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Message-ID: <CAHse=S_32tmusk4ceY4U6GbNpX4PkX12iPPDZFVZ7qgv-RAooA@mail.gmail.com> Date: Thu, 17 Jul 2014 16:04:56 +0100 From: David Drysdale <drysdale@...gle.com> To: Kees Cook <keescook@...omium.org> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andy Lutomirski <luto@...capital.net>, Oleg Nesterov <oleg@...hat.com>, James Morris <jmorris@...ei.org>, "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>, Alexei Starovoitov <ast@...mgrid.com>, Andrew Morton <akpm@...ux-foundation.org>, Daniel Borkmann <dborkman@...hat.com>, Will Drewry <wad@...omium.org>, Julien Tinnes <jln@...omium.org>, Linux API <linux-api@...r.kernel.org>, x86@...nel.org, linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org, linux-arch@...r.kernel.org, LSM List <linux-security-module@...r.kernel.org> Subject: Re: [PATCH v11 11/11] seccomp: implement SECCOMP_FILTER_FLAG_TSYNC On Wed, Jul 16, 2014 at 10:50 PM, Kees Cook <keescook@...omium.org> wrote: > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > index 9065d2c79c56..2125b83ccfd4 100644 > +/** > + * seccomp_can_sync_threads: checks if all threads can be synchronized > + * > + * Expects sighand and cred_guard_mutex locks to be held. > + * > + * Returns 0 on success, -ve on error, or the pid of a thread which was > + * either not in the correct seccomp mode or it did not have an ancestral > + * seccomp filter. > + */ > +static inline pid_t seccomp_can_sync_threads(void) > +{ > + struct task_struct *thread, *caller; > + > + BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); > + BUG_ON(!spin_is_locked(¤t->sighand->siglock)); > + > + if (current->seccomp.mode != SECCOMP_MODE_FILTER) > + return -EACCES; Quick question -- is it possible to apply the first filter and also synchronize it across threads in the same operation? If so, does this arm also need to cope with seccomp.mode being SECCOMP_MODE_DISABLED? [seccomp_set_mode_filter() looks to call this via seccomp_attach_filter() before it does seccomp_assign_mode()] > + > + /* Validate all threads being eligible for synchronization. */ > + caller = current; > + for_each_thread(caller, thread) { > + pid_t failed; > + > + if (thread->seccomp.mode == SECCOMP_MODE_DISABLED || > + (thread->seccomp.mode == SECCOMP_MODE_FILTER && > + is_ancestor(thread->seccomp.filter, > + caller->seccomp.filter))) > + continue; > + > + /* Return the first thread that cannot be synchronized. */ > + failed = task_pid_vnr(thread); > + /* If the pid cannot be resolved, then return -ESRCH */ > + if (unlikely(WARN_ON(failed == 0))) > + failed = -ESRCH; > + return failed; > + } > + > + return 0; > +} -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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