[GH-ISSUE #2931] --seccomp= unknown syscall names/numbers are silently ignored #1829

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opened 2026-05-05 08:29:48 -06:00 by gitea-mirror · 1 comment
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Originally created by @aoand on GitHub (Aug 26, 2019).
Original GitHub issue: https://github.com/netblue30/firejail/issues/2931

If a bogus (unknown) syscall name/number/group-name is supplied to --seccomp=, then it is silently ignored. No warning is printed even with --debug.

This is bad, because a misspelled syscall will not be disabled in the jail, potentially creating a vulnerability. It would be better, if firejail would reject a wrong name/number and refuse to start.

On a related note: why '$' is needed to denote a numeric syscall? If syscall "name" is all numeric, then it is definitely the syscall number, so '$' seems to be redundant.

firejail version: 0.9.56.2-LTS
OS: Ubuntu 16.04.6 LTS

Originally created by @aoand on GitHub (Aug 26, 2019). Original GitHub issue: https://github.com/netblue30/firejail/issues/2931 If a bogus (unknown) syscall name/number/group-name is supplied to --seccomp=, then it is silently ignored. No warning is printed even with --debug. This is bad, because a misspelled syscall will not be disabled in the jail, potentially creating a vulnerability. It would be better, if firejail would reject a wrong name/number and refuse to start. On a related note: why '$' is needed to denote a numeric syscall? If syscall "name" is all numeric, then it is definitely the syscall number, so '$' seems to be redundant. firejail version: 0.9.56.2-LTS OS: Ubuntu 16.04.6 LTS
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labels 2026-05-05 08:29:48 -06:00
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@netblue30 commented on GitHub (Aug 28, 2019):

The fix is on mainline. I'll leave the bug open until we merge it on LTS branch. Thanks.

<!-- gh-comment-id:525793391 --> @netblue30 commented on GitHub (Aug 28, 2019): The fix is on mainline. I'll leave the bug open until we merge it on LTS branch. Thanks.
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Reference: github-starred/firejail#1829
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