Reset the checkpointed uid and gid info on ipc objects.
Right now, we return -EPERM if the user calling sys_restart() isn't
allowed to create an object with the checkpointed uid. We may prefer
to simply use the caller's uid in that case - but that could lead to
subtle userspace bugs? Unsure, so going for the stricter behavior.
TODO: restore kern_ipc_perms->security.
Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
ipc/checkpoint.c | 33 +++++++++++++++++++++++++++++++--
1 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/ipc/checkpoint.c b/ipc/checkpoint.c
index f621226..bc77743 100644
--- a/ipc/checkpoint.c
+++ b/ipc/checkpoint.c
@@ -119,6 +119,26 @@ int checkpoint_ipc_ns(struct ckpt_ctx *ctx, struct ipc_namespace *ipc_ns)
* Restart
*/
+/*
+ * check whether current task may create ipc object with
+ * checkpointed uids and gids.
+ * Return 1 if ok, 0 if not.
+ */
+static int validate_created_perms(struct ckpt_hdr_ipc_perms *h)
+{
+ const struct cred *cred = current_cred();
+ uid_t uid = cred->uid, euid = cred->euid;
+
+ /* actually I don't know - is CAP_IPC_OWNER the right one? */
+ if (((h->uid != uid && h->uid == euid) ||
+ (h->cuid != uid && h->cuid != euid) ||
+ !in_group_p(h->cgid) ||
+ !in_group_p(h->gid)) &&
+ !capable(CAP_IPC_OWNER))
+ return 0;
+ return 1;
+}
+
int restore_load_ipc_perms(struct ckpt_hdr_ipc_perms *h,
struct kern_ipc_perm *perm)
{
@@ -139,14 +159,23 @@ int restore_load_ipc_perms(struct ckpt_hdr_ipc_perms *h,
perm->id = h->id;
perm->key = h->key;
-#if 0 /* FIX: requires security checks */
+
+ if (!validate_created_perms(h))
+ return -EPERM;
perm->uid = h->uid;
perm->gid = h->gid;
perm->cuid = h->cuid;
perm->cgid = h->cgid;
-#endif
perm->mode = h->mode;
perm->seq = h->seq;
+ /*
+ * Todo: restore perm->security.
+ * At the moment it gets set by security_x_alloc() called through
+ * ipcget()->ipcget_public()->ops-.getnew (->nequeue for instance)
+ * We will want to ask the LSM to consider resetting the
+ * checkpointed ->security, based on current_security(),
+ * the checkpointed ->security, and the checkpoint file context.
+ */
return 0;
}
--
1.6.1
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