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

Pull integrity updates from James Morris:
 "This contains a mixture of bug fixes, code cleanup, and new
  functionality. Of note is the integrity cache locking fix, file change
  detection, and support for a new EVM portable and immutable signature
  type.

  The re-introduction of the integrity cache lock (iint) fixes the
  problem of attempting to take the i_rwsem shared a second time, when
  it was previously taken exclusively. Defining atomic flags resolves
  the original iint/i_rwsem circular locking - accessing the file data
  vs. modifying the file metadata. Although it fixes the O_DIRECT
  problem as well, a subsequent patch is needed to remove the explicit
  O_DIRECT prevention.

  For performance reasons, detecting when a file has changed and needs
  to be re-measured, re-appraised, and/or re-audited, was limited to
  after the last writer has closed, and only if the file data has
  changed. Detecting file change is based on i_version. For filesystems
  that do not support i_version, remote filesystems, or userspace
  filesystems, the file was measured, appraised and/or audited once and
  never re-evaluated. Now local filesystems, which do not support
  i_version or are not mounted with the i_version option, assume the
  file has changed and are required to re-evaluate the file. This change
  does not address detecting file change on remote or userspace
  filesystems.

  Unlike file data signatures, which can be included and distributed in
  software packages (eg. rpm, deb), the existing EVM signature, which
  protects the file metadata, could not be included in software
  packages, as it includes file system specific information (eg. i_ino,
  possibly the UUID). This pull request defines a new EVM portable and
  immutable file metadata signature format, which can be included in
  software packages"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  ima/policy: fix parsing of fsuuid
  ima: Use i_version only when filesystem supports it
  integrity: remove unneeded initializations in integrity_iint_cache entries
  ima: log message to module appraisal error
  ima: pass filename to ima_rdwr_violation_check()
  ima: Fix line continuation format
  ima: support new "hash" and "dont_hash" policy actions
  ima: re-introduce own integrity cache lock
  EVM: Add support for portable signature format
  EVM: Allow userland to permit modification of EVM-protected metadata
  ima: relax requiring a file signature for new files with zero length

1 files changed, 26 insertions, 20 deletions

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 65fbcf3c32c7..f2803a40ff82 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -46,14 +46,15 @@ bool is_ima_appraise_enabled(void)
 /*
  * ima_must_appraise - set appraise flag
  *
- * Return 1 to appraise
+ * Return 1 to appraise or hash
  */
 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
 {
 	if (!ima_appraise)
 		return 0;
 
-	return ima_match_policy(inode, func, mask, IMA_APPRAISE, NULL);
+	return ima_match_policy(inode, func, mask, IMA_APPRAISE | IMA_HASH,
+				NULL);
 }
 
 static int ima_fix_xattr(struct dentry *dentry,
@@ -223,13 +224,16 @@ int ima_appraise_measurement(enum ima_hooks func,
 		if (opened & FILE_CREATED)
 			iint->flags |= IMA_NEW_FILE;
 		if ((iint->flags & IMA_NEW_FILE) &&
-		    !(iint->flags & IMA_DIGSIG_REQUIRED))
+		    (!(iint->flags & IMA_DIGSIG_REQUIRED) ||
+		     (inode->i_size == 0)))
 			status = INTEGRITY_PASS;
 		goto out;
 	}
 
 	status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
-	if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
+	if ((status != INTEGRITY_PASS) &&
+	    (status != INTEGRITY_PASS_IMMUTABLE) &&
+	    (status != INTEGRITY_UNKNOWN)) {
 		if ((status == INTEGRITY_NOLABEL)
 		    || (status == INTEGRITY_NOXATTRS))
 			cause = "missing-HMAC";
@@ -248,6 +252,7 @@ int ima_appraise_measurement(enum ima_hooks func,
 			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
@@ -266,7 +271,7 @@ int ima_appraise_measurement(enum ima_hooks func,
 		status = INTEGRITY_PASS;
 		break;
 	case EVM_IMA_XATTR_DIGSIG:
-		iint->flags |= IMA_DIGSIG;
+		set_bit(IMA_DIGSIG, &iint->atomic_flags);
 		rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
 					     (const char *)xattr_value, rc,
 					     iint->ima_hash->digest,
@@ -317,17 +322,20 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
 	int rc = 0;
 
 	/* do not collect and update hash for digital signatures */
-	if (iint->flags & IMA_DIGSIG)
+	if (test_bit(IMA_DIGSIG, &iint->atomic_flags))
 		return;
 
-	if (iint->ima_file_status != INTEGRITY_PASS)
+	if ((iint->ima_file_status != INTEGRITY_PASS) &&
+	    !(iint->flags & IMA_HASH))
 		return;
 
 	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
 	if (rc < 0)
 		return;
 
+	inode_lock(file_inode(file));
 	ima_fix_xattr(dentry, iint);
+	inode_unlock(file_inode(file));
 }
 
 /**
@@ -343,23 +351,21 @@ void ima_inode_post_setattr(struct dentry *dentry)
 {
 	struct inode *inode = d_backing_inode(dentry);
 	struct integrity_iint_cache *iint;
-	int must_appraise;
+	int action;
 
 	if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
 	    || !(inode->i_opflags & IOP_XATTR))
 		return;
 
-	must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
+	action = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
+	if (!action)
+		__vfs_removexattr(dentry, XATTR_NAME_IMA);
 	iint = integrity_iint_find(inode);
 	if (iint) {
-		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
-				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
-				 IMA_ACTION_RULE_FLAGS);
-		if (must_appraise)
-			iint->flags |= IMA_APPRAISE;
+		set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);
+		if (!action)
+			clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
 	}
-	if (!must_appraise)
-		__vfs_removexattr(dentry, XATTR_NAME_IMA);
 }
 
 /*
@@ -388,12 +394,12 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig)
 	iint = integrity_iint_find(inode);
 	if (!iint)
 		return;
-
-	iint->flags &= ~IMA_DONE_MASK;
 	iint->measured_pcrs = 0;
+	set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags);
 	if (digsig)
-		iint->flags |= IMA_DIGSIG;
-	return;
+		set_bit(IMA_DIGSIG, &iint->atomic_flags);
+	else
+		clear_bit(IMA_DIGSIG, &iint->atomic_flags);
 }
 
 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,