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nsenter: add support for the time namespace 

Just as with unshare and lsns this adds time namespace support to
nsenter.

In contrast to unshare nsenter does not have the options '--boottime'
and '--monotonic' as that offset can only be set as long as there have
no processes being started in the corresponding time namespace.

Signed-off-by: Adrian Reber <areber@redhat.com>
This commit is contained in:
Adrian Reber 2020-03-09 13:02:45 +00:00
parent 40c28f51c9
commit 7f1f0584c2
No known key found for this signature in database
GPG Key ID: 82C9378ED3C4906A
2 changed files with 28 additions and 1 deletions
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18
sys-utils/nsenter.1
View File

@ -92,6 +92,13 @@ and the discussion of the
flag in
.BR clone (2).
.TP
.B time namespace
The process can have a distinct view of
.B CLOCK_MONOTONIC
and/or
.B CLOCK_BOOTTIME
which can be changed using \fI/proc/self/timens_offsets\fP.
.TP
See \fBclone\fP(2) for the exact semantics of the flags.
.SH OPTIONS
Various of the options below that relate to namespaces take an optional
@ -144,6 +151,9 @@ the user namespace
/proc/\fIpid\fR/ns/cgroup
the cgroup namespace
.TP
/proc/\fIpid\fR/ns/time
the time namespace
.TP
/proc/\fIpid\fR/root
the root directory
.TP
@ -210,6 +220,14 @@ If
is specified, enter the cgroup namespace specified by
.IR file .
.TP
\fB\-T\fR, \fB\-\-time\fR[=\fIfile\fR]
Enter the time namespace. If no file is specified, enter the time namespace of
the target process.
If
.I file
is specified, enter the time namespace specified by
.IR file .
.TP
\fB\-G\fR, \fB\-\-setgid\fR \fIgid\fR
Set the group ID which will be used in the entered namespace and drop
supplementary groups.

11
sys-utils/nsenter.c
View File

@ -62,6 +62,7 @@ static struct namespace_file {
{ .nstype = CLONE_NEWNET, .name = "ns/net", .fd = -1 },
{ .nstype = CLONE_NEWPID, .name = "ns/pid", .fd = -1 },
{ .nstype = CLONE_NEWNS, .name = "ns/mnt", .fd = -1 },
{ .nstype = CLONE_NEWTIME, .name = "ns/time", .fd = -1 },
{ .nstype = 0, .name = NULL, .fd = -1 }
};
@ -86,6 +87,7 @@ static void __attribute__((__noreturn__)) usage(void)
fputs(_(" -p, --pid[=<file>] enter pid namespace\n"), out);
fputs(_(" -C, --cgroup[=<file>] enter cgroup namespace\n"), out);
fputs(_(" -U, --user[=<file>] enter user namespace\n"), out);
fputs(_(" -T, --time[=<file>] enter time namespace\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(_(" --preserve-credentials do not touch uids or gids\n"), out);
@ -219,6 +221,7 @@ int main(int argc, char *argv[])
{ "pid", optional_argument, NULL, 'p' },
{ "user", optional_argument, NULL, 'U' },
{ "cgroup", optional_argument, NULL, 'C' },
{ "time", optional_argument, NULL, 'T' },
{ "setuid", required_argument, NULL, 'S' },
{ "setgid", required_argument, NULL, 'G' },
{ "root", optional_argument, NULL, 'r' },
@ -248,7 +251,7 @@ int main(int argc, char *argv[])
close_stdout_atexit();
while ((c =
getopt_long(argc, argv, "+ahVt:m::u::i::n::p::C::U::S:G:r::w::FZ",
getopt_long(argc, argv, "+ahVt:m::u::i::n::p::C::U::T::S:G:r::w::FZ",
longopts, NULL)) != -1) {
switch (c) {
case 'a':
@ -300,6 +303,12 @@ int main(int argc, char *argv[])
else
namespaces |= CLONE_NEWUSER;
break;
case 'T':
if (optarg)
open_namespace_fd(CLONE_NEWTIME, optarg);
else
namespaces |= CLONE_NEWTIME;
break;
case 'S':
uid = strtoul_or_err(optarg, _("failed to parse uid"));
force_uid = true;