selinux: verify that writes to /proc/... are on procfs #59
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cyphar
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LGTM |
This is an additional mitigation for CVE-2019-16884. The primary problem is that Docker can be coerced into bind-mounting a file system on top of /proc (resulting in label-related writes to /proc no longer happening). While runc is working on mitigations against permitting the mounts, this helps avoid go-selinux from being tricked into writing to non-procfs files. This is not a perfect solution (after all, there might be a bind-mount of a different procfs file over the target) but in order to exploit that you would need to be able to tweak a config.json pretty specifically (which thankfully Docker doesn't allow). Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
cyphar
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I changed the error message formatting to match the updated runc PR. /cc @opencontainers/selinux-maintainers |
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LGTM |
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This is an additional mitigation for CVE-2019-16884. The primary problem
is that Docker can be coerced into bind-mounting a file system on top of
/proc (resulting in label-related writes to /proc no longer happening).
While runc is working on mitigations against permitting the mounts, this
helps avoid go-selinux from being tricked into writing to non-procfs
files. This is not a perfect solution (after all, there might be a
bind-mount of a different procfs file over the target) but in order to
exploit that you would need to be able to tweak a config.json pretty
specifically (which thankfully Docker doesn't allow).
See opencontainers/runc#2128
Signed-off-by: Aleksa Sarai cyphar@cyphar.com