security: Return xattr name from security_dentry_init_security()

Right now security_dentry_init_security() only supports single security label and is used by SELinux only. There are two users of of this hook, namely ceph and nfs.

NFS does not care about xattr name. Ceph hardcodes the xattr name to security.selinux (XATTR_NAME_SELINUX).

I am making changes to fuse/virtiofs to send security label to virtiofsd and I need to send xattr name as well. I also hardcoded the name of xattr to security.selinux.

Stephen Smalley suggested that it probably is a good idea to modify security_dentry_init_security() to also return name of xattr so that we can avoid this hardcoding in the callers.

This patch adds a new parameter "const char **xattr_name" to security_dentry_init_security() and LSM puts the name of xattr too if caller asked for it (xattr_name != NULL).

Signed-off-by Vivek Goyal <[email protected]>

Reviewed-by Jeff Layton <[email protected]>

---

Right now security_dentry_init_security() only supports single security label and is used by SELinux only. There are two users of of this hook, namely ceph and nfs.

NFS does not care about xattr name. Ceph hardcodes the xattr name to security.selinux (XATTR_NAME_SELINUX).

I am making changes to fuse/virtiofs to send security label to virtiofsd and I need to send xattr name as well. I also hardcoded the name of xattr to security.selinux.

Stephen Smalley suggested that it probably is a good idea to modify security_dentry_init_security() to also return name of xattr so that we can avoid this hardcoding in the callers.

This patch adds a new parameter "const char **xattr_name" to security_dentry_init_security() and LSM puts the name of xattr too if caller asked for it (xattr_name != NULL).

Signed-off-by Vivek Goyal <[email protected]>

Reviewed-by Jeff Layton <[email protected]>

---

Changes since v1:
- Updated comment to make it clear caller does not have to free the xattr_name. (Jeff Layton).
- Captured Jeff's Reviewed-by ack.

I have tested this patch with virtiofs and compile tested for ceph and nfs.

NFS changes are trivial. Looking for an ack from NFS maintainers.

---
 fs/ceph/xattr.c               |    3 +--
 fs/nfs/nfs4proc.c             |    3 ++-
 include/linux/lsm_hook_defs.h |    3 ++-
 include/linux/lsm_hooks.h     |    3 +++
 include/linux/security.h      |    6 ++++--
 security/security.c           |    7 ++++---
 security/selinux/hooks.c      |    6 +++++-
 7 files changed, 21 insertions(+), 10 deletions(-)

Index: redhat-linux/security/selinux/hooks.c
===================================================================

security/selinux/hooks.c +5 -1

@@ -2948,7 +2948,8 @@ static void selinux_inode_free_security(
 }
 
 static int selinux_dentry_init_security(struct dentry *dentry, int mode,
-					const struct qstr *name, void **ctx,
+					const struct qstr *name,
+					const char **xattr_name, void **ctx,
 					u32 *ctxlen)
 {
 	u32 newsid;

@@ -2961,6 +2962,9 @@ static int selinux_dentry_init_security(
 	if (rc)
 		return rc;
 
+	if (xattr_name)
+		*xattr_name = XATTR_NAME_SELINUX;
+
 	return security_sid_to_context(&selinux_state, newsid, (char **)ctx,
 				       ctxlen);
 }

Index: redhat-linux/security/security.c
===================================================================

security/security.c +4 -3

@@ -1052,11 +1052,12 @@ void security_inode_free(struct inode *i
 }
 
 int security_dentry_init_security(struct dentry *dentry, int mode,
-					const struct qstr *name, void **ctx,
-					u32 *ctxlen)
+				  const struct qstr *name,
+				  const char **xattr_name, void **ctx,
+				  u32 *ctxlen)
 {
 	return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode,
-				name, ctx, ctxlen);
+				name, xattr_name, ctx, ctxlen);
 }
 EXPORT_SYMBOL(security_dentry_init_security);
 

Index: redhat-linux/include/linux/lsm_hooks.h
===================================================================

include/linux/lsm_hooks.h +3 -0

@@ -196,6 +196,9 @@
  *	@dentry dentry to use in calculating the context.
  *	@mode mode used to determine resource type.
  *	@name name of the last path component used to create file
+ *	@xattr_name pointer to place the pointer to security xattr name.
+ *		    Caller does not have to free the resulting pointer. Its
+ *		    a pointer to static string.
  *	@ctx pointer to place the pointer to the resulting context in.
  *	@ctxlen point to place the length of the resulting context.
  * @dentry_create_files_as:

Index: redhat-linux/include/linux/security.h
===================================================================

include/linux/security.h +4 -2

@@ -317,8 +317,9 @@ int security_add_mnt_opt(const char *opt
 				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,
+				  const char **xattr_name, void **ctx,
+				  u32 *ctxlen);
 int security_dentry_create_files_as(struct dentry *dentry, int mode,
 					struct qstr *name,
 					const struct cred *old,

@@ -739,6 +740,7 @@ static inline void security_inode_free(s
 static inline int security_dentry_init_security(struct dentry *dentry,
 						 int mode,
 						 const struct qstr *name,
+						 const char **xattr_name,
 						 void **ctx,
 						 u32 *ctxlen)
 {

Index: redhat-linux/include/linux/lsm_hook_defs.h
===================================================================

include/linux/lsm_hook_defs.h +2 -1

@@ -83,7 +83,8 @@ LSM_HOOK(int, 0, sb_add_mnt_opt, const c
 LSM_HOOK(int, 0, move_mount, const struct path *from_path,
 	 const struct path *to_path)
 LSM_HOOK(int, 0, dentry_init_security, struct dentry *dentry,
-	 int mode, const struct qstr *name, void **ctx, u32 *ctxlen)
+	 int mode, const struct qstr *name, const char **xattr_name,
+	 void **ctx, u32 *ctxlen)
 LSM_HOOK(int, 0, dentry_create_files_as, struct dentry *dentry, int mode,
 	 struct qstr *name, const struct cred *old, struct cred *new)
 

Index: redhat-linux/fs/nfs/nfs4proc.c
===================================================================

fs/nfs/nfs4proc.c +2 -1

@@ -127,7 +127,8 @@ nfs4_label_init_security(struct inode *d
 		return NULL;
 
 	err = security_dentry_init_security(dentry, sattr->ia_mode,
-				&dentry->d_name, (void **)&label->label, &label->len);
+				&dentry->d_name, NULL,
+				(void **)&label->label, &label->len);
 	if (err == 0)
 		return label;
 

Index: redhat-linux/fs/ceph/xattr.c
===================================================================

fs/ceph/xattr.c +1 -2

@@ -1311,7 +1311,7 @@ int ceph_security_init_secctx(struct den
 	int err;
 
 	err = security_dentry_init_security(dentry, mode, &dentry->d_name,
-					    &as_ctx->sec_ctx,
+					    &name, &as_ctx->sec_ctx,
 					    &as_ctx->sec_ctxlen);
 	if (err < 0) {
 		WARN_ON_ONCE(err != -EOPNOTSUPP);

@@ -1335,7 +1335,6 @@ int ceph_security_init_secctx(struct den
 	 * It only supports single security module and only selinux has
 	 * dentry_init_security hook.
 	 */
-	name = XATTR_NAME_SELINUX;
 	name_len = strlen(name);
 	err = ceph_pagelist_reserve(pagelist,
 				    4 * 2 + name_len + as_ctx->sec_ctxlen);

Hi James,

I am assuming this patch will need to be routed through security tree. Can you please consider it for inclusion.

Quoted 4 lines · Vivek Goyal

Hi James,

I am assuming this patch will need to be routed through security tree. Can you please consider it for inclusion.

I'm happy for this to go via Paul's tree as it impacts SELinux and is fairly minor in scope.

Right now security_dentry_init_security() only supports single security label and is used by SELinux only. There are two users of of this hook, namely ceph and nfs.

NFS does not care about xattr name. Ceph hardcodes the xattr name to security.selinux (XATTR_NAME_SELINUX).

I am making changes to fuse/virtiofs to send security label to virtiofsd and I need to send xattr name as well. I also hardcoded the name of xattr to security.selinux.

Stephen Smalley suggested that it probably is a good idea to modify security_dentry_init_security() to also return name of xattr so that we can avoid this hardcoding in the callers.

This patch adds a new parameter "const char **xattr_name" to security_dentry_init_security() and LSM puts the name of xattr too if caller asked for it (xattr_name != NULL).

Signed-off-by Vivek Goyal <[email protected]>

Reviewed-by Jeff Layton <[email protected]>

---

Changes since v1:
- Updated comment to make it clear caller does not have to free the xattr_name. (Jeff Layton).
- Captured Jeff's Reviewed-by ack.

I have tested this patch with virtiofs and compile tested for ceph and nfs.

NFS changes are trivial. Looking for an ack from NFS maintainers.

---
 fs/ceph/xattr.c               |    3 +--
 fs/nfs/nfs4proc.c             |    3 ++-
 include/linux/lsm_hook_defs.h |    3 ++-
 include/linux/lsm_hooks.h     |    3 +++
 include/linux/security.h      |    6 ++++--
 security/security.c           |    7 ++++---
 security/selinux/hooks.c      |    6 +++++-
 7 files changed, 21 insertions(+), 10 deletions(-)

Quoted 33 lines · Vivek Goyal

Right now security_dentry_init_security() only supports single security label and is used by SELinux only. There are two users of of this hook, namely ceph and nfs.

NFS does not care about xattr name. Ceph hardcodes the xattr name to security.selinux (XATTR_NAME_SELINUX).

I am making changes to fuse/virtiofs to send security label to virtiofsd and I need to send xattr name as well. I also hardcoded the name of xattr to security.selinux.

Stephen Smalley suggested that it probably is a good idea to modify security_dentry_init_security() to also return name of xattr so that we can avoid this hardcoding in the callers.

This patch adds a new parameter "const char **xattr_name" to security_dentry_init_security() and LSM puts the name of xattr too if caller asked for it (xattr_name != NULL).

Signed-off-by Vivek Goyal <[email protected]>

Reviewed-by Jeff Layton <[email protected]>

---

Changes since v1:
- Updated comment to make it clear caller does not have to free the xattr_name. (Jeff Layton).
- Captured Jeff's Reviewed-by ack.

I have tested this patch with virtiofs and compile tested for ceph and nfs.

NFS changes are trivial. Looking for an ack from NFS maintainers.

Quoted 9 lines

---
 fs/ceph/xattr.c               |    3 +--
 fs/nfs/nfs4proc.c             |    3 ++-
 include/linux/lsm_hook_defs.h |    3 ++-
 include/linux/lsm_hooks.h     |    3 +++
 include/linux/security.h      |    6 ++++--
 security/security.c           |    7 ++++---
 security/selinux/hooks.c      |    6 +++++-
 7 files changed, 21 insertions(+), 10 deletions(-)

This looks fine to me and considering the trivial nature of the NFS changes I'm okay with merging this without an explicit ACK from the NFS folks. Similarly, I generally dislike merging new functionality once we hit -rc6, but this is trivial enough that I think it's okay; I'm merging this into selinux/next now, thanks everyone.