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Diffstat (limited to 'ipc/util.c')
-rw-r--r--ipc/util.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/ipc/util.c b/ipc/util.c
index dc8943aa971..c4f1d33b89e 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -824,6 +824,57 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
| (in->mode & S_IRWXUGO);
}
+/**
+ * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
+ * @ids: the table of ids where to look for the ipc
+ * @id: the id of the ipc to retrieve
+ * @cmd: the cmd to check
+ * @perm: the permission to set
+ * @extra_perm: one extra permission parameter used by msq
+ *
+ * This function does some common audit and permissions check for some IPC_XXX
+ * cmd and is called from semctl_down, shmctl_down and msgctl_down.
+ * It must be called without any lock held and
+ * - retrieves the ipc with the given id in the given table.
+ * - performs some audit and permission check, depending on the given cmd
+ * - returns the ipc with both ipc and rw_mutex locks held in case of success
+ * or an err-code without any lock held otherwise.
+ */
+struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
+ struct ipc64_perm *perm, int extra_perm)
+{
+ struct kern_ipc_perm *ipcp;
+ int err;
+
+ down_write(&ids->rw_mutex);
+ ipcp = ipc_lock_check_down(ids, id);
+ if (IS_ERR(ipcp)) {
+ err = PTR_ERR(ipcp);
+ goto out_up;
+ }
+
+ err = audit_ipc_obj(ipcp);
+ if (err)
+ goto out_unlock;
+
+ if (cmd == IPC_SET) {
+ err = audit_ipc_set_perm(extra_perm, perm->uid,
+ perm->gid, perm->mode);
+ if (err)
+ goto out_unlock;
+ }
+ if (current->euid == ipcp->cuid ||
+ current->euid == ipcp->uid || capable(CAP_SYS_ADMIN))
+ return ipcp;
+
+ err = -EPERM;
+out_unlock:
+ ipc_unlock(ipcp);
+out_up:
+ up_write(&ids->rw_mutex);
+ return ERR_PTR(err);
+}
+
#ifdef __ARCH_WANT_IPC_PARSE_VERSION