When pasta is started from an existing userns and tries to join the
netns from another process it fails to open /proc/$pid/ns/net due the
missing CAP_SYS_PTRACE capability in the --netns-only case.
A simple reproducer for this.
First create a userns:
$ unshare -r
Then create a new netns inside it and try to join that netns with pasta.
$ unshare -n sleep inf &
$ pasta --config-net --netns /proc/$!/ns/net
Signed-off-by: Paul Holzinger
---
isolation.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/isolation.c b/isolation.c
index 19932bf..1866724 100644
--- a/isolation.c
+++ b/isolation.c
@@ -202,9 +202,11 @@ void isolate_initial(void)
* a mapping from UID 0, which only happens with pasta spawning a child
* from a non-init user namespace (pasta can't run as root), we need to
* retain CAP_SETFCAP too.
+ * We also need to keep CAP_SYS_PTRACE in order to join an existing netns
+ * path under /proc/$pid/ns/net which was created in the same userns.
*/
if (!ns_is_init() && !geteuid())
- keep |= BIT(CAP_SETFCAP);
+ keep |= BIT(CAP_SETFCAP) | BIT(CAP_SYS_PTRACE);
drop_caps_ep_except(keep);
}
--
2.41.0