Re: [PATCH v18 01/15] Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execvefrom granting privs
From: Andrew Lutomirski
Date: Fri Apr 13 2012 - 00:26:04 EST
On Thu, Apr 12, 2012 at 9:16 PM, James Morris <jmorris@xxxxxxxxx> wrote:
> On Thu, 12 Apr 2012, Will Drewry wrote:
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index d85b793..0b06685 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -2016,6 +2016,13 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
>> new_tsec->sid = old_tsec->exec_sid;
>> /* Reset exec SID on execve. */
>> new_tsec->exec_sid = 0;
>> +
>> + /*
>> + * Minimize confusion: if no_new_privs and a transition is
>> + * explicitly requested, then fail the exec.
>> + */
>> + if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)
>> + return -EPERM;
>> } else {
>> /* Check for a default transition on this program. */
>> rc = security_transition_sid(old_tsec->sid, isec->sid,
>> @@ -2029,7 +2036,8 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
>> ad.selinux_audit_data = &sad;
>> ad.u.path = bprm->file->f_path;
>>
>> - if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
>> + if ((bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) ||
>> + (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS))
>> new_tsec->sid = old_tsec->sid;
>>
>> if (new_tsec->sid == old_tsec->sid) {
>> --
>
> What about dynamic transitions in SELinux ?
>
What's a dynamic transition?
--Andy
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