rework the daemon to do fork+exec

It uses the 'common' proc.c from various OpenBSD-daemons.

gmid grew organically bit by bit and it was also the first place where I
tried to implement privsep.  It wasn't done very well, in fact the
parent process (that retains root privileges) just fork()s a generation
of servers, all sharing *exactly* the same address space.  No good!

Now, we fork() and re-exec() ourselves, so that each process has a fresh
address space.

Some features (require client ca for example) are temporarly disabled,
will be fixed in subsequent commits.  The "ge" program is also
temporarly disabled as it needs tweaks to do privsep too.

1 files changed, 123 insertions, 0 deletions

diff --git a/proc.h b/proc.h
new file mode 100644
index 0000000..4ebacd1
--- /dev/null
+++ b/proc.h
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2010-2015 Reyk Floeter <reyk@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* imsg */
+struct imsgev {
+	struct imsgbuf		 ibuf;
+	void			(*handler)(int, short, void *);
+	struct event		 ev;
+	struct privsep_proc	*proc;
+	void			*data;
+	short			 events;
+};
+
+#define IMSG_SIZE_CHECK(imsg, p) do {					\
+	if (IMSG_DATA_SIZE(imsg) < sizeof(*p))				\
+		fatalx("bad length imsg received (%s)",	#p);		\
+} while (0)
+#define IMSG_DATA_SIZE(imsg)	((imsg)->hdr.len - IMSG_HEADER_SIZE)
+
+#define PROC_PARENT_SOCK_FILENO	3
+
+/* privsep */
+enum privsep_procid {
+	PROC_PARENT,
+	PROC_SERVER,
+	PROC_LOGGER,
+	PROC_MAX,
+};
+
+#define CONFIG_RELOAD		0x00
+#define CONFIG_SOCKS		0x01
+#define CONFIG_ALL		0xff
+
+struct privsep_pipes {
+	int				*pp_pipes[PROC_MAX];
+};
+
+struct privsep {
+	struct privsep_pipes		*ps_pipes[PROC_MAX];
+	struct privsep_pipes		*ps_pp;
+
+	struct imsgev			*ps_ievs[PROC_MAX];
+	const char			*ps_title[PROC_MAX];
+	uint8_t				 ps_what[PROC_MAX];
+
+	struct passwd			*ps_pw;
+	int				 ps_noaction;
+
+	unsigned int			 ps_instances[PROC_MAX];
+	unsigned int			 ps_instance;
+
+	/* Event and signal handlers */
+	struct event			 ps_evsigint;
+	struct event			 ps_evsigterm;
+	struct event			 ps_evsigchld;
+	struct event			 ps_evsighup;
+
+	void				*ps_env;
+};
+
+struct privsep_proc {
+	const char		*p_title;
+	enum privsep_procid	 p_id;
+	int			(*p_cb)(int, struct privsep_proc *,
+				    struct imsg *);
+	void			(*p_init)(struct privsep *,
+				    struct privsep_proc *);
+	void			(*p_shutdown)(void);
+	const char		*p_chroot;
+	struct passwd		*p_pw;
+	struct privsep		*p_ps;
+};
+
+struct privsep_fd {
+	enum privsep_procid		 pf_procid;
+	unsigned int			 pf_instance;
+};
+
+/* proc.c */
+void	 proc_init(struct privsep *, struct privsep_proc *, unsigned int,
+	    int, int, char **, enum privsep_procid);
+void	 proc_kill(struct privsep *);
+void	 proc_connect(struct privsep *ps);
+void	 proc_dispatch(int, short event, void *);
+void	 proc_range(struct privsep *, enum privsep_procid, int *, int *);
+void	 proc_run(struct privsep *, struct privsep_proc *,
+	    struct privsep_proc *, unsigned int,
+	    void (*)(struct privsep *, struct privsep_proc *, void *), void *);
+void	 imsg_event_add(struct imsgev *);
+int	 imsg_compose_event(struct imsgev *, uint16_t, uint32_t,
+	    pid_t, int, void *, uint16_t);
+int	 imsg_composev_event(struct imsgev *, uint16_t, uint32_t,
+	    pid_t, int, const struct iovec *, int);
+int	 proc_compose_imsg(struct privsep *, enum privsep_procid, int,
+	    uint16_t, uint32_t, int, void *, uint16_t);
+int	 proc_compose(struct privsep *, enum privsep_procid,
+	    uint16_t, void *data, uint16_t);
+int	 proc_composev_imsg(struct privsep *, enum privsep_procid, int,
+	    uint16_t, uint32_t, int, const struct iovec *, int);
+int	 proc_composev(struct privsep *, enum privsep_procid,
+	    uint16_t, const struct iovec *, int);
+int	 proc_forward_imsg(struct privsep *, struct imsg *,
+	    enum privsep_procid, int);
+struct imsgbuf *
+	 proc_ibuf(struct privsep *, enum privsep_procid, int);
+struct imsgev *
+	 proc_iev(struct privsep *, enum privsep_procid, int);
+enum privsep_procid
+	 proc_getid(struct privsep_proc *, unsigned int, const char *);
+int	 proc_flush_imsg(struct privsep *, enum privsep_procid, int);