[v5,19/23] LSM: Use lsmcontext in security_inode_getsecctx
diff mbox series

Message ID 20190703212538.7383-20-casey@schaufler-ca.com
State New
Headers show
Series
  • LSM: Module stacking for AppArmor
Related show

Commit Message

Casey Schaufler July 3, 2019, 9:25 p.m. UTC
Change the security_inode_getsecctx() interface to fill
a lsmcontext structure instead of data and length pointers.
This provides the information about which LSM created the
context so that security_release_secctx() can use the
correct hook. A lsmcontext is used within kernfs to store
the security information as well.

security_inode_getsecctx() does not use the "display"
value. There's only one possible user at any time at
this point, and the use is only internal.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 fs/kernfs/dir.c             |  9 ++-------
 fs/kernfs/inode.c           | 34 ++++++++++++----------------------
 fs/kernfs/kernfs-internal.h |  3 +--
 fs/nfsd/nfs4xdr.c           | 23 +++++++++--------------
 include/linux/security.h    |  5 +++--
 security/security.c         | 13 +++++++++++--
 6 files changed, 38 insertions(+), 49 deletions(-)

Comments

Kees Cook July 3, 2019, 9:44 p.m. UTC | #1
On Wed, Jul 03, 2019 at 02:25:34PM -0700, Casey Schaufler wrote:
> Change the security_inode_getsecctx() interface to fill
> a lsmcontext structure instead of data and length pointers.
> This provides the information about which LSM created the
> context so that security_release_secctx() can use the
> correct hook. A lsmcontext is used within kernfs to store
> the security information as well.
> 
> security_inode_getsecctx() does not use the "display"
> value. There's only one possible user at any time at
> this point, and the use is only internal.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  fs/kernfs/dir.c             |  9 ++-------
>  fs/kernfs/inode.c           | 34 ++++++++++++----------------------
>  fs/kernfs/kernfs-internal.h |  3 +--
>  fs/nfsd/nfs4xdr.c           | 23 +++++++++--------------
>  include/linux/security.h    |  5 +++--
>  security/security.c         | 13 +++++++++++--
>  6 files changed, 38 insertions(+), 49 deletions(-)
> 
> diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
> index c8362b6d556e..1d000289d8b7 100644
> --- a/fs/kernfs/dir.c
> +++ b/fs/kernfs/dir.c
> @@ -532,13 +532,8 @@ void kernfs_put(struct kernfs_node *kn)
>  	kfree_const(kn->name);
>  
>  	if (kn->iattr) {
> -		struct lsmcontext scaff; /* scaffolding */
> -
> -		if (kn->iattr->ia_secdata) {
> -			lsmcontext_init(&scaff, kn->iattr->ia_secdata,
> -					kn->iattr->ia_secdata_len, 0);
> -			security_release_secctx(&scaff);
> -		}
> +		if (kn->iattr->ia_context.context)
> +			security_release_secctx(&kn->iattr->ia_context);
>  		simple_xattrs_free(&kn->iattr->xattrs);
>  		kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
>  	}
> diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
> index 02cde9dac5ee..ffbf7863306d 100644
> --- a/fs/kernfs/inode.c
> +++ b/fs/kernfs/inode.c
> @@ -135,21 +135,14 @@ int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
>  	return error;
>  }
>  
> -static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
> -				  u32 *secdata_len)
> +static void kernfs_node_setsecdata(struct kernfs_iattrs *attrs,
> +				   struct lsmcontext *cp)
>  {
> -	void *old_secdata;
> -	size_t old_secdata_len;
> +	struct lsmcontext old_context;
>  
> -	old_secdata = attrs->ia_secdata;
> -	old_secdata_len = attrs->ia_secdata_len;
> -
> -	attrs->ia_secdata = *secdata;
> -	attrs->ia_secdata_len = *secdata_len;
> -
> -	*secdata = old_secdata;
> -	*secdata_len = old_secdata_len;
> -	return 0;
> +	old_context = attrs->ia_context;
> +	attrs->ia_context = *cp;
> +	*cp = old_context;
>  }
>  
>  ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
> @@ -192,8 +185,8 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
>  		 * persistent copy in kernfs_node.
>  		 */
>  		set_inode_attr(inode, &attrs->ia_iattr);
> -		security_inode_notifysecctx(inode, attrs->ia_secdata,
> -					    attrs->ia_secdata_len);
> +		security_inode_notifysecctx(inode, attrs->ia_context.context,
> +					    attrs->ia_context.len);
>  	}
>  
>  	if (kernfs_type(kn) == KERNFS_DIR)
> @@ -350,8 +343,6 @@ static int kernfs_security_xattr_set(const struct xattr_handler *handler,
>  	struct kernfs_node *kn = inode->i_private;
>  	struct kernfs_iattrs *attrs;
>  	struct lsmcontext context;
> -	void *secdata;
> -	u32 secdata_len = 0;
>  	int error;
>  
>  	attrs = kernfs_iattrs(kn);
> @@ -361,18 +352,17 @@ static int kernfs_security_xattr_set(const struct xattr_handler *handler,
>  	error = security_inode_setsecurity(inode, suffix, value, size, flags);
>  	if (error)
>  		return error;
> -	error = security_inode_getsecctx(inode, &secdata, &secdata_len);
> +	error = security_inode_getsecctx(inode, &context);
>  	if (error)
>  		return error;
>  
>  	mutex_lock(&kernfs_mutex);
> -	error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
> +	kernfs_node_setsecdata(attrs, &context);
>  	mutex_unlock(&kernfs_mutex);
>  
> -	if (secdata) {
> -		lsmcontext_init(&context, secdata, secdata_len, 0);
> +	if (context.context)
>  		security_release_secctx(&context);
> -	}
> +
>  	return error;
>  }
>  
> diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
> index 0b7d197a904c..844a028d282f 100644
> --- a/fs/kernfs/kernfs-internal.h
> +++ b/fs/kernfs/kernfs-internal.h
> @@ -21,8 +21,7 @@
>  
>  struct kernfs_iattrs {
>  	struct iattr		ia_iattr;
> -	void			*ia_secdata;
> -	u32			ia_secdata_len;
> +	struct lsmcontext	ia_context;
>  
>  	struct simple_xattrs	xattrs;
>  };
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index bb3db033e144..d2dbec9c3340 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -2304,11 +2304,11 @@ nfsd4_encode_layout_types(struct xdr_stream *xdr, u32 layout_types)
>  #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
>  static inline __be32
>  nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
> -			    void *context, int len)
> +			    struct lsmcontext *context)
>  {
>  	__be32 *p;
>  
> -	p = xdr_reserve_space(xdr, len + 4 + 4 + 4);
> +	p = xdr_reserve_space(xdr, context->len + 4 + 4 + 4);
>  	if (!p)
>  		return nfserr_resource;
>  
> @@ -2318,13 +2318,13 @@ nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
>  	 */
>  	*p++ = cpu_to_be32(0); /* lfs */
>  	*p++ = cpu_to_be32(0); /* pi */
> -	p = xdr_encode_opaque(p, context, len);
> +	p = xdr_encode_opaque(p, context->context, context->len);
>  	return 0;
>  }
>  #else
>  static inline __be32
>  nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
> -			    void *context, int len)
> +			    struct lsmcontext *context)
>  { return 0; }
>  #endif
>  
> @@ -2420,9 +2420,7 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
>  	__be32 status;
>  	int err;
>  	struct nfs4_acl *acl = NULL;
> -	struct lsmcontext scaff; /* scaffolding */
> -	void *context = NULL;
> -	int contextlen;
> +	struct lsmcontext context = { };
>  	bool contextsupport = false;
>  	struct nfsd4_compoundres *resp = rqstp->rq_resp;
>  	u32 minorversion = resp->cstate.minorversion;
> @@ -2479,7 +2477,7 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
>  	     bmval0 & FATTR4_WORD0_SUPPORTED_ATTRS) {
>  		if (exp->ex_flags & NFSEXP_SECURITY_LABEL)
>  			err = security_inode_getsecctx(d_inode(dentry),
> -						&context, &contextlen);
> +						       &context);
>  		else
>  			err = -EOPNOTSUPP;
>  		contextsupport = (err == 0);
> @@ -2908,8 +2906,7 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
>  	}
>  
>  	if (bmval2 & FATTR4_WORD2_SECURITY_LABEL) {
> -		status = nfsd4_encode_security_label(xdr, rqstp, context,
> -								contextlen);
> +		status = nfsd4_encode_security_label(xdr, rqstp, &context);
>  		if (status)
>  			goto out;
>  	}
> @@ -2920,10 +2917,8 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
>  
>  out:
>  #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
> -	if (context) {
> -		lsmcontext_init(&scaff, context, contextlen, 0); /*scaffolding*/
> -		security_release_secctx(&scaff);
> -	}
> +	if (context.context)
> +		security_release_secctx(&context);
>  #endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
>  	kfree(acl);
>  	if (tempfh) {
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 2674eb70c2d7..c16aea55be97 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -489,7 +489,7 @@ void security_release_secctx(struct lsmcontext *cp);
>  void security_inode_invalidate_secctx(struct inode *inode);
>  int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
>  int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
> -int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
> +int security_inode_getsecctx(struct inode *inode, struct lsmcontext *cp);
>  #else /* CONFIG_SECURITY */
>  
>  static inline int call_lsm_notifier(enum lsm_event event, void *data)
> @@ -1290,7 +1290,8 @@ static inline int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32
>  {
>  	return -EOPNOTSUPP;
>  }
> -static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
> +static inline int security_inode_getsecctx(struct inode *inode,
> +					   struct lsmcontext *cp)
>  {
>  	return -EOPNOTSUPP;
>  }
> diff --git a/security/security.c b/security/security.c
> index 54d7e7f02a8b..7c1c50ac2278 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2179,9 +2179,18 @@ int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
>  }
>  EXPORT_SYMBOL(security_inode_setsecctx);
>  
> -int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
> +int security_inode_getsecctx(struct inode *inode, struct lsmcontext *cp)
>  {
> -	return call_int_hook(inode_getsecctx, -EOPNOTSUPP, inode, ctx, ctxlen);
> +	struct security_hook_list *hp;
> +
> +	memset(cp, 0, sizeof(*cp));
> +
> +	hlist_for_each_entry(hp, &security_hook_heads.inode_getsecctx, list) {
> +		cp->slot = hp->lsmid->slot;
> +		return hp->hook.inode_getsecctx(inode, (void **)&cp->context,
> +						&cp->len);
> +	}
> +	return -EOPNOTSUPP;
>  }
>  EXPORT_SYMBOL(security_inode_getsecctx);
>  
> -- 
> 2.20.1
>

Patch
diff mbox series

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index c8362b6d556e..1d000289d8b7 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -532,13 +532,8 @@  void kernfs_put(struct kernfs_node *kn)
 	kfree_const(kn->name);
 
 	if (kn->iattr) {
-		struct lsmcontext scaff; /* scaffolding */
-
-		if (kn->iattr->ia_secdata) {
-			lsmcontext_init(&scaff, kn->iattr->ia_secdata,
-					kn->iattr->ia_secdata_len, 0);
-			security_release_secctx(&scaff);
-		}
+		if (kn->iattr->ia_context.context)
+			security_release_secctx(&kn->iattr->ia_context);
 		simple_xattrs_free(&kn->iattr->xattrs);
 		kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
 	}
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 02cde9dac5ee..ffbf7863306d 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -135,21 +135,14 @@  int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
 	return error;
 }
 
-static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
-				  u32 *secdata_len)
+static void kernfs_node_setsecdata(struct kernfs_iattrs *attrs,
+				   struct lsmcontext *cp)
 {
-	void *old_secdata;
-	size_t old_secdata_len;
+	struct lsmcontext old_context;
 
-	old_secdata = attrs->ia_secdata;
-	old_secdata_len = attrs->ia_secdata_len;
-
-	attrs->ia_secdata = *secdata;
-	attrs->ia_secdata_len = *secdata_len;
-
-	*secdata = old_secdata;
-	*secdata_len = old_secdata_len;
-	return 0;
+	old_context = attrs->ia_context;
+	attrs->ia_context = *cp;
+	*cp = old_context;
 }
 
 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
@@ -192,8 +185,8 @@  static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
 		 * persistent copy in kernfs_node.
 		 */
 		set_inode_attr(inode, &attrs->ia_iattr);
-		security_inode_notifysecctx(inode, attrs->ia_secdata,
-					    attrs->ia_secdata_len);
+		security_inode_notifysecctx(inode, attrs->ia_context.context,
+					    attrs->ia_context.len);
 	}
 
 	if (kernfs_type(kn) == KERNFS_DIR)
@@ -350,8 +343,6 @@  static int kernfs_security_xattr_set(const struct xattr_handler *handler,
 	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
 	struct lsmcontext context;
-	void *secdata;
-	u32 secdata_len = 0;
 	int error;
 
 	attrs = kernfs_iattrs(kn);
@@ -361,18 +352,17 @@  static int kernfs_security_xattr_set(const struct xattr_handler *handler,
 	error = security_inode_setsecurity(inode, suffix, value, size, flags);
 	if (error)
 		return error;
-	error = security_inode_getsecctx(inode, &secdata, &secdata_len);
+	error = security_inode_getsecctx(inode, &context);
 	if (error)
 		return error;
 
 	mutex_lock(&kernfs_mutex);
-	error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
+	kernfs_node_setsecdata(attrs, &context);
 	mutex_unlock(&kernfs_mutex);
 
-	if (secdata) {
-		lsmcontext_init(&context, secdata, secdata_len, 0);
+	if (context.context)
 		security_release_secctx(&context);
-	}
+
 	return error;
 }
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 0b7d197a904c..844a028d282f 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -21,8 +21,7 @@ 
 
 struct kernfs_iattrs {
 	struct iattr		ia_iattr;
-	void			*ia_secdata;
-	u32			ia_secdata_len;
+	struct lsmcontext	ia_context;
 
 	struct simple_xattrs	xattrs;
 };
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index bb3db033e144..d2dbec9c3340 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2304,11 +2304,11 @@  nfsd4_encode_layout_types(struct xdr_stream *xdr, u32 layout_types)
 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
 static inline __be32
 nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
-			    void *context, int len)
+			    struct lsmcontext *context)
 {
 	__be32 *p;
 
-	p = xdr_reserve_space(xdr, len + 4 + 4 + 4);
+	p = xdr_reserve_space(xdr, context->len + 4 + 4 + 4);
 	if (!p)
 		return nfserr_resource;
 
@@ -2318,13 +2318,13 @@  nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
 	 */
 	*p++ = cpu_to_be32(0); /* lfs */
 	*p++ = cpu_to_be32(0); /* pi */
-	p = xdr_encode_opaque(p, context, len);
+	p = xdr_encode_opaque(p, context->context, context->len);
 	return 0;
 }
 #else
 static inline __be32
 nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
-			    void *context, int len)
+			    struct lsmcontext *context)
 { return 0; }
 #endif
 
@@ -2420,9 +2420,7 @@  nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 	__be32 status;
 	int err;
 	struct nfs4_acl *acl = NULL;
-	struct lsmcontext scaff; /* scaffolding */
-	void *context = NULL;
-	int contextlen;
+	struct lsmcontext context = { };
 	bool contextsupport = false;
 	struct nfsd4_compoundres *resp = rqstp->rq_resp;
 	u32 minorversion = resp->cstate.minorversion;
@@ -2479,7 +2477,7 @@  nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 	     bmval0 & FATTR4_WORD0_SUPPORTED_ATTRS) {
 		if (exp->ex_flags & NFSEXP_SECURITY_LABEL)
 			err = security_inode_getsecctx(d_inode(dentry),
-						&context, &contextlen);
+						       &context);
 		else
 			err = -EOPNOTSUPP;
 		contextsupport = (err == 0);
@@ -2908,8 +2906,7 @@  nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 	}
 
 	if (bmval2 & FATTR4_WORD2_SECURITY_LABEL) {
-		status = nfsd4_encode_security_label(xdr, rqstp, context,
-								contextlen);
+		status = nfsd4_encode_security_label(xdr, rqstp, &context);
 		if (status)
 			goto out;
 	}
@@ -2920,10 +2917,8 @@  nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 
 out:
 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
-	if (context) {
-		lsmcontext_init(&scaff, context, contextlen, 0); /*scaffolding*/
-		security_release_secctx(&scaff);
-	}
+	if (context.context)
+		security_release_secctx(&context);
 #endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
 	kfree(acl);
 	if (tempfh) {
diff --git a/include/linux/security.h b/include/linux/security.h
index 2674eb70c2d7..c16aea55be97 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -489,7 +489,7 @@  void security_release_secctx(struct lsmcontext *cp);
 void security_inode_invalidate_secctx(struct inode *inode);
 int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
 int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
-int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
+int security_inode_getsecctx(struct inode *inode, struct lsmcontext *cp);
 #else /* CONFIG_SECURITY */
 
 static inline int call_lsm_notifier(enum lsm_event event, void *data)
@@ -1290,7 +1290,8 @@  static inline int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32
 {
 	return -EOPNOTSUPP;
 }
-static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
+static inline int security_inode_getsecctx(struct inode *inode,
+					   struct lsmcontext *cp)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/security/security.c b/security/security.c
index 54d7e7f02a8b..7c1c50ac2278 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2179,9 +2179,18 @@  int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
 }
 EXPORT_SYMBOL(security_inode_setsecctx);
 
-int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
+int security_inode_getsecctx(struct inode *inode, struct lsmcontext *cp)
 {
-	return call_int_hook(inode_getsecctx, -EOPNOTSUPP, inode, ctx, ctxlen);
+	struct security_hook_list *hp;
+
+	memset(cp, 0, sizeof(*cp));
+
+	hlist_for_each_entry(hp, &security_hook_heads.inode_getsecctx, list) {
+		cp->slot = hp->lsmid->slot;
+		return hp->hook.inode_getsecctx(inode, (void **)&cp->context,
+						&cp->len);
+	}
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL(security_inode_getsecctx);