On Thu, Feb 20, 2025 at 11:43 AM Stephen Smalley
[off-list ref] wrote:

On Wed, Oct 23, 2024 at 5:23 PM Casey Schaufler [off-list ref] wrote:

quoted

Replace the (secctx,seclen) pointer pair with a single lsm_context
pointer to allow return of the LSM identifier along with the context
and context length. This allows security_release_secctx() to know how
to release the context. Callers have been modified to use or save the
returned data from the new structure.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: ceph-devel@vger.kernel.org
Cc: linux-nfs@vger.kernel.org
---
 fs/ceph/super.h               |  3 +--
 fs/ceph/xattr.c               | 16 ++++++----------
 fs/fuse/dir.c                 | 35 ++++++++++++++++++-----------------
 fs/nfs/nfs4proc.c             | 20 ++++++++++++--------
 include/linux/lsm_hook_defs.h |  2 +-
 include/linux/security.h      | 26 +++-----------------------
 security/security.c           |  9 ++++-----
 security/selinux/hooks.c      |  9 +++++----
 8 files changed, 50 insertions(+), 70 deletions(-)

quoted

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 76776d716744..0b116ef3a752 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c

@@ -114,6 +114,7 @@ static inline struct nfs4_label *
 nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
        struct iattr *sattr, struct nfs4_label *label)
 {
+       struct lsm_context shim;
        int err;

        if (label == NULL)

@@ -128,21 +129,24 @@ nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
        label->label = NULL;

        err = security_dentry_init_security(dentry, sattr->ia_mode,
-                               &dentry->d_name, NULL,
-                               (void **)&label->label, &label->len);
-       if (err == 0)
-               return label;
+                               &dentry->d_name, NULL, &shim);
+       if (err)
+               return NULL;

-       return NULL;
+       label->label = shim.context;
+       label->len = shim.len;
+       return label;
 }
 static inline void
 nfs4_label_release_security(struct nfs4_label *label)
 {
-       struct lsm_context scaff; /* scaffolding */
+       struct lsm_context shim;

        if (label) {
-               lsmcontext_init(&scaff, label->label, label->len, 0);
-               security_release_secctx(&scaff);
+               shim.context = label->label;
+               shim.len = label->len;
+               shim.id = LSM_ID_UNDEF;

Is there a patch that follows this one to fix this? Otherwise, setting
this to UNDEF causes SELinux to NOT free the context, which produces a
memory leak for every NFS inode security context. Reported by kmemleak
when running the selinux-testsuite NFS tests.

I don't recall seeing anything related to this, but patches are
definitely welcome.

-- 
paul-moore.com