Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756448Ab3DXR2e (ORCPT ); Wed, 24 Apr 2013 13:28:34 -0400 Received: from smtpfb1-g21.free.fr ([212.27.42.9]:35679 "EHLO smtpfb1-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754919Ab3DXR2d (ORCPT ); Wed, 24 Apr 2013 13:28:33 -0400 From: Nicolas Schichan To: Will Drewry , Mircea Gherzan , Andrew Morton , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Nicolas Schichan , Al Viro , Frederic Weisbecker , Thomas Gleixner , Steven Rostedt , Dave Jones , Michael Kerrisk , "Paul E. McKenney" , David Howells , Andy Lutomirski , James Morris Subject: [PATCH V3 1/3] seccomp: add generic code for jitted seccomp filters. Date: Wed, 24 Apr 2013 19:27:07 +0200 Message-Id: <1366824429-26652-2-git-send-email-nschichan@freebox.fr> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1366824429-26652-1-git-send-email-nschichan@freebox.fr> References: <1366824429-26652-1-git-send-email-nschichan@freebox.fr> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5455 Lines: 165 Architecture must select HAVE_SECCOMP_FILTER_JIT and implement seccomp_jit_compile() and seccomp_jit_free() if they intend to support jitted seccomp filters. Accessors to struct seccomp_filter fields are provided in to be used by the JIT code. With this, the 'struct seccomp_filter' structure can stay opaque when outside kernel/seccomp.c. In a way similar to the net BPF, the jit compilation code is expected to updates struct seccomp_filter.bpf_func pointer (using the correct accessor) to the generated code. Signed-off-by: Nicolas Schichan --- arch/Kconfig | 14 ++++++++++++++ include/linux/seccomp.h | 18 ++++++++++++++++++ kernel/seccomp.c | 33 ++++++++++++++++++++++++++++++++- 3 files changed, 64 insertions(+), 1 deletion(-) diff --git a/arch/Kconfig b/arch/Kconfig index 1455579..370bc52 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -332,6 +332,10 @@ config HAVE_ARCH_SECCOMP_FILTER - secure_computing return value is checked and a return value of -1 results in the system call being skipped immediately. +# Used by archs to tell that they support SECCOMP_FILTER_JIT +config HAVE_SECCOMP_FILTER_JIT + bool + config SECCOMP_FILTER def_bool y depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET @@ -342,6 +346,16 @@ config SECCOMP_FILTER See Documentation/prctl/seccomp_filter.txt for details. +config SECCOMP_FILTER_JIT + bool "enable Seccomp filter Just In Time compiler" + depends on HAVE_SECCOMP_FILTER_JIT && BPF_JIT && SECCOMP_FILTER + help + Seccomp syscall filtering capabilities are normally handled + by an interpreter. This option allows kernel to generate a native + code when filter is loaded in memory. This should speedup + syscall filtering. Note : Admin should enable this feature + changing /proc/sys/net/core/bpf_jit_enable + config HAVE_CONTEXT_TRACKING bool help diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 6f19cfd..2793607 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -47,6 +47,24 @@ static inline int seccomp_mode(struct seccomp *s) return s->mode; } +#ifdef CONFIG_SECCOMP_FILTER_JIT +extern void seccomp_jit_compile(struct seccomp_filter *fp); +extern void seccomp_jit_free(struct seccomp_filter *fp); + +/* + * accessors used by seccomp JIT code to avoid having to declare the + * seccomp_filter struct here. + */ +unsigned short seccomp_filter_get_len(struct seccomp_filter *fp); +struct sock_filter *seccomp_filter_get_insns(struct seccomp_filter *fp); +void seccomp_filter_set_bpf_func(struct seccomp_filter *fp, void *func); +void *seccomp_filter_get_bpf_func(struct seccomp_filter *fp); + +#else +static inline void seccomp_jit_compile(struct seccomp_filter *fp) { } +static inline void seccomp_jit_free(struct seccomp_filter *fp) { } +#endif + #else /* CONFIG_SECCOMP */ #include diff --git a/kernel/seccomp.c b/kernel/seccomp.c index b7a1004..2377414 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -39,6 +39,8 @@ * is only needed for handling filters shared across tasks. * @prev: points to a previously installed, or inherited, filter * @len: the number of instructions in the program + * @bpf_func: points to either sk_run_filter or the code generated + * by the BPF JIT. * @insns: the BPF program instructions to evaluate * * seccomp_filter objects are organized in a tree linked via the @prev @@ -55,6 +57,8 @@ struct seccomp_filter { atomic_t usage; struct seccomp_filter *prev; unsigned short len; /* Instruction count */ + unsigned int (*bpf_func)(const struct sk_buff *skb, + const struct sock_filter *filter); struct sock_filter insns[]; }; @@ -213,7 +217,7 @@ static u32 seccomp_run_filters(int syscall) * value always takes priority (ignoring the DATA). */ for (f = current->seccomp.filter; f; f = f->prev) { - u32 cur_ret = sk_run_filter(NULL, f->insns); + u32 cur_ret = f->bpf_func(NULL, f->insns); if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION)) ret = cur_ret; } @@ -275,6 +279,9 @@ static long seccomp_attach_filter(struct sock_fprog *fprog) if (ret) goto fail; + filter->bpf_func = sk_run_filter; + seccomp_jit_compile(filter); + /* * If there is an existing filter, make it the prev and don't drop its * task reference. @@ -332,10 +339,34 @@ void put_seccomp_filter(struct task_struct *tsk) while (orig && atomic_dec_and_test(&orig->usage)) { struct seccomp_filter *freeme = orig; orig = orig->prev; + seccomp_jit_free(freeme); kfree(freeme); } } +/* + * seccomp filter accessors for JIT code. + */ +unsigned short seccomp_filter_get_len(struct seccomp_filter *fp) +{ + return fp->len; +} + +struct sock_filter *seccomp_filter_get_insns(struct seccomp_filter *fp) +{ + return fp->insns; +} + +void seccomp_filter_set_bpf_func(struct seccomp_filter *fp, void *func) +{ + fp->bpf_func = func; +} + +void *seccomp_filter_get_bpf_func(struct seccomp_filter *fp) +{ + return fp->bpf_func; +} + /** * seccomp_send_sigsys - signals the task to allow in-process syscall emulation * @syscall: syscall number to send to userland -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/