SELinux: Abstract use of cred security blob

Don't use the cred->security pointer directly.
Provide a helper function that provides the security blob pointer.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
[kees: adjusted for ordered init series]
Signed-off-by: Kees Cook <keescook@chromium.org>

3 files changed, 34 insertions, 29 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c5d9fbbb5e5b..beec1de5c2da 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -226,7 +226,7 @@ static inline u32 cred_sid(const struct cred *cred)
 {
         const struct task_security_struct *tsec;
 
-        tsec = cred->security;
+        tsec = selinux_cred(cred);
         return tsec->sid;
 }
 
@@ -498,7 +498,7 @@ static int may_context_mount_sb_relabel(u32 sid,
                         struct superblock_security_struct *sbsec,
                         const struct cred *cred)
 {
-        const struct task_security_struct *tsec = cred->security;
+        const struct task_security_struct *tsec = selinux_cred(cred);
         int rc;
 
         rc = avc_has_perm(&selinux_state,
@@ -517,7 +517,7 @@ static int may_context_mount_inode_relabel(u32 sid,
                         struct superblock_security_struct *sbsec,
                         const struct cred *cred)
 {
-        const struct task_security_struct *tsec = cred->security;
+        const struct task_security_struct *tsec = selinux_cred(cred);
         int rc;
         rc = avc_has_perm(&selinux_state,
                           tsec->sid, sbsec->sid, SECCLASS_FILESYSTEM,
@@ -1803,7 +1803,7 @@ static int may_create(struct inode *dir,
                       struct dentry *dentry,
                       u16 tclass)
 {
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
         struct inode_security_struct *dsec;
         struct superblock_security_struct *sbsec;
         u32 sid, newsid;
@@ -1825,7 +1825,7 @@ static int may_create(struct inode *dir,
         if (rc)
                 return rc;
 
-        rc = selinux_determine_inode_label(current_security(), dir,
+        rc = selinux_determine_inode_label(selinux_cred(current_cred()), dir,
                                            &dentry->d_name, tclass, &newsid);
         if (rc)
                 return rc;
@@ -2332,8 +2332,8 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
         if (bprm->called_set_creds)
                 return 0;
 
-        old_tsec = current_security();
-        new_tsec = bprm->cred->security;
+        old_tsec = selinux_cred(current_cred());
+        new_tsec = selinux_cred(bprm->cred);
         isec = inode_security(inode);
 
         /* Default to the current task SID. */
@@ -2497,7 +2497,7 @@ static void selinux_bprm_committing_creds(struct linux_binprm *bprm)
         struct rlimit *rlim, *initrlim;
         int rc, i;
 
-        new_tsec = bprm->cred->security;
+        new_tsec = selinux_cred(bprm->cred);
         if (new_tsec->sid == new_tsec->osid)
                 return;
 
@@ -2540,7 +2540,7 @@ static void selinux_bprm_committing_creds(struct linux_binprm *bprm)
  */
 static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
 {
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
         struct itimerval itimer;
         u32 osid, sid;
         int rc, i;
@@ -2777,7 +2777,7 @@ static int selinux_dentry_init_security(struct dentry *dentry, int mode,
         u32 newsid;
         int rc;
 
-        rc = selinux_determine_inode_label(current_security(),
+        rc = selinux_determine_inode_label(selinux_cred(current_cred()),
                                            d_inode(dentry->d_parent), name,
                                            inode_mode_to_security_class(mode),
                                            &newsid);
@@ -2797,14 +2797,14 @@ static int selinux_dentry_create_files_as(struct dentry *dentry, int mode,
         int rc;
         struct task_security_struct *tsec;
 
-        rc = selinux_determine_inode_label(old->security,
+        rc = selinux_determine_inode_label(selinux_cred(old),
                                            d_inode(dentry->d_parent), name,
                                            inode_mode_to_security_class(mode),
                                            &newsid);
         if (rc)
                 return rc;
 
-        tsec = new->security;
+        tsec = selinux_cred(new);
         tsec->create_sid = newsid;
         return 0;
 }
@@ -2814,7 +2814,7 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
                                        const char **name,
                                        void **value, size_t *len)
 {
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
         struct superblock_security_struct *sbsec;
         u32 newsid, clen;
         int rc;
@@ -2824,7 +2824,7 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 
         newsid = tsec->create_sid;
 
-        rc = selinux_determine_inode_label(current_security(),
+        rc = selinux_determine_inode_label(selinux_cred(current_cred()),
                 dir, qstr,
                 inode_mode_to_security_class(inode->i_mode),
                 &newsid);
@@ -3286,7 +3286,7 @@ static int selinux_inode_copy_up(struct dentry *src, struct cred **new)
                         return -ENOMEM;
         }
 
-        tsec = new_creds->security;
+        tsec = selinux_cred(new_creds);
         /* Get label from overlay inode and set it in create_sid */
         selinux_inode_getsecid(d_inode(src), &sid);
         tsec->create_sid = sid;
@@ -3706,7 +3706,7 @@ static int selinux_cred_alloc_blank(struct cred *cred, gfp_t gfp)
  */
 static void selinux_cred_free(struct cred *cred)
 {
-        struct task_security_struct *tsec = cred->security;
+        struct task_security_struct *tsec = selinux_cred(cred);
 
         /*
          * cred->security == NULL if security_cred_alloc_blank() or
@@ -3726,7 +3726,7 @@ static int selinux_cred_prepare(struct cred *new, const struct cred *old,
         const struct task_security_struct *old_tsec;
         struct task_security_struct *tsec;
 
-        old_tsec = old->security;
+        old_tsec = selinux_cred(old);
 
         tsec = kmemdup(old_tsec, sizeof(struct task_security_struct), gfp);
         if (!tsec)
@@ -3741,8 +3741,8 @@ static int selinux_cred_prepare(struct cred *new, const struct cred *old,
  */
 static void selinux_cred_transfer(struct cred *new, const struct cred *old)
 {
-        const struct task_security_struct *old_tsec = old->security;
-        struct task_security_struct *tsec = new->security;
+        const struct task_security_struct *old_tsec = selinux_cred(old);
+        struct task_security_struct *tsec = selinux_cred(new);
 
         *tsec = *old_tsec;
 }
@@ -3758,7 +3758,7 @@ static void selinux_cred_getsecid(const struct cred *c, u32 *secid)
  */
 static int selinux_kernel_act_as(struct cred *new, u32 secid)
 {
-        struct task_security_struct *tsec = new->security;
+        struct task_security_struct *tsec = selinux_cred(new);
         u32 sid = current_sid();
         int ret;
 
@@ -3783,7 +3783,7 @@ static int selinux_kernel_act_as(struct cred *new, u32 secid)
 static int selinux_kernel_create_files_as(struct cred *new, struct inode *inode)
 {
         struct inode_security_struct *isec = inode_security(inode);
-        struct task_security_struct *tsec = new->security;
+        struct task_security_struct *tsec = selinux_cred(new);
         u32 sid = current_sid();
         int ret;
 
@@ -4332,7 +4332,7 @@ static int sock_has_perm(struct sock *sk, u32 perms)
 static int selinux_socket_create(int family, int type,
                                  int protocol, int kern)
 {
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
         u32 newsid;
         u16 secclass;
         int rc;
@@ -4352,7 +4352,7 @@ static int selinux_socket_create(int family, int type,
 static int selinux_socket_post_create(struct socket *sock, int family,
                                       int type, int protocol, int kern)
 {
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
         struct inode_security_struct *isec = inode_security_novalidate(SOCK_INODE(sock));
         struct sk_security_struct *sksec;
         u16 sclass = socket_type_to_security_class(family, type, protocol);
@@ -5233,7 +5233,7 @@ static int selinux_secmark_relabel_packet(u32 sid)
         const struct task_security_struct *__tsec;
         u32 tsid;
 
-        __tsec = current_security();
+        __tsec = selinux_cred(current_cred());
         tsid = __tsec->sid;
 
         return avc_has_perm(&selinux_state,
@@ -6170,7 +6170,7 @@ static int selinux_getprocattr(struct task_struct *p,
         unsigned len;
 
         rcu_read_lock();
-        __tsec = __task_cred(p)->security;
+        __tsec = selinux_cred(__task_cred(p));
 
         if (current != p) {
                 error = avc_has_perm(&selinux_state,
@@ -6293,7 +6293,7 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
            operation.  See selinux_bprm_set_creds for the execve
            checks and may_create for the file creation checks. The
            operation will then fail if the context is not permitted. */
-        tsec = new->security;
+        tsec = selinux_cred(new);
         if (!strcmp(name, "exec")) {
                 tsec->exec_sid = sid;
         } else if (!strcmp(name, "fscreate")) {
@@ -6422,7 +6422,7 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred,
         if (!ksec)
                 return -ENOMEM;
 
-        tsec = cred->security;
+        tsec = selinux_cred(cred);
         if (tsec->keycreate_sid)
                 ksec->sid = tsec->keycreate_sid;
         else
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index cc5e26b0161b..734b6833bdff 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -158,4 +158,9 @@ struct bpf_security_struct {
         u32 sid;  /*SID of bpf obj creater*/
 };
 
+static inline struct task_security_struct *selinux_cred(const struct cred *cred)
+{
+        return cred->security;
+}
+
 #endif /* _SELINUX_OBJSEC_H_ */
diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index bd7d18bdb147..7c57cb7e4146 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -79,7 +79,7 @@ static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
                                    gfp_t gfp)
 {
         int rc;
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
         struct xfrm_sec_ctx *ctx = NULL;
         u32 str_len;
 
@@ -138,7 +138,7 @@ static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx)
  */
 static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
 {
-        const struct task_security_struct *tsec = current_security();
+        const struct task_security_struct *tsec = selinux_cred(current_cred());
 
         if (!ctx)
                 return 0;