From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.hallyn.com (mail.hallyn.com [178.63.66.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D48B28C035; Fri, 31 Oct 2025 23:38:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.63.66.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761953894; cv=none; b=ipPtPdbXe6PU4rFhdgrNvI4dRYYd/DFx+Bpf9xvOO85QqUUJqrBOZPIX91a/CL3CRL1rEFA+kXMn+bEHqyDGBPl4GuLMuOU60Q411a8IIHQDuEAceNY4KW/aorpjmmfZl/ov0lZ3ZwgnNfHoXArVnOQWQQsJhXuLckksDCYrUgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761953894; c=relaxed/simple; bh=ZZBwwZAqyH37jixgU+9Ikj79If/LNQFAF0IsdYlO+Us=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qbZFGIFj3kLZlPiHmMZCDESepa1Pp2+BRluEn5318F0TJmkEqi2XsrN5u0lDtkAiGBd8V2g0BA4mfjUMIysIxsyGjbOqvNRk+nbrwNPP/tDBzPO2+8cKW29k9+yaTtx1jBMh38nrHLvQiX+Uy6hWMZyuBPlybR5NSX5XBHxGz7c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com; spf=pass smtp.mailfrom=mail.hallyn.com; arc=none smtp.client-ip=178.63.66.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mail.hallyn.com Received: by mail.hallyn.com (Postfix, from userid 1001) id 30158C8C; Fri, 31 Oct 2025 18:38:08 -0500 (CDT) Date: Fri, 31 Oct 2025 18:38:08 -0500 From: "Serge E. Hallyn" To: Thorsten Blum Cc: David Laight , Paul Moore , James Morris , "Serge E. Hallyn" , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] device_cgroup: Refactor devcgroup_seq_show to use seq_put* helpers Message-ID: References: <20251031213915.211046-1-thorsten.blum@linux.dev> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251031213915.211046-1-thorsten.blum@linux.dev> On Fri, Oct 31, 2025 at 10:39:14PM +0100, Thorsten Blum wrote: > Replace set_access(), set_majmin(), and type_to_char() with new helpers > seq_putaccess(), seq_puttype(), and seq_putversion() that write directly > to 'seq_file'. > > Simplify devcgroup_seq_show() by hard-coding "a *:* rwm", and use the > new seq_put* helper functions to list the exceptions otherwise. > > This allows us to remove the intermediate string buffers while > maintaining the same functionality, including wildcard handling. > > Signed-off-by: Thorsten Blum Thank you, that is much nicer. Acked-by: Serge Hallyn > --- > Changes in v2: > - Add setq_put* helpers to modify seq_file directly (David) > - Update patch subject and description > - Link to v1: https://lore.kernel.org/lkml/20251031110647.102728-2-thorsten.blum@linux.dev/ > --- > security/device_cgroup.c | 56 ++++++++++++++++++---------------------- > 1 file changed, 25 insertions(+), 31 deletions(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index dc4df7475081..7fec575d32d6 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -244,45 +244,40 @@ static void devcgroup_css_free(struct cgroup_subsys_state *css) > #define DEVCG_DENY 2 > #define DEVCG_LIST 3 > > -#define MAJMINLEN 13 > -#define ACCLEN 4 > - > -static void set_access(char *acc, short access) > +static void seq_putaccess(struct seq_file *m, short access) > { > - int idx = 0; > - memset(acc, 0, ACCLEN); > if (access & DEVCG_ACC_READ) > - acc[idx++] = 'r'; > + seq_putc(m, 'r'); > if (access & DEVCG_ACC_WRITE) > - acc[idx++] = 'w'; > + seq_putc(m, 'w'); > if (access & DEVCG_ACC_MKNOD) > - acc[idx++] = 'm'; > + seq_putc(m, 'm'); > } > > -static char type_to_char(short type) > +static void seq_puttype(struct seq_file *m, short type) > { > if (type == DEVCG_DEV_ALL) I do think a switch would be easier to read here, but that's personal preference... > - return 'a'; > - if (type == DEVCG_DEV_CHAR) > - return 'c'; > - if (type == DEVCG_DEV_BLOCK) > - return 'b'; > - return 'X'; > + seq_putc(m, 'a'); > + else if (type == DEVCG_DEV_CHAR) > + seq_putc(m, 'c'); > + else if (type == DEVCG_DEV_BLOCK) > + seq_putc(m, 'b'); > + else > + seq_putc(m, 'X'); > } > > -static void set_majmin(char *str, unsigned m) > +static void seq_putversion(struct seq_file *m, unsigned int version) > { > - if (m == ~0) > - strcpy(str, "*"); > + if (version == ~0) > + seq_putc(m, '*'); > else > - sprintf(str, "%u", m); > + seq_printf(m, "%u", version); > } > > static int devcgroup_seq_show(struct seq_file *m, void *v) > { > struct dev_cgroup *devcgroup = css_to_devcgroup(seq_css(m)); > struct dev_exception_item *ex; > - char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; > > rcu_read_lock(); > /* > @@ -292,18 +287,17 @@ static int devcgroup_seq_show(struct seq_file *m, void *v) > * This way, the file remains as a "whitelist of devices" > */ > if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { > - set_access(acc, DEVCG_ACC_MASK); > - set_majmin(maj, ~0); > - set_majmin(min, ~0); > - seq_printf(m, "%c %s:%s %s\n", type_to_char(DEVCG_DEV_ALL), > - maj, min, acc); > + seq_puts(m, "a *:* rwm\n"); > } else { > list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { > - set_access(acc, ex->access); > - set_majmin(maj, ex->major); > - set_majmin(min, ex->minor); > - seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type), > - maj, min, acc); > + seq_puttype(m, ex->type); > + seq_putc(m, ' '); > + seq_putversion(m, ex->major); > + seq_putc(m, ':'); > + seq_putversion(m, ex->minor); > + seq_putc(m, ' '); > + seq_putaccess(m, ex->access); > + seq_putc(m, '\n'); > } > } > rcu_read_unlock(); > -- > 2.51.1