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* [PATCH v2 0/2] unshare: add some chroot magic
@ 2018-10-05 11:09 Laurent Vivier
  2018-10-05 11:09 ` [PATCH v2 1/2] unshare: allow to set a new root Laurent Vivier
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Laurent Vivier @ 2018-10-05 11:09 UTC (permalink / raw)
  To: util-linux; +Cc: Laurent Vivier

This couple of patches merges "unshare chroot" in one command.
Parameter names are copied from nsenter.
Doing like this the /proc filesystem is correctly mounted in the
new root with "--mount-proc".

v2: allow to use --wd without --root
    fix a bug when we use --mount-proc with --root
    -> don't remount /proc to none
    fix tabulation

Laurent Vivier (2):
  unshare: allow to set a new root
  unshare: allow to set user ID and group ID

 bash-completion/unshare |  6 +++-
 sys-utils/unshare.1     | 13 +++++++++
 sys-utils/unshare.c     | 62 ++++++++++++++++++++++++++++++++++++-----
 3 files changed, 73 insertions(+), 8 deletions(-)

-- 
2.17.1

^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH v2 1/2] unshare: allow to set a new root
  2018-10-05 11:09 [PATCH v2 0/2] unshare: add some chroot magic Laurent Vivier
@ 2018-10-05 11:09 ` Laurent Vivier
  2018-10-05 11:09 ` [PATCH v2 2/2] unshare: allow to set user ID and group ID Laurent Vivier
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 5+ messages in thread
From: Laurent Vivier @ 2018-10-05 11:09 UTC (permalink / raw)
  To: util-linux; +Cc: Laurent Vivier

This patch instroduces two new parameters to set the new
root and the new working directory in this new root.

This allows to combine "unshare chroot" in one command,
and doing like this the /proc filesystem is correctly
mounted in the new root with "--mount-proc".

The new parameters are -R, --root and -w, --wd. The names
are the same as for nsenter, except for "-r" that is already
used by "--map-root-user" and replaced by "-R".

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---

Notes:
    v2: allow to use --wd without --root
        fix a bug when we use --mount-proc with --root
        -> don't remount /proc to none
        fix tabulation

 bash-completion/unshare |  4 +++-
 sys-utils/unshare.1     |  6 ++++++
 sys-utils/unshare.c     | 34 +++++++++++++++++++++++++++++-----
 3 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/bash-completion/unshare b/bash-completion/unshare
index 3fda4a194..64aea6784 100644
--- a/bash-completion/unshare
+++ b/bash-completion/unshare
@@ -33,7 +33,9 @@ _unshare_module()
 				--propagation
 				--setgroups
 				--help
-				--version"
+				--version
+				--root
+				--wd"
 			COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) )
 			return 0
 			;;
diff --git a/sys-utils/unshare.1 b/sys-utils/unshare.1
index 746c41152..40cbedbd1 100644
--- a/sys-utils/unshare.1
+++ b/sys-utils/unshare.1
@@ -186,6 +186,12 @@ the GID map becomes writable by unprivileged processes when
 .BR \%setgroups (2)
 is permanently disabled (with \fBdeny\fR).
 .TP
+.BR \-R, "\-\-root=\fIdir"
+run the command with root directory set to \fIdir\fP.
+.TP
+.BR \-w, "\-\-wd=\fIdir"
+change working directory to \fIdir\fP.
+.TP
 .BR \-V , " \-\-version"
 Display version information and exit.
 .TP
diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c
index 661665aeb..12ef044f8 100644
--- a/sys-utils/unshare.c
+++ b/sys-utils/unshare.c
@@ -269,6 +269,9 @@ static void __attribute__((__noreturn__)) usage(void)
 	fputs(_(" --propagation slave|shared|private|unchanged\n"
 	        "                           modify mount propagation in mount namespace\n"), out);
 	fputs(_(" --setgroups allow|deny    control the setgroups syscall in user namespaces\n"), out);
+	fputs(USAGE_SEPARATOR, out);
+	fputs(_(" -R, --root=<dir>	    run the command with root directory set to <dir>\n"), out);
+	fputs(_(" -w, --wd=<dir>	    change working directory to <dir>\n"), out);
 
 	fputs(USAGE_SEPARATOR, out);
 	printf(USAGE_HELP_OPTIONS(27));
@@ -283,7 +286,7 @@ int main(int argc, char *argv[])
 		OPT_MOUNTPROC = CHAR_MAX + 1,
 		OPT_PROPAGATION,
 		OPT_SETGROUPS,
-		OPT_KILLCHILD
+		OPT_KILLCHILD,
 	};
 	static const struct option longopts[] = {
 		{ "help",          no_argument,       NULL, 'h'             },
@@ -303,6 +306,8 @@ int main(int argc, char *argv[])
 		{ "map-root-user", no_argument,       NULL, 'r'             },
 		{ "propagation",   required_argument, NULL, OPT_PROPAGATION },
 		{ "setgroups",     required_argument, NULL, OPT_SETGROUPS   },
+		{ "root",	   required_argument, NULL, 'R'		    },
+		{ "wd",		   required_argument, NULL, 'w'		    },
 		{ NULL, 0, NULL, 0 }
 	};
 
@@ -311,6 +316,8 @@ int main(int argc, char *argv[])
 	int c, forkit = 0, maproot = 0;
 	int kill_child_signo = 0; /* 0 means --kill-child was not used */
 	const char *procmnt = NULL;
+	const char *newroot = NULL;
+	const char *newdir = NULL;
 	pid_t pid = 0;
 	int fds[2];
 	int status;
@@ -323,7 +330,7 @@ int main(int argc, char *argv[])
 	textdomain(PACKAGE);
 	atexit(close_stdout);
 
-	while ((c = getopt_long(argc, argv, "+fhVmuinpCUr", longopts, NULL)) != -1) {
+	while ((c = getopt_long(argc, argv, "+fhVmuinpCUrR:w:", longopts, NULL)) != -1) {
 		switch (c) {
 		case 'f':
 			forkit = 1;
@@ -392,6 +399,12 @@ int main(int argc, char *argv[])
 				kill_child_signo = SIGKILL;
 			}
 			break;
+		case 'R':
+			newroot = optarg;
+			break;
+		case 'w':
+			newdir = optarg;
+			break;
 		default:
 			errtryhelp(EXIT_FAILURE);
 		}
@@ -471,10 +484,21 @@ int main(int argc, char *argv[])
 	if ((unshare_flags & CLONE_NEWNS) && propagation)
 		set_propagation(propagation);
 
-	if (procmnt &&
-	    (mount("none", procmnt, NULL, MS_PRIVATE|MS_REC, NULL) != 0 ||
-	     mount("proc", procmnt, "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) != 0))
+	if (newroot) {
+		if (chroot(newroot) != 0)
+			err(EXIT_FAILURE,
+			    _("cannot change root directory to '%s'"), newroot);
+		newdir = newdir ?: "/";
+	}
+	if (newdir && chdir(newdir))
+		err(EXIT_FAILURE, _("cannot chdir to '%s'"), newdir);
+
+	if (procmnt) {
+		if (!newroot && mount("none", procmnt, NULL, MS_PRIVATE|MS_REC, NULL) != 0)
+			err(EXIT_FAILURE, _("umount %s failed"), procmnt);
+		if (mount("proc", procmnt, "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) != 0)
 			err(EXIT_FAILURE, _("mount %s failed"), procmnt);
+	}
 
 	if (optind < argc) {
 		execvp(argv[optind], argv + optind);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH v2 2/2] unshare: allow to set user ID and group ID
  2018-10-05 11:09 [PATCH v2 0/2] unshare: add some chroot magic Laurent Vivier
  2018-10-05 11:09 ` [PATCH v2 1/2] unshare: allow to set a new root Laurent Vivier
@ 2018-10-05 11:09 ` Laurent Vivier
  2018-10-08 12:30 ` [PATCH v2 0/2] unshare: add some chroot magic Karel Zak
  2018-11-12 11:00 ` Karel Zak
  3 siblings, 0 replies; 5+ messages in thread
From: Laurent Vivier @ 2018-10-05 11:09 UTC (permalink / raw)
  To: util-linux; +Cc: Laurent Vivier

This patch introduces two new parameters to set the
user ID and the group ID of the program to be executed.
Setting group ID also drops supplementary groups.

The option names used are the same as for nsenter,
-S, --setuid and -G, --setgid.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---

Notes:
    v2: fix tabulation

 bash-completion/unshare |  4 +++-
 sys-utils/unshare.1     |  7 +++++++
 sys-utils/unshare.c     | 30 +++++++++++++++++++++++++++---
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/bash-completion/unshare b/bash-completion/unshare
index 64aea6784..10afffe19 100644
--- a/bash-completion/unshare
+++ b/bash-completion/unshare
@@ -35,7 +35,9 @@ _unshare_module()
 				--help
 				--version
 				--root
-				--wd"
+				--wd
+				--setuid
+				--setgid"
 			COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) )
 			return 0
 			;;
diff --git a/sys-utils/unshare.1 b/sys-utils/unshare.1
index 40cbedbd1..d2ba6c3a5 100644
--- a/sys-utils/unshare.1
+++ b/sys-utils/unshare.1
@@ -192,6 +192,13 @@ run the command with root directory set to \fIdir\fP.
 .BR \-w, "\-\-wd=\fIdir"
 change working directory to \fIdir\fP.
 .TP
+.BR \-S, "\-\-setuid \fIuid"
+Set the user ID which will be used in the entered namespace.
+.TP
+.BR \-G, "\-\-setgid \fIgid"
+Set the group ID which will be used in the entered namespace and drop
+supplementary groups.
+.TP
 .BR \-V , " \-\-version"
 Display version information and exit.
 .TP
diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c
index 12ef044f8..e9ddb09de 100644
--- a/sys-utils/unshare.c
+++ b/sys-utils/unshare.c
@@ -29,6 +29,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/prctl.h>
+#include <grp.h>
 
 /* we only need some defines missing in sys/mount.h, no libmount linkage */
 #include <libmount.h>
@@ -42,6 +43,7 @@
 #include "pathnames.h"
 #include "all-io.h"
 #include "signames.h"
+#include "strutils.h"
 
 /* synchronize parent and child by pipe */
 #define PIPE_SYNC_BYTE	0x06
@@ -272,6 +274,8 @@ static void __attribute__((__noreturn__)) usage(void)
 	fputs(USAGE_SEPARATOR, out);
 	fputs(_(" -R, --root=<dir>	    run the command with root directory set to <dir>\n"), out);
 	fputs(_(" -w, --wd=<dir>	    change working directory to <dir>\n"), out);
+	fputs(_(" -S, --setuid <uid>	    set uid in entered namespace\n"), out);
+	fputs(_(" -G, --setgid <gid>	    set gid in entered namespace\n"), out);
 
 	fputs(USAGE_SEPARATOR, out);
 	printf(USAGE_HELP_OPTIONS(27));
@@ -306,6 +310,8 @@ int main(int argc, char *argv[])
 		{ "map-root-user", no_argument,       NULL, 'r'             },
 		{ "propagation",   required_argument, NULL, OPT_PROPAGATION },
 		{ "setgroups",     required_argument, NULL, OPT_SETGROUPS   },
+		{ "setuid",	   required_argument, NULL, 'S'		    },
+		{ "setgid",	   required_argument, NULL, 'G'		    },
 		{ "root",	   required_argument, NULL, 'R'		    },
 		{ "wd",		   required_argument, NULL, 'w'		    },
 		{ NULL, 0, NULL, 0 }
@@ -322,15 +328,16 @@ int main(int argc, char *argv[])
 	int fds[2];
 	int status;
 	unsigned long propagation = UNSHARE_PROPAGATION_DEFAULT;
-	uid_t real_euid = geteuid();
-	gid_t real_egid = getegid();
+	int force_uid = 0, force_gid = 0;
+	uid_t uid = 0, real_euid = geteuid();
+	gid_t gid = 0, real_egid = getegid();
 
 	setlocale(LC_ALL, "");
 	bindtextdomain(PACKAGE, LOCALEDIR);
 	textdomain(PACKAGE);
 	atexit(close_stdout);
 
-	while ((c = getopt_long(argc, argv, "+fhVmuinpCUrR:w:", longopts, NULL)) != -1) {
+	while ((c = getopt_long(argc, argv, "+fhVmuinpCUrR:w:S:G:", longopts, NULL)) != -1) {
 		switch (c) {
 		case 'f':
 			forkit = 1;
@@ -399,6 +406,14 @@ int main(int argc, char *argv[])
 				kill_child_signo = SIGKILL;
 			}
 			break;
+		case 'S':
+			uid = strtoul_or_err(optarg, _("failed to parse uid"));
+			force_uid = 1;
+			break;
+		case 'G':
+			gid = strtoul_or_err(optarg, _("failed to parse gid"));
+			force_gid = 1;
+			break;
 		case 'R':
 			newroot = optarg;
 			break;
@@ -500,6 +515,15 @@ int main(int argc, char *argv[])
 			err(EXIT_FAILURE, _("mount %s failed"), procmnt);
 	}
 
+	if (force_gid) {
+		if (setgroups(0, NULL) != 0)	/* drop supplementary groups */
+			err(EXIT_FAILURE, _("setgroups failed"));
+		if (setgid(gid) < 0)		/* change GID */
+			err(EXIT_FAILURE, _("setgid failed"));
+	}
+	if (force_uid && setuid(uid) < 0)	/* change UID */
+		err(EXIT_FAILURE, _("setuid failed"));
+
 	if (optind < argc) {
 		execvp(argv[optind], argv + optind);
 		errexec(argv[optind]);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH v2 0/2] unshare: add some chroot magic
  2018-10-05 11:09 [PATCH v2 0/2] unshare: add some chroot magic Laurent Vivier
  2018-10-05 11:09 ` [PATCH v2 1/2] unshare: allow to set a new root Laurent Vivier
  2018-10-05 11:09 ` [PATCH v2 2/2] unshare: allow to set user ID and group ID Laurent Vivier
@ 2018-10-08 12:30 ` Karel Zak
  2018-11-12 11:00 ` Karel Zak
  3 siblings, 0 replies; 5+ messages in thread
From: Karel Zak @ 2018-10-08 12:30 UTC (permalink / raw)
  To: Laurent Vivier; +Cc: util-linux

On Fri, Oct 05, 2018 at 01:09:28PM +0200, Laurent Vivier wrote:
> v2: allow to use --wd without --root
>     fix a bug when we use --mount-proc with --root
>     -> don't remount /proc to none
>     fix tabulation

Seems good. Thanks.

I'm going to merge it later after release v2.33.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH v2 0/2] unshare: add some chroot magic
  2018-10-05 11:09 [PATCH v2 0/2] unshare: add some chroot magic Laurent Vivier
                   ` (2 preceding siblings ...)
  2018-10-08 12:30 ` [PATCH v2 0/2] unshare: add some chroot magic Karel Zak
@ 2018-11-12 11:00 ` Karel Zak
  3 siblings, 0 replies; 5+ messages in thread
From: Karel Zak @ 2018-11-12 11:00 UTC (permalink / raw)
  To: Laurent Vivier; +Cc: util-linux

On Fri, Oct 05, 2018 at 01:09:28PM +0200, Laurent Vivier wrote:
> Laurent Vivier (2):
>   unshare: allow to set a new root
>   unshare: allow to set user ID and group ID

Applied, thanks.

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

^ permalink raw reply	[flat|nested] 5+ messages in thread

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-- links below jump to the message on this page --
2018-10-05 11:09 [PATCH v2 0/2] unshare: add some chroot magic Laurent Vivier
2018-10-05 11:09 ` [PATCH v2 1/2] unshare: allow to set a new root Laurent Vivier
2018-10-05 11:09 ` [PATCH v2 2/2] unshare: allow to set user ID and group ID Laurent Vivier
2018-10-08 12:30 ` [PATCH v2 0/2] unshare: add some chroot magic Karel Zak
2018-11-12 11:00 ` Karel Zak

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