Upstart jobs as appropriate. I.e., if a job exists in the old but
not the new configuration, stop it; if it exists in the new but not
the old, start it; and most interesting, if it exists in both but
its store paths differ, restart it. So the purely functional model
combined cryptographic hashing allows us to precisely identify how
two configurations differ from each other
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installation to prevent horrible accidents.
* Add the kernel parameters to isolinux.cfg.
* Use useradd/groupadd to create users/groups; use Glibc's getent to
check for existence.
* Create the root account properly.
svn path=/nixos/trunk/; revision=7357
at boot time into a separate script. This will allow us to change
the configuration without rebooting (provided that the configuration
doesn't have a different kernel, init, etc.).
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except for the fonts, which are still hardcoded. The current
configuration uses the VESA driver, which should work on most
machines. Of course, the configuration should now be generated from
a higher-level specification.
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program.
The Nix store cannot directly support setuid binaries for a number
of reasons:
- Builds are generally not performed as root (and they shouldn't
be), so the builder cannot chown/chmod executables to the right
setuid ownership.
- Unpacking a NAR archive containing a setuid binary would only work
when Nix is run as root.
- Worst of all, setuid binaries don't fit in the purely functional
model: if a security bug is discovered in a setuid binary, that
binary should be removed from the system to prevent users from
calling it. But we cannot garbage collect it unless all
references to it are gone, which might never happen. Of course,
we could just remove setuid permission, but that would also be
impure.
So the solution is to keep setuid-ness out of the Nix store.
Rather, for programs that we want to execute as setuid, we generate
wrapper programs (as root) that are setuid and do an execve() to
call the real, non-setuid program in the Nix store.
That's what setuid-wrapper does. It determines its own name (e.g.,
/var/setuid-wrappers/passwd), reads the name of the wrapped program
from <self>.real (e.g., /var/setuid-wrappers/passwd.real, which
might contain /nix/var/nix/profiles/system/bin/passwd), and executes
it. Thus, the non-setuid passwd in the Nix store would be executed
with the effective user set to root.
Setuid-wrapper also performs a few security checks to prevent it
from reading a fake <self>.real file through hard-linking tricks.
svn path=/nixos/trunk/; revision=7157
