Date: Fri, 12 Jan 2018 23:37:51 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Mark Johnston <markj@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r327888 - in head: cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/safety cddl/contrib/opensolaris/lib/libdtrace/common cddl/usr.sbin/dtrace/tests/common/safety sys/cddl/contrib/ope... Message-ID: <CAGudoHHQGT_S5LS6QLMLbmGY2XZ1cCGHMi1-x3U7%2Bpkg3_=JVQ@mail.gmail.com> In-Reply-To: <201801121959.w0CJxlaw010074@repo.freebsd.org> References: <201801121959.w0CJxlaw010074@repo.freebsd.org>
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On Fri, Jan 12, 2018 at 8:59 PM, Mark Johnston <markj@freebsd.org> wrote: > Modified: head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c > ============================================================ > ================== > --- head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c > Fri Jan 12 18:44:28 2018 (r327887) > +++ head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c > Fri Jan 12 19:59:46 2018 (r327888) > @@ -3654,6 +3654,24 @@ dtrace_dif_variable(dtrace_mstate_t *mstate, > dtrace_st > return (dtrace_dif_varstr( > (uintptr_t)curthread->t_procp->p_zone->zone_name, > state, mstate)); > +#elif defined(__FreeBSD__) > + /* > + * On FreeBSD, we introduce compatibility to zonename by falling > through > + * into jailname. > + */ > + case DIF_VAR_JAILNAME: > + if (!dtrace_priv_kernel(state)) > + return (0); > + > + return (dtrace_dif_varstr( > + (uintptr_t)curthread->t_procp- > >p_ucred->cr_prison->pr_name, > + state, mstate)); > + > Why t_procp? curthread->td_proc creds are what is used for permission checking and it rarely temporarily goes out of sync with proc's creds. However, if someone changes creds while this tracing is enabled this extra dereference risks accessing a freed object. On the other hand curthread creads are always safe to read. > + case DIF_VAR_JID: > + if (!dtrace_priv_kernel(state)) > + return (0); > + > + return ((uint64_t)curthread->t_procp- > >p_ucred->cr_prison->pr_id); > #else > return (0); > #endif >
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