From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: <serge@hallyn.com>, <ebiederm@xmission.com>,
<agruenba@redhat.com>, <gregkh@linuxfoundation.org>,
<oleg@redhat.com>, <linux-kernel@vger.kernel.org>,
<paul@paul-moore.com>, <ktkhai@virtuozzo.com>,
<viro@zeniv.linux.org.uk>, <avagin@openvz.org>,
<gorcunov@openvz.org>, <mtk.manpages@gmail.com>,
<akpm@linux-foundation.org>, <luto@amacapital.net>,
<mingo@kernel.org>, <keescook@chromium.org>
Subject: [PATCH v2] security: Use user_namespace::level to avoid redundant iterations in cap_capable()
Date: Tue, 2 May 2017 20:11:52 +0300 [thread overview]
Message-ID: <149374507992.8805.9670925184482786336.stgit@localhost.localdomain> (raw)
When ns->level is not larger then cred->user_ns->level,
then ns can't be cred->user_ns's descendant, and
there is no a sence to search in parents.
So, breake the cycle earlier and skip needless iterations.
v2: Change comment on suggested by Andy Lutomirski.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
security/commoncap.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/security/commoncap.c b/security/commoncap.c
index 78b37838a2d3..a424aa0123af 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -82,8 +82,11 @@ int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
if (ns == cred->user_ns)
return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
- /* Have we tried all of the parent namespaces? */
- if (ns == &init_user_ns)
+ /*
+ * If we're already at a lower level than we're looking for, we're
+ * done searching.
+ */
+ if (ns->level <= cred->user_ns->level)
return -EPERM;
/*
reply other threads:[~2017-05-02 17:12 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=149374507992.8805.9670925184482786336.stgit@localhost.localdomain \
--to=ktkhai@virtuozzo.com \
--cc=agruenba@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=avagin@openvz.org \
--cc=ebiederm@xmission.com \
--cc=gorcunov@openvz.org \
--cc=gregkh@linuxfoundation.org \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mingo@kernel.org \
--cc=mtk.manpages@gmail.com \
--cc=oleg@redhat.com \
--cc=paul@paul-moore.com \
--cc=serge@hallyn.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®