[systemd-devel] [PATCH] Do not cache use_smack() value unless /sys is mounted

[Łukasz Stelmach]

It was <2014-03-11 wto 05:12>, when Lennart Poettering wrote:
> On Fri, 28.02.14 17:09, Łukasz Stelmach (l.stelmach at samsung.com) wrote:
>
>> use_smack() is called very early via mkdir_p_label(). This happens
>> before /sys is mounted and hence before the authoritative information
>> about smack is even available. To prevent caching of the invalid value
>> check whether /sys/fs exists.
>
> Hmm, it appears to me that we probably shouldn't invoke mkdir_p_label()
> that early? Do you know which invocation this is?

mount_one() called from mount_setup_early() at src/core/mount-setup.c

> It sounds really wrong trying to relabel a dir before the policy is
> actually loaded...

mount_one() is used for both mount_setup() and mount_setup_early() and
distinguishing them would look odd.

>
>> ---
>>  src/shared/smack-util.c |    3 +++
>>  1 file changed, 3 insertions(+)
>> 
>> diff --git a/src/shared/smack-util.c b/src/shared/smack-util.c
>> index df194e0..96f365c 100644
>> --- a/src/shared/smack-util.c
>> +++ b/src/shared/smack-util.c
>> @@ -33,6 +33,9 @@ bool use_smack(void) {
>>  #ifdef HAVE_SMACK
>>          static int use_smack_cached = -1;
>>  
>> +        if (use_smack_cached < 0 && access("/sys/fs/", F_OK) < 0)
>> +                return false;
>> +
>>          if (use_smack_cached < 0)
>>                  use_smack_cached = access("/sys/fs/smackfs/", F_OK) >= 0;
>>  
>
>
> Lennart

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics
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