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

Pull Integrity subsystem fix from James Morris:
 "These changes fix a bug in xattr handling, where the evm and ima
  inode_setxattr() functions do not check for empty xattrs being passed
  from userspace (leading to user-triggerable null pointer
  dereferences)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  evm: check xattr value length and type in evm_inode_setxattr()
  ima: check xattr value length and type in the ima_inode_setxattr()

3 files changed, 9 insertions, 3 deletions

diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 9685af330de5..c5ee1a7c5e8a 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -319,9 +319,12 @@ int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 {
         const struct evm_ima_xattr_data *xattr_data = xattr_value;
 
-        if ((strcmp(xattr_name, XATTR_NAME_EVM) == 0)
-            && (xattr_data->type == EVM_XATTR_HMAC))
-                return -EPERM;
+        if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+                if (!xattr_value_len)
+                        return -EINVAL;
+                if (xattr_data->type != EVM_IMA_XATTR_DIGSIG)
+                        return -EPERM;
+        }
         return evm_protect_xattr(dentry, xattr_name, xattr_value,
                                  xattr_value_len);
 }
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 922685483bd3..7c8f41e618b6 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -378,6 +378,8 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
         result = ima_protect_xattr(dentry, xattr_name, xattr_value,
                                    xattr_value_len);
         if (result == 1) {
+                if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
+                        return -EINVAL;
                 ima_reset_appraise_flags(dentry->d_inode,
                          (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
                 result = 0;
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index c0379d13dbe1..9d1c2ebfe12a 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -61,6 +61,7 @@ enum evm_ima_xattr_type {
         EVM_XATTR_HMAC,
         EVM_IMA_XATTR_DIGSIG,
         IMA_XATTR_DIGEST_NG,
+        IMA_XATTR_LAST
 };
 
 struct evm_ima_xattr_data {