4.9-stable patches

added patches:
	binder-use-cred-instead-of-task-for-selinux-checks.patch
	binder-use-euid-from-cred-instead-of-using-task.patch

diff --git a/queue-4.9/binder-use-cred-instead-of-task-for-selinux-checks.patch b/queue-4.9/binder-use-cred-instead-of-task-for-selinux-checks.patch
new file mode 100644 (file)
index 0000000..af1a51a
--- /dev/null
+++ b/queue-4.9/binder-use-cred-instead-of-task-for-selinux-checks.patch
@@ -0,0 +1,295 @@
+From 52f88693378a58094c538662ba652aff0253c4fe Mon Sep 17 00:00:00 2001
+From: Todd Kjos <tkjos@google.com>
+Date: Tue, 12 Oct 2021 09:56:13 -0700
+Subject: binder: use cred instead of task for selinux checks
+
+From: Todd Kjos <tkjos@google.com>
+
+commit 52f88693378a58094c538662ba652aff0253c4fe upstream.
+
+Since binder was integrated with selinux, it has passed
+'struct task_struct' associated with the binder_proc
+to represent the source and target of transactions.
+The conversion of task to SID was then done in the hook
+implementations. It turns out that there are race conditions
+which can result in an incorrect security context being used.
+
+Fix by using the 'struct cred' saved during binder_open and pass
+it to the selinux subsystem.
+
+Cc: stable@vger.kernel.org # 5.14 (need backport for earlier stables)
+Fixes: 79af73079d75 ("Add security hooks to binder and implement the hooks for SELinux.")
+Suggested-by: Jann Horn <jannh@google.com>
+Signed-off-by: Todd Kjos <tkjos@google.com>
+Acked-by: Casey Schaufler <casey@schaufler-ca.com>
+Signed-off-by: Paul Moore <paul@paul-moore.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/android/binder.c  |   18 +++++++++---------
+ include/linux/lsm_hooks.h |   32 ++++++++++++++++----------------
+ include/linux/security.h  |   28 ++++++++++++++--------------
+ security/security.c       |   14 +++++++-------
+ security/selinux/hooks.c  |   31 +++++++++++++------------------
+ 5 files changed, 59 insertions(+), 64 deletions(-)
+
+--- a/drivers/android/binder.c
++++ b/drivers/android/binder.c
+@@ -1432,8 +1432,8 @@ static void binder_transaction(struct bi
+                       return_error = BR_FAILED_REPLY;
+                       goto err_invalid_target_handle;
+               }
+-              if (security_binder_transaction(proc->tsk,
+-                                              target_proc->tsk) < 0) {
++              if (security_binder_transaction(proc->cred,
++                                              target_proc->cred) < 0) {
+                       return_error = BR_FAILED_REPLY;
+                       goto err_invalid_target_handle;
+               }
+@@ -1594,8 +1594,8 @@ static void binder_transaction(struct bi
+                               return_error = BR_FAILED_REPLY;
+                               goto err_binder_get_ref_for_node_failed;
+                       }
+-                      if (security_binder_transfer_binder(proc->tsk,
+-                                                          target_proc->tsk)) {
++                      if (security_binder_transfer_binder(proc->cred,
++                                                          target_proc->cred)) {
+                               return_error = BR_FAILED_REPLY;
+                               goto err_binder_get_ref_for_node_failed;
+                       }
+@@ -1634,8 +1634,8 @@ static void binder_transaction(struct bi
+                               return_error = BR_FAILED_REPLY;
+                               goto err_binder_get_ref_failed;
+                       }
+-                      if (security_binder_transfer_binder(proc->tsk,
+-                                                          target_proc->tsk)) {
++                      if (security_binder_transfer_binder(proc->cred,
++                                                          target_proc->cred)) {
+                               return_error = BR_FAILED_REPLY;
+                               goto err_binder_get_ref_failed;
+                       }
+@@ -1698,8 +1698,8 @@ static void binder_transaction(struct bi
+                               return_error = BR_FAILED_REPLY;
+                               goto err_fget_failed;
+                       }
+-                      if (security_binder_transfer_file(proc->tsk,
+-                                                        target_proc->tsk,
++                      if (security_binder_transfer_file(proc->cred,
++                                                        target_proc->cred,
+                                                         file) < 0) {
+                               fput(file);
+                               return_error = BR_FAILED_REPLY;
+@@ -2781,7 +2781,7 @@ static int binder_ioctl_set_ctx_mgr(stru
+               ret = -EBUSY;
+               goto out;
+       }
+-      ret = security_binder_set_context_mgr(proc->tsk);
++      ret = security_binder_set_context_mgr(proc->cred);
+       if (ret < 0)
+               goto out;
+       if (uid_valid(binder_context_mgr_uid)) {
+--- a/include/linux/lsm_hooks.h
++++ b/include/linux/lsm_hooks.h
+@@ -1147,22 +1147,22 @@
+  *
+  * @binder_set_context_mgr
+  *    Check whether @mgr is allowed to be the binder context manager.
+- *    @mgr contains the task_struct for the task being registered.
++ *    @mgr contains the struct cred for the current binder process.
+  *    Return 0 if permission is granted.
+  * @binder_transaction
+  *    Check whether @from is allowed to invoke a binder transaction call
+  *    to @to.
+- *    @from contains the task_struct for the sending task.
+- *    @to contains the task_struct for the receiving task.
+- * @binder_transfer_binder
++ *    @from contains the struct cred for the sending process.
++ *    @to contains the struct cred for the receiving process.
++ * @binder_transfer_binder:
+  *    Check whether @from is allowed to transfer a binder reference to @to.
+- *    @from contains the task_struct for the sending task.
+- *    @to contains the task_struct for the receiving task.
+- * @binder_transfer_file
++ *    @from contains the struct cred for the sending process.
++ *    @to contains the struct cred for the receiving process.
++ * @binder_transfer_file:
+  *    Check whether @from is allowed to transfer @file to @to.
+- *    @from contains the task_struct for the sending task.
++ *    @from contains the struct cred for the sending process.
+  *    @file contains the struct file being transferred.
+- *    @to contains the task_struct for the receiving task.
++ *    @to contains the struct cred for the receiving process.
+  *
+  * @ptrace_access_check:
+  *    Check permission before allowing the current process to trace the
+@@ -1332,13 +1332,13 @@
+  */
+ 
+ union security_list_options {
+-      int (*binder_set_context_mgr)(struct task_struct *mgr);
+-      int (*binder_transaction)(struct task_struct *from,
+-                                      struct task_struct *to);
+-      int (*binder_transfer_binder)(struct task_struct *from,
+-                                      struct task_struct *to);
+-      int (*binder_transfer_file)(struct task_struct *from,
+-                                      struct task_struct *to,
++      int (*binder_set_context_mgr)(const struct cred *mgr);
++      int (*binder_transaction)(const struct cred *from,
++                                      const struct cred *to);
++      int (*binder_transfer_binder)(const struct cred *from,
++                                      const struct cred *to);
++      int (*binder_transfer_file)(const struct cred *from,
++                                      const struct cred *to,
+                                       struct file *file);
+ 
+       int (*ptrace_access_check)(struct task_struct *child,
+--- a/include/linux/security.h
++++ b/include/linux/security.h
+@@ -184,13 +184,13 @@ static inline void security_free_mnt_opt
+ extern int security_init(void);
+ 
+ /* Security operations */
+-int security_binder_set_context_mgr(struct task_struct *mgr);
+-int security_binder_transaction(struct task_struct *from,
+-                              struct task_struct *to);
+-int security_binder_transfer_binder(struct task_struct *from,
+-                                  struct task_struct *to);
+-int security_binder_transfer_file(struct task_struct *from,
+-                                struct task_struct *to, struct file *file);
++int security_binder_set_context_mgr(const struct cred *mgr);
++int security_binder_transaction(const struct cred *from,
++                              const struct cred *to);
++int security_binder_transfer_binder(const struct cred *from,
++                                  const struct cred *to);
++int security_binder_transfer_file(const struct cred *from,
++                                const struct cred *to, struct file *file);
+ int security_ptrace_access_check(struct task_struct *child, unsigned int mode);
+ int security_ptrace_traceme(struct task_struct *parent);
+ int security_capget(struct task_struct *target,
+@@ -394,25 +394,25 @@ static inline int security_init(void)
+       return 0;
+ }
+ 
+-static inline int security_binder_set_context_mgr(struct task_struct *mgr)
++static inline int security_binder_set_context_mgr(const struct cred *mgr)
+ {
+       return 0;
+ }
+ 
+-static inline int security_binder_transaction(struct task_struct *from,
+-                                            struct task_struct *to)
++static inline int security_binder_transaction(const struct cred *from,
++                                            const struct cred *to)
+ {
+       return 0;
+ }
+ 
+-static inline int security_binder_transfer_binder(struct task_struct *from,
+-                                                struct task_struct *to)
++static inline int security_binder_transfer_binder(const struct cred *from,
++                                                const struct cred *to)
+ {
+       return 0;
+ }
+ 
+-static inline int security_binder_transfer_file(struct task_struct *from,
+-                                              struct task_struct *to,
++static inline int security_binder_transfer_file(const struct cred *from,
++                                              const struct cred *to,
+                                               struct file *file)
+ {
+       return 0;
+--- a/security/security.c
++++ b/security/security.c
+@@ -131,25 +131,25 @@ int __init security_module_enable(const
+ 
+ /* Security operations */
+ 
+-int security_binder_set_context_mgr(struct task_struct *mgr)
++int security_binder_set_context_mgr(const struct cred *mgr)
+ {
+       return call_int_hook(binder_set_context_mgr, 0, mgr);
+ }
+ 
+-int security_binder_transaction(struct task_struct *from,
+-                              struct task_struct *to)
++int security_binder_transaction(const struct cred *from,
++                              const struct cred *to)
+ {
+       return call_int_hook(binder_transaction, 0, from, to);
+ }
+ 
+-int security_binder_transfer_binder(struct task_struct *from,
+-                                  struct task_struct *to)
++int security_binder_transfer_binder(const struct cred *from,
++                                  const struct cred *to)
+ {
+       return call_int_hook(binder_transfer_binder, 0, from, to);
+ }
+ 
+-int security_binder_transfer_file(struct task_struct *from,
+-                                struct task_struct *to, struct file *file)
++int security_binder_transfer_file(const struct cred *from,
++                                const struct cred *to, struct file *file)
+ {
+       return call_int_hook(binder_transfer_file, 0, from, to, file);
+ }
+--- a/security/selinux/hooks.c
++++ b/security/selinux/hooks.c
+@@ -2065,21 +2065,18 @@ static inline u32 open_file_to_av(struct
+ 
+ /* Hook functions begin here. */
+ 
+-static int selinux_binder_set_context_mgr(struct task_struct *mgr)
++static int selinux_binder_set_context_mgr(const struct cred *mgr)
+ {
+-      u32 mysid = current_sid();
+-      u32 mgrsid = task_sid(mgr);
+-
+-      return avc_has_perm(mysid, mgrsid, SECCLASS_BINDER,
++      return avc_has_perm(current_sid(), cred_sid(mgr), SECCLASS_BINDER,
+                           BINDER__SET_CONTEXT_MGR, NULL);
+ }
+ 
+-static int selinux_binder_transaction(struct task_struct *from,
+-                                    struct task_struct *to)
++static int selinux_binder_transaction(const struct cred *from,
++                                    const struct cred *to)
+ {
+       u32 mysid = current_sid();
+-      u32 fromsid = task_sid(from);
+-      u32 tosid = task_sid(to);
++      u32 fromsid = cred_sid(from);
++      u32 tosid = cred_sid(to);
+       int rc;
+ 
+       if (mysid != fromsid) {
+@@ -2093,21 +2090,19 @@ static int selinux_binder_transaction(st
+                           NULL);
+ }
+ 
+-static int selinux_binder_transfer_binder(struct task_struct *from,
+-                                        struct task_struct *to)
++static int selinux_binder_transfer_binder(const struct cred *from,
++                                        const struct cred *to)
+ {
+-      u32 fromsid = task_sid(from);
+-      u32 tosid = task_sid(to);
+-
+-      return avc_has_perm(fromsid, tosid, SECCLASS_BINDER, BINDER__TRANSFER,
++      return avc_has_perm(cred_sid(from), cred_sid(to),
++                          SECCLASS_BINDER, BINDER__TRANSFER,
+                           NULL);
+ }
+ 
+-static int selinux_binder_transfer_file(struct task_struct *from,
+-                                      struct task_struct *to,
++static int selinux_binder_transfer_file(const struct cred *from,
++                                      const struct cred *to,
+                                       struct file *file)
+ {
+-      u32 sid = task_sid(to);
++      u32 sid = cred_sid(to);
+       struct file_security_struct *fsec = file->f_security;
+       struct dentry *dentry = file->f_path.dentry;
+       struct inode_security_struct *isec;

diff --git a/queue-4.9/binder-use-euid-from-cred-instead-of-using-task.patch b/queue-4.9/binder-use-euid-from-cred-instead-of-using-task.patch
new file mode 100644 (file)
index 0000000..50976e4
--- /dev/null
+++ b/queue-4.9/binder-use-euid-from-cred-instead-of-using-task.patch
@@ -0,0 +1,67 @@
+From 29bc22ac5e5bc63275e850f0c8fc549e3d0e306b Mon Sep 17 00:00:00 2001
+From: Todd Kjos <tkjos@google.com>
+Date: Tue, 12 Oct 2021 09:56:12 -0700
+Subject: binder: use euid from cred instead of using task
+
+From: Todd Kjos <tkjos@google.com>
+
+commit 29bc22ac5e5bc63275e850f0c8fc549e3d0e306b upstream.
+
+Save the 'struct cred' associated with a binder process
+at initial open to avoid potential race conditions
+when converting to an euid.
+
+Set a transaction's sender_euid from the 'struct cred'
+saved at binder_open() instead of looking up the euid
+from the binder proc's 'struct task'. This ensures
+the euid is associated with the security context that
+of the task that opened binder.
+
+Cc: stable@vger.kernel.org # 4.4+
+Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
+Signed-off-by: Todd Kjos <tkjos@google.com>
+Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
+Suggested-by: Jann Horn <jannh@google.com>
+Acked-by: Casey Schaufler <casey@schaufler-ca.com>
+Signed-off-by: Paul Moore <paul@paul-moore.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/android/binder.c |    5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+--- a/drivers/android/binder.c
++++ b/drivers/android/binder.c
+@@ -303,6 +303,7 @@ struct binder_proc {
+       struct task_struct *tsk;
+       struct files_struct *files;
+       struct mutex files_lock;
++      const struct cred *cred;
+       struct hlist_node deferred_work_node;
+       int deferred_work;
+       void *buffer;
+@@ -1505,7 +1506,7 @@ static void binder_transaction(struct bi
+               t->from = thread;
+       else
+               t->from = NULL;
+-      t->sender_euid = task_euid(proc->tsk);
++      t->sender_euid = proc->cred->euid;
+       t->to_proc = target_proc;
+       t->to_thread = target_thread;
+       t->code = tr->code;
+@@ -3036,6 +3037,7 @@ static int binder_open(struct inode *nod
+       get_task_struct(current->group_leader);
+       proc->tsk = current->group_leader;
+       mutex_init(&proc->files_lock);
++      proc->cred = get_cred(filp->f_cred);
+       INIT_LIST_HEAD(&proc->todo);
+       init_waitqueue_head(&proc->wait);
+       proc->default_priority = task_nice(current);
+@@ -3241,6 +3243,7 @@ static void binder_deferred_release(stru
+       }
+ 
+       put_task_struct(proc->tsk);
++      put_cred(proc->cred);
+ 
+       binder_debug(BINDER_DEBUG_OPEN_CLOSE,
+                    "%s: %d threads %d, nodes %d (ref %d), refs %d, active transactions %d, buffers %d, pages %d\n",

diff --git a/queue-4.9/series b/queue-4.9/series
new file mode 100644 (file)
index 0000000..c3082c8
--- /dev/null
+++ b/queue-4.9/series
@@ -0,0 +1,2 @@
+binder-use-euid-from-cred-instead-of-using-task.patch
+binder-use-cred-instead-of-task-for-selinux-checks.patch