Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
On Thu, 4 Oct 2018, Jann Horn wrote: > > Well, we can't really call out into audit from scheduler code, and the > > previous versions of the patchsets didn't have PTRACE_MODE_SCHED, so it > > had to be included in PTRACE_MODE_IBPB in order to make sure we're not > > calling into audit from context switch code. > > > > Or did I misunderstand the question? > > If I understand Casey correctly, he is saying that your patch > (https://lore.kernel.org/lkml/nycvar.yfh.7.76.1809251437340.15...@cbobk.fhfr.pm/) > doesn't include PTRACE_MODE_NOAUDIT for IBPB, but the previous v6 of > your patch > (https://lore.kernel.org/lkml/nycvar.yfh.7.76.1809121105330.15...@cbobk.fhfr.pm/) > did include it, and therefore Casey thinks that there is a specific > reason why you removed PTRACE_MODE_NOAUDIT, Quite honestly, I don't remember. I dont't think there is any deadlock that'd be triggered by this. > and therefore Casey is adding special-case logic for PTRACE_MODE_SCHED > to Smack when simply using PTRACE_MODE_NOAUDIT would also work. > > I think that Casey should change ptrace_may_access_sched() to use > "mode | PTRACE_MODE_SCHED | PTRACE_MODE_NOAUDIT". Agreed, that should work. Thanks, -- Jiri Kosina SUSE Labs ___ Selinux mailing list Selinux@tycho.nsa.gov To unsubscribe, send email to selinux-le...@tycho.nsa.gov. To get help, send an email containing "help" to selinux-requ...@tycho.nsa.gov.
Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
On Thu, 27 Sep 2018, Jann Horn wrote: > > Yes. Since the PTRACE_MODE_NOAUDIT was in PTRACE_MODE_IBPB in Jiri's > > previous patch set and not in PTRACE_MODE_SCHED in this one I assumed > > that there was a good reason for it. > > Jiri, was there a good reason for it, and if so, what was it? [ FWIW PTRACE_MODE_NOAUDIT being in PTRACE_MODE_IBPB goes back to original Tim's pre-CRD patchset ] Well, we can't really call out into audit from scheduler code, and the previous versions of the patchsets didn't have PTRACE_MODE_SCHED, so it had to be included in PTRACE_MODE_IBPB in order to make sure we're not calling into audit from context switch code. Or did I misunderstand the question? Thanks, -- Jiri Kosina SUSE Labs ___ Selinux mailing list Selinux@tycho.nsa.gov To unsubscribe, send email to selinux-le...@tycho.nsa.gov. To get help, send an email containing "help" to selinux-requ...@tycho.nsa.gov.
Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
On Thu, Oct 4, 2018 at 9:47 AM Jiri Kosina wrote: > On Thu, 27 Sep 2018, Jann Horn wrote: > > > Yes. Since the PTRACE_MODE_NOAUDIT was in PTRACE_MODE_IBPB in Jiri's > > > previous patch set and not in PTRACE_MODE_SCHED in this one I assumed > > > that there was a good reason for it. > > > > Jiri, was there a good reason for it, and if so, what was it? > > [ FWIW PTRACE_MODE_NOAUDIT being in PTRACE_MODE_IBPB goes back to original > Tim's pre-CRD patchset ] > > Well, we can't really call out into audit from scheduler code, and the > previous versions of the patchsets didn't have PTRACE_MODE_SCHED, so it > had to be included in PTRACE_MODE_IBPB in order to make sure we're not > calling into audit from context switch code. > > Or did I misunderstand the question? If I understand Casey correctly, he is saying that your patch (https://lore.kernel.org/lkml/nycvar.yfh.7.76.1809251437340.15...@cbobk.fhfr.pm/) doesn't include PTRACE_MODE_NOAUDIT for IBPB, but the previous v6 of your patch (https://lore.kernel.org/lkml/nycvar.yfh.7.76.1809121105330.15...@cbobk.fhfr.pm/) did include it, and therefore Casey thinks that there is a specific reason why you removed PTRACE_MODE_NOAUDIT, and therefore Casey is adding special-case logic for PTRACE_MODE_SCHED to Smack when simply using PTRACE_MODE_NOAUDIT would also work. I think that Casey should change ptrace_may_access_sched() to use "mode | PTRACE_MODE_SCHED | PTRACE_MODE_NOAUDIT". ___ Selinux mailing list Selinux@tycho.nsa.gov To unsubscribe, send email to selinux-le...@tycho.nsa.gov. To get help, send an email containing "help" to selinux-requ...@tycho.nsa.gov.
Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
On Wed, Sep 26, 2018 at 10:35 PM Casey Schaufler
wrote:
> A ptrace access check with mode PTRACE_MODE_SCHED gets called
> from process switching code. This precludes the use of audit,
> as the locking is incompatible. Don't do audit in the PTRACE_MODE_SCHED
> case.
>
> Signed-off-by: Casey Schaufler
> ---
> security/smack/smack_lsm.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 340fc30ad85d..ffa95bcab599 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -422,7 +422,8 @@ static int smk_ptrace_rule_check(struct task_struct
> *tracer,
> struct task_smack *tsp;
> struct smack_known *tracer_known;
>
> - if ((mode & PTRACE_MODE_NOAUDIT) == 0) {
> + if ((mode & PTRACE_MODE_NOAUDIT) == 0 &&
> + (mode & PTRACE_MODE_SCHED) == 0) {
If you ORed PTRACE_MODE_NOAUDIT into the flags when calling the
security hook, you could drop this patch, right?
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RE: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
> -Original Message-
> From: Jann Horn [mailto:ja...@google.com]
> Sent: Wednesday, September 26, 2018 2:31 PM
> To: Schaufler, Casey
> Cc: Kernel Hardening ; kernel list
> ; linux-security-module mod...@vger.kernel.org>; selinux@tycho.nsa.gov; Hansen, Dave
> ; Dock, Deneen T ;
> kris...@linux.intel.com; Arjan van de Ven
> Subject: Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
>
> On Wed, Sep 26, 2018 at 10:35 PM Casey Schaufler
> wrote:
> > A ptrace access check with mode PTRACE_MODE_SCHED gets called
> > from process switching code. This precludes the use of audit,
> > as the locking is incompatible. Don't do audit in the PTRACE_MODE_SCHED
> > case.
> >
> > Signed-off-by: Casey Schaufler
> > ---
> > security/smack/smack_lsm.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> > index 340fc30ad85d..ffa95bcab599 100644
> > --- a/security/smack/smack_lsm.c
> > +++ b/security/smack/smack_lsm.c
> > @@ -422,7 +422,8 @@ static int smk_ptrace_rule_check(struct task_struct
> *tracer,
> > struct task_smack *tsp;
> > struct smack_known *tracer_known;
> >
> > - if ((mode & PTRACE_MODE_NOAUDIT) == 0) {
> > + if ((mode & PTRACE_MODE_NOAUDIT) == 0 &&
> > + (mode & PTRACE_MODE_SCHED) == 0) {
>
> If you ORed PTRACE_MODE_NOAUDIT into the flags when calling the
> security hook, you could drop this patch, right?
Yes. Since the PTRACE_MODE_NOAUDIT was in PTRACE_MODE_IBPB
in Jiri's previous patch set and not in PTRACE_MODE_SCHED in this one
I assumed that there was a good reason for it.
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Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
+Jiri
On Thu, Sep 27, 2018 at 12:54 AM Schaufler, Casey
wrote:
> > -Original Message-
> > From: Jann Horn [mailto:ja...@google.com]
> > Sent: Wednesday, September 26, 2018 2:31 PM
> > To: Schaufler, Casey
> > Cc: Kernel Hardening ; kernel list
> > ; linux-security-module > mod...@vger.kernel.org>; selinux@tycho.nsa.gov; Hansen, Dave
> > ; Dock, Deneen T ;
> > kris...@linux.intel.com; Arjan van de Ven
> > Subject: Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
> >
> > On Wed, Sep 26, 2018 at 10:35 PM Casey Schaufler
> > wrote:
> > > A ptrace access check with mode PTRACE_MODE_SCHED gets called
> > > from process switching code. This precludes the use of audit,
> > > as the locking is incompatible. Don't do audit in the PTRACE_MODE_SCHED
> > > case.
> > >
> > > Signed-off-by: Casey Schaufler
> > > ---
> > > security/smack/smack_lsm.c | 3 ++-
> > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> > > index 340fc30ad85d..ffa95bcab599 100644
> > > --- a/security/smack/smack_lsm.c
> > > +++ b/security/smack/smack_lsm.c
> > > @@ -422,7 +422,8 @@ static int smk_ptrace_rule_check(struct task_struct
> > *tracer,
> > > struct task_smack *tsp;
> > > struct smack_known *tracer_known;
> > >
> > > - if ((mode & PTRACE_MODE_NOAUDIT) == 0) {
> > > + if ((mode & PTRACE_MODE_NOAUDIT) == 0 &&
> > > + (mode & PTRACE_MODE_SCHED) == 0) {
> >
> > If you ORed PTRACE_MODE_NOAUDIT into the flags when calling the
> > security hook, you could drop this patch, right?
>
> Yes. Since the PTRACE_MODE_NOAUDIT was in PTRACE_MODE_IBPB
> in Jiri's previous patch set and not in PTRACE_MODE_SCHED in this one
> I assumed that there was a good reason for it.
Jiri, was there a good reason for it, and if so, what was it?
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[PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED
From: Casey Schaufler
A ptrace access check with mode PTRACE_MODE_SCHED gets called
from process switching code. This precludes the use of audit,
as the locking is incompatible. Don't do audit in the PTRACE_MODE_SCHED
case.
Signed-off-by: Casey Schaufler
---
security/smack/smack_lsm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 340fc30ad85d..ffa95bcab599 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -422,7 +422,8 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
struct task_smack *tsp;
struct smack_known *tracer_known;
- if ((mode & PTRACE_MODE_NOAUDIT) == 0) {
+ if ((mode & PTRACE_MODE_NOAUDIT) == 0 &&
+ (mode & PTRACE_MODE_SCHED) == 0) {
smk_ad_init(, func, LSM_AUDIT_DATA_TASK);
smk_ad_setfield_u_tsk(, tracer);
saip =
--
2.17.1
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