatures
  ima: Factor xattr_verify() out of ima_appraise_measurement()
  ima: Add modsig appraise_type option for module-style appended signatures
  integrity: Select CONFIG_KEYS instead of depending on it
  PKCS#7: Introduce pkcs7_get_digest()
  PKCS#7: Refactor verify_pkcs7_signature()
  MODSIGN: Export module signature definitions
  ima: initialize the "template" field with the default template

15 files changed, 627 insertions, 105 deletions

diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index c352532b8f84..0bae6adb63a9 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -18,8 +18,8 @@ if INTEGRITY
 
 config INTEGRITY_SIGNATURE
 	bool "Digital signature verification using multiple keyrings"
-	depends on KEYS
 	default n
+	select KEYS
 	select SIGNATURE
 	help
 	  This option enables digital signature verification support
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 868ade3e8970..ea1aae3d07b3 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -39,11 +39,10 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
 #define restrict_link_to_ima restrict_link_by_builtin_trusted
 #endif
 
-int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
-			    const char *digest, int digestlen)
+static struct key *integrity_keyring_from_id(const unsigned int id)
 {
-	if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
-		return -EINVAL;
+	if (id >= INTEGRITY_KEYRING_MAX)
+		return ERR_PTR(-EINVAL);
 
 	if (!keyring[id]) {
 		keyring[id] =
@@ -52,23 +51,49 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			int err = PTR_ERR(keyring[id]);
 			pr_err("no %s keyring: %d\n", keyring_name[id], err);
 			keyring[id] = NULL;
-			return err;
+			return ERR_PTR(err);
 		}
 	}
 
+	return keyring[id];
+}
+
+int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
+			    const char *digest, int digestlen)
+{
+	struct key *keyring;
+
+	if (siglen < 2)
+		return -EINVAL;
+
+	keyring = integrity_keyring_from_id(id);
+	if (IS_ERR(keyring))
+		return PTR_ERR(keyring);
+
 	switch (sig[1]) {
 	case 1:
 		/* v1 API expect signature without xattr type */
-		return digsig_verify(keyring[id], sig + 1, siglen - 1,
-				     digest, digestlen);
+		return digsig_verify(keyring, sig + 1, siglen - 1, digest,
+				     digestlen);
 	case 2:
-		return asymmetric_verify(keyring[id], sig, siglen,
-					 digest, digestlen);
+		return asymmetric_verify(keyring, sig, siglen, digest,
+					 digestlen);
 	}
 
 	return -EOPNOTSUPP;
 }
 
+int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
+{
+	struct key *keyring;
+
+	keyring = integrity_keyring_from_id(id);
+	if (IS_ERR(keyring))
+		return PTR_ERR(keyring);
+
+	return ima_modsig_verify(keyring, modsig);
+}
+
 static int __init __integrity_init_keyring(const unsigned int id,
 					   key_perm_t perm,
 					   struct key_restriction *restriction)
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 2ced99dde694..897bafc59a33 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -233,6 +233,19 @@ config IMA_APPRAISE_BOOTPARAM
 	  This option enables the different "ima_appraise=" modes
 	  (eg. fix, log) from the boot command line.
 
+config IMA_APPRAISE_MODSIG
+	bool "Support module-style signatures for appraisal"
+	depends on IMA_APPRAISE
+	depends on INTEGRITY_ASYMMETRIC_KEYS
+	select PKCS7_MESSAGE_PARSER
+	select MODULE_SIG_FORMAT
+	default n
+	help
+	   Adds support for signatures appended to files. The format of the
+	   appended signature is the same used for signed kernel modules.
+	   The modsig keyword can be used in the IMA policy to allow a hook
+	   to accept such signatures.
+
 config IMA_TRUSTED_KEYRING
 	bool "Require all keys on the .ima keyring be signed (deprecated)"
 	depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index d921dc4f9eb0..31d57cdf2421 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -9,5 +9,6 @@ obj-$(CONFIG_IMA) += ima.o
 ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
 	 ima_policy.o ima_template.o ima_template_lib.o
 ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
+ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o
 ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
 obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 011b91c79351..19769bf5f6ab 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -60,6 +60,7 @@ struct ima_event_data {
 	const unsigned char *filename;
 	struct evm_ima_xattr_data *xattr_value;
 	int xattr_len;
+	const struct modsig *modsig;
 	const char *violation;
 	const void *buf;
 	int buf_len;
@@ -149,6 +150,7 @@ int template_desc_init_fields(const char *template_fmt,
 			      int *num_fields);
 struct ima_template_desc *ima_template_desc_current(void);
 struct ima_template_desc *lookup_template_desc(const char *name);
+bool ima_template_has_modsig(const struct ima_template_desc *ima_template);
 int ima_restore_measurement_entry(struct ima_template_entry *entry);
 int ima_restore_measurement_list(loff_t bufsize, void *buf);
 int ima_measurements_show(struct seq_file *m, void *v);
@@ -196,6 +198,10 @@ enum ima_hooks {
 	__ima_hooks(__ima_hook_enumify)
 };
 
+extern const char *const func_tokens[];
+
+struct modsig;
+
 /* LIM API function definitions */
 int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
 		   int mask, enum ima_hooks func, int *pcr,
@@ -203,11 +209,11 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
 int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
 int ima_collect_measurement(struct integrity_iint_cache *iint,
 			    struct file *file, void *buf, loff_t size,
-			    enum hash_algo algo);
+			    enum hash_algo algo, struct modsig *modsig);
 void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
 			   const unsigned char *filename,
 			   struct evm_ima_xattr_data *xattr_value,
-			   int xattr_len, int pcr,
+			   int xattr_len, const struct modsig *modsig, int pcr,
 			   struct ima_template_desc *template_desc);
 void ima_audit_measurement(struct integrity_iint_cache *iint,
 			   const unsigned char *filename);
@@ -249,7 +255,7 @@ int ima_appraise_measurement(enum ima_hooks func,
 			     struct integrity_iint_cache *iint,
 			     struct file *file, const unsigned char *filename,
 			     struct evm_ima_xattr_data *xattr_value,
-			     int xattr_len);
+			     int xattr_len, const struct modsig *modsig);
 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func);
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);
 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
@@ -265,7 +271,8 @@ static inline int ima_appraise_measurement(enum ima_hooks func,
 					   struct file *file,
 					   const unsigned char *filename,
 					   struct evm_ima_xattr_data *xattr_value,
-					   int xattr_len)
+					   int xattr_len,
+					   const struct modsig *modsig)
 {
 	return INTEGRITY_UNKNOWN;
 }
@@ -302,6 +309,51 @@ static inline int ima_read_xattr(struct dentry *dentry,
 
 #endif /* CONFIG_IMA_APPRAISE */
 
+#ifdef CONFIG_IMA_APPRAISE_MODSIG
+bool ima_hook_supports_modsig(enum ima_hooks func);
+int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
+		    struct modsig **modsig);
+void ima_collect_modsig(struct modsig *modsig, const void *buf, loff_t size);
+int ima_get_modsig_digest(const struct modsig *modsig, enum hash_algo *algo,
+			  const u8 **digest, u32 *digest_size);
+int ima_get_raw_modsig(const struct modsig *modsig, const void **data,
+		       u32 *data_len);
+void ima_free_modsig(struct modsig *modsig);
+#else
+static inline bool ima_hook_supports_modsig(enum ima_hooks func)
+{
+	return false;
+}
+
+static inline int ima_read_modsig(enum ima_hooks func, const void *buf,
+				  loff_t buf_len, struct modsig **modsig)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void ima_collect_modsig(struct modsig *modsig, const void *buf,
+				      loff_t size)
+{
+}
+
+static inline int ima_get_modsig_digest(const struct modsig *modsig,
+					enum hash_algo *algo, const u8 **digest,
+					u32 *digest_size)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int ima_get_raw_modsig(const struct modsig *modsig,
+				     const void **data, u32 *data_len)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void ima_free_modsig(struct modsig *modsig)
+{
+}
+#endif /* CONFIG_IMA_APPRAISE_MODSIG */
+
 /* LSM based policy rules require audit */
 #ifdef CONFIG_IMA_LSM_RULES
 
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index f614e22bf39f..610759fe63b8 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -45,8 +45,8 @@ int ima_alloc_init_template(struct ima_event_data *event_data,
 	else
 		template_desc = ima_template_desc_current();
 
-	*entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
-			 sizeof(struct ima_field_data), GFP_NOFS);
+	*entry = kzalloc(struct_size(*entry, template_data,
+				     template_desc->num_fields), GFP_NOFS);
 	if (!*entry)
 		return -ENOMEM;
 
@@ -205,7 +205,7 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
  */
 int ima_collect_measurement(struct integrity_iint_cache *iint,
 			    struct file *file, void *buf, loff_t size,
-			    enum hash_algo algo)
+			    enum hash_algo algo, struct modsig *modsig)
 {
 	const char *audit_cause = "failed";
 	struct inode *inode = file_inode(file);
@@ -219,6 +219,14 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 		char digest[IMA_MAX_DIGEST_SIZE];
 	} hash;
 
+	/*
+	 * Always collect the modsig, because IMA might have already collected
+	 * the file digest without collecting the modsig in a previous
+	 * measurement rule.
+	 */
+	if (modsig)
+		ima_collect_modsig(modsig, buf, size);
+
 	if (iint->flags & IMA_COLLECTED)
 		goto out;
 
@@ -285,7 +293,7 @@ out:
 void ima_store_measurement(struct integrity_iint_cache *iint,
 			   struct file *file, const unsigned char *filename,
 			   struct evm_ima_xattr_data *xattr_value,
-			   int xattr_len, int pcr,
+			   int xattr_len, const struct modsig *modsig, int pcr,
 			   struct ima_template_desc *template_desc)
 {
 	static const char op[] = "add_template_measure";
@@ -297,10 +305,17 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
 					     .file = file,
 					     .filename = filename,
 					     .xattr_value = xattr_value,
-					     .xattr_len = xattr_len };
+					     .xattr_len = xattr_len,
+					     .modsig = modsig };
 	int violation = 0;
 
-	if (iint->measured_pcrs & (0x1 << pcr))
+	/*
+	 * We still need to store the measurement in the case of MODSIG because
+	 * we only have its contents to put in the list at the time of
+	 * appraisal, but a file measurement from earlier might already exist in
+	 * the measurement list.
+	 */
+	if (iint->measured_pcrs & (0x1 << pcr) && !modsig)
 		return;
 
 	result = ima_alloc_init_template(&event_data, &entry, template_desc);
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 89b83194d1dc..136ae4e0ee92 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -200,6 +200,110 @@ int ima_read_xattr(struct dentry *dentry,
 }
 
 /*
+ * xattr_verify - verify xattr digest or signature
+ *
+ * Verify whether the hash or signature matches the file contents.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint,
+			struct evm_ima_xattr_data *xattr_value, int xattr_len,
+			enum integrity_status *status, const char **cause)
+{
+	int rc = -EINVAL, hash_start = 0;
+
+	switch (xattr_value->type) {
+	case IMA_XATTR_DIGEST_NG:
+		/* first byte contains algorithm id */
+		hash_start = 1;
+		/* fall through */
+	case IMA_XATTR_DIGEST:
+		if (iint->flags & IMA_DIGSIG_REQUIRED) {
+			*cause = "IMA-signature-required";
+			*status = INTEGRITY_FAIL;
+			break;
+		}
+		clear_bit(IMA_DIGSIG, &iint->atomic_flags);
+		if (xattr_len - sizeof(xattr_value->type) - hash_start >=
+				iint->ima_hash->length)
+			/*
+			 * xattr length may be longer. md5 hash in previous
+			 * version occupied 20 bytes in xattr, instead of 16
+			 */
+			rc = memcmp(&xattr_value->data[hash_start],
+				    iint->ima_hash->digest,
+				    iint->ima_hash->length);
+		else
+			rc = -EINVAL;
+		if (rc) {
+			*cause = "invalid-hash";
+			*status = INTEGRITY_FAIL;
+			break;
+		}
+		*status = INTEGRITY_PASS;
+		break;
+	case EVM_IMA_XATTR_DIGSIG:
+		set_bit(IMA_DIGSIG, &iint->atomic_flags);
+		rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
+					     (const char *)xattr_value,
+					     xattr_len,
+					     iint->ima_hash->digest,
+					     iint->ima_hash->length);
+		if (rc == -EOPNOTSUPP) {
+			*status = INTEGRITY_UNKNOWN;
+			break;
+		}
+		if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
+		    func == KEXEC_KERNEL_CHECK)
+			rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM,
+						     (const char *)xattr_value,
+						     xattr_len,
+						     iint->ima_hash->digest,
+						     iint->ima_hash->length);
+		if (rc) {
+			*cause = "invalid-signature";
+			*status = INTEGRITY_FAIL;
+		} else {
+			*status = INTEGRITY_PASS;
+		}
+		break;
+	default:
+		*status = INTEGRITY_UNKNOWN;
+		*cause = "unknown-ima-data";
+		break;
+	}
+
+	return rc;
+}
+
+/*
+ * modsig_verify - verify modsig signature
+ *
+ * Verify whether the signature matches the file contents.
+ *
+ * Return 0 on success, error code otherwise.
+ */
+static int modsig_verify(enum ima_hooks func, const struct modsig *modsig,
+			 enum integrity_status *status, const char **cause)
+{
+	int rc;
+
+	rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig);
+	if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
+	    func == KEXEC_KERNEL_CHECK)
+		rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM,
+					     modsig);
+	if (rc) {
+		*cause = "invalid-signature";
+		*status = INTEGRITY_FAIL;
+	} else {
+		*status = INTEGRITY_PASS;
+	}
+
+	return rc;
+}
+
+/*
  * ima_appraise_measurement - appraise file measurement
  *
  * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
@@ -211,19 +315,22 @@ int ima_appraise_measurement(enum ima_hooks func,
 			     struct integrity_iint_cache *iint,
 			     struct file *file, const unsigned char *filename,
 			     struct evm_ima_xattr_data *xattr_value,
-			     int xattr_len)
+			     int xattr_len, const struct modsig *modsig)
 {
 	static const char op[] = "appraise_data";
 	const char *cause = "unknown";
 	struct dentry *dentry = file_dentry(file);
 	struct inode *inode = d_backing_inode(dentry);
 	enum integrity_status status = INTEGRITY_UNKNOWN;
-	int rc = xattr_len, hash_start = 0;
+	int rc = xattr_len;
+	bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig;
 
-	if (!(inode->i_opflags & IOP_XATTR))
+	/* If not appraising a modsig, we need an xattr. */
+	if (!(inode->i_opflags & IOP_XATTR) && !try_modsig)
 		return INTEGRITY_UNKNOWN;
 
-	if (rc <= 0) {
+	/* If reading the xattr failed and there's no modsig, error out. */
+	if (rc <= 0 && !try_modsig) {
 		if (rc && rc != -ENODATA)
 			goto out;
 
@@ -246,6 +353,10 @@ int ima_appraise_measurement(enum ima_hooks func,
 	case INTEGRITY_UNKNOWN:
 		break;
 	case INTEGRITY_NOXATTRS:	/* No EVM protected xattrs. */
+		/* It's fine not to have xattrs when using a modsig. */
+		if (try_modsig)
+			break;
+		/* fall through */
 	case INTEGRITY_NOLABEL:		/* No security.evm xattr. */
 		cause = "missing-HMAC";
 		goto out;
@@ -256,65 +367,18 @@ int ima_appraise_measurement(enum ima_hooks func,
 		WARN_ONCE(true, "Unexpected integrity status %d\n", status);
 	}
 
-	switch (xattr_value->type) {
-	case IMA_XATTR_DIGEST_NG:
-		/* first byte contains algorithm id */
-		hash_start = 1;
-		/* fall through */
-	case IMA_XATTR_DIGEST:
-		if (iint->flags & IMA_DIGSIG_REQUIRED) {
-			cause = "IMA-signature-required";
-			status = INTEGRITY_FAIL;
-			break;
-		}
-		clear_bit(IMA_DIGSIG, &iint->atomic_flags);
-		if (xattr_len - sizeof(xattr_value->type) - hash_start >=
-				iint->ima_hash->length)
-			/* xattr length may be longer. md5 hash in previous
-			   version occupied 20 bytes in xattr, instead of 16
-			 */
-			rc = memcmp(&xattr_value->data[hash_start],
-				    iint->ima_hash->digest,
-				    iint->ima_hash->length);
-		else
-			rc = -EINVAL;
-		if (rc) {
-			cause = "invalid-hash";
-			status = INTEGRITY_FAIL;
-			break;
-		}
-		status = INTEGRITY_PASS;
-		break;
-	case EVM_IMA_XATTR_DIGSIG:
-		set_bit(IMA_DIGSIG, &iint->atomic_flags);
-		rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
-					     (const char *)xattr_value,
-					     xattr_len,
-					     iint->ima_hash->digest,
-					     iint->ima_hash->length);
-		if (rc == -EOPNOTSUPP) {
-			status = INTEGRITY_UNKNOWN;
-			break;
-		}
-		if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc &&
-		    func == KEXEC_KERNEL_CHECK)
-			rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM,
-						     (const char *)xattr_value,
-						     xattr_len,
-						     iint->ima_hash->digest,
-						     iint->ima_hash->length);
-		if (rc) {
-			cause = "invalid-signature";
-			status = INTEGRITY_FAIL;
-		} else {
-			status = INTEGRITY_PASS;
-		}
-		break;
-	default:
-		status = INTEGRITY_UNKNOWN;
-		cause = "unknown-ima-data";
-		break;
-	}
+	if (xattr_value)
+		rc = xattr_verify(func, iint, xattr_value, xattr_len, &status,
+				  &cause);
+
+	/*
+	 * If we have a modsig and either no imasig or the imasig's key isn't
+	 * known, then try verifying the modsig.
+	 */
+	if (try_modsig &&
+	    (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG ||
+	     rc == -ENOKEY))
+		rc = modsig_verify(func, modsig, &status, &cause);
 
 out:
 	/*
@@ -332,7 +396,7 @@ out:
 				    op, cause, rc, 0);
 	} else if (status != INTEGRITY_PASS) {
 		/* Fix mode, but don't replace file signatures. */
-		if ((ima_appraise & IMA_APPRAISE_FIX) &&
+		if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig &&
 		    (!xattr_value ||
 		     xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
 			if (!ima_fix_xattr(dentry, iint))
@@ -371,7 +435,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
 	    !(iint->flags & IMA_HASH))
 		return;
 
-	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
+	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL);
 	if (rc < 0)
 		return;
 
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index d4c7b8e1b083..73044fc6a952 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -268,8 +268,16 @@ static int ima_calc_file_hash_atfm(struct file *file,
 		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
 		rc = integrity_kernel_read(file, offset, rbuf[active],
 					   rbuf_len);
-		if (rc != rbuf_len)
+		if (rc != rbuf_len) {
+			if (rc >= 0)
+				rc = -EINVAL;
+			/*
+			 * Forward current rc, do not overwrite with return value
+			 * from ahash_wait()
+			 */
+			ahash_wait(ahash_rc, &wait);
 			goto out3;
+		}
 
 		if (rbuf[1] && offset) {
 			/* Using two buffers, and it is not the first
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 584019728660..79c01516211b 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -202,6 +202,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
 	int rc = 0, action, must_appraise = 0;
 	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 	struct evm_ima_xattr_data *xattr_value = NULL;
+	struct modsig *modsig = NULL;
 	int xattr_len = 0;
 	bool violation_check;
 	enum hash_algo hash_algo;
@@ -302,13 +303,27 @@ static int process_measurement(struct file *file, const struct cred *cred,
 	}
 
 	if ((action & IMA_APPRAISE_SUBMASK) ||
-		    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
+	    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 		/* read 'security.ima' */
 		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
 
+		/*
+		 * Read the appended modsig if allowed by the policy, and allow
+		 * an additional measurement list entry, if needed, based on the
+		 * template format and whether the file was already measured.
+		 */
+		if (iint->flags & IMA_MODSIG_ALLOWED) {
+			rc = ima_read_modsig(func, buf, size, &modsig);
+
+			if (!rc && ima_template_has_modsig(template_desc) &&
+			    iint->flags & IMA_MEASURED)
+				action |= IMA_MEASURE;
+		}
+	}
+
 	hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 
-	rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
+	rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
 	if (rc != 0 && rc != -EBADF && rc != -EINVAL)
 		goto out_locked;
 
@@ -317,12 +332,12 @@ static int process_measurement(struct file *file, const struct cred *cred,
 
 	if (action & IMA_MEASURE)
 		ima_store_measurement(iint, file, pathname,
-				      xattr_value, xattr_len, pcr,
+				      xattr_value, xattr_len, modsig, pcr,
 				      template_desc);
 	if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
 		inode_lock(inode);
 		rc = ima_appraise_measurement(func, iint, file, pathname,
-					      xattr_value, xattr_len);
+					      xattr_value, xattr_len, modsig);
 		inode_unlock(inode);
 		if (!rc)
 			rc = mmap_violation_check(func, file, &pathbuf,
@@ -339,6 +354,7 @@ out_locked:
 		rc = -EACCES;
 	mutex_unlock(&iint->mutex);
 	kfree(xattr_value);
+	ima_free_modsig(modsig);
 out:
 	if (pathbuf)
 		__putname(pathbuf);
diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c
new file mode 100644
index 000000000000..d106885cc495
--- /dev/null
+++ b/security/integrity/ima/ima_modsig.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * IMA support for appraising module-style appended signatures.
+ *
+ * Copyright (C) 2019  IBM Corporation
+ *
+ * Author:
+ * Thiago Jung Bauermann <bauerman@linux.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/module_signature.h>
+#include <keys/asymmetric-type.h>
+#include <crypto/pkcs7.h>
+
+#include "ima.h"
+
+struct modsig {
+	struct pkcs7_message *pkcs7_msg;
+
+	enum hash_algo hash_algo;
+
+	/* This digest will go in the 'd-modsig' field of the IMA template. */
+	const u8 *digest;
+	u32 digest_size;
+
+	/*
+	 * This is what will go to the measurement list if the template requires
+	 * storing the signature.
+	 */
+	int raw_pkcs7_len;
+	u8 raw_pkcs7[];
+};
+
+/**
+ * ima_hook_supports_modsig - can the policy allow modsig for this hook?
+ *
+ * modsig is only supported by hooks using ima_post_read_file(), because only
+ * they preload the contents of the file in a buffer. FILE_CHECK does that in
+ * some cases, but not when reached from vfs_open(). POLICY_CHECK can support
+ * it, but it's not useful in practice because it's a text file so deny.
+ */
+bool ima_hook_supports_modsig(enum ima_hooks func)
+{
+	switch (func) {
+	case KEXEC_KERNEL_CHECK:
+	case KEXEC_INITRAMFS_CHECK:
+	case MODULE_CHECK:
+		return true;
+	default:
+		return false;
+	}
+}
+
+/*
+ * ima_read_modsig - Read modsig from buf.
+ *
+ * Return: 0 on success, error code otherwise.
+ */
+int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
+		    struct modsig **modsig)
+{
+	const size_t marker_len = strlen(MODULE_SIG_STRING);
+	const struct module_signature *sig;
+	struct modsig *hdr;
+	size_t sig_len;
+	const void *p;
+	int rc;
+
+	if (buf_len <= marker_len + sizeof(*sig))
+		return -ENOENT;
+
+	p = buf + buf_len - marker_len;
+	if (memcmp(p, MODULE_SIG_STRING, marker_len))
+		return -ENOENT;
+
+	buf_len -= marker_len;
+	sig = (const struct module_signature *)(p - sizeof(*sig));
+
+	rc = mod_check_sig(sig, buf_len, func_tokens[func]);
+	if (rc)
+		return rc;
+
+	sig_len = be32_to_cpu(sig->sig_len);
+	buf_len -= sig_len + sizeof(*sig);
+
+	/* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */
+	hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL);
+	if (!hdr)
+		return -ENOMEM;
+
+	hdr->pkcs7_msg = pkcs7_parse_message(buf + buf_len, sig_len);
+	if (IS_ERR(hdr->pkcs7_msg)) {
+		rc = PTR_ERR(hdr->pkcs7_msg);
+		kfree(hdr);
+		return rc;
+	}
+
+	memcpy(hdr->raw_pkcs7, buf + buf_len, sig_len);
+	hdr->raw_pkcs7_len = sig_len;
+
+	/* We don't know the hash algorithm yet. */
+	hdr->hash_algo = HASH_ALGO__LAST;
+
+	*modsig = hdr;
+
+	return 0;
+}
+
+/**
+ * ima_collect_modsig - Calculate the file hash without the appended signature.
+ *
+ * Since the modsig is part of the file contents, the hash used in its signature
+ * isn't the same one ordinarily calculated by IMA. Therefore PKCS7 code
+ * calculates a separate one for signature verification.
+ */
+void ima_collect_modsig(struct modsig *modsig, const void *buf, loff_t size)
+{
+	int rc;
+
+	/*
+	 * Provide the file contents (minus the appended sig) so that the PKCS7
+	 * code can calculate the file hash.
+	 */
+	size -= modsig->raw_pkcs7_len + strlen(MODULE_SIG_STRING) +
+		sizeof(struct module_signature);
+	rc = pkcs7_supply_detached_data(modsig->pkcs7_msg, buf, size);
+	if (rc)
+		return;
+
+	/* Ask the PKCS7 code to calculate the file hash. */
+	rc = pkcs7_get_digest(modsig->pkcs7_msg, &modsig->digest,
+			      &modsig->digest_size, &modsig->hash_algo);
+}
+
+int ima_modsig_verify(struct key *keyring, const struct modsig *modsig)
+{
+	return verify_pkcs7_message_sig(NULL, 0, modsig->pkcs7_msg, keyring,
+					VERIFYING_MODULE_SIGNATURE, NULL, NULL);
+}
+
+int ima_get_modsig_digest(const struct modsig *modsig, enum hash_algo *algo,
+			  const u8 **digest, u32 *digest_size)
+{
+	*algo = modsig->hash_algo;
+	*digest = modsig->digest;
+	*digest_size = modsig->digest_size;
+
+	return 0;
+}
+
+int ima_get_raw_modsig(const struct modsig *modsig, const void **data,
+		       u32 *data_len)
+{
+	*data = &modsig->raw_pkcs7;
+	*data_len = modsig->raw_pkcs7_len;
+
+	return 0;
+}
+
+void ima_free_modsig(struct modsig *modsig)
+{
+	if (!modsig)
+		return;
+
+	pkcs7_free_message(modsig->pkcs7_msg);
+	kfree(modsig);
+}
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 6df7f641ff66..4badc4fcda98 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -6,6 +6,9 @@
  * ima_policy.c
  *	- initialize default measure policy rules
  */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/fs.h>
@@ -491,6 +494,9 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid,
 	struct ima_rule_entry *entry;
 	int action = 0, actmask = flags | (flags << 1);
 
+	if (template_desc)
+		*template_desc = ima_template_desc_current();
+
 	rcu_read_lock();
 	list_for_each_entry_rcu(entry, ima_rules, list) {
 
@@ -510,6 +516,7 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid,
 				action |= IMA_FAIL_UNVERIFIABLE_SIGS;
 		}
 
+
 		if (entry->action & IMA_DO_MASK)
 			actmask &= ~(entry->action | entry->action << 1);
 		else
@@ -520,8 +527,6 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid,
 
 		if (template_desc && entry->template)
 			*template_desc = entry->template;
-		else if (template_desc)
-			*template_desc = ima_template_desc_current();
 
 		if (!actmask)
 			break;
@@ -843,6 +848,38 @@ static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 	ima_log_string_op(ab, key, value, NULL);
 }
 
+/*
+ * Validating the appended signature included in the measurement list requires
+ * the file hash calculated without the appended signature (i.e., the 'd-modsig'
+ * field). Therefore, notify the user if they have the 'modsig' field but not
+ * the 'd-modsig' field in the template.
+ */
+static void check_template_modsig(const struct ima_template_desc *template)
+{
+#define MSG "template with 'modsig' field also needs 'd-modsig' field\n"
+	bool has_modsig, has_dmodsig;
+	static bool checked;
+	int i;
+