From cba167983914f33868e45bfc0ccf5347dd4a1402 Mon Sep 17 00:00:00 2001 From: Colin Walters Date: Mon, 16 Jan 2017 17:29:27 -0500 Subject: [PATCH] Add --unshare-all and --share-net In discussion in https://github.com/projectatomic/bubblewrap/pull/150 it was noted that most of the bwrap command line tends towards "closed by default, request open". But the `--unshare` options are inverse. Now, I suspect in practice there's only one namespace that most users will care about, which is the network namespace. There are very useful programs to build on both cases. I think everything else (pid, ipc, uts) people will want as a group. Any cases that are unusual enough to want to turn one of them off can still fall back to the previous bwrap behavior of explicitly unsharing. They're likely to be security sensitive enough that if a new namespace were added, it would make sense to evaluate the tool. But again I think most users will want all namespaces, with the network one as a primary "enable it" option. --- bubblewrap.c | 19 +++++++++++++++++++ demos/bubblewrap-shell.sh | 12 ++++++++---- 2 files changed, 27 insertions(+), 4 deletions(-) diff --git a/bubblewrap.c b/bubblewrap.c index f0adb073..e8a95bda 100644 --- a/bubblewrap.c +++ b/bubblewrap.c @@ -179,6 +179,8 @@ usage (int ecode, FILE *out) " --help Print this help\n" " --version Print version\n" " --args FD Parse nul-separated args from FD\n" + " --unshare-all Unshare every namespace we support by default\n" + " --share-net Retain the network namespace (can only combine with --unshare-all)\n" " --unshare-user Create new user namespace (may be automatically implied if not setuid)\n" " --unshare-user-try Create new user namespace if possible else continue by skipping it\n" " --unshare-ipc Create new ipc namespace\n" @@ -1208,6 +1210,17 @@ parse_args_recurse (int *argcp, argv += 1; argc -= 1; } + else if (strcmp (arg, "--unshare-all") == 0) + { + /* Keep this in order with the older (legacy) --unshare arguments, + * we use the --try variants of user and cgroup, since we want + * to support systems/kernels without support for those. + */ + opt_unshare_user_try = opt_unshare_ipc = opt_unshare_pid = + opt_unshare_uts = opt_unshare_cgroup_try = + opt_unshare_net = TRUE; + } + /* Begin here the older individual --unshare variants */ else if (strcmp (arg, "--unshare-user") == 0) { opt_unshare_user = TRUE; @@ -1240,6 +1253,12 @@ parse_args_recurse (int *argcp, { opt_unshare_cgroup_try = TRUE; } + /* Begin here the newer --share variants */ + else if (strcmp (arg, "--share-net") == 0) + { + opt_unshare_net = FALSE; + } + /* End --share variants, other arguments begin */ else if (strcmp (arg, "--chdir") == 0) { if (argc < 2) diff --git a/demos/bubblewrap-shell.sh b/demos/bubblewrap-shell.sh index 96b87b6f..2f0bb1b7 100755 --- a/demos/bubblewrap-shell.sh +++ b/demos/bubblewrap-shell.sh @@ -1,9 +1,12 @@ #!/usr/bin/env bash # Use bubblewrap to run /bin/sh reusing the host OS binaries (/usr), but with -# separate /tmp, /var, /run, and /etc. For /etc we just inherit the host's -# resolv.conf, and set up "stub" passwd/group files. +# separate /tmp, /home, /var, /run, and /etc. For /etc we just inherit the +# host's resolv.conf, and set up "stub" passwd/group files. Not sharing +# /home for example is intentional. If you wanted to, you could design +# a bwrap-using program that shared individual parts of /home, perhaps +# public content. # -# You can build on this example; for example, use --unshare-net to disable +# Another way to build on this example is to remove --share-net to disable # networking. set -euo pipefail (exec bwrap --ro-bind /usr /usr \ @@ -18,7 +21,8 @@ set -euo pipefail --symlink usr/bin /bin \ --symlink usr/sbin /sbin \ --chdir / \ - --unshare-pid \ + --unshare-all \ + --share-net \ --dir /run/user/$(id -u) \ --setenv XDG_RUNTIME_DIR "/run/user/`id -u`" \ --setenv PS1 "bwrap-demo$ " \