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authorEric W. Biederman <ebiederm@xmission.com>2011-11-22 01:22:31 (GMT)
committerEric W. Biederman <ebiederm@xmission.com>2012-11-19 13:59:24 (GMT)
commit5eaf563e53294d6696e651466697eb9d491f3946 (patch)
treea09a97b50613493b18eba220d7e7d2bcf4d383fa
parentuserns: Ignore suid and sgid on binaries if the uid or gid can not be mapped (diff)
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userns: Allow unprivileged users to create user namespaces.
Now that we have been through every permission check in the kernel having uid == 0 and gid == 0 in your local user namespace no longer adds any special privileges. Even having a full set of caps in your local user namespace is safe because capabilies are relative to your local user namespace, and do not confer unexpected privileges. Over the long term this should allow much more of the kernels functionality to be safely used by non-root users. Functionality like unsharing the mount namespace that is only unsafe because it can fool applications whose privileges are raised when they are executed. Since those applications have no privileges in a user namespaces it becomes safe to spoof and confuse those applications all you want. Those capabilities will still need to be enabled carefully because we may still need things like rlimits on the number of unprivileged mounts but that is to avoid DOS attacks not to avoid fooling root owned processes. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
-rw-r--r--kernel/fork.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 811ffba..8c29abb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1569,14 +1569,6 @@ long do_fork(unsigned long clone_flags,
if (clone_flags & (CLONE_THREAD|CLONE_PARENT))
return -EINVAL;
}
- if (clone_flags & CLONE_NEWUSER) {
- /* hopefully this check will go away when userns support is
- * complete
- */
- if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
- !capable(CAP_SETGID))
- return -EPERM;
- }
/*
* Determine whether and which event to report to ptracer. When