Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

[1.1] nsexec: retry unshare on EINVAL #3776

Merged
merged 1 commit into from
Mar 26, 2023
Merged

[1.1] nsexec: retry unshare on EINVAL #3776

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
30 changes: 22 additions & 8 deletions libcontainer/nsenter/nsexec.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -832,6 +832,25 @@ void send_mountsources(int sockfd, pid_t child, char *mountsources, size_t mount
bail("failed to close container mount namespace fd %d", container_mntns_fd);
}

void try_unshare(int flags, const char *msg)
{
write_log(DEBUG, "unshare %s", msg);
/*
* Kernels prior to v4.3 may return EINVAL on unshare when another process
* reads runc's /proc/$PID/status or /proc/$PID/maps. To work around this,
* retry on EINVAL a few times.
*/
int retries = 5;
for (; retries > 0; retries--) {
if (unshare(flags) == 0) {
return;
}
if (errno != EINVAL)
break;
}
bail("failed to unshare %s", msg);
}

void nsexec(void)
{
int pipenum;
Expand Down Expand Up @@ -1170,9 +1189,7 @@ void nsexec(void)
* problem.
*/
if (config.cloneflags & CLONE_NEWUSER) {
write_log(DEBUG, "unshare user namespace");
if (unshare(CLONE_NEWUSER) < 0)
bail("failed to unshare user namespace");
try_unshare(CLONE_NEWUSER, "user namespace");
config.cloneflags &= ~CLONE_NEWUSER;

/*
Expand Down Expand Up @@ -1224,9 +1241,7 @@ void nsexec(void)
* some old kernel versions where clone(CLONE_PARENT | CLONE_NEWPID)
* was broken, so we'll just do it the long way anyway.
*/
write_log(DEBUG, "unshare remaining namespace (except cgroupns)");
if (unshare(config.cloneflags & ~CLONE_NEWCGROUP) < 0)
bail("failed to unshare remaining namespaces (except cgroupns)");
try_unshare(config.cloneflags & ~CLONE_NEWCGROUP, "remaining namespaces (except cgroupns)");

/* Ask our parent to send the mount sources fds. */
if (config.mountsources) {
Expand Down Expand Up @@ -1344,8 +1359,7 @@ void nsexec(void)
}

if (config.cloneflags & CLONE_NEWCGROUP) {
if (unshare(CLONE_NEWCGROUP) < 0)
bail("failed to unshare cgroup namespace");
try_unshare(CLONE_NEWCGROUP, "cgroup namespace");
}

write_log(DEBUG, "signal completion to stage-0");
Expand Down