mirror of
https://github.com/HackTricks-wiki/hacktricks.git
synced 2025-10-10 18:36:50 +00:00
Translated ['src/linux-hardening/privilege-escalation/docker-security/na
This commit is contained in:
parent
965e85e0af
commit
d0c7e60807
@ -4,7 +4,7 @@
|
||||
|
||||
## Basic Information
|
||||
|
||||
Namespace ya muda katika Linux inaruhusu offsets za kila namespace kwa saa za mfumo zisizobadilika na saa za kuanzisha. Inatumika sana katika kontena za Linux kubadilisha tarehe/saa ndani ya kontena na kurekebisha saa baada ya kurejesha kutoka kwa alama ya ukaguzi au picha.
|
||||
Namespace ya muda katika Linux inaruhusu offsets za kila namespace kwa saa za mfumo zisizobadilika na saa za kuanzisha. Inatumika sana katika kontena za Linux kubadilisha tarehe/saa ndani ya kontena na kurekebisha saa baada ya kurejesha kutoka kwa alama ya kuangalia au picha.
|
||||
|
||||
## Lab:
|
||||
|
||||
@ -14,29 +14,29 @@ Namespace ya muda katika Linux inaruhusu offsets za kila namespace kwa saa za mf
|
||||
```bash
|
||||
sudo unshare -T [--mount-proc] /bin/bash
|
||||
```
|
||||
Kwa kuunganisha mfano mpya wa mfumo wa `/proc` ikiwa unatumia param `--mount-proc`, unahakikisha kwamba namespace mpya ya kuunganisha ina **mtazamo sahihi na wa kutengwa wa taarifa za mchakato maalum kwa namespace hiyo**.
|
||||
Kwa kuunganisha mfano mpya wa mfumo wa `/proc` ikiwa unatumia param `--mount-proc`, unahakikisha kwamba namespace mpya ya kuunganisha ina **mtazamo sahihi na uliojitegemea wa taarifa za mchakato zinazohusiana na namespace hiyo**.
|
||||
|
||||
<details>
|
||||
|
||||
<summary>Hitilafu: bash: fork: Haiwezekani kugawa kumbukumbu</summary>
|
||||
<summary>Kosa: bash: fork: Haiwezekani kugawa kumbukumbu</summary>
|
||||
|
||||
Wakati `unshare` inatekelezwa bila chaguo la `-f`, hitilafu inakutana kutokana na jinsi Linux inavyoshughulikia namespaces mpya za PID (Kitambulisho cha Mchakato). Maelezo muhimu na suluhisho yameelezwa hapa chini:
|
||||
Wakati `unshare` inatekelezwa bila chaguo la `-f`, kosa linakutana kutokana na jinsi Linux inavyoshughulikia namespaces mpya za PID (Kitambulisho cha Mchakato). Maelezo muhimu na suluhisho yameelezwa hapa chini:
|
||||
|
||||
1. **Maelezo ya Tatizo**:
|
||||
|
||||
- Kernel ya Linux inaruhusu mchakato kuunda namespaces mpya kwa kutumia wito wa mfumo wa `unshare`. Hata hivyo, mchakato unaoanzisha uundaji wa namespace mpya ya PID (inayojulikana kama mchakato wa "unshare") hauingii kwenye namespace mpya; ni watoto wake tu wanajumuishwa.
|
||||
- Kernel ya Linux inaruhusu mchakato kuunda namespaces mpya kwa kutumia wito wa mfumo wa `unshare`. Hata hivyo, mchakato unaoanzisha uundaji wa namespace mpya ya PID (inayojulikana kama mchakato wa "unshare") hauingii kwenye namespace mpya; ni watoto wake tu ndio wanaingia.
|
||||
- Kuendesha `%unshare -p /bin/bash%` kunaanzisha `/bin/bash` katika mchakato sawa na `unshare`. Kwa hivyo, `/bin/bash` na watoto wake wako katika namespace ya awali ya PID.
|
||||
- Mchakato wa kwanza wa mtoto wa `/bin/bash` katika namespace mpya unakuwa PID 1. Wakati mchakato huu unapoondoka, unachochea usafishaji wa namespace ikiwa hakuna mchakato mwingine, kwani PID 1 ina jukumu maalum la kupokea mchakato wa yatima. Kernel ya Linux itazima ugawaji wa PID katika namespace hiyo.
|
||||
- Mchakato wa kwanza wa mtoto wa `/bin/bash` katika namespace mpya unakuwa PID 1. Wakati mchakato huu unapoondoka, unachochea usafishaji wa namespace ikiwa hakuna mchakato mwingine, kwani PID 1 ina jukumu maalum la kupokea mchakato yatima. Kernel ya Linux itazima kisha ugawaji wa PID katika namespace hiyo.
|
||||
|
||||
2. **Matokeo**:
|
||||
|
||||
- Kuondoka kwa PID 1 katika namespace mpya kunasababisha usafishaji wa bendera ya `PIDNS_HASH_ADDING`. Hii inasababisha kazi ya `alloc_pid` kushindwa kugawa PID mpya wakati wa kuunda mchakato mpya, ikitoa hitilafu ya "Haiwezekani kugawa kumbukumbu".
|
||||
- Kuondoka kwa PID 1 katika namespace mpya kunasababisha usafishaji wa bendera ya `PIDNS_HASH_ADDING`. Hii inasababisha kazi ya `alloc_pid` kushindwa kugawa PID mpya wakati wa kuunda mchakato mpya, na kutoa kosa la "Haiwezekani kugawa kumbukumbu".
|
||||
|
||||
3. **Suluhisho**:
|
||||
- Tatizo linaweza kutatuliwa kwa kutumia chaguo la `-f` pamoja na `unshare`. Chaguo hili linafanya `unshare` kuunda mchakato mpya baada ya kuunda namespace mpya ya PID.
|
||||
- Kutekeleza `%unshare -fp /bin/bash%` kunahakikisha kwamba amri ya `unshare` yenyewe inakuwa PID 1 katika namespace mpya. `/bin/bash` na watoto wake wanajumuishwa salama ndani ya namespace hii mpya, kuzuia kuondoka mapema kwa PID 1 na kuruhusu ugawaji wa kawaida wa PID.
|
||||
- Kutekeleza `%unshare -fp /bin/bash%` kunahakikisha kwamba amri ya `unshare` yenyewe inakuwa PID 1 katika namespace mpya. `/bin/bash` na watoto wake wanakuwa salama ndani ya namespace hii mpya, kuzuia kuondoka mapema kwa PID 1 na kuruhusu ugawaji wa PID wa kawaida.
|
||||
|
||||
Kwa kuhakikisha kwamba `unshare` inatekelezwa na bendera ya `-f`, namespace mpya ya PID inatunzwa kwa usahihi, ikiruhusu `/bin/bash` na mchakato wake wa chini kufanya kazi bila kukutana na hitilafu ya ugawaji wa kumbukumbu.
|
||||
Kwa kuhakikisha kwamba `unshare` inatekelezwa na bendera ya `-f`, namespace mpya ya PID inatunzwa ipasavyo, ikiruhusu `/bin/bash` na michakato yake ya chini kufanya kazi bila kukutana na kosa la kugawa kumbukumbu.
|
||||
|
||||
</details>
|
||||
|
||||
@ -59,4 +59,82 @@ sudo find /proc -maxdepth 3 -type l -name time -exec ls -l {} \; 2>/dev/null |
|
||||
```bash
|
||||
nsenter -T TARGET_PID --pid /bin/bash
|
||||
```
|
||||
## Manipulating Time Offsets
|
||||
|
||||
Kuanzia Linux 5.6, saa mbili zinaweza kuundwa kwa njia ya muda:
|
||||
|
||||
* `CLOCK_MONOTONIC`
|
||||
* `CLOCK_BOOTTIME`
|
||||
|
||||
Deltas zao za kila namespace zinapatikana (na zinaweza kubadilishwa) kupitia faili `/proc/<PID>/timens_offsets`:
|
||||
```
|
||||
$ sudo unshare -Tr --mount-proc bash # -T creates a new timens, -r drops capabilities
|
||||
$ cat /proc/$$/timens_offsets
|
||||
monotonic 0
|
||||
boottime 0
|
||||
```
|
||||
Faili lina mistari miwili - mmoja kwa kila saa - ukiwa na tofauti katika **nanoseconds**. Mchakato ambao unashikilia **CAP_SYS_TIME** _katika eneo la muda_ unaweza kubadilisha thamani:
|
||||
```
|
||||
# advance CLOCK_MONOTONIC by two days (172 800 s)
|
||||
echo "monotonic 172800000000000" > /proc/$$/timens_offsets
|
||||
# verify
|
||||
$ cat /proc/$$/uptime # first column uses CLOCK_MONOTONIC
|
||||
172801.37 13.57
|
||||
```
|
||||
Ikiwa unahitaji saa ya ukuta (`CLOCK_REALTIME`) ibadilike pia, bado unapaswa kutegemea mitambo ya jadi (`date`, `hwclock`, `chronyd`, …); **sio** yenye majina.
|
||||
|
||||
### `unshare(1)` bendera za msaada (util-linux ≥ 2.38)
|
||||
```
|
||||
sudo unshare -T \
|
||||
--monotonic="+24h" \
|
||||
--boottime="+7d" \
|
||||
--mount-proc \
|
||||
bash
|
||||
```
|
||||
The long options automatically write the chosen deltas to `timens_offsets` right after the namespace is created, saving a manual `echo`.
|
||||
|
||||
---
|
||||
|
||||
## OCI & Runtime support
|
||||
|
||||
* The **OCI Runtime Specification v1.1** (Nov 2023) added a dedicated `time` namespace type and the `linux.timeOffsets` field so that container engines can request time virtualisation in a portable way.
|
||||
* **runc >= 1.2.0** implements that part of the spec. A minimal `config.json` fragment looks like:
|
||||
```json
|
||||
{
|
||||
"linux": {
|
||||
"namespaces": [
|
||||
{"type": "time"}
|
||||
],
|
||||
"timeOffsets": {
|
||||
"monotonic": 86400,
|
||||
"boottime": 600
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
Then run the container with `runc run <id>`.
|
||||
|
||||
> NOTE: runc **1.2.6** (Feb 2025) fixed an "exec into container with private timens" bug that could lead to a hang and potential DoS. Make sure you are on ≥ 1.2.6 in production.
|
||||
|
||||
---
|
||||
|
||||
## Security considerations
|
||||
|
||||
1. **Required capability** – A process needs **CAP_SYS_TIME** inside its user/time namespace to change the offsets. Dropping that capability in the container (default in Docker & Kubernetes) prevents tampering.
|
||||
2. **No wall-clock changes** – Because `CLOCK_REALTIME` is shared with the host, attackers cannot spoof certificate lifetimes, JWT expiry, etc. via timens alone.
|
||||
3. **Log / detection evasion** – Software that relies on `CLOCK_MONOTONIC` (e.g. rate-limiters based on uptime) can be confused if the namespace user adjusts the offset. Prefer `CLOCK_REALTIME` for security-relevant timestamps.
|
||||
4. **Kernel attack surface** – Even with `CAP_SYS_TIME` removed, the kernel code remains accessible; keep the host patched. Linux 5.6 → 5.12 received multiple timens bug-fixes (NULL-deref, signedness issues).
|
||||
|
||||
### Hardening checklist
|
||||
|
||||
* Drop `CAP_SYS_TIME` in your container runtime default profile.
|
||||
* Keep runtimes updated (runc ≥ 1.2.6, crun ≥ 1.12).
|
||||
* Pin util-linux ≥ 2.38 if you rely on the `--monotonic/--boottime` helpers.
|
||||
* Audit in-container software that reads **uptime** or **CLOCK_MONOTONIC** for security-critical logic.
|
||||
|
||||
## References
|
||||
|
||||
* man7.org – Time namespaces manual page: <https://man7.org/linux/man-pages/man7/time_namespaces.7.html>
|
||||
* OCI blog – "OCI v1.1: new time and RDT namespaces" (Nov 15 2023): <https://opencontainers.org/blog/2023/11/15/oci-spec-v1.1>
|
||||
|
||||
{{#include ../../../../banners/hacktricks-training.md}}
|
||||
|
Loading…
x
Reference in New Issue
Block a user