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authorLinus Torvalds <torvalds@linux-foundation.org>2008-12-28 20:43:54 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2008-12-28 20:43:54 +0100
commitbb26c6c29b7cc9f39e491b074b09f3c284738d36 (patch)
treec7867af2bb4ff0feae889183efcd4d79b0f9a325 /lib
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 (diff)
parentMerge branch 'next' into for-linus (diff)
downloadlinux-bb26c6c29b7cc9f39e491b074b09f3c284738d36.tar.xz
linux-bb26c6c29b7cc9f39e491b074b09f3c284738d36.zip
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: (105 commits) SELinux: don't check permissions for kernel mounts security: pass mount flags to security_sb_kern_mount() SELinux: correctly detect proc filesystems of the form "proc/foo" Audit: Log TIOCSTI user namespaces: document CFS behavior user namespaces: require cap_set{ug}id for CLONE_NEWUSER user namespaces: let user_ns be cloned with fairsched CRED: fix sparse warnings User namespaces: use the current_user_ns() macro User namespaces: set of cleanups (v2) nfsctl: add headers for credentials coda: fix creds reference capabilities: define get_vfs_caps_from_disk when file caps are not enabled CRED: Allow kernel services to override LSM settings for task actions CRED: Add a kernel_service object class to SELinux CRED: Differentiate objective and effective subjective credentials on a task CRED: Documentation CRED: Use creds in file structs CRED: Prettify commoncap.c CRED: Make execve() take advantage of copy-on-write credentials ...
Diffstat (limited to 'lib')
-rw-r--r--lib/Makefile2
-rw-r--r--lib/is_single_threaded.c45
2 files changed, 46 insertions, 1 deletions
diff --git a/lib/Makefile b/lib/Makefile
index 7cb65d85aeb0..80fe8a3ec12a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -11,7 +11,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
rbtree.o radix-tree.o dump_stack.o \
idr.o int_sqrt.o extable.o prio_tree.o \
sha1.o irq_regs.o reciprocal_div.o argv_split.o \
- proportions.o prio_heap.o ratelimit.o show_mem.o
+ proportions.o prio_heap.o ratelimit.o show_mem.o is_single_threaded.o
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c
new file mode 100644
index 000000000000..f1ed2fe76c65
--- /dev/null
+++ b/lib/is_single_threaded.c
@@ -0,0 +1,45 @@
+/* Function to determine if a thread group is single threaded or not
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ * - Derived from security/selinux/hooks.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/sched.h>
+
+/**
+ * is_single_threaded - Determine if a thread group is single-threaded or not
+ * @p: A task in the thread group in question
+ *
+ * This returns true if the thread group to which a task belongs is single
+ * threaded, false if it is not.
+ */
+bool is_single_threaded(struct task_struct *p)
+{
+ struct task_struct *g, *t;
+ struct mm_struct *mm = p->mm;
+
+ if (atomic_read(&p->signal->count) != 1)
+ goto no;
+
+ if (atomic_read(&p->mm->mm_users) != 1) {
+ read_lock(&tasklist_lock);
+ do_each_thread(g, t) {
+ if (t->mm == mm && t != p)
+ goto no_unlock;
+ } while_each_thread(g, t);
+ read_unlock(&tasklist_lock);
+ }
+
+ return true;
+
+no_unlock:
+ read_unlock(&tasklist_lock);
+no:
+ return false;
+}