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| author | Mimi Zohar <zohar@linux.vnet.ibm.com> | 2011-05-13 12:53:38 -0400 |
|---|---|---|
| committer | Mimi Zohar <zohar@linux.vnet.ibm.com> | 2011-07-18 12:29:50 -0400 |
| commit | 817b54aa45db03437c6d09a7693fc6926eb8e822 (patch) | |
| tree | 03d43f3abfbd8670e3a30a33ef868ec7705ef2c4 | |
| parent | 7102ebcd65c1cdb5d5a87c7c5cf7a46f5afb0cac (diff) | |
| download | lwn-817b54aa45db03437c6d09a7693fc6926eb8e822.tar.gz lwn-817b54aa45db03437c6d09a7693fc6926eb8e822.zip | |
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.h | 6 | ||||
| -rw-r--r-- | security/integrity/evm/evm_main.c | 15 | ||||
| -rw-r--r-- | security/security.c | 7 |
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); |