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Tue, 30 Jan 2024 21:46:27 +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, miklos@szeredi.hu, Stefan Berger Subject: [PATCH 1/5] security: allow finer granularity in permitting copy-up of security xattrs Date: Tue, 30 Jan 2024 16:46:16 -0500 Message-ID: <20240130214620.3155380-2-stefanb@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240130214620.3155380-1-stefanb@linux.ibm.com> References: <20240130214620.3155380-1-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-GUID: nsNshzt1SCogKEXlGy533T4CUsAVBwI3 X-Proofpoint-ORIG-GUID: YWDCNKq7p8-nPtFrvnuRxTAM3vP-0P-x 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=2024-01-30_12,2024-01-30_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=562 impostorscore=0 phishscore=0 adultscore=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 spamscore=0 malwarescore=0 priorityscore=1501 suspectscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2401300162 Copying up xattrs is solely based on the security xattr name. For finer granularity add a dentry parameter to the security_inode_copy_up_xattr hook definition, allowing decisions to be based on the xattr content as well. Signed-off-by: Stefan Berger --- fs/overlayfs/copy_up.c | 2 +- include/linux/evm.h | 2 +- include/linux/lsm_hook_defs.h | 3 ++- include/linux/security.h | 4 ++-- security/integrity/evm/evm_main.c | 2 +- security/security.c | 7 ++++--- security/selinux/hooks.c | 2 +- security/smack/smack_lsm.c | 2 +- 8 files changed, 13 insertions(+), 11 deletions(-) diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index b8e25ca51016..bd9ddcefb7a7 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -114,7 +114,7 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct de if (ovl_is_private_xattr(sb, name)) continue; - error = security_inode_copy_up_xattr(name); + error = security_inode_copy_up_xattr(old, name); if (error < 0 && error != -EOPNOTSUPP) break; if (error == 1) { diff --git a/include/linux/evm.h b/include/linux/evm.h index 36ec884320d9..d8c0343436b8 100644 --- a/include/linux/evm.h +++ b/include/linux/evm.h @@ -31,7 +31,7 @@ extern void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, const void *xattr_value, size_t xattr_value_len); -extern int evm_inode_copy_up_xattr(const char *name); +extern int evm_inode_copy_up_xattr(struct dentry *dentry, const char *name); extern int evm_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *xattr_name); extern void evm_inode_post_removexattr(struct dentry *dentry, diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 185924c56378..7dd61f51d84a 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -163,7 +163,8 @@ LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer, size_t buffer_size) LSM_HOOK(void, LSM_RET_VOID, inode_getsecid, struct inode *inode, u32 *secid) LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new) -LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, const char *name) +LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, struct dentry *src, + const char *name) LSM_HOOK(int, 0, kernfs_init_security, struct kernfs_node *kn_dir, struct kernfs_node *kn) LSM_HOOK(int, 0, file_permission, struct file *file, int mask) diff --git a/include/linux/security.h b/include/linux/security.h index d0eb20f90b26..9fc9ca6284d6 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -387,7 +387,7 @@ int security_inode_setsecurity(struct inode *inode, const char *name, const void int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size); void security_inode_getsecid(struct inode *inode, u32 *secid); int security_inode_copy_up(struct dentry *src, struct cred **new); -int security_inode_copy_up_xattr(const char *name); +int security_inode_copy_up_xattr(struct dentry *src, const char *name); int security_kernfs_init_security(struct kernfs_node *kn_dir, struct kernfs_node *kn); int security_file_permission(struct file *file, int mask); @@ -980,7 +980,7 @@ static inline int security_kernfs_init_security(struct kernfs_node *kn_dir, return 0; } -static inline int security_inode_copy_up_xattr(const char *name) +static inline int security_inode_copy_up_xattr(struct dentry *src, const char *name) { return -EOPNOTSUPP; } diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index cc7956d7878b..2555aa4501ae 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -896,7 +896,7 @@ void evm_inode_post_setattr(struct dentry *dentry, int ia_valid) evm_update_evmxattr(dentry, NULL, NULL, 0); } -int evm_inode_copy_up_xattr(const char *name) +int evm_inode_copy_up_xattr(struct dentry *src, const char *name) { if (strcmp(name, XATTR_NAME_EVM) == 0) return 1; /* Discard */ diff --git a/security/security.c b/security/security.c index 0144a98d3712..ee63863c1dc0 100644 --- a/security/security.c +++ b/security/security.c @@ -2596,6 +2596,7 @@ EXPORT_SYMBOL(security_inode_copy_up); /** * security_inode_copy_up_xattr() - Filter xattrs in an overlayfs copy-up op + * @src: union dentry of copy-up file * @name: xattr name * * Filter the xattrs being copied up when a unioned file is copied up from a @@ -2606,7 +2607,7 @@ EXPORT_SYMBOL(security_inode_copy_up); * if the security module does not know about attribute, or a negative * error code to abort the copy up. */ -int security_inode_copy_up_xattr(const char *name) +int security_inode_copy_up_xattr(struct dentry *src, const char *name) { struct security_hook_list *hp; int rc; @@ -2618,12 +2619,12 @@ int security_inode_copy_up_xattr(const char *name) */ hlist_for_each_entry(hp, &security_hook_heads.inode_copy_up_xattr, list) { - rc = hp->hook.inode_copy_up_xattr(name); + rc = hp->hook.inode_copy_up_xattr(src, name); if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr)) return rc; } - return evm_inode_copy_up_xattr(name); + return evm_inode_copy_up_xattr(src, name); } EXPORT_SYMBOL(security_inode_copy_up_xattr); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index a6bf90ace84c..ebb8876837c6 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3530,7 +3530,7 @@ static int selinux_inode_copy_up(struct dentry *src, struct cred **new) return 0; } -static int selinux_inode_copy_up_xattr(const char *name) +static int selinux_inode_copy_up_xattr(struct dentry *dentry, const char *name) { /* The copy_up hook above sets the initial context on an inode, but we * don't then want to overwrite it by blindly copying all the lower diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 0fdbf04cc258..bffca165f07f 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4873,7 +4873,7 @@ static int smack_inode_copy_up(struct dentry *dentry, struct cred **new) return 0; } -static int smack_inode_copy_up_xattr(const char *name) +static int smack_inode_copy_up_xattr(struct dentry *src, const char *name) { /* * Return 1 if this is the smack access Smack attribute.