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 <[email protected]>
---
security/device_cgroup.c | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
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
On Tue, Oct 25, 2022 at 7:02 AM Wang Weiyang <[email protected]> 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 <[email protected]>
> ---
> 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
On Tue, Oct 25, 2022 at 07:31:01PM +0800, Wang Weiyang 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 <[email protected]>
> ---
> security/device_cgroup.c | 33 +++++++++++++++++++++++++++++----
> 1 file changed, 29 insertions(+), 4 deletions(-)
>
> 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))
Reviewed-by: Aristeu Rozanski <[email protected]>
--
Aristeu
Hi, Paul
Can this patch be applied or something to improve?
Thanks
on 2022/10/28 19:19, Paul Moore wrote:
> On Tue, Oct 25, 2022 at 7:02 AM Wang Weiyang <[email protected]> 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 <[email protected]>
>> ---
>> 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
>>
>
>
On Mon, Nov 14, 2022 at 10:54 PM wangweiyang <[email protected]> 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 <[email protected]> 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 <[email protected]>
> >> ---
> >> 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
On Tue, Oct 25, 2022 at 7:02 AM Wang Weiyang <[email protected]> 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 <[email protected]>
> ---
> security/device_cgroup.c | 33 +++++++++++++++++++++++++++++----
> 1 file changed, 29 insertions(+), 4 deletions(-)
Merged into lsm/next, but with a stable@vger tag. Normally I would
merge something like this into lsm/stable-X.Y and send it up to Linus
after a few days, but I'd really like this to spend some time in
linux-next before going up to Linus.
--
paul-moore.com
On 2022/11/17 7:33, Paul Moore wrote:
> On Tue, Oct 25, 2022 at 7:02 AM Wang Weiyang <[email protected]> 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 <[email protected]>
>> ---
>> security/device_cgroup.c | 33 +++++++++++++++++++++++++++++----
>> 1 file changed, 29 insertions(+), 4 deletions(-)
>
> Merged into lsm/next, but with a stable@vger tag. Normally I would
> merge something like this into lsm/stable-X.Y and send it up to Linus
> after a few days, but I'd really like this to spend some time in
> linux-next before going up to Linus.
Thanks Paul. This sounds fine.