[PATCH v12 16/25] LSM: Use lsmcontext in security_dentry_init_security
From: Casey Schaufler <casey@schaufler-ca.com>
Date: 2019-12-24 23:21:57
Also in:
selinux
Subsystem:
filesystems (vfs and infrastructure), nfs, sunrpc, and lockd clients, security subsystem, the rest · Maintainers:
Alexander Viro, Christian Brauner, Trond Myklebust, Anna Schumaker, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
Possibly related (same subject, not in this thread)
- 2019-12-18 · Re: [PATCH v12 16/25] LSM: Use lsmcontext in security_dentry_init_security · Stephen Smalley <hidden>
- 2019-12-16 · [PATCH v12 16/25] LSM: Use lsmcontext in security_dentry_init_security · Casey Schaufler <casey@schaufler-ca.com>
- 2019-12-16 · [PATCH v12 16/25] LSM: Use lsmcontext in security_dentry_init_security · Casey Schaufler <casey@schaufler-ca.com>
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, so the coward's way out is taken, and the lsmcontext data from security_dentry_init_security() is copied, then released directly. This interface does not use the "display". There is currently not case where that is useful or reasonable. Reviewed-by: Kees Cook <redacted> Reviewed-by: John Johansen <john.johansen@canonical.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> --- fs/nfs/nfs4proc.c | 26 ++++++++++++++++---------- include/linux/security.h | 7 +++---- security/security.c | 29 +++++++++++++++++++++++++---- 3 files changed, 44 insertions(+), 18 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a30e36654c57..78d63f7f0088 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 +122,26 @@ 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); - if (err == 0) - return label; + &dentry->d_name, &context); + + if (err) + return NULL; + + label->label = kmemdup(context.context, context.len, GFP_KERNEL); + if (label->label == NULL) + label = NULL; + else + label->len = context.len; + + security_release_secctx(&context); + + 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 00421941f683..a5eba06a9382 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h@@ -398,8 +398,8 @@ 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,
@@ -790,8 +790,7 @@ 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 4ba1a6ed36e0..8aa107b57af9 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);
--
2.20.1