Match VT device paths to be blocked from mounting exactly #17104
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Looks good to me: |
mheon
reviewed
Jan 13, 2023
rhatdan
reviewed
Jan 18, 2023
As @mheon pointed out in PR containers#17055[^1], isVirtualConsoleDevice() does not only matches VT device paths but also devices named like /dev/tty0abcd. This causes that non VT device paths named /dev/tty[0-9]+[A-Za-z]+ are not mounted into privileged container and systemd containers accidentally. This is an unlikely issue because the Linux kernel does not use device paths like that. To make it failproof and prevent issues in unlikely scenarios, change isVirtualConsoleDevice() to exactly match ^/dev/tty[0-9]+$ paths. Because it is not possible to match this path exactly with Glob syntax, the path is now checked with strings.TrimPrefix() and strconv.ParseUint(). ParseUint uses a bitsize of 16, this is sufficient because the max number of TTY devices is 512 in Linux 6.1.5. (Checked via 'git grep -e '#define' --and -e 'TTY_MINORS'). The commit also adds a unit-test for isVirtualConsoleDevice(). Fixes: f4c81b0 ("Only prevent VTs to be mounted inside...") [^1]: containers#17055 (comment) Signed-off-by: Fabian Holler <mail@fholler.de>
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CI errors look unrelated: |
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LGTM |
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/lgtm |
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/approve |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: fho, mupuf, rhatdan The full list of commands accepted by this bot can be found here. The pull request process is described here
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Could you rebase this PR, it does not seem to be getting beyond the podman build tests. |
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already merged via #17265 |
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Thanks @fho for the PR. |
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locked - please file new issue/PR
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As @mheon pointed out in PR #170551, isVirtualConsoleDevice() does not only matches VT device paths but also devices named like /dev/tty0abcd.
This causes that non VT device paths named /dev/tty[0-9]+[A-Za-z]+ are not mounted into privileged container and systemd containers accidentally.
This is an unlikely issue because the Linux kernel does not use device paths like that.
To make it failproof and prevent issues in unlikely scenarios, change isVirtualConsoleDevice() to exactly match ^/dev/tty[0-9]+$ paths.
Because it is not possible to match this path exactly with Glob syntax, the path is now checked with strings.TrimPrefix() and strconv.ParseUint().
ParseUint uses a bitsize of 16, this is sufficient because the max number of TTY devices is 512 in Linux 6.1.5.
(Checked via 'git grep -e '#define' --and -e 'TTY_MINORS').
The commit also adds a unit-test for isVirtualConsoleDevice().
Fixes: f4c81b0 ("Only prevent VTs to be mounted inside...")
Signed-off-by: Fabian Holler mail@fholler.de
Does this PR introduce a user-facing change?
Footnotes
https://github.com/containers/podman/pull/17055#issuecomment-1378904068 ↩