linux: patch request-key binary path

This is necessary for id mapping to work with NFS + Kerberos, and also
touches #68106 and 634638.

pkgs/os-specific/linux/kernel/patches.nix

···
       patch = ./bridge-stp-helper.patch;
     };
 
+  request_key_helper =
+    { name = "request-key-helper";
+      patch = ./request-key-helper.patch;
+    };
+
   p9_fixes =
     { name = "p9-fixes";
       patch = ./p9-fixes.patch;

pkgs/os-specific/linux/kernel/request-key-helper.patch

···
+diff --git a/security/keys/request_key.c b/security/keys/request_key.c
+index 957b9e3e1492..5436a0d8b81d 100644
+--- a/security/keys/request_key.c
++++ b/security/keys/request_key.c
+@@ -114,7 +114,7 @@ static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
+  */
+ static int call_sbin_request_key(struct key *authkey, void *aux)
+ {
+-	static char const request_key[] = "/sbin/request-key";
++	static char const request_key[] = "/run/current-system/sw/bin/request-key";
+ 	struct request_key_auth *rka = get_request_key_auth(authkey);
+ 	const struct cred *cred = current_cred();
+ 	key_serial_t prkey, sskey;

pkgs/top-level/all-packages.nix

···
   linux_mptcp_94 = callPackage ../os-specific/linux/kernel/linux-mptcp-94.nix {
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
+        kernelPatches.request_key_helper
         kernelPatches.cpu-cgroup-v2."4.11"
         kernelPatches.modinst_arg_list_too_long
       ]
···
   linux_rpi1 = callPackage ../os-specific/linux/kernel/linux-rpi.nix {
     kernelPatches = with kernelPatches; [
       bridge_stp_helper
+      request_key_helper
     ];
     rpiVersion = 1;
   };
···
   linux_rpi2 = callPackage ../os-specific/linux/kernel/linux-rpi.nix {
     kernelPatches = with kernelPatches; [
       bridge_stp_helper
+      request_key_helper
     ];
     rpiVersion = 2;
   };
···
   linux_rpi3 = callPackage ../os-specific/linux/kernel/linux-rpi.nix {
     kernelPatches = with kernelPatches; [
       bridge_stp_helper
+      request_key_helper
     ];
     rpiVersion = 3;
   };
···
   linux_rpi4 = callPackage ../os-specific/linux/kernel/linux-rpi.nix {
     kernelPatches = with kernelPatches; [
       bridge_stp_helper
+      request_key_helper
     ];
     rpiVersion = 4;
   };
···
   linux_4_4 = callPackage ../os-specific/linux/kernel/linux-4.4.nix {
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
+        kernelPatches.request_key_helper
         kernelPatches.cpu-cgroup-v2."4.4"
         kernelPatches.modinst_arg_list_too_long
         # https://github.com/NixOS/nixpkgs/issues/42755
···
   linux_4_9 = callPackage ../os-specific/linux/kernel/linux-4.9.nix {
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
+        kernelPatches.request_key_helper
         kernelPatches.cpu-cgroup-v2."4.9"
         kernelPatches.modinst_arg_list_too_long
       ];
···
   linux_4_14 = callPackage ../os-specific/linux/kernel/linux-4.14.nix {
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
+        kernelPatches.request_key_helper
         # See pkgs/os-specific/linux/kernel/cpu-cgroup-v2-patches/README.md
         # when adding a new linux version
         kernelPatches.cpu-cgroup-v2."4.11"
···
   linux_4_19 = callPackage ../os-specific/linux/kernel/linux-4.19.nix {
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
+        kernelPatches.request_key_helper
         kernelPatches.modinst_arg_list_too_long
         kernelPatches.export_kernel_fpu_functions."4.14"
       ];
···
   linux_5_3 = callPackage ../os-specific/linux/kernel/linux-5.3.nix {
     kernelPatches = [
       kernelPatches.bridge_stp_helper
+      kernelPatches.request_key_helper
       kernelPatches.export_kernel_fpu_functions."5.3"
     ];
   };
···
   linux_5_4 = callPackage ../os-specific/linux/kernel/linux-5.4.nix {
     kernelPatches = [
       kernelPatches.bridge_stp_helper
+      kernelPatches.request_key_helper
     ];
   };
 
   linux_testing = callPackage ../os-specific/linux/kernel/linux-testing.nix {
     kernelPatches = [
       kernelPatches.bridge_stp_helper
+      kernelPatches.request_key_helper
     ];
   };
 
   linux_testing_bcachefs = callPackage ../os-specific/linux/kernel/linux-testing-bcachefs.nix {
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
+        kernelPatches.request_key_helper
         kernelPatches.modinst_arg_list_too_long
       ];
   };
···
   linux_hardkernel_4_14 = callPackage ../os-specific/linux/kernel/linux-hardkernel-4.14.nix {
     kernelPatches = [
       kernelPatches.bridge_stp_helper
+      kernelPatches.request_key_helper
       kernelPatches.modinst_arg_list_too_long
     ];
   };