Hi Stefan,
I think we are somewhat talking different directions here... ;-)
Yes, tcsd should only be started as root and change to tss:tss to access
/dev/tpm0 /etc/tcsd.conf and /var/lib/tpm/system.data (or what it's called).
This should be packaged and not changed.
Even with your (fixed) patch, starting tcsd will not succeed starting, because
/var/lib/tpm/system.data shall not be readable only be user/group tss:tss.
Otherwise your package is broken...
So if you want to create a development environment for tpm-emulator-use, I
recommend:
- compile trousers with --disable-usercheck and --prefix=/path/to/your/env
- compile tpmd with a prefix to /path/to/your/env (so it also does not access
/var/lib/tpm for persistend data and socket anymore) (p.s. don't know if
patches for this are upstream or not)
- select tpmd's tddl in your tcsd.conf in order to avoid having to load
tpmd_dev kernel-module...
Then start your devel-tcsd, which will now not try to setuid anymore and use a
different tcsd.conf and system.data from your env-prefix. So you are completely
contained inside your development-environment... :-)
Feel free to contact me if things don't work as expected. I have some setups of
this kind for development here. Maybe I can help...
Cheers,
Andreas
________________________________
From: Stefan Berger [[email protected]]
Sent: Tuesday, November 18, 2014 14:59
To: Fuchs, Andreas
Cc: Stefan Berger; [email protected]
Subject: Re: [TrouSerS-tech] [PATCH] Allow to run tcsd as normal user
"Fuchs, Andreas" <[email protected]> wrote on 11/18/2014 07:48:21
AM:
>
> Hi Stefan,
>
> how does your use case differ in functionality from the --disable-
> usercheck configure switch ?
The tcsd daemon using /dev/tpm0 has to be started as root. It should also
change to a non-privileged user, here tss. No changes in this case.
So in the (intended) use case a non-privileged user can then also start tcsd
using sockets to talk to an emulator.
> (see the #ifdef NOUSERCHECK right before your code additions)
> I think the use case is better covered by the configure-switch,
> since in a standard-environment you want to be warned / failed when
> there is uid-problems. And for your (and my) dev-envs we can have a
> second tssd-executable...
Packages only get compiled in one way. On Fedora at least the part checking the
access rights to the config file and the setuid() part are always compiled in
and that's good this way.
>
> Regarding the code: It seems as if you skip whenever getuid() == 0
> Isn't that reverse to what you described in the commit message ?
My bad. Will repost.
Stefan
>
> Just my 2 cents on things,
>
> Cheers,
> Andreas
>
> ________________________________________
> From: Stefan Berger [[email protected]]
> Sent: Tuesday, November 18, 2014 13:28
> To: [email protected]
> Subject: [TrouSerS-tech] [PATCH] Allow to run tcsd as normal user
>
> Currently TCSD requires that it is run by root or the tss user sinceonly then
> it will be able to setuid to tss or read the TCSD configuration
> file, which must
> also be owned by tss:tss. However, there are use cases when TCSD does not need
> to be started as root, particularly when it communicates with a TPM emulator
> over sockets. In this case we should be able to start the TCSD from a
> non-privileged user account.
>
> Signed-off-by: Stefan Berger <[email protected]>
> ---
> src/tcsd/svrside.c | 4 ++++
> src/tcsd/tcsd_conf.c | 5 +++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/src/tcsd/svrside.c b/src/tcsd/svrside.c
> index 1ae1636..f00ff38 100644
> --- a/src/tcsd/svrside.c
> +++ b/src/tcsd/svrside.c
> @@ -463,6 +463,9 @@ main(int argc, char **argv)
> "(Compiled with --disable-usercheck)");
> #else
> #ifndef SOLARIS
> + if (getuid() == 0)
> + goto skip_setuid;
> +
> pwd = getpwnam(TSS_USER_NAME);
> if (pwd == NULL) {
> if (errno == 0) {
> @@ -474,6 +477,7 @@ main(int argc, char **argv)
> return TCSERR(TSS_E_INTERNAL_ERROR);
> }
> setuid(pwd->pw_uid);
> + skip_setuid:
> #endif
> #endif
>
> diff --git a/src/tcsd/tcsd_conf.c b/src/tcsd/tcsd_conf.c
> index a31503d..549c2bb 100644
> --- a/src/tcsd/tcsd_conf.c
> +++ b/src/tcsd/tcsd_conf.c
> @@ -772,6 +772,9 @@ conf_file_init(struct tcsd_config *conf)
>
> #ifndef NOUSERCHECK
> #ifndef SOLARIS
> + if (getuid() == 0)
> + goto skip_tss_check;
> +
> /* find the gid that owns the conf file */
> errno = 0;
> grp = getgrnam(TSS_GROUP_NAME);
> @@ -809,6 +812,8 @@ conf_file_init(struct tcsd_config *conf)
> LogError("TCSD config file (%s) must be mode 0600",
> tcsd_config_file);
> return TCSERR(TSS_E_INTERNAL_ERROR);
> }
> +
> + skip_tss_check:
> #endif /* SOLARIS */
> #endif /* NOUSERCHECK */
>
> --
> 1.9.3
>
>
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