Re: [Xen-devel] [PATCH v1 3/5] tmem: By default to join an shared pool it must be authorized.

[Jan Beulich]

>>> On 19.03.17 at 14:41,  wrote:
> Having an off by default option allowing guests to join
> _any_ shared pool is not very secure.
> 
> Lets eliminate tmem_shared_auth bootup option (which
> was disabled by default) and have the code force this by default.
> 
> Signed-off-by: Konrad Rzeszutek Wilk 

LGTM (can't ack and don't feel like giving R-b)

Jan


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[Xen-devel] [PATCH v1 3/5] tmem: By default to join an shared pool it must be authorized.

[Konrad Rzeszutek Wilk]

Having an off by default option allowing guests to join
_any_ shared pool is not very secure.

Lets eliminate tmem_shared_auth bootup option (which
was disabled by default) and have the code force this by default.

Signed-off-by: Konrad Rzeszutek Wilk 
---
 docs/misc/tmem-internals.html   | 6 ++
 docs/misc/xen-command-line.markdown | 3 ---
 xen/common/tmem.c   | 4 ++--
 xen/common/tmem_xen.c   | 3 ---
 xen/include/xen/tmem_xen.h  | 7 ---
 5 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/docs/misc/tmem-internals.html b/docs/misc/tmem-internals.html
index 2d8635d..9b7e70e 100644
--- a/docs/misc/tmem-internals.html
+++ b/docs/misc/tmem-internals.html
@@ -715,11 +715,9 @@ Ocfs2 has only very limited security; it is assumed that 
anyone who can
 access the filesystem bits on the shared disk can mount the filesystem and use
 it.  But in a virtualized data center,
 higher isolation requirements may apply.
-As a result, a Xen boot option -- tmem_shared_auth -- was
-added.  The option defaults to disabled,
-but when it is enabled, management tools must explicitly authenticate (or may
+As a result, management tools must explicitly authenticate (or may
 explicitly deny) shared pool access to any client.
-On Xen, this is done with the xm
+On Xen, this is done with the xl
 tmem-shared-auth command.
 
 32-bit implementation.
diff --git a/docs/misc/xen-command-line.markdown 
b/docs/misc/xen-command-line.markdown
index bad20db..9c20dad 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1543,9 +1543,6 @@ pages) must also be specified via the tbuf\_size 
parameter.
 ### tmem\_compress
 > `= `
 
-### tmem\_shared\_auth
-> `= `
-
 ### tsc
 > `= unstable | skewed | stable:socket`
 
diff --git a/xen/common/tmem.c b/xen/common/tmem.c
index 504e9eb..ff74292 100644
--- a/xen/common/tmem.c
+++ b/xen/common/tmem.c
@@ -846,7 +846,6 @@ struct client *client_create(domid_t cli_id)
 client->info.version = TMEM_SPEC_VERSION;
 client->info.maxpools = MAX_POOLS_PER_DOMAIN;
 client->info.flags.u.compress = tmem_compression_enabled();
-client->shared_auth_required = tmem_shared_auth();
 for ( i = 0; i < MAX_GLOBAL_SHARED_POOLS; i++)
 client->shared_auth_uuid[i][0] =
 client->shared_auth_uuid[i][1] = -1L;
@@ -1530,7 +1529,8 @@ int do_tmem_new_pool(domid_t this_cli_id,
 pool->shared = 0;
 goto out;
 }
-if ( client->shared_auth_required && !tmem_global.shared_auth )
+/* By default only join domains that are authorized by admin. */
+if ( !tmem_global.shared_auth )
 {
 for ( i = 0; i < MAX_GLOBAL_SHARED_POOLS; i++)
 if ( (client->shared_auth_uuid[i][0] == uuid_lo) &&
diff --git a/xen/common/tmem_xen.c b/xen/common/tmem_xen.c
index 7d60b71..06ce3ef 100644
--- a/xen/common/tmem_xen.c
+++ b/xen/common/tmem_xen.c
@@ -20,9 +20,6 @@ boolean_param("tmem", opt_tmem);
 bool_t __read_mostly opt_tmem_compress = 0;
 boolean_param("tmem_compress", opt_tmem_compress);
 
-bool_t __read_mostly opt_tmem_shared_auth = 0;
-boolean_param("tmem_shared_auth", opt_tmem_shared_auth);
-
 atomic_t freeable_page_count = ATOMIC_INIT(0);
 
 /* these are a concurrency bottleneck, could be percpu and dynamically
diff --git a/xen/include/xen/tmem_xen.h b/xen/include/xen/tmem_xen.h
index 70cc108..dc5888c 100644
--- a/xen/include/xen/tmem_xen.h
+++ b/xen/include/xen/tmem_xen.h
@@ -41,12 +41,6 @@ static inline bool_t tmem_compression_enabled(void)
 return opt_tmem_compress;
 }
 
-extern bool_t opt_tmem_shared_auth;
-static inline bool_t tmem_shared_auth(void)
-{
-return opt_tmem_shared_auth;
-}
-
 #ifdef CONFIG_TMEM
 extern bool_t opt_tmem;
 static inline bool_t tmem_enabled(void)
@@ -291,7 +285,6 @@ struct client {
 long eph_count, eph_count_max;
 domid_t cli_id;
 xen_tmem_client_t info;
-bool_t shared_auth_required;
 /* For save/restore/migration. */
 bool_t was_frozen;
 struct list_head persistent_invalidated_list;
-- 
2.7.4


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