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Give more information why we fork & exec, pointed out by kurtm.

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Florian Obser 2023-02-19 11:17:28 +01:00
parent 76dedab468
commit f1fbf312bd
1 changed files with 7 additions and 4 deletions
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@ -427,10 +427,13 @@ flags =-E= and =-F= control if the child process runs as /frontend/ or
execvp(argv0, argv);
#+end_src
Using fork & exec ensures that the child processes get a different
memory layout. If there is an information leak in one process it
cannot be used by an attacker to find gadgets in a different,
potentially more privileged process.
We used to only fork child processes, which is good enough for
privilege separation. [[https://github.com/openbsd/src/commit/13ff36d2c36132325d9cc409c0621ef948f1e2e3][It then occurred to us that the child process
will have the same memory layout and use the same stack protector
cookies.]] Using fork & exec ensures that the child processes get a
different memory layout. If there is an information leak in one
process it cannot be used by an attacker to find gadgets in a
different, potentially more privileged process.
Going back to the main function, [[https://github.com/openbsd/src/blob/3c46ceeaef274bbef234dac63245c4b6567168d7/sbin/dhcpleased/dhcpleased.c#L200][after option parsing]] we know if we
are still in the parent process or in /engine/ or /frontend/ process: