Messages in this thread | | | From | Paul Moore <> | Date | Tue, 15 Nov 2022 15:55:58 -0500 | Subject | Re: [PATCH] device_cgroup: Roll back to original exceptions after copy failure |
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On Mon, Nov 14, 2022 at 10:54 PM wangweiyang <wangweiyang2@huawei.com> wrote: > > Hi, Paul > Can this patch be applied or something to improve?
Possibly. I need to find the time to properly review the patch; it's in my queue, I just haven't gotten to it yet. I'll reply to the patch posting with either a note that the patch has been merged, or a set of questions/feedback that needs to be resolved. If you haven't heard from me on the patch, the best thing you can do is exercise patience.
> on 2022/10/28 19:19, Paul Moore wrote: > > On Tue, Oct 25, 2022 at 7:02 AM Wang Weiyang <wangweiyang2@huawei.com> wrote: > >> > >> When add the 'a *:* rwm' entry to devcgroup A's whitelist, at first A's > >> exceptions will be cleaned and A's behavior is changed to > >> DEVCG_DEFAULT_ALLOW. Then parent's exceptions will be copyed to A's > >> whitelist. If copy failure occurs, just return leaving A to grant > >> permissions to all devices. And A may grant more permissions than > >> parent. > >> > >> Backup A's whitelist and recover original exceptions after copy > >> failure. > >> > >> Fixes: 4cef7299b478 ("device_cgroup: add proper checking when changing default behavior") > >> Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com> > >> --- > >> security/device_cgroup.c | 33 +++++++++++++++++++++++++++++---- > >> 1 file changed, 29 insertions(+), 4 deletions(-) > > > > On quick glance this looks reasonable to me, but I'm working with > > limited time connected to a network so I can't say I've given this a > > full and proper review; if a third party could spend some time to give > > this an additional review before I merge it I would greatly appreciate > > it. > > > >> diff --git a/security/device_cgroup.c b/security/device_cgroup.c > >> index a9f8c63a96d1..bef2b9285fb3 100644 > >> --- a/security/device_cgroup.c > >> +++ b/security/device_cgroup.c > >> @@ -82,6 +82,17 @@ static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig) > >> return -ENOMEM; > >> } > >> > >> +static void dev_exceptions_move(struct list_head *dest, struct list_head *orig) > >> +{ > >> + struct dev_exception_item *ex, *tmp; > >> + > >> + lockdep_assert_held(&devcgroup_mutex); > >> + > >> + list_for_each_entry_safe(ex, tmp, orig, list) { > >> + list_move_tail(&ex->list, dest); > >> + } > >> +} > >> + > >> /* > >> * called under devcgroup_mutex > >> */ > >> @@ -604,11 +615,13 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, > >> int count, rc = 0; > >> struct dev_exception_item ex; > >> struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent); > >> + struct dev_cgroup tmp_devcgrp; > >> > >> if (!capable(CAP_SYS_ADMIN)) > >> return -EPERM; > >> > >> memset(&ex, 0, sizeof(ex)); > >> + memset(&tmp_devcgrp, 0, sizeof(tmp_devcgrp)); > >> b = buffer; > >> > >> switch (*b) { > >> @@ -620,15 +633,27 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, > >> > >> if (!may_allow_all(parent)) > >> return -EPERM; > >> - dev_exception_clean(devcgroup); > >> - devcgroup->behavior = DEVCG_DEFAULT_ALLOW; > >> - if (!parent) > >> + if (!parent) { > >> + devcgroup->behavior = DEVCG_DEFAULT_ALLOW; > >> + dev_exception_clean(devcgroup); > >> break; > >> + } > >> > >> + INIT_LIST_HEAD(&tmp_devcgrp.exceptions); > >> + rc = dev_exceptions_copy(&tmp_devcgrp.exceptions, > >> + &devcgroup->exceptions); > >> + if (rc) > >> + return rc; > >> + dev_exception_clean(devcgroup); > >> rc = dev_exceptions_copy(&devcgroup->exceptions, > >> &parent->exceptions); > >> - if (rc) > >> + if (rc) { > >> + dev_exceptions_move(&devcgroup->exceptions, > >> + &tmp_devcgrp.exceptions); > >> return rc; > >> + } > >> + devcgroup->behavior = DEVCG_DEFAULT_ALLOW; > >> + dev_exception_clean(&tmp_devcgrp); > >> break; > >> case DEVCG_DENY: > >> if (css_has_online_children(&devcgroup->css)) > >> -- > >> 2.17.1 > >> > > > >
-- paul-moore.com
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