[v13,16/25] LSM: Use lsmcontext in security_dentry_init_security
diff mbox series

Message ID 20191224235939.7483-17-casey@schaufler-ca.com
State Superseded
Headers show
Series
  • LSM: Module stacking for AppArmor
Related show

Commit Message

Casey Schaufler Dec. 24, 2019, 11:59 p.m. UTC
Change the security_dentry_init_security() interface to
fill an lsmcontext structure instead of a void * data area
and a length. The lone caller of this interface is NFS4,
which may make copies of the data using its own mechanisms.
A rework of the nfs4 code to use the lsmcontext properly
is a significant project. SELinux is handled correctly, and
is the only current user.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 fs/nfs/nfs4proc.c        | 15 ++++++++-------
 include/linux/security.h |  7 +++----
 security/security.c      | 29 +++++++++++++++++++++++++----
 3 files changed, 36 insertions(+), 15 deletions(-)

Comments

Stephen Smalley Jan. 7, 2020, 7:23 p.m. UTC | #1
On 12/24/19 6:59 PM, Casey Schaufler wrote:
> Change the security_dentry_init_security() interface to
> fill an lsmcontext structure instead of a void * data area
> and a length. The lone caller of this interface is NFS4,
> which may make copies of the data using its own mechanisms.
> A rework of the nfs4 code to use the lsmcontext properly
> is a significant project. SELinux is handled correctly, and
> is the only current user.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
>   fs/nfs/nfs4proc.c        | 15 ++++++++-------
>   include/linux/security.h |  7 +++----
>   security/security.c      | 29 +++++++++++++++++++++++++----
>   3 files changed, 36 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index a30e36654c57..6cd2463f890b 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -112,6 +112,7 @@ static inline struct nfs4_label *
>   nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
>   	struct iattr *sattr, struct nfs4_label *label)
>   {
> +	struct lsmcontext context;
>   	int err;
>   
>   	if (label == NULL)
> @@ -121,21 +122,21 @@ nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
>   		return NULL;
>   
>   	err = security_dentry_init_security(dentry, sattr->ia_mode,
> -				&dentry->d_name, (void **)&label->label, &label->len);
> +					    &dentry->d_name, &context);
> +
> +	label->label = context.context;
> +	label->len = context.len;

No point in setting label->label/len if err != 0.

> +
>   	if (err == 0)
>   		return label;
>   
>   	return NULL;
> +
>   }

Leftover empty line.

>   static inline void
>   nfs4_label_release_security(struct nfs4_label *label)
>   {
> -	struct lsmcontext scaff; /* scaffolding */
> -
> -	if (label) {
> -		lsmcontext_init(&scaff, label->label, label->len, 0);
> -		security_release_secctx(&scaff);
> -	}
> +	kfree(label->label);
>   }
>   static inline u32 *nfs4_bitmask(struct nfs_server *server, struct nfs4_label *label)
>   {

Not sure why you don't just leave the scaffolding here?

Patch
diff mbox series

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a30e36654c57..6cd2463f890b 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -112,6 +112,7 @@  static inline struct nfs4_label *
 nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
 	struct iattr *sattr, struct nfs4_label *label)
 {
+	struct lsmcontext context;
 	int err;
 
 	if (label == NULL)
@@ -121,21 +122,21 @@  nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
 		return NULL;
 
 	err = security_dentry_init_security(dentry, sattr->ia_mode,
-				&dentry->d_name, (void **)&label->label, &label->len);
+					    &dentry->d_name, &context);
+
+	label->label = context.context;
+	label->len = context.len;
+
 	if (err == 0)
 		return label;
 
 	return NULL;
+
 }
 static inline void
 nfs4_label_release_security(struct nfs4_label *label)
 {
-	struct lsmcontext scaff; /* scaffolding */
-
-	if (label) {
-		lsmcontext_init(&scaff, label->label, label->len, 0);
-		security_release_secctx(&scaff);
-	}
+	kfree(label->label);
 }
 static inline u32 *nfs4_bitmask(struct nfs_server *server, struct nfs4_label *label)
 {
diff --git a/include/linux/security.h b/include/linux/security.h
index 390cc0561bb3..ea98dff5ec03 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -394,8 +394,8 @@  int security_add_mnt_opt(const char *option, const char *val,
 				int len, void **mnt_opts);
 int security_move_mount(const struct path *from_path, const struct path *to_path);
 int security_dentry_init_security(struct dentry *dentry, int mode,
-					const struct qstr *name, void **ctx,
-					u32 *ctxlen);
+					const struct qstr *name,
+					struct lsmcontext *ctx);
 int security_dentry_create_files_as(struct dentry *dentry, int mode,
 					struct qstr *name,
 					const struct cred *old,
@@ -786,8 +786,7 @@  static inline void security_inode_free(struct inode *inode)
 static inline int security_dentry_init_security(struct dentry *dentry,
 						 int mode,
 						 const struct qstr *name,
-						 void **ctx,
-						 u32 *ctxlen)
+						 struct lsmcontext *ctx)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/security/security.c b/security/security.c
index e80b71c03062..29f070aa172c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1011,12 +1011,33 @@  void security_inode_free(struct inode *inode)
 				inode_free_by_rcu);
 }
 
+/*
+ * security_dentry_init_security - initial context for a dentry
+ * @dentry: directory entry
+ * @mode: access mode
+ * @name: path name
+ * @context: resulting security context
+ *
+ * Use at most one security module to get the initial
+ * security context. Do not use the "display".
+ *
+ * Returns -EOPNOTSUPP if not supplied by any module or the module result.
+ */
 int security_dentry_init_security(struct dentry *dentry, int mode,
-					const struct qstr *name, void **ctx,
-					u32 *ctxlen)
+				  const struct qstr *name,
+				  struct lsmcontext *cp)
 {
-	return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode,
-				name, ctx, ctxlen);
+	struct security_hook_list *hp;
+
+	hlist_for_each_entry(hp, &security_hook_heads.dentry_init_security,
+			     list) {
+		cp->slot = hp->lsmid->slot;
+		return hp->hook.dentry_init_security(dentry, mode, name,
+						     (void **)&cp->context,
+						     &cp->len);
+	}
+
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL(security_dentry_init_security);