On Jan 15, 2024 Roberto Sassu <roberto.sassu@huaweicloud.com> wrote:
>
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the inode_post_remove_acl hook.
>
> At inode_remove_acl hook, EVM verifies the file's existing HMAC value. At
> inode_post_remove_acl, EVM re-calculates the file's HMAC with the passed
> POSIX ACL removed and other file metadata.
>
> Other LSMs could similarly take some action after successful POSIX ACL
> removal.
>
> The new hook cannot return an error and cannot cause the operation to be
> reverted.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
> fs/posix_acl.c | 1 +
> include/linux/lsm_hook_defs.h | 2 ++
> include/linux/security.h | 8 ++++++++
> security/security.c | 17 +++++++++++++++++
> 4 files changed, 28 insertions(+)
Acked-by: Paul Moore <paul@paul-moore.com>
--
paul-moore.com
On Mon, Jan 15, 2024 at 07:18:01PM +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the inode_post_remove_acl hook.
>
> At inode_remove_acl hook, EVM verifies the file's existing HMAC value. At
> inode_post_remove_acl, EVM re-calculates the file's HMAC with the passed
> POSIX ACL removed and other file metadata.
>
> Other LSMs could similarly take some action after successful POSIX ACL
> removal.
>
> The new hook cannot return an error and cannot cause the operation to be
> reverted.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
> fs/posix_acl.c | 1 +
Acked-by: Christian Brauner <brauner@kernel.org>
@@ -1246,6 +1246,7 @@ int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
error = -EIO;
if (!error) {
fsnotify_xattr(dentry);
+ security_inode_post_remove_acl(idmap, dentry, acl_name);
evm_inode_post_remove_acl(idmap, dentry, acl_name);
}
@@ -163,6 +163,8 @@ LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
struct dentry *dentry, const char *acl_name)
LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap,
struct dentry *dentry, const char *acl_name)
+LSM_HOOK(void, LSM_RET_VOID, inode_post_remove_acl, struct mnt_idmap *idmap,
+ struct dentry *dentry, const char *acl_name)
LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry)
LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap,
struct dentry *dentry)
@@ -378,6 +378,9 @@ int security_inode_get_acl(struct mnt_idmap *idmap,
struct dentry *dentry, const char *acl_name);
int security_inode_remove_acl(struct mnt_idmap *idmap,
struct dentry *dentry, const char *acl_name);
+void security_inode_post_remove_acl(struct mnt_idmap *idmap,
+ struct dentry *dentry,
+ const char *acl_name);
void security_inode_post_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags);
int security_inode_getxattr(struct dentry *dentry, const char *name);
@@ -936,6 +939,11 @@ static inline int security_inode_remove_acl(struct mnt_idmap *idmap,
return 0;
}
+static inline void security_inode_post_remove_acl(struct mnt_idmap *idmap,
+ struct dentry *dentry,
+ const char *acl_name)
+{ }
+
static inline void security_inode_post_setxattr(struct dentry *dentry,
const char *name, const void *value, size_t size, int flags)
{ }
@@ -2413,6 +2413,23 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,
return evm_inode_remove_acl(idmap, dentry, acl_name);
}
+/**
+ * security_inode_post_remove_acl() - Update inode security after rm posix acls
+ * @idmap: idmap of the mount
+ * @dentry: file
+ * @acl_name: acl name
+ *
+ * Update inode security data after successfully removing posix acls on
+ * @dentry in @idmap. The posix acls are identified by @acl_name.
+ */
+void security_inode_post_remove_acl(struct mnt_idmap *idmap,
+ struct dentry *dentry, const char *acl_name)
+{
+ if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+ return;
+ call_void_hook(inode_post_remove_acl, idmap, dentry, acl_name);
+}
+
/**
* security_inode_post_setxattr() - Update the inode after a setxattr operation
* @dentry: file