Merge bitcoin/bitcoin#28167: init: Add option for rpccookie permissions (replace 26088)

73f0a6cbd0b628675028fbd5a37eff8115e7ccfe doc: detail -rpccookieperms option (willcl-ark)
d2afa2690cceb0012b2aa1960e1cfa497f3103fa test: add rpccookieperms test (willcl-ark)
f467aede78533dac60a118e1566138d65522c213 init: add option for rpccookie permissions (willcl-ark)
7df03f1a923e239cea8c9b0d603a9eb00863a40c util: add perm string helper functions (willcl-ark)

Pull request description:

  This PR picks up #26088 by aureleoules which adds a bitcoind launch option `-rpccookieperms` to set the file permissions of the cookie generated by bitcoin core.

  Example usage to make the generated cookie group-readable: `./src/bitcoind -rpccookieperms=group`.

  Accepted values for `-rpccookieperms` are `[owner|group|all]`. We let `fs::perms` handle platform-specific permissions changes.

ACKs for top commit:
  achow101:
    ACK 73f0a6cbd0b628675028fbd5a37eff8115e7ccfe
  ryanofsky:
    Code review ACK 73f0a6cbd0b628675028fbd5a37eff8115e7ccfe. Main change since last review is no longer throwing a skip exception in the rpc test on windows, so other checks can run after it, and overall test result is passing, not skipped. Also were clarifying renames and documentation improvements.
  tdb3:
    cr ACK 73f0a6cbd0b628675028fbd5a37eff8115e7ccfe

Tree-SHA512: e800d59a44aca10e1c58ca69bf3fdde9f6ccf5eab4b7b962645af6d6bc0cfa3a357701e409c8c60d8d7744fcd33a91e77ada11790aa88cd7811ef60fab86ab11

1 files changed, 17 insertions, 2 deletions

diff --git a/src/httprpc.cpp b/src/httprpc.cpp
index 128597157d..af809eaf38 100644
--- a/src/httprpc.cpp
+++ b/src/httprpc.cpp
@@ -11,6 +11,8 @@
 #include <netaddress.h>
 #include <rpc/protocol.h>
 #include <rpc/server.h>
+#include <util/fs.h>
+#include <util/fs_helpers.h>
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <walletinitinterface.h>
@@ -19,6 +21,7 @@
 #include <iterator>
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <vector>
@@ -291,8 +294,20 @@ static bool InitRPCAuthentication()
 {
     if (gArgs.GetArg("-rpcpassword", "") == "")
     {
-        LogPrintf("Using random cookie authentication.\n");
-        if (!GenerateAuthCookie(&strRPCUserColonPass)) {
+        LogInfo("Using random cookie authentication.\n");
+
+        std::optional<fs::perms> cookie_perms{std::nullopt};
+        auto cookie_perms_arg{gArgs.GetArg("-rpccookieperms")};
+        if (cookie_perms_arg) {
+            auto perm_opt = InterpretPermString(*cookie_perms_arg);
+            if (!perm_opt) {
+                LogInfo("Invalid -rpccookieperms=%s; must be one of 'owner', 'group', or 'all'.\n", *cookie_perms_arg);
+                return false;
+            }
+            cookie_perms = *perm_opt;
+        }
+
+        if (!GenerateAuthCookie(&strRPCUserColonPass, cookie_perms)) {
             return false;
         }
     } else {