selinux: add gfp argument to security_xfrm_policy_alloc and fix callers

security_xfrm_policy_alloc can be called in atomic context so the
allocation should be done with GFP_ATOMIC. Add an argument to let the
callers choose the appropriate way. In order to do so a gfp argument
needs to be added to the method xfrm_policy_alloc_security in struct
security_operations and to the internal function
selinux_xfrm_alloc_user. After that switch to GFP_ATOMIC in the atomic
callers and leave GFP_KERNEL as before for the rest.
The path that needed the gfp argument addition is:
security_xfrm_policy_alloc -> security_ops.xfrm_policy_alloc_security ->
all users of xfrm_policy_alloc_security (e.g. selinux_xfrm_policy_alloc) ->
selinux_xfrm_alloc_user (here the allocation used to be GFP_KERNEL only)

Now adding a gfp argument to selinux_xfrm_alloc_user requires us to also
add it to security_context_to_sid which is used inside and prior to this
patch did only GFP_KERNEL allocation. So add gfp argument to
security_context_to_sid and adjust all of its callers as well.

CC: Paul Moore <paul@paul-moore.com>
CC: Dave Jones <davej@redhat.com>
CC: Steffen Klassert <steffen.klassert@secunet.com>
CC: Fan Du <fan.du@windriver.com>
CC: David S. Miller <davem@davemloft.net>
CC: LSM list <linux-security-module@vger.kernel.org>
CC: SELinux list <selinux@tycho.nsa.gov>

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 5d0144ee8ed6..4bca49414a40 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -1289,16 +1289,18 @@ out:
  * @scontext: security context
  * @scontext_len: length in bytes
  * @sid: security identifier, SID
+ * @gfp: context for the allocation
  *
  * Obtains a SID associated with the security context that
  * has the string representation specified by @scontext.
  * Returns -%EINVAL if the context is invalid, -%ENOMEM if insufficient
  * memory is available, or 0 on success.
  */
-int security_context_to_sid(const char *scontext, u32 scontext_len, u32 *sid)
+int security_context_to_sid(const char *scontext, u32 scontext_len, u32 *sid,
+			    gfp_t gfp)
 {
 	return security_context_to_sid_core(scontext, scontext_len,
-					    sid, SECSID_NULL, GFP_KERNEL, 0);
+					    sid, SECSID_NULL, gfp, 0);
 }
 
 /**