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authorEric W. Biederman <ebiederm@xmission.com>2011-11-15 00:24:06 (GMT)
committerEric W. Biederman <ebiederm@xmission.com>2012-04-08 00:02:46 (GMT)
commit1a48e2ac034d47ed843081c4523b63c46b46888b (patch)
treed3a32ac7ffc47b075a64701a2fd74e00bbccf84d /kernel/capability.c
parent973c5914260d75292f71a4729753086b9e863d57 (diff)
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userns: Replace the hard to write inode_userns with inode_capable.
This represents a change in strategy of how to handle user namespaces. Instead of tagging everything explicitly with a user namespace and bulking up all of the comparisons of uids and gids in the kernel, all uids and gids in use will have a mapping to a flat kuid and kgid spaces respectively. This allows much more of the existing logic to be preserved and in general allows for faster code. In this new and improved world we allow someone to utiliize capabilities over an inode if the inodes owner mapps into the capabilities holders user namespace and the user has capabilities in their user namespace. Which is simple and efficient. Moving the fs uid comparisons to be comparisons in a flat kuid space follows in later patches, something that is only significant if you are using user namespaces. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/capability.c')
-rw-r--r--kernel/capability.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/capability.c b/kernel/capability.c
index 3f1adb6..cc5f071 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -419,3 +419,22 @@ bool nsown_capable(int cap)
{
return ns_capable(current_user_ns(), cap);
}
+
+/**
+ * inode_capable - Check superior capability over inode
+ * @inode: The inode in question
+ * @cap: The capability in question
+ *
+ * Return true if the current task has the given superior capability
+ * targeted at it's own user namespace and that the given inode is owned
+ * by the current user namespace or a child namespace.
+ *
+ * Currently inodes can only be owned by the initial user namespace.
+ *
+ */
+bool inode_capable(const struct inode *inode, int cap)
+{
+ struct user_namespace *ns = current_user_ns();
+
+ return ns_capable(ns, cap) && (ns == &init_user_ns);
+}