[PATCH v6 2/6] lsm: introduce new hooks for setting/getting inode fsxattr

Andrey Albershteyn
2025-06-30T16:20:37Z

Introduce new hooks for setting and getting filesystem extended
attributes on inode (FS_IOC_FSGETXATTR).

Cc: selinux@vger.kernel.org
Cc: Paul Moore <paul@paul-moore.com>

Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
fs/file_attr.c | 19 ++++++++++++++++---
include/linux/lsm_hook_defs.h | 2 ++
include/linux/security.h | 16 ++++++++++++++++
security/security.c | 30 ++++++++++++++++++++++++++++++
4 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/fs/file_attr.c b/fs/file_attr.c
index 2910b7047721..be62d97cc444 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -76,10 +76,15 @@ EXPORT_SYMBOL(fileattr_fill_flags);
int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
struct inode *inode = d_inode(dentry);
+ int error;

if (!inode->i_op->fileattr_get)
return -ENOIOCTLCMD;

+ error = security_inode_file_getattr(dentry, fa);
+ if (error)
+ return error;
+
return inode->i_op->fileattr_get(dentry, fa);
}
EXPORT_SYMBOL(vfs_fileattr_get);
@@ -242,12 +247,20 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
} else {
fa->flags |= old_ma.flags & ~FS_COMMON_FL;
}
+
err = fileattr_set_prepare(inode, &old_ma, fa);
- if (!err)
- err = inode->i_op->fileattr_set(idmap, dentry, fa);
+ if (err)
+ goto out;
+ err = security_inode_file_setattr(dentry, fa);
+ if (err)
+ goto out;
+ err = inode->i_op->fileattr_set(idmap, dentry, fa);
+ if (err)
+ goto out;
}
+
+out:
inode_unlock(inode);
-
return err;
}
EXPORT_SYMBOL(vfs_fileattr_set);
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index bf3bbac4e02a..9600a4350e79 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -157,6 +157,8 @@ LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
struct dentry *dentry, const char *name)
LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
const char *name)
+LSM_HOOK(int, 0, inode_file_setattr, struct dentry *dentry, struct fileattr *fa)
+LSM_HOOK(int, 0, inode_file_getattr, struct dentry *dentry, struct fileattr *fa)
LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
LSM_HOOK(void, LSM_RET_VOID, inode_post_set_acl, struct dentry *dentry,
diff --git a/include/linux/security.h b/include/linux/security.h
index dba349629229..9ed0d0e0c81f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -451,6 +451,10 @@ int security_inode_listxattr(struct dentry *dentry);
int security_inode_removexattr(struct mnt_idmap *idmap,
struct dentry *dentry, const char *name);
void security_inode_post_removexattr(struct dentry *dentry, const char *name);
+int security_inode_file_setattr(struct dentry *dentry,
+ struct fileattr *fa);
+int security_inode_file_getattr(struct dentry *dentry,
+ struct fileattr *fa);
int security_inode_need_killpriv(struct dentry *dentry);
int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
int security_inode_getsecurity(struct mnt_idmap *idmap,
@@ -1052,6 +1056,18 @@ static inline void security_inode_post_removexattr(struct dentry *dentry,
const char *name)
{ }

+static inline int security_inode_file_setattr(struct dentry *dentry,
+ struct fileattr *fa)
+{
+ return 0;
+}
+
+static inline int security_inode_file_getattr(struct dentry *dentry,
+ struct fileattr *fa)
+{
+ return 0;
+}
+
static inline int security_inode_need_killpriv(struct dentry *dentry)
{
return cap_inode_need_killpriv(dentry);
diff --git a/security/security.c b/security/security.c
index 596d41818577..711b4de40b8d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2622,6 +2622,36 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name)
call_void_hook(inode_post_removexattr, dentry, name);
}

+/**
+ * security_inode_file_setattr() - check if setting fsxattr is allowed
+ * @dentry: file to set filesystem extended attributes on
+ * @fa: extended attributes to set on the inode
+ *
+ * Called when file_setattr() syscall or FS_IOC_FSSETXATTR ioctl() is called on
+ * inode
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_inode_file_setattr(struct dentry *dentry, struct fileattr *fa)
+{
+ return call_int_hook(inode_file_setattr, dentry, fa);
+}
+
+/**
+ * security_inode_file_getattr() - check if retrieving fsxattr is allowed
+ * @dentry: file to retrieve filesystem extended attributes from
+ * @fa: extended attributes to get
+ *
+ * Called when file_getattr() syscall or FS_IOC_FSGETXATTR ioctl() is called on
+ * inode
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_inode_file_getattr(struct dentry *dentry, struct fileattr *fa)
+{
+ return call_int_hook(inode_file_getattr, dentry, fa);
+}
+
/**
* security_inode_need_killpriv() - Check if security_inode_killpriv() required
* @dentry: associated dentry

--
2.47.2