On Wed, Sep 26, 2018, 4:35 PM Casey Schaufler <[email protected]> wrote:
> From: Casey Schaufler <[email protected]> > > A ptrace access check with mode PTRACE_MODE_SCHED gets called > from process switching code. This precludes the use of audit or avc, > as the locking is incompatible. The only available check that > can be made without using avc is a comparison of the secids. > This is not very satisfactory as it will indicate possible > vulnerabilies much too aggressively. > We already have a flag to disable audit. What locking conflict is presented by the avc, which uses rcu? > Signed-off-by: Casey Schaufler <[email protected]> > --- > security/selinux/hooks.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index ad9a9b8e9979..160239791007 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -2267,6 +2267,8 @@ static int selinux_ptrace_access_check(struct > task_struct *child, > u32 sid = current_sid(); > u32 csid = task_sid(child); > > + if (mode & PTRACE_MODE_SCHED) > + return sid == csid ? 0 : -EACCES; > if (mode & PTRACE_MODE_READ) > return avc_has_perm(&selinux_state, > sid, csid, SECCLASS_FILE, FILE__READ, > NULL); > -- > 2.17.1 > >
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