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

…ernel/git/jmorris/linux-security

Pull integrity updates from James Morris:
 "A mixture of bug fixes, code cleanup, and continues to close
  IMA-measurement, IMA-appraisal, and IMA-audit gaps.

  Also note the addition of a new cred_getsecid LSM hook by Matthew
  Garrett:

     For IMA purposes, we want to be able to obtain the prepared secid
     in the bprm structure before the credentials are committed. Add a
     cred_getsecid hook that makes this possible.

  which is used by a new CREDS_CHECK target in IMA:

     In ima_bprm_check(), check with both the existing process
     credentials and the credentials that will be committed when the new
     process is started. This will not change behaviour unless the
     system policy is extended to include CREDS_CHECK targets -
     BPRM_CHECK will continue to check the same credentials that it did
     previously"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  ima: Fallback to the builtin hash algorithm
  ima: Add smackfs to the default appraise/measure list
  evm: check for remount ro in progress before writing
  ima: Improvements in ima_appraise_measurement()
  ima: Simplify ima_eventsig_init()
  integrity: Remove unused macro IMA_ACTION_RULE_FLAGS
  ima: drop vla in ima_audit_measurement()
  ima: Fix Kconfig to select TPM 2.0 CRB interface
  evm: Constify *integrity_status_msg[]
  evm: Move evm_hmac and evm_hash from evm_main.c to evm_crypto.c
  fuse: define the filesystem as untrusted
  ima: fail signature verification based on policy
  ima: clear IMA_HASH
  ima: re-evaluate files on privileged mounted filesystems
  ima: fail file signature verification on non-init mounted filesystems
  IMA: Support using new creds in appraisal policy
  security: Add a cred_getsecid hook

Documentation/ABI/testing/ima_policy

@@ -26,7 +26,7 @@ Description:
 				 [obj_user=] [obj_role=] [obj_type=]]
 			option:	[[appraise_type=]] [permit_directio]
 
-		base: 	func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
+		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
 				[FIRMWARE_CHECK]
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
 			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]

Documentation/admin-guide/kernel-parameters.txt

@@ -1521,7 +1521,8 @@
 
 	ima_policy=	[IMA]
 			The builtin policies to load during IMA setup.
-			Format: "tcb | appraise_tcb | secure_boot"
+			Format: "tcb | appraise_tcb | secure_boot |
+				 fail_securely"
 
 			The "tcb" policy measures all programs exec'd, files
 			mmap'd for exec, and all files opened with the read
@@ -1536,6 +1537,11 @@
 			of files (eg. kexec kernel image, kernel modules,
 			firmware, policy, etc) based on file signatures.
 
+			The "fail_securely" policy forces file signature
+			verification failure also on privileged mounted
+			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
+			flag.
+
 	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
 			Load a policy which meets the needs of the Trusted
 			Computing Base.  This means IMA will measure all

fs/fuse/inode.c

@@ -1080,6 +1080,9 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_time_gran = 1;
 	sb->s_export_op = &fuse_export_operations;
+	sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE;
+	if (sb->s_user_ns != &init_user_ns)
+		sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER;
 
 	file = fget(d.fd);
 	err = -EINVAL;

include/linux/fs.h

@@ -1321,6 +1321,8 @@ extern int send_sigurg(struct fown_struct *fown);
 
 /* sb->s_iflags to limit user namespace mounts */
 #define SB_I_USERNS_VISIBLE		0x00000010 /* fstype already mounted */
+#define SB_I_IMA_UNVERIFIABLE_SIGNATURE	0x00000020
+#define SB_I_UNTRUSTED_MOUNTER		0x00000040
 
 /* Possible states of 'frozen' field */
 enum {

include/linux/lsm_hooks.h

@@ -554,6 +554,10 @@
  *	@new points to the new credentials.
  *	@old points to the original credentials.
  *	Transfer data from original creds to new creds
+ * @cred_getsecid:
+ *	Retrieve the security identifier of the cred structure @c
+ *	@c contains the credentials, secid will be placed into @secid.
+ *	In case of failure, @secid will be set to zero.
  * @kernel_act_as:
  *	Set the credentials for a kernel service to act as (subjective context).
  *	@new points to the credentials to be modified.
@@ -1569,6 +1573,7 @@ union security_list_options {
 	int (*cred_prepare)(struct cred *new, const struct cred *old,
 				gfp_t gfp);
 	void (*cred_transfer)(struct cred *new, const struct cred *old);
+	void (*cred_getsecid)(const struct cred *c, u32 *secid);
 	int (*kernel_act_as)(struct cred *new, u32 secid);
 	int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
 	int (*kernel_module_request)(char *kmod_name);
@@ -1858,6 +1863,7 @@ struct security_hook_heads {
 	struct hlist_head cred_free;
 	struct hlist_head cred_prepare;
 	struct hlist_head cred_transfer;
+	struct hlist_head cred_getsecid;
 	struct hlist_head kernel_act_as;
 	struct hlist_head kernel_create_files_as;
 	struct hlist_head kernel_read_file;

include/linux/security.h

@@ -322,6 +322,7 @@ int security_cred_alloc_blank(struct cred *cred, gfp_t gfp);
 void security_cred_free(struct cred *cred);
 int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
 void security_transfer_creds(struct cred *new, const struct cred *old);
+void security_cred_getsecid(const struct cred *c, u32 *secid);
 int security_kernel_act_as(struct cred *new, u32 secid);
 int security_kernel_create_files_as(struct cred *new, struct inode *inode);
 int security_kernel_module_request(char *kmod_name);

security/integrity/evm/evm.h

@@ -31,8 +31,6 @@
 		       EVM_ALLOW_METADATA_WRITES)
 
 extern int evm_initialized;
-extern char *evm_hmac;
-extern char *evm_hash;
 
 #define EVM_ATTR_FSUUID		0x0001
 

security/integrity/evm/evm_crypto.c

@@ -37,6 +37,9 @@ static DEFINE_MUTEX(mutex);
 
 static unsigned long evm_set_key_flags;
 
+static char * const evm_hmac = "hmac(sha1)";
+static char * const evm_hash = "sha1";
+
 /**
  * evm_set_key() - set EVM HMAC key from the kernel
  * @key: pointer to a buffer with the key data

security/integrity/evm/evm_main.c

@@ -30,11 +30,9 @@
 
 int evm_initialized;
 
-static char *integrity_status_msg[] = {
+static const char * const integrity_status_msg[] = {
 	"pass", "pass_immutable", "fail", "no_label", "no_xattrs", "unknown"
 };
-char *evm_hmac = "hmac(sha1)";
-char *evm_hash = "sha1";
 int evm_hmac_attrs;
 
 char *evm_config_xattrnames[] = {
@@ -126,6 +124,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 	struct evm_ima_xattr_data *xattr_data = NULL;
 	struct evm_ima_xattr_data calc;
 	enum integrity_status evm_status = INTEGRITY_PASS;
+	struct inode *inode;
 	int rc, xattr_len;
 
 	if (iint && (iint->evm_status == INTEGRITY_PASS ||
@@ -180,12 +179,15 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 					(const char *)xattr_data, xattr_len,
 					calc.digest, sizeof(calc.digest));
 		if (!rc) {
+			inode = d_backing_inode(dentry);
+
 			if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
 				if (iint)
 					iint->flags |= EVM_IMMUTABLE_DIGSIG;
 				evm_status = INTEGRITY_PASS_IMMUTABLE;
-			} else if (!IS_RDONLY(d_backing_inode(dentry)) &&
-				   !IS_IMMUTABLE(d_backing_inode(dentry))) {
+			} else if (!IS_RDONLY(inode) &&
+				   !(inode->i_sb->s_readonly_remount) &&
+				   !IS_IMMUTABLE(inode)) {
 				evm_update_evmxattr(dentry, xattr_name,
 						    xattr_value,
 						    xattr_value_len);

security/integrity/iint.c

@@ -79,6 +79,7 @@ static void iint_free(struct integrity_iint_cache *iint)
 	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 	iint->ima_read_status = INTEGRITY_UNKNOWN;
+	iint->ima_creds_status = INTEGRITY_UNKNOWN;
 	iint->evm_status = INTEGRITY_UNKNOWN;
 	iint->measured_pcrs = 0;
 	kmem_cache_free(iint_cache, iint);
@@ -158,6 +159,7 @@ static void init_once(void *foo)
 	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 	iint->ima_read_status = INTEGRITY_UNKNOWN;
+	iint->ima_creds_status = INTEGRITY_UNKNOWN;
 	iint->evm_status = INTEGRITY_UNKNOWN;
 	mutex_init(&iint->mutex);
 }

security/integrity/ima/Kconfig

@@ -10,6 +10,7 @@ config IMA
 	select CRYPTO_HASH_INFO
 	select TCG_TPM if HAS_IOMEM && !UML
 	select TCG_TIS if TCG_TPM && X86
+	select TCG_CRB if TCG_TPM && ACPI
 	select TCG_IBMVTPM if TCG_TPM && PPC_PSERIES
 	help
 	  The Trusted Computing Group(TCG) runtime Integrity

security/integrity/ima/ima.h

@@ -177,6 +177,7 @@ static inline unsigned long ima_hash_key(u8 *digest)
 	hook(FILE_CHECK)		\
 	hook(MMAP_CHECK)		\
 	hook(BPRM_CHECK)		\
+	hook(CREDS_CHECK)		\
 	hook(POST_SETATTR)		\
 	hook(MODULE_CHECK)		\
 	hook(FIRMWARE_CHECK)		\
@@ -191,8 +192,8 @@ enum ima_hooks {
 };
 
 /* LIM API function definitions */
-int ima_get_action(struct inode *inode, int mask,
-		   enum ima_hooks func, int *pcr);
+int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
+		   int mask, enum ima_hooks func, int *pcr);
 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,
@@ -212,8 +213,8 @@ void ima_free_template_entry(struct ima_template_entry *entry);
 const char *ima_d_path(const struct path *path, char **pathbuf, char *filename);
 
 /* IMA policy related functions */
-int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
-		     int flags, int *pcr);
+int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid,
+		     enum ima_hooks func, int mask, int flags, int *pcr);
 void ima_init_policy(void);
 void ima_update_policy(void);
 void ima_update_policy_flag(void);

security/integrity/ima/ima_api.c

@@ -158,6 +158,8 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
 /**
  * ima_get_action - appraise & measure decision based on policy.
  * @inode: pointer to inode to measure
+ * @cred: pointer to credentials structure to validate
+ * @secid: secid of the task being validated
  * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXEC,
  *        MAY_APPEND)
  * @func: caller identifier
@@ -166,20 +168,21 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
  * The policy is defined in terms of keypairs:
  *		subj=, obj=, type=, func=, mask=, fsmagic=
  *	subj,obj, and type: are LSM specific.
- *	func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK
+ *	func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK
  *	mask: contains the permission mask
  *	fsmagic: hex value
  *
  * Returns IMA_MEASURE, IMA_APPRAISE mask.
  *
  */
-int ima_get_action(struct inode *inode, int mask, enum ima_hooks func, int *pcr)
+int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
+		   int mask, enum ima_hooks func, int *pcr)
 {
 	int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE | IMA_HASH;
 
 	flags &= ima_policy_flag;
 
-	return ima_match_policy(inode, func, mask, flags, pcr);
+	return ima_match_policy(inode, cred, secid, func, mask, flags, pcr);
 }
 
 /*
@@ -308,33 +311,37 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
 			   const unsigned char *filename)
 {
 	struct audit_buffer *ab;
-	char hash[(iint->ima_hash->length * 2) + 1];
+	char *hash;
 	const char *algo_name = hash_algo_name[iint->ima_hash->algo];
-	char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
 	int i;
 
 	if (iint->flags & IMA_AUDITED)
 		return;
 
+	hash = kzalloc((iint->ima_hash->length * 2) + 1, GFP_KERNEL);
+	if (!hash)
+		return;
+
 	for (i = 0; i < iint->ima_hash->length; i++)
 		hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
 	hash[i * 2] = '\0';
 
 	ab = audit_log_start(current->audit_context, GFP_KERNEL,
 			     AUDIT_INTEGRITY_RULE);
 	if (!ab)
-		return;
+		goto out;
 
 	audit_log_format(ab, "file=");
 	audit_log_untrustedstring(ab, filename);
-	audit_log_format(ab, " hash=");
-	snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
-	audit_log_untrustedstring(ab, algo_hash);
+	audit_log_format(ab, " hash=\"%s:%s\"", algo_name, hash);
 
 	audit_log_task_info(ab, current);
 	audit_log_end(ab);
 
 	iint->flags |= IMA_AUDITED;
+out:
+	kfree(hash);
+	return;
 }
 
 /*