From d6a2f067979186eb1c8422317ea2816d98eee083 Mon Sep 17 00:00:00 2001
From: Antonio SJ Musumeci <trapexit@spawn.link>
Date: Sun, 29 Oct 2023 01:44:18 -0500
Subject: [PATCH] Only set allow_other when running as root

---
 libfuse/lib/mount_generic.c | 21 +++++++++++----------
 src/mergerfs.cpp            | 11 ++++++++---
 src/option_parser.cpp       |  6 +++++-
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/libfuse/lib/mount_generic.c b/libfuse/lib/mount_generic.c
index f4252587..9d1cdd23 100644
--- a/libfuse/lib/mount_generic.c
+++ b/libfuse/lib/mount_generic.c
@@ -61,6 +61,7 @@ enum {
 };
 
 struct mount_opts {
+  int allow_other;
   int ishelp;
   int flags;
   int auto_unmount;
@@ -76,13 +77,15 @@ struct mount_opts {
 #define FUSE_MOUNT_OPT(t, p) { t, offsetof(struct mount_opts, p), 1 }
 
 static const struct fuse_opt fuse_mount_opts[] = {
+  FUSE_MOUNT_OPT("allow_other",         allow_other),
   FUSE_MOUNT_OPT("blkdev",		blkdev),
-  FUSE_MOUNT_OPT("auto_unmount",		auto_unmount),
+  FUSE_MOUNT_OPT("auto_unmount",	auto_unmount),
   FUSE_MOUNT_OPT("fsname=%s",		fsname),
   FUSE_MOUNT_OPT("subtype=%s",		subtype),
+  FUSE_OPT_KEY("allow_other",           KEY_KERN_OPT),
   FUSE_OPT_KEY("auto_unmount",		KEY_FUSERMOUNT_OPT),
-  FUSE_OPT_KEY("blkdev",			KEY_FUSERMOUNT_OPT),
-  FUSE_OPT_KEY("fsname=",			KEY_FUSERMOUNT_OPT),
+  FUSE_OPT_KEY("blkdev",		KEY_FUSERMOUNT_OPT),
+  FUSE_OPT_KEY("fsname=",		KEY_FUSERMOUNT_OPT),
   FUSE_OPT_KEY("subtype=",		KEY_SUBTYPE_OPT),
   FUSE_OPT_KEY("large_read",		KEY_KERN_OPT),
   FUSE_OPT_KEY("blksize=",		KEY_KERN_OPT),
@@ -98,18 +101,18 @@ static const struct fuse_opt fuse_mount_opts[] = {
   FUSE_OPT_KEY("ro",			KEY_KERN_FLAG),
   FUSE_OPT_KEY("rw",			KEY_KERN_FLAG),
   FUSE_OPT_KEY("suid",			KEY_KERN_FLAG),
-  FUSE_OPT_KEY("nosuid",			KEY_KERN_FLAG),
+  FUSE_OPT_KEY("nosuid",		KEY_KERN_FLAG),
   FUSE_OPT_KEY("dev",			KEY_KERN_FLAG),
   FUSE_OPT_KEY("nodev",			KEY_KERN_FLAG),
   FUSE_OPT_KEY("exec",			KEY_KERN_FLAG),
-  FUSE_OPT_KEY("noexec",			KEY_KERN_FLAG),
+  FUSE_OPT_KEY("noexec",		KEY_KERN_FLAG),
   FUSE_OPT_KEY("async",			KEY_KERN_FLAG),
   FUSE_OPT_KEY("sync",			KEY_KERN_FLAG),
-  FUSE_OPT_KEY("dirsync",			KEY_KERN_FLAG),
+  FUSE_OPT_KEY("dirsync",		KEY_KERN_FLAG),
   FUSE_OPT_KEY("atime",			KEY_KERN_FLAG),
-  FUSE_OPT_KEY("noatime",			KEY_KERN_FLAG),
+  FUSE_OPT_KEY("noatime",		KEY_KERN_FLAG),
   FUSE_OPT_KEY("-h",			KEY_HELP),
-  FUSE_OPT_KEY("--help",			KEY_HELP),
+  FUSE_OPT_KEY("--help",		KEY_HELP),
   FUSE_OPT_KEY("-V",			KEY_VERSION),
   FUSE_OPT_KEY("--version",		KEY_VERSION),
   FUSE_OPT_END
@@ -549,8 +552,6 @@ int fuse_kern_mount(const char *mountpoint, struct fuse_args *args)
       fuse_opt_parse(args, &mo, fuse_mount_opts, fuse_mount_opt_proc) == -1)
     return -1;
 
-  fuse_opt_add_opt(&mo.kernel_opts,"allow_other");
-
   res = 0;
   if (mo.ishelp)
     goto out;
diff --git a/src/mergerfs.cpp b/src/mergerfs.cpp
index 89bf531e..6460c134 100644
--- a/src/mergerfs.cpp
+++ b/src/mergerfs.cpp
@@ -249,6 +249,7 @@ namespace l
   main(const int   argc_,
        char      **argv_)
   {
+    int rv;
     Config::Read    cfg;
     Config::ErrVec  errs;
     fuse_args       args;
@@ -283,9 +284,13 @@ namespace l
 
     procfs::init();
 
-    return fuse_main(args.argc,
-                     args.argv,
-                     &ops);
+    rv = fuse_main(args.argc,
+                   args.argv,
+                   &ops);
+
+    syslog_info("exiting main loop with return code %d",rv);
+
+    return rv;
   }
 }
 
diff --git a/src/option_parser.cpp b/src/option_parser.cpp
index 4d14a467..8bd3e613 100644
--- a/src/option_parser.cpp
+++ b/src/option_parser.cpp
@@ -26,6 +26,7 @@
 #include "num.hpp"
 #include "policy.hpp"
 #include "str.hpp"
+#include "syslog.hpp"
 #include "version.hpp"
 
 #include "fuse.h"
@@ -116,6 +117,10 @@ void
 set_default_options(fuse_args *args_)
 {
   set_option("default_permissions",args_);
+  if(geteuid() == 0)
+    set_option("allow_other",args_);
+  else
+    syslog_notice("not auto setting allow_other since not running as root");
 }
 
 static
@@ -124,7 +129,6 @@ should_ignore(const std::string &key_)
 {
   static const std::set<std::string> IGNORED_KEYS =
     {
-      "allow_other",
       "atomic_o_trunc",
       "big_writes",
       "cache.open",