PTY Improvements for kissattach, kissnetd

PTY Improvements for kissattach, kissnetd

[me]

This is a re-based patchset for ax25-tools based on commit
18fa7fa6776da35da34a7e148fa2d96be8921e2.  It adds command line options to
kissattach and kissnet to permit two things:

- symbolic linking of pseudo TTYs to consistent names for referencing in
  configuration files.
- changing ownership/mode of pseudo TTYs so that they can be accessed by
  designated users/groups.

These patches have been in successful operation on my APRS digipeater here
in Brisbane.  http://aprs.fi/info/a/VK4MSL-1

[PATCH 1/2] kissattach: Add support for pty symlinking

[me]

From: Stuart Longland <stuartl@longlandclan.yi.org>

This patch adds abilities for symlinking of dynamically allocated slave
PTY interfaces to kissattach.  This enables other services to make use
of these PTYs without manually editing their configuration files to
point to the dynamically allocated PTY.

In addition, the patch includes the ability to change the ownership and
permissions on the allocated PTY, allowing an unpriviged process to make
use of it.
---
 kiss/kissattach.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 103 insertions(+), 7 deletions(-)

diff --git a/kiss/kissattach.c b/kiss/kissattach.c
index e30ed05..a872d0a 100644
--- a/kiss/kissattach.c
+++ b/kiss/kissattach.c
@@ -18,6 +18,9 @@
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 
+#include <pwd.h>
+#include <grp.h>
+
 #include <net/if.h>
 #include <netax25/ax25.h>
 #include <netrose/rose.h>
@@ -32,6 +35,8 @@
 #define N_6PACK 7	/* This is valid for all architectures in 2.2.x */
 #endif
 
+#define PTMX_TTY	"/dev/ptmx"
+
 static char *callsign;
 static int  speed;
 static int  mtu;
@@ -42,6 +47,7 @@ static char *portname;
 static char *inetaddr;
 static int allow_broadcast;
 static int i_am_unix98_pty_master;		/* unix98 ptmx support */
+static int symlink_pty = 0;
 
 static char *kiss_basename(char *s)
 {
@@ -58,6 +64,8 @@ static void terminate(int sig)
 
 	if (!i_am_unix98_pty_master)
 		tty_unlock(kttyname);
+	else if (symlink_pty)
+		unlink(kttyname);
 
 	exit(0);
 }
@@ -214,7 +222,8 @@ static int startiface(char *dev, struct hostent *hp)
 
 static void usage(void)
 {
-	fprintf(stderr, "usage: %s [-b] [-l] [-m mtu] [-v] tty port [inetaddr]\n", progname);
+	fprintf(stderr, "usage: %s [-b] [-l] [-m mtu] [-v] [-o user:group] [-p mode] tty port [inetaddr]\n",
+			progname);
 }
 
 int main(int argc, char *argv[])
@@ -227,12 +236,18 @@ int main(int argc, char *argv[])
 				* the client has to use */
 	struct hostent *hp = NULL;
 
+	/* Name of the user and group who will "own" the pty */
+	char* pty_owner_user = NULL;
+	char* pty_owner_group = NULL;
+	/* Mode for pty: if 0; use defaults */
+	mode_t pty_mode = 0;
+
 	progname = kiss_basename(argv[0]);
 
 	if (!strcmp(progname, "spattach"))
 		disc = N_6PACK;
 
-	while ((fd = getopt(argc, argv, "b6i:lm:v")) != -1) {
+	while ((fd = getopt(argc, argv, "b6i:lm:o:p:v")) != -1) {
 		switch (fd) {
 		case '6':
 			disc = N_6PACK;
@@ -250,9 +265,24 @@ int main(int argc, char *argv[])
 		case 'm':
 			if ((mtu = atoi(optarg)) <= 0) {
 				fprintf(stderr, "%s: invalid mtu size - %s\n", progname, optarg);
-				return 1;
+		case 'o':
+			/* Change the owner of the pty */
+			{
+				char* colon = index(optarg,':');
+				if (colon) {
+					pty_owner_user = optarg;
+					pty_owner_group = colon + 1;
+					*colon = 0;
+				} else {
+					fprintf(stderr, "%s: Must specify user:group\n", progname);
+					return 1;
+				}
 			}
 			break;
+		case 'p':
+			/* Change the permissions (mode) of the pty */
+			pty_mode = (mode_t)strtoul(optarg, NULL, 8);
+			break;
 		case 'v':
 			printf("%s: %s\n", progname, VERSION);
 			return 0;
@@ -278,8 +308,17 @@ int main(int argc, char *argv[])
 	if (argc-1 >= optind && !inetaddr)
 		inetaddr = argv[optind];
 
-	if (!strcmp("/dev/ptmx", kttyname))
+	if (!strcmp(PTMX_TTY, kttyname)) {
+		i_am_unix98_pty_master = 1;
+	} else if (strstr(kttyname, "pty:") == kttyname) {
+		/*
+		 * If the path starts with pty:, then create a
+		 * new pty (Unix98 style) and make a symlink to it
+		 */
 		i_am_unix98_pty_master = 1;
+		kttyname = index(kttyname, ':') + 1;
+		symlink_pty = 1;
+	}
 
 	if (!i_am_unix98_pty_master) {
 		if (tty_is_locked(kttyname)) {
@@ -296,7 +335,7 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 
-	if ((fd = open(kttyname, O_RDONLY | O_NONBLOCK)) == -1) {
+	if ((fd = open((symlink_pty ? PTMX_TTY : kttyname), O_RDONLY | O_NONBLOCK)) == -1) {
 		if (errno == ENOENT) {
 			fprintf(stderr, "%s: Cannot find serial device %s, no such file or directory.\n", progname, kttyname);
 		} else {
@@ -353,12 +392,69 @@ int main(int argc, char *argv[])
 
 	printf("AX.25 port %s bound to device %s\n", portname, dev);
 	if (i_am_unix98_pty_master) {
-		/* Users await the slave pty to be referenced in the 3d line */
-		printf("Awaiting client connects on\n%s\n", namepts);
+		/* Are we being asked to chown? */
+		if (pty_owner_user) {
+			/* Look up the user */
+			struct passwd user;
+			struct passwd* user_ptr = NULL;
+			struct group grp;
+			struct group* grp_ptr = NULL;
+			char buffer[512];
+			int err = getpwnam_r(pty_owner_user, &user,
+				buffer, sizeof(buffer)-1, &user_ptr);
+			if (err) {
+				fprintf(stderr,
+					"Failed to look up user: %s (%d)\n",
+					strerror(err), err);
+				return 1;
+			}
+
+			err = getgrnam_r(pty_owner_group, &grp,
+				buffer, sizeof(buffer)-1, &grp_ptr);
+			if (err) {
+				fprintf(stderr,
+					"Failed to look up group: %s (%d)\n",
+					strerror(err), err);
+				return 1;
+			}
+
+			if (user_ptr && grp_ptr &&
+					chown(namepts, user_ptr->pw_uid,
+						grp_ptr->gr_gid)) {
+				fprintf(stderr,
+					"Failed to change ownership: %s (%d)\n",
+					strerror(errno), errno);
+				return 1;
+			}
+		}
+
+		/* Are we being asked to chmod? */
+		if (pty_mode) {
+			if (chmod(namepts, pty_mode)) {
+				fprintf(stderr,
+					"Failed to change mode: %s (%d)\n",
+					strerror(errno), errno);
+			}
+		}
+
+		if (symlink_pty) {
+			/* Create the symlink */
+			if (symlink(namepts, kttyname)) {
+				fprintf(stderr,
+					"Failed to symlink PTY %s to %s: %s (%d)\n",
+					kttyname, namepts, strerror(errno), errno);
+				return 1;
+			}
+		} else {
+			/* Users await the slave pty to be referenced in the 3d line */
+			printf("Awaiting client connects on\n%s\n", namepts);
+		}
 	}
 	if (logging) {
 		openlog(progname, LOG_PID, LOG_DAEMON);
 		syslog(LOG_INFO, "AX.25 port %s bound to device %s%s%s\n", portname, dev, (i_am_unix98_pty_master ? " with slave pty " : ""), (i_am_unix98_pty_master ? namepts : ""));
+		if (symlink_pty)
+			syslog(LOG_INFO, "Slave pty %s is symlinked to %s.", namepts, kttyname);
 
 	}
 
-- 
2.3.6

[PATCH 2/2] kissnetd: Add support for symlinking PTYs

[me]

From: Stuart Longland <stuartl@longlandclan.yi.org>

This patch adds abilities for symlinking of dynamically allocated slave
PTY interfaces to kissattach.  This enables other services to make use
of these PTYs without manually editing their configuration files to
point to the dynamically allocated PTY.

In addition, the patch includes the ability to change the ownership and
permissions on the allocated PTY, allowing an unpriviged process to make
use of it.
---
 kiss/kissnetd.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 169 insertions(+), 8 deletions(-)

diff --git a/kiss/kissnetd.c b/kiss/kissnetd.c
index 8c8fce9..db3bb27 100644
--- a/kiss/kissnetd.c
+++ b/kiss/kissnetd.c
@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <string.h>
 #include <unistd.h>
 #include <assert.h>
@@ -23,11 +24,17 @@
 #include <syslog.h>
 #include <time.h>
 #include <limits.h>
+#include <signal.h>
+
+#include <pwd.h>
+#include <grp.h>
 
 static char *Version = "1.5";
 static int VerboseMode;
 static int MaxFrameSize = 512;
 
+#define PTMX_TTY	"/dev/ptmx"
+
 #define REOPEN_TIMEOUT	30	/* try tio reopen every 10 s */
 
 struct PortDescriptor {
@@ -39,15 +46,29 @@ struct PortDescriptor {
 	char		namepts[PATH_MAX];	/* name of the unix98 pts slaves, which
 						 * the client has to use */
 	int		is_active;
+	int		is_unix98;
+	int		is_symlinked;
+
+	int		do_chown;
+	uid_t		pty_uid;
+	gid_t		pty_gid;
+
+	mode_t		pty_mode;
 };
 
 static struct PortDescriptor *PortList[FD_SETSIZE];
 
 static int NbPort;
 
+static int SetPtyOwner = 0;
+static uid_t PtyOwnerUid = 0;
+static gid_t PtyOwnerGid = 0;
+
+static mode_t PtyMode = 0;
+
 static void Usage(void)
 {
-	fprintf(stderr, "\nUsage : kissnetd [-v] [-f size] [-p num | /dev/pty?? [/dev/pty??]* ]\n");
+	fprintf(stderr, "\nUsage : kissnetd [-v] [-f size] [-p num | /dev/pty?? [/dev/pty??]* | [owner=USER:GROUP] [mode=MODE] pty:/dev/symlink1 [pty:/dev/symlink2]* ]\n");
 	fprintf(stderr, " -v       : Verbose mode, trace on stdout\n");
 	fprintf(stderr, " -f size  : Set max frame size to size bytes (default 512)\n");
 	fprintf(stderr, " -p num   : Number of /dev/ptmx-master-devices has to open\n");
@@ -90,13 +111,24 @@ static void NewPort(char *Name)
 		exit(1);
 	}
 
-	strncpy(MyPort->Name, Name, PATH_MAX-1);
+	MyPort->is_symlinked = (strstr(Name, "pty:") == Name);
+	MyPort->is_unix98 = MyPort->is_symlinked
+				|| (!strcmp(PTMX_TTY, Name));
+
+	strncpy(MyPort->Name, (MyPort->is_symlinked
+				? index(Name, ':') + 1
+				: Name), PATH_MAX-1);
+
 	MyPort->Name[PATH_MAX-1] = '\0';
 	MyPort->Fd = -1;
 	MyPort->FrameBuffer[0] = 0xC0;
 	MyPort->BufferIndex = 1;
 	MyPort->namepts [0] = '\0';
 	MyPort->is_active = 0;
+	MyPort->do_chown = SetPtyOwner;
+	MyPort->pty_uid = PtyOwnerUid;
+	MyPort->pty_gid = PtyOwnerGid;
+	MyPort->pty_mode= PtyMode;
 	PortList[NbPort++] = MyPort;
 }
 
@@ -112,7 +144,10 @@ static void ReopenPort(int PortNumber)
 	if (PortList[PortNumber]->namepts[0] == '\0') {
 
 		syslog(LOG_WARNING, "kissnetd : Opening port %s\n", PortList[PortNumber]->Name);
-		PortList[PortNumber]->Fd = open(PortList[PortNumber]->Name, O_RDWR | O_NONBLOCK);
+		PortList[PortNumber]->Fd = open(
+				(PortList[PortNumber]->is_symlinked
+				 ? PTMX_TTY
+				 : PortList[PortNumber]->Name), O_RDWR | O_NONBLOCK);
 		if (PortList[PortNumber]->Fd < 0) {
 			syslog(LOG_WARNING, "kissnetd : Error opening port %s : %s\n",
 				PortList[PortNumber]->Name, strerror(errno));
@@ -123,7 +158,7 @@ static void ReopenPort(int PortNumber)
 			return;
 		}
 		PortList[PortNumber]->is_active = 1;
-		if (!strcmp(PortList[PortNumber]->Name, "/dev/ptmx")) {
+		if (PortList[PortNumber]->is_unix98) {
 			char *npts;
 			/* get name of pts-device */
 			if ((npts = ptsname(PortList[PortNumber]->Fd)) == NULL) {
@@ -140,7 +175,35 @@ static void ReopenPort(int PortNumber)
 				syslog(LOG_WARNING, "kissnetd : Cannot unlock pts-device %s\n", PortList[PortNumber]->namepts);
 				exit(1);
 			}
-			syslog(LOG_WARNING, "kissnetd : Using /dev/ptmx with slave pty %s\n", PortList[PortNumber]->namepts);
+
+			if (PortList[PortNumber]->do_chown) {
+				if (chown(PortList[PortNumber]->namepts,
+						PortList[PortNumber]->pty_uid,
+						PortList[PortNumber]->pty_gid)) {
+					syslog(LOG_CRIT, "Cannot chown %s\n",
+							PortList[PortNumber]->namepts);
+					exit(1);
+				}
+			}
+			if (PortList[PortNumber]->pty_mode) {
+				if (chmod(PortList[PortNumber]->namepts,
+						PortList[PortNumber]->pty_mode)) {
+					syslog(LOG_CRIT, "Cannot chmod %s\n",
+							PortList[PortNumber]->namepts);
+					exit(1);
+				}
+			}
+
+			if (PortList[PortNumber]->is_symlinked) {
+				/* Create symbolic link */
+				if (symlink(PortList[PortNumber]->namepts, PortList[PortNumber]->Name)) {
+					syslog(LOG_CRIT, "Cannot symlink %s to %s\n", PortList[PortNumber]->namepts,
+							PortList[PortNumber]->Name);
+					exit(1);
+				}
+			} else {
+				syslog(LOG_WARNING, "kissnetd : Using /dev/ptmx with slave pty %s\n", PortList[PortNumber]->namepts);
+			}
 		}
 	} else {
 		if (PortList[PortNumber]->Fd == -1) {
@@ -324,6 +387,63 @@ static void ProcessPortList(void)
 	}
 }
 
+/*
+ * Parse the owner string; given as a user:group pair.  Result is stored
+ * in PtyOwnerUid and PtyOwnerGid; and overrides previously set defaults.
+ */
+static int ParseOwner(char* owner)
+{
+	char* colon;
+	char* pty_owner_group;
+
+	if (!strcmp(owner, "default")) {
+		SetPtyOwner = 0;
+		return 0;
+	}
+
+	colon = index(owner, ':');
+	if (!colon) {
+		fprintf(stderr, "Owner must be given in the form user:group\n");
+		return 1;
+	}
+	*colon = 0;
+	pty_owner_group = colon + 1;
+
+	if (owner) {
+		/* Look up the user */
+		struct passwd user;
+		struct passwd* user_ptr = NULL;
+		struct group grp;
+		struct group* grp_ptr = NULL;
+		char buffer[512];
+		int err = getpwnam_r(owner, &user,
+				buffer, sizeof(buffer)-1, &user_ptr);
+		if (err) {
+			fprintf(stderr,
+				"Failed to look up user: %s (%d)\n",
+				strerror(err), err);
+			return 1;
+		}
+
+		err = getgrnam_r(pty_owner_group, &grp,
+				buffer, sizeof(buffer)-1, &grp_ptr);
+		if (err) {
+			fprintf(stderr,
+				"Failed to look up group: %s (%d)\n",
+				strerror(err), err);
+			return 1;
+		}
+
+		if (user_ptr && grp_ptr) {
+			PtyOwnerUid = user_ptr->pw_uid;
+			PtyOwnerGid = grp_ptr->gr_gid;
+			SetPtyOwner = 1;
+			return 0;
+		}
+	}
+	return 1;
+}
+
 static void ProcessArgv(int argc, char *argv[])
 {
 	int opt;
@@ -345,7 +465,16 @@ static void ProcessArgv(int argc, char *argv[])
 				exit(1);
 			}
 			for (i=0; i < ptmxdevices; i++)
-				NewPort("/dev/ptmx");
+				NewPort(PTMX_TTY);
+			break;
+		case 'o':
+			/* Change the owner of the ptys */
+			if (ParseOwner(optarg))
+				exit(1);
+			break;
+		case 'm':
+			/* Change the mode of the pty */
+			PtyMode = (mode_t)strtoul(optarg, NULL, 8);
 			break;
 		default:
 			fprintf(stderr, "Invalid option %s\n", argv[optind]);
@@ -354,8 +483,18 @@ static void ProcessArgv(int argc, char *argv[])
 		}
 	}
 
-	while (optind < argc)
-		NewPort(argv[optind++]);
+	while (optind < argc) {
+		char* arg = argv[optind++];
+		if (strstr(arg, "owner=") == arg) {
+			if (ParseOwner(index(arg,'=')+1))
+				exit(1);
+		} else if (strstr(arg, "mode=") == arg) {
+			PtyMode = (mode_t)strtoul(index(arg,'=')+1,
+				NULL, 8);
+		} else {
+			NewPort(arg);
+		}
+	}
 
 	if (NbPort < 2) {
 		fprintf(stderr, "This multiplexer needs at least two pty's\n");
@@ -363,6 +502,23 @@ static void ProcessArgv(int argc, char *argv[])
 	}
 }
 
+void cleanup(void)
+{
+	/* Clean up symbolic links */
+	int i;
+	for (i=0; i<NbPort; i++) {
+		if (PortList[i]->is_symlinked) {
+			if (unlink(PortList[i]->Name))
+				syslog(LOG_WARNING, "Failed to unlink %s",
+					PortList[i]->Name);
+		}
+	}
+}
+void cleanup_sig(int signal)
+{
+	cleanup();
+	exit(0);
+}
 
 int main(int argc, char *argv[])
 {
@@ -374,6 +530,11 @@ int main(int argc, char *argv[])
 		Banner(1);
 	}
 
+	atexit(cleanup);
+	signal(SIGTERM, cleanup_sig);
+	signal(SIGINT, cleanup_sig);
+	signal(SIGQUIT, cleanup_sig);
+
 	ProcessArgv(argc, argv);
 	while (1) ProcessPortList();
 	return 0;
-- 
2.3.6

Re: PTY Improvements for kissattach, kissnetd

[Stuart Longland]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

On 28/06/15 13:04, me@vk4msl.yi.org wrote:
> This is a re-based patchset for ax25-tools based on commit 
> 18fa7fa6776da35da34a7e148fa2d96be8921e2.  It adds command line
> options to kissattach and kissnet to permit two things:
> 
> - symbolic linking of pseudo TTYs to consistent names for
> referencing in configuration files. - changing ownership/mode of
> pseudo TTYs so that they can be accessed by designated
> users/groups.

As an alternative to applying the patches by hand, I also have the
patches available via Git:
> The following changes since commit
> 18fa7fa6776da35da34a7e148fa2d96be8921e2e:
> 
> axparms: Accept numeric user ID. (2015-06-19 20:42:04 +0200)
> 
> are available in the git repository at:
> 
> git://git.longlandclan.yi.org/for-upstream/ax25/ax25-tools.git
> pty-improvements
> 
> for you to fetch changes up to
> 029a09b26fa1d6335ff9ee99b2d1217e55822ca2:
> 
> kissnetd: Add support for symlinking PTYs (2015-06-28 12:49:39
> +1000)
> 
> ---------------------------------------------------------------- 
> Stuart Longland (2): kissattach: Add support for pty symlinking 
> kissnetd: Add support for symlinking PTYs
> 
> kiss/kissattach.c | 110
> +++++++++++++++++++++++++++++++++++++++++++++++++---- 
> kiss/kissnetd.c   | 177
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
>
> 
2 files changed, 272 insertions(+), 15 deletions(-)

Regards,
- -- 
Stuart Longland (aka Redhatter, VK4MSL)

I haven't lost my mind...
  ...it's backed up on a tape somewhere.
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Re: [PATCH 1/2] kissattach: Add support for pty symlinking

[walter harms]

Am 28.06.2015 05:04, schrieb me@vk4msl.yi.org:
> From: Stuart Longland <stuartl@longlandclan.yi.org>
> 
> This patch adds abilities for symlinking of dynamically allocated slave
> PTY interfaces to kissattach.  This enables other services to make use
> of these PTYs without manually editing their configuration files to
> point to the dynamically allocated PTY.
> 
> In addition, the patch includes the ability to change the ownership and
> permissions on the allocated PTY, allowing an unpriviged process to make
> use of it.
> ---
>  kiss/kissattach.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 103 insertions(+), 7 deletions(-)
> 
> diff --git a/kiss/kissattach.c b/kiss/kissattach.c
> index e30ed05..a872d0a 100644
> --- a/kiss/kissattach.c
> +++ b/kiss/kissattach.c
> @@ -18,6 +18,9 @@
>  #include <sys/socket.h>
>  #include <sys/ioctl.h>
>  
> +#include <pwd.h>
> +#include <grp.h>
> +
>  #include <net/if.h>
>  #include <netax25/ax25.h>
>  #include <netrose/rose.h>
> @@ -32,6 +35,8 @@
>  #define N_6PACK 7	/* This is valid for all architectures in 2.2.x */
>  #endif
>  
> +#define PTMX_TTY	"/dev/ptmx"
> +
>  static char *callsign;
>  static int  speed;
>  static int  mtu;
> @@ -42,6 +47,7 @@ static char *portname;
>  static char *inetaddr;
>  static int allow_broadcast;
>  static int i_am_unix98_pty_master;		/* unix98 ptmx support */
> +static int symlink_pty = 0;
>  
>  static char *kiss_basename(char *s)
>  {
> @@ -58,6 +64,8 @@ static void terminate(int sig)
>  
>  	if (!i_am_unix98_pty_master)
>  		tty_unlock(kttyname);
> +	else if (symlink_pty)
> +		unlink(kttyname);
>  
>  	exit(0);
>  }
> @@ -214,7 +222,8 @@ static int startiface(char *dev, struct hostent *hp)
>  
>  static void usage(void)
>  {
> -	fprintf(stderr, "usage: %s [-b] [-l] [-m mtu] [-v] tty port [inetaddr]\n", progname);
> +	fprintf(stderr, "usage: %s [-b] [-l] [-m mtu] [-v] [-o user:group] [-p mode] tty port [inetaddr]\n",
> +			progname);
>  }
>  
>  int main(int argc, char *argv[])
> @@ -227,12 +236,18 @@ int main(int argc, char *argv[])
>  				* the client has to use */
>  	struct hostent *hp = NULL;
>  
> +	/* Name of the user and group who will "own" the pty */
> +	char* pty_owner_user = NULL;
> +	char* pty_owner_group = NULL;
> +	/* Mode for pty: if 0; use defaults */
> +	mode_t pty_mode = 0;
> +
>  	progname = kiss_basename(argv[0]);
>  
>  	if (!strcmp(progname, "spattach"))
>  		disc = N_6PACK;
>  
> -	while ((fd = getopt(argc, argv, "b6i:lm:v")) != -1) {
> +	while ((fd = getopt(argc, argv, "b6i:lm:o:p:v")) != -1) {
>  		switch (fd) {
>  		case '6':
>  			disc = N_6PACK;
> @@ -250,9 +265,24 @@ int main(int argc, char *argv[])
>  		case 'm':
>  			if ((mtu = atoi(optarg)) <= 0) {
>  				fprintf(stderr, "%s: invalid mtu size - %s\n", progname, optarg);
> -				return 1;
> +		case 'o':
> +			/* Change the owner of the pty */
> +			{
> +				char* colon = index(optarg,':');
> +				if (colon) {
> +					pty_owner_user = optarg;
> +					pty_owner_group = colon + 1;
> +					*colon = 0;
> +				} else {
> +					fprintf(stderr, "%s: Must specify user:group\n", progname);
> +					return 1;
> +				}
>  			}
>  			break;
> +		case 'p':
> +			/* Change the permissions (mode) of the pty */
> +			pty_mode = (mode_t)strtoul(optarg, NULL, 8);
> +			break;
>  		case 'v':
>  			printf("%s: %s\n", progname, VERSION);
>  			return 0;

hi Stuart,
what was the model for you cli ? i was looking at 'install' and it uses
-g group
-o owner
-m mode


> @@ -278,8 +308,17 @@ int main(int argc, char *argv[])
>  	if (argc-1 >= optind && !inetaddr)
>  		inetaddr = argv[optind];
>  
> -	if (!strcmp("/dev/ptmx", kttyname))
> +	if (!strcmp(PTMX_TTY, kttyname)) {
> +		i_am_unix98_pty_master = 1;
> +	} else if (strstr(kttyname, "pty:") == kttyname) {
> +		/*
> +		 * If the path starts with pty:, then create a
> +		 * new pty (Unix98 style) and make a symlink to it
> +		 */
>  		i_am_unix98_pty_master = 1;
> +		kttyname = index(kttyname, ':') + 1;
> +		symlink_pty = 1;
> +	}
>  
>  	if (!i_am_unix98_pty_master) {
>  		if (tty_is_locked(kttyname)) {
> @@ -296,7 +335,7 @@ int main(int argc, char *argv[])
>  		return 1;
>  	}
>  
> -	if ((fd = open(kttyname, O_RDONLY | O_NONBLOCK)) == -1) {
> +	if ((fd = open((symlink_pty ? PTMX_TTY : kttyname), O_RDONLY | O_NONBLOCK)) == -1) {
>  		if (errno == ENOENT) {
>  			fprintf(stderr, "%s: Cannot find serial device %s, no such file or directory.\n", progname, kttyname);
>  		} else {
> @@ -353,12 +392,69 @@ int main(int argc, char *argv[])
>  
>  	printf("AX.25 port %s bound to device %s\n", portname, dev);
>  	if (i_am_unix98_pty_master) {
> -		/* Users await the slave pty to be referenced in the 3d line */
> -		printf("Awaiting client connects on\n%s\n", namepts);
> +		/* Are we being asked to chown? */
> +		if (pty_owner_user) {
> +			/* Look up the user */
> +			struct passwd user;
> +			struct passwd* user_ptr = NULL;
> +			struct group grp;
> +			struct group* grp_ptr = NULL;
> +			char buffer[512];
> +			int err = getpwnam_r(pty_owner_user, &user,
> +				buffer, sizeof(buffer)-1, &user_ptr);

why _r ? any need to make it thread safe ?

just my 2 cents,
re,
 wh

> +			if (err) {
> +				fprintf(stderr,
> +					"Failed to look up user: %s (%d)\n",
> +					strerror(err), err);
> +				return 1;
> +			}
> +
> +			err = getgrnam_r(pty_owner_group, &grp,
> +				buffer, sizeof(buffer)-1, &grp_ptr);
> +			if (err) {
> +				fprintf(stderr,
> +					"Failed to look up group: %s (%d)\n",
> +					strerror(err), err);
> +				return 1;
> +			}
> +
> +			if (user_ptr && grp_ptr &&
> +					chown(namepts, user_ptr->pw_uid,
> +						grp_ptr->gr_gid)) {
> +				fprintf(stderr,
> +					"Failed to change ownership: %s (%d)\n",
> +					strerror(errno), errno);
> +				return 1;
> +			}
> +		}
> +
> +		/* Are we being asked to chmod? */
> +		if (pty_mode) {
> +			if (chmod(namepts, pty_mode)) {
> +				fprintf(stderr,
> +					"Failed to change mode: %s (%d)\n",
> +					strerror(errno), errno);
> +			}
> +		}
> +
> +		if (symlink_pty) {
> +			/* Create the symlink */
> +			if (symlink(namepts, kttyname)) {
> +				fprintf(stderr,
> +					"Failed to symlink PTY %s to %s: %s (%d)\n",
> +					kttyname, namepts, strerror(errno), errno);
> +				return 1;
> +			}
> +		} else {
> +			/* Users await the slave pty to be referenced in the 3d line */
> +			printf("Awaiting client connects on\n%s\n", namepts);
> +		}
>  	}
>  	if (logging) {
>  		openlog(progname, LOG_PID, LOG_DAEMON);
>  		syslog(LOG_INFO, "AX.25 port %s bound to device %s%s%s\n", portname, dev, (i_am_unix98_pty_master ? " with slave pty " : ""), (i_am_unix98_pty_master ? namepts : ""));
> +		if (symlink_pty)
> +			syslog(LOG_INFO, "Slave pty %s is symlinked to %s.", namepts, kttyname);
>  
>  	}
>  

Re: [PATCH 1/2] kissattach: Add support for pty symlinking

[Stuart Longland (VK4MSL)]

Hi Walter,
On 14/07/15 19:17, walter harms wrote:
> Am 28.06.2015 05:04, schrieb me@vk4msl.yi.org:
>> From: Stuart Longland <stuartl@longlandclan.yi.org>
>> -	fprintf(stderr, "usage: %s [-b] [-l] [-m mtu] [-v] tty port [inetaddr]\n", progname);
>> +	fprintf(stderr, "usage: %s [-b] [-l] [-m mtu] [-v] [-o user:group] [-p mode] tty port [inetaddr]\n",
>> +			progname);
> hi Stuart,
> what was the model for you cli ? i was looking at 'install' and it uses
> -g group
> -o owner
> -m mode

Well, -m was already taken with MTU and I didn't want to break backward
compatibility, so I was thinking along the lines of "permissions" and
"ownership", hence -p and -o.

I could split ownership into -u (user) and -g (group) however people are
probably used to chown specifying ownership as user:group.

>> +		/* Are we being asked to chown? */
>> +		if (pty_owner_user) {
>> +			/* Look up the user */
>> +			struct passwd user;
>> +			struct passwd* user_ptr = NULL;
>> +			struct group grp;
>> +			struct group* grp_ptr = NULL;
>> +			char buffer[512];
>> +			int err = getpwnam_r(pty_owner_user, &user,
>> +				buffer, sizeof(buffer)-1, &user_ptr);
> 
> why _r ? any need to make it thread safe ?
> 
> just my 2 cents,
> re,
>  wh

Call it paranoia, or an allergy to the non-threadsafe versions of the
function. :-)

I have a similar allergy to `int` and `unsigned int` for what it's
worth, preferring to use stdint.h or as a fallback, `char`, `short`,
`long` and `long long` since those are at least guaranteed to be a
certain size. (That said: I have seen a system where char was two bytes.)
-- 
Stuart Longland (aka Redhatter, VK4MSL)

I haven't lost my mind...
  ...it's backed up on a tape somewhere.