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Fri, 23 Feb 2024 17:25:24 +0000 (GMT) From: Stefan Berger To: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-unionfs@vger.kernel.org Cc: linux-kernel@vger.kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, zohar@linux.ibm.com, roberto.sassu@huawei.com, amir73il@gmail.com, brauner@kernel.org, miklos@szeredi.hu, Stefan Berger Subject: [PATCH v3 06/10] evm: Store and detect metadata inode attributes changes Date: Fri, 23 Feb 2024 12:25:09 -0500 Message-ID: <20240223172513.4049959-7-stefanb@linux.ibm.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240223172513.4049959-1-stefanb@linux.ibm.com> References: <20240223172513.4049959-1-stefanb@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: e_QrGgerAJUVMuykYqcHw0goeNliW3w- X-Proofpoint-GUID: KdMqPSLvVlyuwRUn_7e2mInceBcH8qMX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-23_03,2024-02-23_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 mlxscore=0 lowpriorityscore=0 adultscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 spamscore=0 impostorscore=0 phishscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2402230127 On stacked filesystem the metadata inode may be different than the one file data inode and therefore changes to it need to be detected independently. Therefore, store the i_version, device number, and inode number associated with the file metadata inode. Implement a function to detect changes to the inode and if a change is detected reset the evm_status. This function will be called by IMA when IMA detects that the metadata inode is different from the file's inode. Co-developed-by: Mimi Zohar Signed-off-by: Stefan Berger --- include/linux/evm.h | 8 ++++++++ security/integrity/evm/evm.h | 6 ++++-- security/integrity/evm/evm_crypto.c | 23 ++++++++++++++++------ security/integrity/evm/evm_main.c | 30 +++++++++++++++++++++++++++-- 4 files changed, 57 insertions(+), 10 deletions(-) diff --git a/include/linux/evm.h b/include/linux/evm.h index d48d6da32315..ddece4a6b25d 100644 --- a/include/linux/evm.h +++ b/include/linux/evm.h @@ -26,6 +26,8 @@ extern int evm_protected_xattr_if_enabled(const char *req_xattr_name); extern int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, int buffer_size, char type, bool canonical_fmt); +extern bool evm_metadata_changed(struct inode *inode, + struct inode *metadata_inode); #ifdef CONFIG_FS_POSIX_ACL extern int posix_xattr_acl(const char *xattrname); #else @@ -76,5 +78,11 @@ static inline int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, return -EOPNOTSUPP; } +static inline bool evm_metadata_changed(struct inode *inode, + struct inode *metadata_inode) +{ + return false; +} + #endif /* CONFIG_EVM */ #endif /* LINUX_EVM_H */ diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h index eb1a2c343bd7..b357c0ca8d23 100644 --- a/security/integrity/evm/evm.h +++ b/security/integrity/evm/evm.h @@ -39,6 +39,7 @@ struct xattr_list { struct evm_iint_cache { unsigned long flags; enum integrity_status evm_status:4; + struct integrity_inode_attributes metadata_inode; }; extern struct lsm_blob_sizes evm_blob_sizes; @@ -74,11 +75,12 @@ int evm_update_evmxattr(struct dentry *dentry, size_t req_xattr_value_len); int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name, const char *req_xattr_value, - size_t req_xattr_value_len, struct evm_digest *data); + size_t req_xattr_value_len, struct evm_digest *data, + struct evm_iint_cache *iint); int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name, const char *req_xattr_value, size_t req_xattr_value_len, char type, - struct evm_digest *data); + struct evm_digest *data, struct evm_iint_cache *iint); int evm_init_hmac(struct inode *inode, const struct xattr *xattrs, char *hmac_val); int evm_init_secfs(void); diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 35416f55391c..7c06ffd633d2 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -221,7 +221,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, const char *req_xattr_name, const char *req_xattr_value, size_t req_xattr_value_len, - uint8_t type, struct evm_digest *data) + uint8_t type, struct evm_digest *data, + struct evm_iint_cache *iint) { struct inode *inode = d_inode(d_real(dentry, D_REAL_METADATA)); struct xattr_list *xattr; @@ -231,6 +232,7 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, int error; int size, user_space_size; bool ima_present = false; + u64 i_version = 0; if (!(inode->i_opflags & IOP_XATTR) || inode->i_sb->s_user_ns != &init_user_ns) @@ -294,6 +296,13 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, } hmac_add_misc(desc, inode, type, data->digest); + if (inode != d_backing_inode(dentry) && iint) { + if (IS_I_VERSION(inode)) + i_version = inode_query_iversion(inode); + integrity_inode_attrs_store(&iint->metadata_inode, i_version, + inode); + } + /* Portable EVM signatures must include an IMA hash */ if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present) error = -EPERM; @@ -305,18 +314,19 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name, const char *req_xattr_value, size_t req_xattr_value_len, - struct evm_digest *data) + struct evm_digest *data, struct evm_iint_cache *iint) { return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value, - req_xattr_value_len, EVM_XATTR_HMAC, data); + req_xattr_value_len, EVM_XATTR_HMAC, data, + iint); } int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name, const char *req_xattr_value, size_t req_xattr_value_len, - char type, struct evm_digest *data) + char type, struct evm_digest *data, struct evm_iint_cache *iint) { return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value, - req_xattr_value_len, type, data); + req_xattr_value_len, type, data, iint); } static int evm_is_immutable(struct dentry *dentry, struct inode *inode) @@ -357,6 +367,7 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, const char *xattr_value, size_t xattr_value_len) { struct inode *inode = d_backing_inode(dentry); + struct evm_iint_cache *iint = evm_iint_inode(inode); struct evm_digest data; int rc = 0; @@ -372,7 +383,7 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, data.hdr.algo = HASH_ALGO_SHA1; rc = evm_calc_hmac(dentry, xattr_name, xattr_value, - xattr_value_len, &data); + xattr_value_len, &data, iint); if (rc == 0) { data.hdr.xattr.sha1.type = EVM_XATTR_HMAC; rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index c658d2f1494b..c1ca0894cd8a 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -226,7 +226,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, digest.hdr.algo = HASH_ALGO_SHA1; rc = evm_calc_hmac(dentry, xattr_name, xattr_value, - xattr_value_len, &digest); + xattr_value_len, &digest, iint); if (rc) break; rc = crypto_memneq(xattr_data->data, digest.digest, @@ -247,7 +247,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, hdr = (struct signature_v2_hdr *)xattr_data; digest.hdr.algo = hdr->hash_algo; rc = evm_calc_hash(dentry, xattr_name, xattr_value, - xattr_value_len, xattr_data->type, &digest); + xattr_value_len, xattr_data->type, &digest, + iint); if (rc) break; rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM, @@ -733,6 +734,31 @@ static void evm_reset_status(struct inode *inode) iint->evm_status = INTEGRITY_UNKNOWN; } +/** + * evm_metadata_changed: Detect changes to the metadata + * @inode: a file's inode + * @metadata_inode: metadata inode + * + * On a stacked filesystem detect whether the metadata has changed. If this is + * the case reset the evm_status associated with the inode that represents the + * file. + */ +bool evm_metadata_changed(struct inode *inode, struct inode *metadata_inode) +{ + struct evm_iint_cache *iint = evm_iint_inode(inode); + bool ret = false; + + if (iint) { + ret = (!IS_I_VERSION(metadata_inode) || + integrity_inode_attrs_changed(&iint->metadata_inode, + metadata_inode)); + if (ret) + iint->evm_status = INTEGRITY_UNKNOWN; + } + + return ret; +} + /** * evm_revalidate_status - report whether EVM status re-validation is necessary * @xattr_name: pointer to the affected extended attribute name