[PATCH v6 20/20] evm: add evm_inode_setattr to prevent updating an invalid security.evm
From: Mimi Zohar <hidden>
Date: 2011-06-02 12:25:53
Also in:
lkml
Subsystem:
extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
Permit changing of security.evm only when valid, unless in fixmode. Reported-by: Roberto Sassu <redacted> Signed-off-by: Mimi Zohar <redacted> --- include/linux/evm.h | 6 ++++++ security/integrity/evm/evm_main.c | 15 +++++++++++++++ security/security.c | 7 ++++++- 3 files changed, 27 insertions(+), 1 deletions(-)
diff --git a/include/linux/evm.h b/include/linux/evm.h
index 8db7b74..afc0669 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 03524e4..b0ce1e7 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 e00d2d7..4e9b89f 100644
--- a/security/security.c
+++ b/security/security.c@@ -532,9 +532,14 @@ 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);
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1.7.3.4