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, 7 insertions, 3 deletions

diff --git a/include/linux/security.h b/include/linux/security.h
index 5623a7f965b7..2fc42d191f79 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1040,6 +1040,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *      Allocate a security structure to the xp->security field; the security
  *      field is initialized to NULL when the xfrm_policy is allocated.
  *      Return 0 if operation was successful (memory to allocate, legal context)
+ *      @gfp is to specify the context for the allocation
  * @xfrm_policy_clone_security:
  *      @old_ctx contains an existing xfrm_sec_ctx.
  *      @new_ctxp contains a new xfrm_sec_ctx being cloned from old.
@@ -1683,7 +1684,7 @@ struct security_operations {
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
         int (*xfrm_policy_alloc_security) (struct xfrm_sec_ctx **ctxp,
-                        struct xfrm_user_sec_ctx *sec_ctx);
+                        struct xfrm_user_sec_ctx *sec_ctx, gfp_t gfp);
         int (*xfrm_policy_clone_security) (struct xfrm_sec_ctx *old_ctx, struct xfrm_sec_ctx **new_ctx);
         void (*xfrm_policy_free_security) (struct xfrm_sec_ctx *ctx);
         int (*xfrm_policy_delete_security) (struct xfrm_sec_ctx *ctx);
@@ -2859,7 +2860,8 @@ static inline void security_skb_owned_by(struct sk_buff *skb, struct sock *sk)
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
 
-int security_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_user_sec_ctx *sec_ctx);
+int security_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
+                               struct xfrm_user_sec_ctx *sec_ctx, gfp_t gfp);
 int security_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx, struct xfrm_sec_ctx **new_ctxp);
 void security_xfrm_policy_free(struct xfrm_sec_ctx *ctx);
 int security_xfrm_policy_delete(struct xfrm_sec_ctx *ctx);
@@ -2877,7 +2879,9 @@ void security_skb_classify_flow(struct sk_buff *skb, struct flowi *fl);
 
 #else   /* CONFIG_SECURITY_NETWORK_XFRM */
 
-static inline int security_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_user_sec_ctx *sec_ctx)
+static inline int security_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
+                                             struct xfrm_user_sec_ctx *sec_ctx,
+                                             gfp_t gfp)
 {
         return 0;
 }