It's followup for #5890.
The containerd-shim process depends on the mount package to init rootfs
for container. For the container enable user namespace, the mount
package needs to fork child process to get the brand-new user namespace.
However, there are two reapers in one process (described by the
following list) and there are race-condition cases.
1. mount package
2. sys.Reaper as global one which watch all the SIGCHLD.
=== [kill(2)][kill] the wrong process ===
Currently, we use pipe to ensure that child process is alive. However,
the pide file descriptor can be hold by other process, which the child
process cannot exit by self. We should use [kill(2)][kill] to ensure the
child process. But we might kill the wrong process if the child process
might be reaped by containerd-shim and the PID might be reused by other
process.
=== [waitid(2)][waitid] on the wrong child process ===
```
containerd-shim process:
Goroutine 1(GetUsernsFD): Goroutine 2(Reaper)
1. Ready to wait for child process X
2. Received SIGCHLD from X
3. Reaped the zombie child process X
(X has been reused by other child process)
4. Wait on process X
The goroutine 1 will be stuck until the process X has been terminated.
```
=== open `/proc/X/ns/user` on the wrong child process ===
There is also pid-reused risk between opening `/proc/$pid/ns/user` and
writing `/proc/$pid/u[g]id_map`.
```
containerd-shim process:
Goroutine 1(GetUsernsFD): Goroutine 2(Reaper)
1. Fork child process X
2. Write /proc/X/uid_map,gid_map
3. Received SIGCHLD from X
4. Reaped the zombie child process X
(X has been reused by other process)
5. Open /proc/X/ns/user file as usernsFD
The usernsFD links to the wrong X!!!
```
In order to fix the race-condition, we should use [CLONE_PIDFD][clone2] (Since
Linux v5.2).
When we fork child process `X`, the kernel will return a process file
descriptor `X_PIDFD` referencing to child process `X`. With the pidfd, we can
use [pidfd_send_signal(2)][pidfd_send_signal] (Since Linux v5.1)
to send signal(0) to ensure the child process `X` is alive. If the `X` has
terminated and its PID has been recycled for another process. The
pidfd_send_signal fails with the error ESRCH.
Therefore, we can open `/proc/X/{ns/user,uid_map,gid_map}` file
descriptors as first and then use pidfd_send_signal to check the process
is still alive. If so, we can ensure the file descriptors are valid and
reference to the child process `X`. Even if the `X` PID has been reused
after pidfd_send_signal call, the file descriptors are still valid.
```code
X, pidfd = clone2(CLONE_PIDFD)
usernsFD = open /proc/X/ns/user
uidmapFD = open /proc/X/uid_map
gidmapFD = open /proc/X/gid_map
pidfd_send_signal pidfd, signal(0)
return err if no such process
== When we arrive here, we can ensure usernsFD/uidmapFD/gidmapFD are correct
== even if X has been reused after pidfd_send_signal call.
update uid/gid mapping by uidmapFD/gidmapFD
return usernsFD
```
And the [waitid(2)][waitid] also supports pidfd type (Since Linux 5.4).
We can use pidfd type waitid to ensure we are waiting for the correct
process. All the PID related race-condition issues can be resolved by
pidfd.
```bash
➜ mount git:(followup-idmapped) pwd
/home/fuwei/go/src/github.com/containerd/containerd/mount
➜ mount git:(followup-idmapped) sudo go test -test.root -run TestGetUsernsFD -count=1000 -failfast -p 100 ./...
PASS
ok github.com/containerd/containerd/mount 3.446s
```
[kill]: <https://man7.org/linux/man-pages/man2/kill.2.html>
[clone2]: <https://man7.org/linux/man-pages/man2/clone.2.html>
[pidfd_send_signal]: <https://man7.org/linux/man-pages/man2/pidfd_send_signal.2.html>
[waitid]: <https://man7.org/linux/man-pages/man2/waitid.2.html>
Signed-off-by: Wei Fu <fuweid89@gmail.com>
The point of this test is to see that we successfully can get all of
the pids running in the container and they match the number expected,
but for Windows this concept is a bit different. Windows containers
essentially go through the usermode boot phase of the operating system,
and have quite a few processes and system services running outside of
the "init" process you specify. Because of this, there's not a great
way to say "there should only be N processes running" like we can ensure
for Linux. So, on Windows check that we're at least greater than one.
Signed-off-by: Danny Canter <danny@dcantah.dev>
go1.21.3 (released 2023-10-10) includes a security fix to the net/http package.
See the Go 1.21.3 milestone on our issue tracker for details:
https://github.com/golang/go/issues?q=milestone%3AGo1.21.3+label%3ACherryPickApproved
full diff: https://github.com/golang/go/compare/go1.21.2...go1.21.3
From the security mailing:
[security] Go 1.21.3 and Go 1.20.10 are released
Hello gophers,
We have just released Go versions 1.21.3 and 1.20.10, minor point releases.
These minor releases include 1 security fixes following the security policy:
- net/http: rapid stream resets can cause excessive work
A malicious HTTP/2 client which rapidly creates requests and
immediately resets them can cause excessive server resource consumption.
While the total number of requests is bounded to the
http2.Server.MaxConcurrentStreams setting, resetting an in-progress
request allows the attacker to create a new request while the existing
one is still executing.
HTTP/2 servers now bound the number of simultaneously executing
handler goroutines to the stream concurrency limit. New requests
arriving when at the limit (which can only happen after the client
has reset an existing, in-flight request) will be queued until a
handler exits. If the request queue grows too large, the server
will terminate the connection.
This issue is also fixed in golang.org/x/net/http2 v0.17.0,
for users manually configuring HTTP/2.
The default stream concurrency limit is 250 streams (requests)
per HTTP/2 connection. This value may be adjusted using the
golang.org/x/net/http2 package; see the Server.MaxConcurrentStreams
setting and the ConfigureServer function.
This is CVE-2023-39325 and Go issue https://go.dev/issue/63417.
This is also tracked by CVE-2023-44487.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
go1.21.2 (released 2023-10-05) includes one security fixes to the cmd/go package,
as well as bug fixes to the compiler, the go command, the linker, the runtime,
and the runtime/metrics package. See the Go 1.21.2 milestone on our issue
tracker for details:
https://github.com/golang/go/issues?q=milestone%3AGo1.21.2+label%3ACherryPickApproved
full diff: https://github.com/golang/go/compare/go1.21.1...go1.21.2
From the security mailing:
[security] Go 1.21.2 and Go 1.20.9 are released
Hello gophers,
We have just released Go versions 1.21.2 and 1.20.9, minor point releases.
These minor releases include 1 security fixes following the security policy:
- cmd/go: line directives allows arbitrary execution during build
"//line" directives can be used to bypass the restrictions on "//go:cgo_"
directives, allowing blocked linker and compiler flags to be passed during
compliation. This can result in unexpected execution of arbitrary code when
running "go build". The line directive requires the absolute path of the file in
which the directive lives, which makes exploting this issue significantly more
complex.
This is CVE-2023-39323 and Go issue https://go.dev/issue/63211.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Both pigz and igzip can be disabled via the environment variables.
If disabled, calling exec.LookPath and logging "not found" message is,
even in the debug level, doesn't make much sense.
Signed-off-by: Kazuyoshi Kato <kaz@fly.io>
Intel ISA-L is Intel's open source (BSD) library that outperforms both
gzip and pigz. This commit checks and uses igzip if available.
Signed-off-by: Kazuyoshi Kato <kaz@fly.io>
Windows Containers have a default path already configured at bootup. WithDefaultPathEnv overwrites this with a unix path
Signed-off-by: charitykathure <kathurecharity505@gmail.com>
Windows Containers have a default path already configured at bootup. WithDefaultPathEnv overwrites this with a unix path
Signed-off-by: charitykathure <kathurecharity505@gmail.com>
`MountedFrom` was prefixed with the whole target repository instead of
just the registry hostname.
Also adjust the test cases to use the registry hostname.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
Pass the passed in context into some nested function calls, wrap
errors instead of %+v, and change some tests to strictly just test
for an error and not an exact error.
Signed-off-by: Danny Canter <danny@dcantah.dev>
This silences govulncheck detecting
https://pkg.go.dev/vuln/GO-2023-1988.
containerd does not directly use x/net
Signed-off-by: Kern Walster <walster@amazon.com>
When a endpoint is configured for http and has a tls configuration,
always try to the tls connection and fallback to http when the tls
connections fails from receiving an http response. This fixes an issue
with default localhost endpoints which get defaulted to http with
insecure tls also configured but are using tls.
Signed-off-by: Derek McGowan <derek@mcg.dev>
