Try to get the VSM ownership right.

The general rule is that if varnishd is started as root, you need
to be root or in group "varnish" to access the shared memory.

Fixes	#2419

bin/varnishd/mgt/mgt.h

@@ -166,7 +166,6 @@ void mgt_SHM_static_alloc(const void *, ssize_t size,
 void mgt_SHM_Create(void);
 void mgt_SHM_Destroy(int keep);
 
-extern struct vsmw *mgt_vsmw;
 void mgt_SHM_ChildNew(void);
 void mgt_SHM_ChildDestroy(void);
 

bin/varnishd/mgt/mgt_cli.c

@@ -504,9 +504,9 @@ mgt_cli_secret(const char *S_arg)
 	char buf[BUFSIZ];
 
 	/* Save in shmem */
-	VJ_master(JAIL_MASTER_FILE);
 	mgt_SHM_static_alloc(S_arg, strlen(S_arg) + 1L, "Arg", "-S");
 
+	VJ_master(JAIL_MASTER_FILE);
 	fd = open(S_arg, O_RDONLY);
 	if (fd < 0) {
 		fprintf(stderr, "Can not open secret-file \"%s\"\n", S_arg);
@@ -574,9 +574,7 @@ mgt_cli_telnet(const char *T_arg)
 	if (VSB_len(vsb) == 0)
 		ARGV_ERR("-T %s could not be listened on.\n", T_arg);
 	/* Save in shmem */
-	VJ_master(JAIL_MASTER_FILE);
 	mgt_SHM_static_alloc(VSB_data(vsb), VSB_len(vsb) + 1, "Arg", "-T");
-	VJ_master(JAIL_MASTER_LOW);
 	VSB_destroy(&vsb);
 }
 

bin/varnishd/mgt/mgt_main.c

@@ -839,10 +839,8 @@ main(int argc, char * const *argv)
 
 	mgt_SHM_Init();
 
-	VJ_master(JAIL_MASTER_FILE);
 	mgt_SHM_static_alloc(i_arg, strlen(i_arg) + 1L, "Arg", "-i");
 	VSC_C_mgt = VSC_mgt_New("");
-	VJ_master(JAIL_MASTER_LOW);
 
 	if (M_arg != NULL)
 		mgt_cli_master(M_arg);

bin/varnishd/mgt/mgt_shmem.c

@@ -47,7 +47,7 @@
 #include "vsm_priv.h"
 #include "vsmw.h"
 
-struct vsmw	*mgt_vsmw;
+static struct vsmw *mgt_vsmw;
 
 /*--------------------------------------------------------------------
  */
@@ -90,13 +90,16 @@ mgt_shm_atexit(void)
 void
 mgt_SHM_Init(void)
 {
+	int fd;
 
 	VJ_master(JAIL_MASTER_FILE);
 	AZ(system("rm -rf " VSM_MGT_DIRNAME));
 	AZ(mkdir(VSM_MGT_DIRNAME, 0755));
-	mgt_vsmw = VSMW_New(open(VSM_MGT_DIRNAME, O_RDONLY), 0640, "_.index");
-	AN(mgt_vsmw);
+	fd = open(VSM_MGT_DIRNAME, O_RDONLY);
+	VJ_fix_vsm_dir(fd);
 	VJ_master(JAIL_MASTER_LOW);
+	mgt_vsmw = VSMW_New(fd, 0640, "_.index");
+	AN(mgt_vsmw);
 
 	proc_vsmw = mgt_vsmw;
 
@@ -119,7 +122,6 @@ mgt_SHM_ChildNew(void)
 
 	MCH_Fd_Inherit(heritage.vsm_fd, "VSMW");
 
-	VJ_master(JAIL_MASTER_FILE);
 	heritage.param = VSMW_Allocf(mgt_vsmw, VSM_CLASS_PARAM,
 	    sizeof *heritage.param, "");
 	AN(heritage.param);
@@ -129,7 +131,6 @@ mgt_SHM_ChildNew(void)
 	heritage.panic_str = VSMW_Allocf(mgt_vsmw, "Panic",
 	    heritage.panic_str_len, "");
 	AN(heritage.panic_str);
-	VJ_master(JAIL_MASTER_LOW);
 }
 
 void