Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751821AbdISUIb (ORCPT ); Tue, 19 Sep 2017 16:08:31 -0400 Received: from mail-io0-f176.google.com ([209.85.223.176]:52741 "EHLO mail-io0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751519AbdISUI3 (ORCPT ); Tue, 19 Sep 2017 16:08:29 -0400 X-Google-Smtp-Source: AOwi7QAJr+l3G1RwLkAgJFU+sImyewSh55vXXgK9Zjimfa18JGxP01NtSAIVMaQ2CPjiDQP/a2f2QI5SHrbg1PdrCPo= MIME-Version: 1.0 In-Reply-To: <20170919174743.19814-1-tycho@docker.com> References: <20170919174743.19814-1-tycho@docker.com> From: Kees Cook Date: Tue, 19 Sep 2017 13:08:28 -0700 X-Google-Sender-Auth: ZDWWLIskNQW5cODgI4QVjkusoNs Message-ID: Subject: Re: [PATCH] ptrace, seccomp: add support for retrieving seccomp flags To: Tycho Andersen Cc: LKML , criu@openvz.org, Andy Lutomirski , Oleg Nesterov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6746 Lines: 199 On Tue, Sep 19, 2017 at 10:47 AM, Tycho Andersen wrote: > With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these > flags for checkpoint restore, since they describe the state of a filter. > > So, let's add PTRACE_SECCOMP_GET_FLAGS, similar to ..._GET_FILTER, which > returns the flags of the nth filter. Can you split this up into factoring out the nth helper, and then adding the new get? For naming, perhaps "GET_FILTER_FLAGS" instead of "GET_FLAGS" since there may be seccomp flags in the future, etc. Is there any sane way to add the flags to the existing GET_FILTER? -Kees > > Signed-off-by: Tycho Andersen > CC: Kees Cook > CC: Andy Lutomirski > CC: Oleg Nesterov > --- > include/linux/seccomp.h | 7 +++++ > include/uapi/linux/ptrace.h | 1 + > kernel/ptrace.c | 4 +++ > kernel/seccomp.c | 74 ++++++++++++++++++++++++++++++++++----------- > 4 files changed, 68 insertions(+), 18 deletions(-) > > diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h > index c8bef436b61d..4713d62378e3 100644 > --- a/include/linux/seccomp.h > +++ b/include/linux/seccomp.h > @@ -94,11 +94,18 @@ static inline void get_seccomp_filter(struct task_struct *tsk) > #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) > extern long seccomp_get_filter(struct task_struct *task, > unsigned long filter_off, void __user *data); > +extern long seccomp_get_flags(struct task_struct *task, > + unsigned long filter_off); > #else > static inline long seccomp_get_filter(struct task_struct *task, > unsigned long n, void __user *data) > { > return -EINVAL; > } > +static inline long seccomp_get_flags(struct task_struct *task, > + unsigned long filter_off) > +{ > + return -EINVAL; > +} > #endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */ > #endif /* _LINUX_SECCOMP_H */ > diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h > index fb8106509000..52903f0f6600 100644 > --- a/include/uapi/linux/ptrace.h > +++ b/include/uapi/linux/ptrace.h > @@ -65,6 +65,7 @@ struct ptrace_peeksiginfo_args { > #define PTRACE_SETSIGMASK 0x420b > > #define PTRACE_SECCOMP_GET_FILTER 0x420c > +#define PTRACE_SECCOMP_GET_FLAGS 0x420d > > /* Read signals from a shared (process wide) queue */ > #define PTRACE_PEEKSIGINFO_SHARED (1 << 0) > diff --git a/kernel/ptrace.c b/kernel/ptrace.c > index 60f356d91060..fa3d2b4d3bf0 100644 > --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -1094,6 +1094,10 @@ int ptrace_request(struct task_struct *child, long request, > ret = seccomp_get_filter(child, addr, datavp); > break; > > + case PTRACE_SECCOMP_GET_FLAGS: > + ret = seccomp_get_flags(child, addr); > + break; > + > default: > break; > } > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > index c24579dfa7a1..67768aaa7952 100644 > --- a/kernel/seccomp.c > +++ b/kernel/seccomp.c > @@ -968,24 +968,16 @@ long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter) > } > > #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) > -long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, > - void __user *data) > +static struct seccomp_filter *get_nth_filter(struct task_struct *task, > + unsigned long filter_off) > { > struct seccomp_filter *filter; > - struct sock_fprog_kern *fprog; > - long ret; > unsigned long count = 0; > > - if (!capable(CAP_SYS_ADMIN) || > - current->seccomp.mode != SECCOMP_MODE_DISABLED) { > - return -EACCES; > - } > + WARN_ON_ONCE(!spin_is_locked(&task->sighand->siglock)); > > - spin_lock_irq(&task->sighand->siglock); > - if (task->seccomp.mode != SECCOMP_MODE_FILTER) { > - ret = -EINVAL; > - goto out; > - } > + if (task->seccomp.mode != SECCOMP_MODE_FILTER) > + return ERR_PTR(-EINVAL); > > filter = task->seccomp.filter; > while (filter) { > @@ -993,10 +985,9 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, > count++; > } > > - if (filter_off >= count) { > - ret = -ENOENT; > - goto out; > - } > + if (filter_off >= count) > + return ERR_PTR(-ENOENT); > + > count -= filter_off; > > filter = task->seccomp.filter; > @@ -1007,7 +998,28 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, > > if (WARN_ON(count != 1 || !filter)) { > /* The filter tree shouldn't shrink while we're using it. */ > - ret = -ENOENT; > + return ERR_PTR(-ENOENT); > + } > + > + return filter; > +} > + > +long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, > + void __user *data) > +{ > + struct seccomp_filter *filter; > + struct sock_fprog_kern *fprog; > + long ret; > + > + if (!capable(CAP_SYS_ADMIN) || > + current->seccomp.mode != SECCOMP_MODE_DISABLED) { > + return -EACCES; > + } > + > + spin_lock_irq(&task->sighand->siglock); > + filter = get_nth_filter(task, filter_off); > + if (IS_ERR(filter)) { > + ret = PTR_ERR(filter); > goto out; > } > > @@ -1038,6 +1050,32 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, > spin_unlock_irq(&task->sighand->siglock); > return ret; > } > + > +long seccomp_get_flags(struct task_struct *task, unsigned long filter_off) > +{ > + long flags = 0L; > + struct seccomp_filter *filter; > + > + if (!capable(CAP_SYS_ADMIN) || > + current->seccomp.mode != SECCOMP_MODE_DISABLED) { > + return -EACCES; > + } > + > + spin_lock_irq(&task->sighand->siglock); > + filter = get_nth_filter(task, filter_off); > + if (IS_ERR(filter)) { > + flags = PTR_ERR(filter); > + goto out; > + } > + > + if (filter->log) > + flags |= SECCOMP_FILTER_FLAG_LOG; > + > +out: > + spin_unlock_irq(&task->sighand->siglock); > + return flags; > + > +} > #endif > > #ifdef CONFIG_SYSCTL > -- > 2.11.0 > -- Kees Cook Pixel Security