seccomp: allow mode setting across threads (3ba2530c) · Commits · 戴 / test

kernel/seccomp.c

+25 −11

Original line number	Diff line number	Diff line
		@@ -173,21 +173,24 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
		*/
		static u32 seccomp_run_filters(int syscall)
		{
		struct seccomp_filter *f;
		struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
		struct seccomp_data sd;
		u32 ret = SECCOMP_RET_ALLOW;

		/* Ensure unexpected behavior doesn't result in failing open. */
		if (WARN_ON(current->seccomp.filter == NULL))
		if (unlikely(WARN_ON(f == NULL)))
		return SECCOMP_RET_KILL;

		/* Make sure cross-thread synced filter points somewhere sane. */
		smp_read_barrier_depends();

		populate_seccomp_data(&sd);

		/*
		* All filters in the list are evaluated and the lowest BPF return
		* value always takes priority (ignoring the DATA).
		*/
		for (f = current->seccomp.filter; f; f = f->prev) {
		for (; f; f = f->prev) {
		u32 cur_ret = SK_RUN_FILTER(f->prog, (void *)&sd);

		if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
		@@ -207,12 +210,18 @@ static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
		return true;
		}

		static inline void seccomp_assign_mode(unsigned long seccomp_mode)
		static inline void seccomp_assign_mode(struct task_struct *task,
		unsigned long seccomp_mode)
		{
		BUG_ON(!spin_is_locked(&current->sighand->siglock));
		BUG_ON(!spin_is_locked(&task->sighand->siglock));

		current->seccomp.mode = seccomp_mode;
		set_tsk_thread_flag(current, TIF_SECCOMP);
		task->seccomp.mode = seccomp_mode;
		/*
		* Make sure TIF_SECCOMP cannot be set before the mode (and
		* filter) is set.
		*/
		smp_mb__before_atomic();
		set_tsk_thread_flag(task, TIF_SECCOMP);
		}

		#ifdef CONFIG_SECCOMP_FILTER
		@@ -435,12 +444,17 @@ static int mode1_syscalls_32[] = {

		int __secure_computing(int this_syscall)
		{
		int mode = current->seccomp.mode;
		int exit_sig = 0;
		int *syscall;
		u32 ret;

		switch (mode) {
		/*
		* Make sure that any changes to mode from another thread have
		* been seen after TIF_SECCOMP was seen.
		*/
		rmb();

		switch (current->seccomp.mode) {
		case SECCOMP_MODE_STRICT:
		syscall = mode1_syscalls;
		#ifdef CONFIG_COMPAT
		@@ -545,7 +559,7 @@ static long seccomp_set_mode_strict(void)
		#ifdef TIF_NOTSC
		disable_TSC();
		#endif
		seccomp_assign_mode(seccomp_mode);
		seccomp_assign_mode(current, seccomp_mode);
		ret = 0;

		out:
		@@ -595,7 +609,7 @@ static long seccomp_set_mode_filter(unsigned int flags,
		/* Do not free the successfully attached filter. */
		prepared = NULL;

		seccomp_assign_mode(seccomp_mode);
		seccomp_assign_mode(current, seccomp_mode);
		out:
		spin_unlock_irq(&current->sighand->siglock);
		seccomp_filter_free(prepared);

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