Make linux build with server.

Add suid infrastructure.
Demo proc_map.

libgtop-sysdeps.m4

@@ -33,9 +33,10 @@ AC_DEFUN([GNOME_LIBGTOP_SYSDEPS],[
 	linux*)
 	  libgtop_sysdeps_dir=linux
 	  libgtop_have_sysinfo=yes
-	  libgtop_need_server=no
+	  libgtop_need_server=yes
 	  libgtop_sysdeps_private_mountlist=yes
 	  libgtop_sysdeps_private_fsusage=yes
+	  libgtop_postinstall='chown root $(bindir)/libgtop_server2 && chmod 4755 $(bindir)/libgtop_server2'
 	  ;;
 	netbsd*|bsdi*)
 	  libgtop_sysdeps_dir=bsd

sysdeps/linux/Makefile.am

@@ -1,6 +1,6 @@
 AM_CPPFLAGS			= @AM_CPPFLAGS@
 
-noinst_LTLIBRARIES		= libgtop_sysdeps-2.0.la
+noinst_LTLIBRARIES		= libgtop_sysdeps-2.0.la libgtop_sysdeps_suid-2.0.la
 
 EXTRA_DIST			= procmap_smaps.gperf procmap_smaps.c
 
@@ -17,7 +17,9 @@ libgtop_sysdeps_2_0_la_LIBADD	=  @GLIB_LIBS@
 
 # libgtop_sysdeps_2_0_la_LDFLAGS	= $(LT_VERSION_INFO)
 
-libgtopinclude_HEADERS		= glibtop_server.h glibtop_machine.h
+libgtop_sysdeps_suid_2_0_la_SOURCES = suid_open.c
+
+libgtopinclude_HEADERS		= glibtop_server.h glibtop_machine.h glibtop_suid.h
 libgtopincludedir		= $(includedir)/libgtop-2.0
 
 noinst_HEADERS			= glibtop_private.h

sysdeps/linux/glibtop_machine.h

@@ -28,6 +28,10 @@ G_BEGIN_DECLS
 
 struct _glibtop_machine
 {
+  uid_t uid;
+  uid_t euid;
+  gid_t gid;
+  gid_t egid;
 };
 
 G_END_DECLS

sysdeps/linux/glibtop_server.h

@@ -39,7 +39,7 @@
 #define GLIBTOP_SUID_PROC_KERNEL	0
 #define GLIBTOP_SUID_PROC_SEGMENT	0
 #define GLIBTOP_SUID_PROC_ARGS		0
-#define GLIBTOP_SUID_PROC_MAP		0
+#define GLIBTOP_SUID_PROC_MAP		(1 << GLIBTOP_SYSDEPS_PROC_MAP)
 #define GLIBTOP_SUID_NETLOAD		0
 #define GLIBTOP_SUID_NETLIST		0
 #define GLIBTOP_SUID_PROC_WD		0

sysdeps/linux/glibtop_suid.h

@@ -0,0 +1,49 @@
+/* Copyright (C) 2018 Benoît Dejean
+
+   LibGTop is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License,
+   or (at your option) any later version.
+
+   LibGTop is distributed in the hope that it will be useful, but WITHOUT
+   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+   for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with LibGTop; see the file COPYING. If not, write to the
+   Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.
+*/
+
+#ifndef __GLIBTOP_SUID_H__
+#define __GLIBTOP_SUID_H__
+
+G_BEGIN_DECLS
+
+#include <glibtop_machine.h>
+
+static inline void glibtop_suid_enter (glibtop *server) {
+	glibtop_debug ("uid=%d euid=%d gid=%d egid=%d", getuid(), geteuid(), getgid(), getegid());
+	setreuid (server->machine->uid, server->machine->euid);
+	glibtop_debug ("uid=%d euid=%d gid=%d egid=%d", getuid(), geteuid(), getgid(), getegid());
+};
+
+static inline void glibtop_suid_leave (glibtop *server) {
+	glibtop_debug ("uid=%d euid=%d gid=%d egid=%d", getuid(), geteuid(), getgid(), getegid());
+	if (setreuid (server->machine->euid, server->machine->uid))
+		_exit (1);
+	glibtop_debug ("uid=%d euid=%d gid=%d egid=%d", getuid(), geteuid(), getgid(), getegid());
+};
+
+void
+glibtop_init_p (glibtop *server, const unsigned long features,
+		const unsigned flags);
+void
+glibtop_open_p (glibtop *server, const char *program_name,
+		const unsigned long features,
+		const unsigned flags);
+
+G_END_DECLS
+
+#endif

sysdeps/linux/procmap.c

@@ -30,6 +30,7 @@
 #include <stddef.h>
 
 #include "glibtop_private.h"
+#include "glibtop_suid.h"
 
 #include "procmap_smaps.c"
 
@@ -60,7 +61,7 @@ static const unsigned long _glibtop_sysdeps_map_entry_smaps =
 /* Init function. */
 
 void
-_glibtop_init_proc_map_s (glibtop *server)
+_glibtop_init_proc_map_p (glibtop *server)
 {
 	server->sysdeps.proc_map = _glibtop_sysdeps_proc_map;
 }
@@ -184,7 +185,7 @@ parse_line(char* line,
 
 
 glibtop_map_entry *
-glibtop_get_proc_map_s (glibtop *server, glibtop_proc_map *buf,	pid_t pid)
+glibtop_get_proc_map_p (glibtop *server, glibtop_proc_map *buf,	pid_t pid)
 {
 	char procfilename[GLIBTOP_MAP_FILENAME_LEN+1];
 
@@ -214,10 +215,17 @@ glibtop_get_proc_map_s (glibtop *server, glibtop_proc_map *buf,	pid_t pid)
 
 	snprintf (procfilename, sizeof procfilename, filename, (unsigned)pid);
 
+	glibtop_suid_enter (server);
+
 	if((maps = fopen (procfilename, "r")) == NULL) {
+	  glibtop_suid_leave (server);
 	  return (glibtop_map_entry*) g_array_free(entry_list, TRUE);
 	}
 
+	glibtop_debug("opened %p", maps);
+
+	glibtop_suid_leave (server);
+
 	while(TRUE)
 	{
 		unsigned long perm;

sysdeps/linux/suid_open.c

@@ -0,0 +1,80 @@
+/* Copyright (C) 2018 Benoît Dejean
+
+   LibGTop is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License,
+   or (at your option) any later version.
+
+   LibGTop is distributed in the hope that it will be useful, but WITHOUT
+   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+   for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with LibGTop; see the file COPYING. If not, write to the
+   Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.
+*/
+
+#include <config.h>
+#include <glibtop.h>
+#include <glibtop/error.h>
+#include <glibtop/cpu.h>
+#include <glibtop/open.h>
+#include <glibtop/init_hooks.h>
+#include <glibtop/machine.h>
+
+
+/* !!! THIS FUNCTION RUNS SUID ROOT - CHANGE WITH CAUTION !!! */
+
+void
+glibtop_init_p (glibtop *server, const unsigned long features,
+		const unsigned flags)
+{
+	const _glibtop_init_func_t *init_fkt;
+
+	if (server == NULL)
+		glibtop_error_r (NULL, "glibtop_init_p (server == NULL)");
+
+	/* Do the initialization, but only if not already initialized. */
+
+	if ((server->flags & _GLIBTOP_INIT_STATE_SYSDEPS) == 0) {
+		glibtop_open_p (server, "glibtop", features, flags);
+
+		for (init_fkt = _glibtop_init_hook_p; *init_fkt; init_fkt++)
+			(*init_fkt) (server);
+
+		server->flags |= _GLIBTOP_INIT_STATE_SYSDEPS;
+	}
+}
+
+void
+glibtop_open_p (glibtop *server, const char *program_name,
+		const unsigned long features,
+		const unsigned flags)
+{
+	glibtop_debug ("glibtop_open_p ()");
+
+	/* !!! WE ARE ROOT HERE - CHANGE WITH CAUTION !!! */
+	server->machine->uid = getuid ();
+	server->machine->euid = geteuid ();
+	server->machine->gid = getgid ();
+	server->machine->egid = getegid ();
+
+	/* Drop priviledges. */
+
+	glibtop_debug ("uid=%d euid=%d gid=%d egid=%d", getuid(), geteuid(), getgid(), getegid());
+
+	if (setreuid (server->machine->euid, server->machine->uid))
+		_exit (1);
+
+	if (setregid (server->machine->egid, server->machine->gid))
+		_exit (1);
+
+	glibtop_debug ("uid=%d euid=%d gid=%d egid=%d", getuid(), geteuid(), getgid(), getegid());
+
+	/* !!! END OF SUID ROOT PART !!! */
+
+	/* Our effective uid is now those of the user invoking the server,
+	 * so we do no longer have any priviledges. */
+}