CRED: Separate per-task-group keyrings from signal_struct (bb952bb9) · Commits · e / devices / android_kernel_fairphone_FP3

include/linux/cred.h

+16 −0

Original line number	Diff line number	Diff line
		@@ -71,6 +71,21 @@ extern int groups_search(const struct group_info *, gid_t);
		extern int in_group_p(gid_t);
		extern int in_egroup_p(gid_t);

		/*
		* The common credentials for a thread group
		* - shared by CLONE_THREAD
		*/
		#ifdef CONFIG_KEYS
		struct thread_group_cred {
		atomic_t usage;
		pid_t tgid; /* thread group process ID */
		spinlock_t lock;
		struct key session_keyring; / keyring inherited over fork */
		struct key process_keyring; / keyring private to this process */
		struct rcu_head rcu; /* RCU deletion hook */
		};
		#endif

		/*
		* The security context of a task
		*
		@@ -114,6 +129,7 @@ struct cred {
		* keys to */
		struct key thread_keyring; / keyring private to this thread */
		struct key request_key_auth; / assumed request_key authority */
		struct thread_group_cred tgcred; / thread-group shared credentials */
		#endif
		#ifdef CONFIG_SECURITY
		void security; / subjective LSM security */

include/linux/key.h

+2 −6

Original line number	Diff line number	Diff line
		@@ -278,9 +278,7 @@ extern ctl_table key_sysctls[];
		*/
		extern void switch_uid_keyring(struct user_struct *new_user);
		extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
		extern int copy_thread_group_keys(struct task_struct *tsk);
		extern void exit_keys(struct task_struct *tsk);
		extern void exit_thread_group_keys(struct signal_struct *tg);
		extern int suid_keys(struct task_struct *tsk);
		extern int exec_keys(struct task_struct *tsk);
		extern void key_fsuid_changed(struct task_struct *tsk);
		@@ -289,8 +287,8 @@ extern void key_init(void);

		#define __install_session_keyring(keyring) \
		({ \
		struct key *old_session = current->signal->session_keyring; \
		current->signal->session_keyring = keyring; \
		struct key *old_session = current->cred->tgcred->session_keyring; \
		current->cred->tgcred->session_keyring = keyring; \
		old_session; \
		})

		@@ -308,9 +306,7 @@ extern void key_init(void);
		#define switch_uid_keyring(u) do { } while(0)
		#define __install_session_keyring(k) ({ NULL; })
		#define copy_keys(f,t) 0
		#define copy_thread_group_keys(t) 0
		#define exit_keys(t) do { } while(0)
		#define exit_thread_group_keys(tg) do { } while(0)
		#define suid_keys(t) do { } while(0)
		#define exec_keys(t) do { } while(0)
		#define key_fsuid_changed(t) do { } while(0)

include/linux/sched.h

+0 −6

Original line number	Diff line number	Diff line
		@@ -571,12 +571,6 @@ struct signal_struct {
		*/
		struct rlimit rlim[RLIM_NLIMITS];

		/* keep the process-shared keyrings here so that they do the right
		* thing in threads created with CLONE_THREAD */
		#ifdef CONFIG_KEYS
		struct key session_keyring; / keyring inherited over fork */
		struct key process_keyring; / keyring private to this process */
		#endif
		#ifdef CONFIG_BSD_PROCESS_ACCT
		struct pacct_struct pacct; /* per-process accounting information */
		#endif

kernel/cred.c

+63 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,17 @@
		#include <linux/init_task.h>
		#include <linux/security.h>

		/*
		* The common credentials for the initial task's thread group
		*/
		#ifdef CONFIG_KEYS
		static struct thread_group_cred init_tgcred = {
		.usage = ATOMIC_INIT(2),
		.tgid = 0,
		.lock = SPIN_LOCK_UNLOCKED,
		};
		#endif

		/*
		* The initial credentials for the initial task
		*/
		@@ -28,8 +39,41 @@ struct cred init_cred = {
		.cap_bset = CAP_INIT_BSET,
		.user = INIT_USER,
		.group_info = &init_groups,
		#ifdef CONFIG_KEYS
		.tgcred = &init_tgcred,
		#endif
		};

		/*
		* Dispose of the shared task group credentials
		*/
		#ifdef CONFIG_KEYS
		static void release_tgcred_rcu(struct rcu_head *rcu)
		{
		struct thread_group_cred *tgcred =
		container_of(rcu, struct thread_group_cred, rcu);

		BUG_ON(atomic_read(&tgcred->usage) != 0);

		key_put(tgcred->session_keyring);
		key_put(tgcred->process_keyring);
		kfree(tgcred);
		}
		#endif

		/*
		* Release a set of thread group credentials.
		*/
		static void release_tgcred(struct cred *cred)
		{
		#ifdef CONFIG_KEYS
		struct thread_group_cred *tgcred = cred->tgcred;

		if (atomic_dec_and_test(&tgcred->usage))
		call_rcu(&tgcred->rcu, release_tgcred_rcu);
		#endif
		}

		/*
		* The RCU callback to actually dispose of a set of credentials
		*/
		@@ -41,6 +85,7 @@ static void put_cred_rcu(struct rcu_head *rcu)

		key_put(cred->thread_keyring);
		key_put(cred->request_key_auth);
		release_tgcred(cred);
		put_group_info(cred->group_info);
		free_uid(cred->user);
		security_cred_free(cred);
		@@ -71,12 +116,30 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
		if (!pcred)
		return -ENOMEM;

		#ifdef CONFIG_KEYS
		if (clone_flags & CLONE_THREAD) {
		atomic_inc(&pcred->tgcred->usage);
		} else {
		pcred->tgcred = kmalloc(sizeof(struct cred), GFP_KERNEL);
		if (!pcred->tgcred) {
		kfree(pcred);
		return -ENOMEM;
		}
		atomic_set(&pcred->tgcred->usage, 1);
		spin_lock_init(&pcred->tgcred->lock);
		pcred->tgcred->process_keyring = NULL;
		pcred->tgcred->session_keyring =
		key_get(p->cred->tgcred->session_keyring);
		}
		#endif

		#ifdef CONFIG_SECURITY
		pcred->security = NULL;
		#endif

		ret = security_cred_alloc(pcred);
		if (ret < 0) {
		release_tgcred(pcred);
		kfree(pcred);
		return ret;
		}

kernel/fork.c

+0 −7

Original line number	Diff line number	Diff line
		@@ -802,12 +802,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
		if (!sig)
		return -ENOMEM;

		ret = copy_thread_group_keys(tsk);
		if (ret < 0) {
		kmem_cache_free(signal_cachep, sig);
		return ret;
		}

		atomic_set(&sig->count, 1);
		atomic_set(&sig->live, 1);
		init_waitqueue_head(&sig->wait_chldexit);
		@@ -852,7 +846,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
		void __cleanup_signal(struct signal_struct *sig)
		{
		thread_group_cputime_free(sig);
		exit_thread_group_keys(sig);
		tty_kref_put(sig->tty);
		kmem_cache_free(signal_cachep, sig);
		}