diff --git a/sys-utils/unshare.1 b/sys-utils/unshare.1 index 420b48b73..65dc55ce9 100644 --- a/sys-utils/unshare.1 +++ b/sys-utils/unshare.1 @@ -138,10 +138,11 @@ by bind mount. Fork the specified \fIprogram\fR as a child process of \fBunshare\fR rather than running it directly. This is useful when creating a new PID namespace. .TP -.BR \-\-kill\-child -When \fBunshare\fR terminates, have \fBSIGKILL\fR be sent to the forked child process. +.BR \-\-kill\-child [ =\fIsigname ] +When \fBunshare\fR terminates, have \fIsigname\fP be sent to the forked child process. Combined with \fB--pid\fR this allows for an easy and realiable killing of the entire process tree below \fBunshare\fR. +If not given, \fIsigname\fP defaults to \fBSIGKILL\fR. This option implies \fB--fork\fR. .TP .BR \-\-mount\-proc [ =\fImountpoint ] diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c index b7448420b..00afc7dd8 100644 --- a/sys-utils/unshare.c +++ b/sys-utils/unshare.c @@ -41,6 +41,7 @@ #include "xalloc.h" #include "pathnames.h" #include "all-io.h" +#include "signames.h" /* synchronize parent and child by pipe */ #define PIPE_SYNC_BYTE 0x06 @@ -259,7 +260,7 @@ static void __attribute__((__noreturn__)) usage(void) fputs(_(" -U, --user[=] unshare user namespace\n"), out); fputs(_(" -C, --cgroup[=] unshare cgroup namespace\n"), out); fputs(_(" -f, --fork fork before launching \n"), out); - fputs(_(" --kill-child when dying, kill the forked child (implies --fork)\n"), out); + fputs(_(" --kill-child[=] when dying, kill the forked child (implies --fork); defaults to SIGKILL\n"), out); fputs(_(" --mount-proc[=] mount proc filesystem first (implies --mount)\n"), out); fputs(_(" -r, --map-root-user map current user to root (implies --user)\n"), out); fputs(_(" --propagation slave|shared|private|unchanged\n" @@ -294,7 +295,7 @@ int main(int argc, char *argv[]) { "cgroup", optional_argument, NULL, 'C' }, { "fork", no_argument, NULL, 'f' }, - { "kill-child", no_argument, NULL, OPT_KILLCHILD }, + { "kill-child", optional_argument, NULL, OPT_KILLCHILD }, { "mount-proc", optional_argument, NULL, OPT_MOUNTPROC }, { "map-root-user", no_argument, NULL, 'r' }, { "propagation", required_argument, NULL, OPT_PROPAGATION }, @@ -305,7 +306,7 @@ int main(int argc, char *argv[]) int setgrpcmd = SETGROUPS_NONE; int unshare_flags = 0; int c, forkit = 0, maproot = 0; - int kill_child = 0; + int kill_child_signo = 0; /* 0 means --kill-child was not used */ const char *procmnt = NULL; pid_t pid = 0; int fds[2]; @@ -379,8 +380,14 @@ int main(int argc, char *argv[]) propagation = parse_propagation(optarg); break; case OPT_KILLCHILD: - kill_child = 1; forkit = 1; + if (optarg) { + if ((kill_child_signo = signame_to_signum(optarg)) < 0) + errx(EXIT_FAILURE, _("unknown signal: %s"), + optarg); + } else { + kill_child_signo = SIGKILL; + } break; default: errtryhelp(EXIT_FAILURE); @@ -439,8 +446,8 @@ int main(int argc, char *argv[]) } } - if (kill_child) - if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0) + if (kill_child_signo != 0) + if (prctl(PR_SET_PDEATHSIG, kill_child_signo) < 0) err(EXIT_FAILURE, "prctl failed"); if (maproot) {