[PATCH v2] Allowing setting and overriding parameters in smb.conf

[Henrik Carlqvist <hc981@poolhem.se>]

From a6dfb322a88965281e3bba00a92f8d5e437bfa95 Mon Sep 17 00:00:00 2001
From: Henrik Carlqvist <hc1245@poolhem.se>
Date: Thu, 3 Aug 2023 16:52:25 +0200
Subject: [PATCH] Allowing setting and overriding parameters in smb.conf,
 moving some parameters from the [qemu] section to the [global] section to
 allow them to get overridden by custom user settings.

Signed-off-by: Henrik Carlqvist <hc1245@poolhem.se>
---

In this second version of the patch I have moved also the "force user" 
parameter to the global section of smb.conf. Even though I do not self see the
usefullness of altering that parameter we might just as well give the users
the freedom to alter anything in smb.conf. Maybe someone else will see the 
need to alter that parameter.

Best regards Henrik

 net/slirp.c     | 50 ++++++++++++++++++++++++++++++++++++++++---------
 qapi/net.json   |  3 +++
 qemu-options.hx | 15 ++++++++++++---
 3 files changed, 56 insertions(+), 12 deletions(-)

diff --git a/net/slirp.c b/net/slirp.c
index c33b3e02e7..e27d115bc4 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -106,7 +106,8 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp);
 
 #if defined(CONFIG_SMBD_COMMAND)
 static int slirp_smb(SlirpState *s, const char *exported_dir,
-                     struct in_addr vserver_addr, Error **errp);
+                     struct in_addr vserver_addr, const char *smbparams,
+                     Error **errp);
 static void slirp_smb_cleanup(SlirpState *s);
 #else
 static inline void slirp_smb_cleanup(SlirpState *s) { }
@@ -424,6 +425,7 @@ static int net_slirp_init(NetClientState *peer, const char *model,
                           const char *bootfile, const char *vdhcp_start,
                           const char *vnameserver, const char *vnameserver6,
                           const char *smb_export, const char *vsmbserver,
+                          const char *smbparams,
                           const char **dnssearch, const char *vdomainname,
                           const char *tftp_server_name,
                           Error **errp)
@@ -678,7 +680,7 @@ static int net_slirp_init(NetClientState *peer, const char *model,
     }
 #if defined(CONFIG_SMBD_COMMAND)
     if (smb_export) {
-        if (slirp_smb(s, smb_export, smbsrv, errp) < 0) {
+        if (slirp_smb(s, smb_export, smbsrv, smbparams, errp) < 0) {
             goto error;
         }
     }
@@ -891,7 +893,8 @@ static void slirp_smb_cleanup(SlirpState *s)
 }
 
 static int slirp_smb(SlirpState* s, const char *exported_dir,
-                     struct in_addr vserver_addr, Error **errp)
+                     struct in_addr vserver_addr, const char *smbparams,
+                     Error **errp)
 {
     char *smb_conf;
     char *smb_cmdline;
@@ -950,11 +953,12 @@ static int slirp_smb(SlirpState* s, const char *exported_dir,
             "printing = bsd\n"
             "disable spoolss = yes\n"
             "usershare max shares = 0\n"
-            "[qemu]\n"
-            "path=%s\n"
             "read only=no\n"
             "guest ok=yes\n"
-            "force user=%s\n",
+            "force user=%s\n"
+	    "%s"
+            "[qemu]\n"
+            "path=%s\n",
             s->smb_dir,
             s->smb_dir,
             s->smb_dir,
@@ -963,8 +967,9 @@ static int slirp_smb(SlirpState* s, const char *exported_dir,
             s->smb_dir,
             s->smb_dir,
             s->smb_dir,
-            exported_dir,
-            passwd->pw_name
+            passwd->pw_name,
+            smbparams,
+            exported_dir
             );
     fclose(f);
 
@@ -1143,6 +1148,29 @@ static const char **slirp_dnssearch(const StringList *dnsname)
     return ret;
 }
 
+static char *slirp_smbparams(const StringList *smbparam)
+{
+    const StringList *c = smbparam;
+    size_t i = 1; /* for string terminating 0 */
+    char *ret;
+
+    while (c) {
+        i += strlen(c->value->str);
+        i++; /* for \n */
+        c = c->next;
+    }
+    ret = g_malloc(i * sizeof(*ret));
+    ret[0]=0; /* Start with empty string */
+
+    c = smbparam;
+    while (c) {
+        pstrcat(ret, i * sizeof(*ret), c->value->str);
+        pstrcat(ret, i * sizeof(*ret), "\n");
+        c = c->next;
+    }
+    return ret;
+}
+
 int net_init_slirp(const Netdev *netdev, const char *name,
                    NetClientState *peer, Error **errp)
 {
@@ -1151,6 +1179,7 @@ int net_init_slirp(const Netdev *netdev, const char *name,
     int ret;
     const NetdevUserOptions *user;
     const char **dnssearch;
+    char *smbparams;
     bool ipv4 = true, ipv6 = true;
 
     assert(netdev->type == NET_CLIENT_DRIVER_USER);
@@ -1170,6 +1199,7 @@ int net_init_slirp(const Netdev *netdev, const char *name,
            NULL;
 
     dnssearch = slirp_dnssearch(user->dnssearch);
+    smbparams = slirp_smbparams(user->smbparam);
 
     /* all optional fields are initialized to "all bits zero" */
 
@@ -1182,7 +1212,8 @@ int net_init_slirp(const Netdev *netdev, const char *name,
                          user->ipv6_host, user->hostname, user->tftp,
                          user->bootfile, user->dhcpstart,
                          user->dns, user->ipv6_dns, user->smb,
-                         user->smbserver, dnssearch, user->domainname,
+                         user->smbserver, smbparams,
+                         dnssearch, user->domainname,
                          user->tftp_server_name, errp);
 
     while (slirp_configs) {
@@ -1193,6 +1224,7 @@ int net_init_slirp(const Netdev *netdev, const char *name,
 
     g_free(vnet);
     g_free(dnssearch);
+    g_free(smbparams);
 
     return ret;
 }
diff --git a/qapi/net.json b/qapi/net.json
index 313c8a606e..163091719c 100644
--- a/qapi/net.json
+++ b/qapi/net.json
@@ -156,6 +156,8 @@
 #
 # @smbserver: IP address of the built-in SMB server
 #
+# @smbparam: list of parameters with values for smb.conf
+#
 # @hostfwd: redirect incoming TCP or UDP host connections to guest
 #     endpoints
 #
@@ -186,6 +188,7 @@
     '*ipv6-dns':         'str',
     '*smb':       'str',
     '*smbserver': 'str',
+    '*smbparam': ['String'],
     '*hostfwd':   ['String'],
     '*guestfwd':  ['String'],
     '*tftp-server-name': 'str' } }
diff --git a/qemu-options.hx b/qemu-options.hx
index 29b98c3d4c..7b92d08c3e 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2758,9 +2758,9 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
     "         [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
     "         [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
     "         [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
-    "         [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
+    "         [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]\n"
 #ifndef _WIN32
-                                             "[,smb=dir[,smbserver=addr]]\n"
+    "         [,smb=dir[,smbserver=addr][,smbparam=parameter=value]]\n"
 #endif
     "                configure a user mode network backend with ID 'str',\n"
     "                its DHCP server and optional services\n"
@@ -3062,7 +3062,7 @@ SRST
             |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\
                 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
 
-    ``smb=dir[,smbserver=addr]``
+    ``smb=dir[,smbserver=addr][,smbparam=parameter=value]``
         When using the user mode network stack, activate a built-in SMB
         server so that Windows OSes can access to the host files in
         ``dir`` transparently. The IP address of the SMB server can be
@@ -3081,6 +3081,15 @@ SRST
 
         Then ``dir`` can be accessed in ``\\smbserver\qemu``.
 
+        It is possible to set samba parameters in the generated smb.conf
+        with one or more ``smbparam=parameter=value``. Example:
+
+        .. parsed-literal::
+
+            |qemu_system| -nic user,smb=/tmp,smbparam="read only"=yes,smbparam="server min protocol"=NT1
+
+        See the man page of smb.conf for a complete listing of parameters.
+
         Note that a SAMBA server must be installed on the host OS.
 
     ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
-- 
2.35.1