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

Commit Message

Konrad Rzeszutek Wilk March 19, 2017, 1:41 p.m. UTC

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 <[e-mail]>
---
 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(-)

Comments

Jan Beulich March 21, 2017, 3:19 p.m. UTC | #1

>>> On 19.03.17 at 14:41, <[e-mail]> 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 <[e-mail]>

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

Jan

Patch

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.
 <P>
 <b><i>32-bit implementation</i>.</b>
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
 > `= <boolean>`
 
-### tmem\_shared\_auth
-> `= <boolean>`
-
 ### 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;