diff mbox series

[10/11] selinux: Implement the watch_key security hook [ver #7]

Message ID 156717352079.2204.16378075382991665807.stgit@warthog.procyon.org.uk (mailing list archive)
State New, archived
Headers show
Series Keyrings, Block and USB notifications [ver #7] | expand

Commit Message

David Howells Aug. 30, 2019, 1:58 p.m. UTC 
Implement the watch_key security hook to make sure that a key grants the
caller View permission in order to set a watch on a key.

For the moment, the watch_devices security hook is left unimplemented as
it's not obvious what the object should be since the queue is global and
didn't previously exist.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 security/selinux/hooks.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

Comments

Stephen Smalley Aug. 30, 2019, 2:15 p.m. UTC | #1 
On 8/30/19 9:58 AM, David Howells wrote:
> Implement the watch_key security hook to make sure that a key grants the
> caller View permission in order to set a watch on a key.
> 
> For the moment, the watch_devices security hook is left unimplemented as
> it's not obvious what the object should be since the queue is global and
> didn't previously exist.
> 
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
> 
>   security/selinux/hooks.c |   14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 74dd46de01b6..a63249ad98ab 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6533,6 +6533,17 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
>   	*_buffer = context;
>   	return rc;
>   }
> +
> +#ifdef CONFIG_KEY_NOTIFICATIONS
> +static int selinux_watch_key(struct key *key)
> +{
> +	struct key_security_struct *ksec = key->security;
> +	u32 sid = cred_sid(current_cred());

How does this differ from current_sid()?

And has current_sid() not been converted to use selinux_cred()? Looks 
like selinux_kernfs_init_security() also uses current_security() directly.

> +
> +	return avc_has_perm(&selinux_state,
> +			    sid, ksec->sid, SECCLASS_KEY, KEY_NEED_VIEW, NULL);
> +}
> +#endif
>   #endif
>   
>   #ifdef CONFIG_SECURITY_INFINIBAND
> @@ -6965,6 +6976,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>   	LSM_HOOK_INIT(key_free, selinux_key_free),
>   	LSM_HOOK_INIT(key_permission, selinux_key_permission),
>   	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
> +#ifdef CONFIG_KEY_NOTIFICATIONS
> +	LSM_HOOK_INIT(watch_key, selinux_watch_key),
> +#endif
>   #endif
>   
>   #ifdef CONFIG_AUDIT
>
David Howells Aug. 30, 2019, 2:23 p.m. UTC | #2 
Stephen Smalley <sds@tycho.nsa.gov> wrote:

> > +	u32 sid = cred_sid(current_cred());
> 
> How does this differ from current_sid()?
> 
> And has current_sid() not been converted to use selinux_cred()? Looks like
> selinux_kernfs_init_security() also uses current_security() directly.

It probably doesn't - okay I'll use that instead.

David
David Howells Aug. 30, 2019, 2:41 p.m. UTC | #3 
How about the attached instead, then?

David
---
commit 00444a695b35c602230ac2cabb4f1d7e94e3966d
Author: David Howells <dhowells@redhat.com>
Date:   Thu Aug 29 17:01:34 2019 +0100

    selinux: Implement the watch_key security hook
    
    Implement the watch_key security hook to make sure that a key grants the
    caller View permission in order to set a watch on a key.
    
    For the moment, the watch_devices security hook is left unimplemented as
    it's not obvious what the object should be since the queue is global and
    didn't previously exist.
    
    Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 74dd46de01b6..88df06969bed 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6533,6 +6533,17 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
 	*_buffer = context;
 	return rc;
 }
+
+#ifdef CONFIG_KEY_NOTIFICATIONS
+static int selinux_watch_key(struct key *key)
+{
+	struct key_security_struct *ksec = key->security;
+	u32 sid = current_sid();
+
+	return avc_has_perm(&selinux_state,
+			    sid, ksec->sid, SECCLASS_KEY, KEY_NEED_VIEW, NULL);
+}
+#endif
 #endif
 
 #ifdef CONFIG_SECURITY_INFINIBAND
@@ -6965,6 +6976,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(key_free, selinux_key_free),
 	LSM_HOOK_INIT(key_permission, selinux_key_permission),
 	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
+#ifdef CONFIG_KEY_NOTIFICATIONS
+	LSM_HOOK_INIT(watch_key, selinux_watch_key),
+#endif
 #endif
 
 #ifdef CONFIG_AUDIT
Stephen Smalley Aug. 30, 2019, 3:41 p.m. UTC | #4 
On 8/30/19 10:41 AM, David Howells wrote:
> How about the attached instead, then?

Works for me.

> 
> David
> ---
> commit 00444a695b35c602230ac2cabb4f1d7e94e3966d
> Author: David Howells <dhowells@redhat.com>
> Date:   Thu Aug 29 17:01:34 2019 +0100
> 
>      selinux: Implement the watch_key security hook
>      
>      Implement the watch_key security hook to make sure that a key grants the
>      caller View permission in order to set a watch on a key.
>      
>      For the moment, the watch_devices security hook is left unimplemented as
>      it's not obvious what the object should be since the queue is global and
>      didn't previously exist.
>      
>      Signed-off-by: David Howells <dhowells@redhat.com>

Acked-by: Stephen Smalley <sds@tycho.nsa.gov>

> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 74dd46de01b6..88df06969bed 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6533,6 +6533,17 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
>   	*_buffer = context;
>   	return rc;
>   }
> +
> +#ifdef CONFIG_KEY_NOTIFICATIONS
> +static int selinux_watch_key(struct key *key)
> +{
> +	struct key_security_struct *ksec = key->security;
> +	u32 sid = current_sid();
> +
> +	return avc_has_perm(&selinux_state,
> +			    sid, ksec->sid, SECCLASS_KEY, KEY_NEED_VIEW, NULL);
> +}
> +#endif
>   #endif
>   
>   #ifdef CONFIG_SECURITY_INFINIBAND
> @@ -6965,6 +6976,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>   	LSM_HOOK_INIT(key_free, selinux_key_free),
>   	LSM_HOOK_INIT(key_permission, selinux_key_permission),
>   	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
> +#ifdef CONFIG_KEY_NOTIFICATIONS
> +	LSM_HOOK_INIT(watch_key, selinux_watch_key),
> +#endif
>   #endif
>   
>   #ifdef CONFIG_AUDIT
>
diff mbox series

Patch

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 74dd46de01b6..a63249ad98ab 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6533,6 +6533,17 @@  static int selinux_key_getsecurity(struct key *key, char **_buffer)
 	*_buffer = context;
 	return rc;
 }
+
+#ifdef CONFIG_KEY_NOTIFICATIONS
+static int selinux_watch_key(struct key *key)
+{
+	struct key_security_struct *ksec = key->security;
+	u32 sid = cred_sid(current_cred());
+
+	return avc_has_perm(&selinux_state,
+			    sid, ksec->sid, SECCLASS_KEY, KEY_NEED_VIEW, NULL);
+}
+#endif
 #endif
 
 #ifdef CONFIG_SECURITY_INFINIBAND
@@ -6965,6 +6976,9 @@  static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(key_free, selinux_key_free),
 	LSM_HOOK_INIT(key_permission, selinux_key_permission),
 	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
+#ifdef CONFIG_KEY_NOTIFICATIONS
+	LSM_HOOK_INIT(watch_key, selinux_watch_key),
+#endif
 #endif
 
 #ifdef CONFIG_AUDIT