On Thu, 2009-02-12 at 14:50 -0500, Eric Paris wrote:
> The avc update node callbacks do not check the seqno of the caller with the
> seqno of the node found. It is possible that a policy change could happen
> (although almost impossibly unlikely) in which a permissive or
> permissive_domain decision is not valid for the entry found. Simply pass
> and check that the seqno of the caller and the seqno of the node found
> match.
>
> Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
>
> security/selinux/avc.c | 9 ++++++---
> 1 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> index e5cda02..703aba1 100644
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -747,13 +747,15 @@ static inline int avc_sidcmp(u32 x, u32 y)
> * @event : Updating event
> * @perms : Permission mask bits
> * @ssid,@tsid,@tclass : identifier of an AVC entry
> + * @seqno : sequence number when decision was made
> *
> * if a valid AVC entry doesn't exist,this function returns -ENOENT.
> * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
> * otherwise, this function update the AVC entry. The original AVC-entry object
> * will release later by RCU.
> */
> -static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
> +static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
> + u32 seqno)
> {
> int hvalue, rc = 0;
> unsigned long flag;
> @@ -772,7 +774,8 @@ static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
> list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
> if (ssid == pos->ae.ssid &&
> tsid == pos->ae.tsid &&
> - tclass == pos->ae.tclass){
> + tclass == pos->ae.tclass &&
> + seqno == pos->ae.avd.seqno){
> orig = pos;
> break;
> }
> @@ -913,7 +916,7 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid,
> rc = -EACCES;
> else if (!selinux_enforcing || security_permissive_sid(ssid))
> avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
> - tsid, tclass);
> + tsid, tclass, p_ae->avd.seqno);
> else
> rc = -EACCES;
> }
>
>
> --
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--
Stephen Smalley
National Security Agency
--
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