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authorMimi Zohar <zohar@linux.vnet.ibm.com>2011-05-13 12:53:38 -0400
committerMimi Zohar <zohar@linux.vnet.ibm.com>2011-07-18 12:29:50 -0400
commit817b54aa45db03437c6d09a7693fc6926eb8e822 (patch)
tree03d43f3abfbd8670e3a30a33ef868ec7705ef2c4
parent7102ebcd65c1cdb5d5a87c7c5cf7a46f5afb0cac (diff)
evm: add evm_inode_setattr to prevent updating an invalid security.evm
Permit changing of security.evm only when valid, unless in fixmode. Reported-by: Roberto Sassu <roberto.sassu@polito.it> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
-rw-r--r--include/linux/evm.h6
-rw-r--r--security/integrity/evm/evm_main.c15
-rw-r--r--security/security.c7
3 files changed, 27 insertions, 1 deletions
diff --git a/include/linux/evm.h b/include/linux/evm.h
index 6d4e89b020c5..db5556dcdd27 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h
@@ -19,6 +19,7 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry,
void *xattr_value,
size_t xattr_value_len,
struct integrity_iint_cache *iint);
+extern int evm_inode_setattr(struct dentry *dentry, struct iattr *attr);
extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
extern int evm_inode_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size);
@@ -44,6 +45,11 @@ static inline enum integrity_status evm_verifyxattr(struct dentry *dentry,
}
#endif
+static int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ return 0;
+}
+
static inline void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
{
return;
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 94d66af07aa4..8fc5b5d7ceaa 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -278,6 +278,21 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
}
/**
+ * evm_inode_setattr - prevent updating an invalid EVM extended attribute
+ * @dentry: pointer to the affected dentry
+ */
+int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ unsigned int ia_valid = attr->ia_valid;
+ enum integrity_status evm_status;
+
+ if (ia_valid & ~(ATTR_MODE | ATTR_UID | ATTR_GID))
+ return 0;
+ evm_status = evm_verify_current_integrity(dentry);
+ return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
+}
+
+/**
* evm_inode_post_setattr - update 'security.evm' after modifying metadata
* @dentry: pointer to the affected dentry
* @ia_valid: for the UID and GID status
diff --git a/security/security.c b/security/security.c
index 181990ae90c1..19251ccb2de0 100644
--- a/security/security.c
+++ b/security/security.c
@@ -571,9 +571,14 @@ int security_inode_exec_permission(struct inode *inode, unsigned int flags)
int security_inode_setattr(struct dentry *dentry, struct iattr *attr)
{
+ int ret;
+
if (unlikely(IS_PRIVATE(dentry->d_inode)))
return 0;
- return security_ops->inode_setattr(dentry, attr);
+ ret = security_ops->inode_setattr(dentry, attr);
+ if (ret)
+ return ret;
+ return evm_inode_setattr(dentry, attr);
}
EXPORT_SYMBOL_GPL(security_inode_setattr);