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| author | Wang Weiyang <wangweiyang2@huawei.com> | 2022-10-25 19:31:01 +0800 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2022-11-16 18:28:55 -0500 |
| commit | e68bfbd3b3c3a0ec3cf8c230996ad8cabe90322f (patch) | |
| tree | 38c521ea4ca6b0b842517a26d1833c9a3e9feef2 /security | |
| parent | 86ef3c735ec81566cd38174ed5e90e9721473064 (diff) | |
| download | lwn-e68bfbd3b3c3a0ec3cf8c230996ad8cabe90322f.tar.gz lwn-e68bfbd3b3c3a0ec3cf8c230996ad8cabe90322f.zip | |
device_cgroup: Roll back to original exceptions after copy failure
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.
Cc: stable@vger.kernel.org
Fixes: 4cef7299b478 ("device_cgroup: add proper checking when changing default behavior")
Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>
Reviewed-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security')
| -rw-r--r-- | security/device_cgroup.c | 33 |
1 files 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 @@ free_and_exit: 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)) |