From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta21.hihonor.com (mta21.hihonor.com [81.70.160.142]) (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 8F6AC191F7E; Sat, 23 Aug 2025 01:53:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=81.70.160.142 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755914046; cv=none; b=XUtYXgMtdBmkpvTsDQiPH/OlP34Mi0E7a+3Ut6xsvOfW5kzieXhNSPbHpOLT0ygCOsQo1ENcXfaXrdNXUnuvhkWgK3D52IqsaVi0iE2gHpM8NLJGWCXUTuiosW9Tfvy3WqqqWvzyAgM/1Ixvw+7/bcUfEViN3UyzYnbLxiWFYR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755914046; c=relaxed/simple; bh=lb7ETmThEA98Kjs2wgXrXw1GpQW5I8d/r66x6z+1ol0=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=W2b0KIUTfcKcc1u9CJ+H57TvkjlapZf3TK+2kxWZk94RRyK3O4UTTfR8LS4jB/NolSFR4+ISvktTtYuW/FNjbI1zXKvthiHw3MdTckQ4VXmZI1Xkty6T8EJkzscoJLqx5uRw1eY8rJvaziQbEweoPR4taUXO9V0Zl34QFS3RxVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=honor.com; spf=pass smtp.mailfrom=honor.com; arc=none smtp.client-ip=81.70.160.142 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=honor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=honor.com Received: from w012.hihonor.com (unknown [10.68.27.189]) by mta21.hihonor.com (SkyGuard) with ESMTPS id 4c80TD2sQXzYnXLf; Sat, 23 Aug 2025 09:53:36 +0800 (CST) Received: from a011.hihonor.com (10.68.31.243) by w012.hihonor.com (10.68.27.189) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 23 Aug 2025 09:53:50 +0800 Received: from localhost.localdomain (10.144.23.14) by a011.hihonor.com (10.68.31.243) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 23 Aug 2025 09:53:50 +0800 From: wangzijie To: CC: , , , , , , , , , , , Subject: Re: [PATCH] proc: Bring back lseek() operations for /proc/net entries Date: Sat, 23 Aug 2025 09:53:49 +0800 Message-ID: <20250823015349.1650855-1-wangzijie1@honor.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20250822172335.3187858-1-sbrivio@redhat.com> References: <20250822172335.3187858-1-sbrivio@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: w001.hihonor.com (10.68.25.235) To a011.hihonor.com (10.68.31.243) > Commit ff7ec8dc1b64 ("proc: use the same treatment to check proc_lseek > as ones for proc_read_iter et.al") breaks lseek() for all /proc/net > entries, as shown for instance by pasta(1), a user-mode network > implementation using those entries to scan for bound ports: > > $ strace -e openat,lseek -e s=none pasta -- true > [...] > openat(AT_FDCWD, "/proc/net/tcp", O_RDONLY|O_CLOEXEC) = 12 > openat(AT_FDCWD, "/proc/net/tcp6", O_RDONLY|O_CLOEXEC) = 13 > lseek(12, 0, SEEK_SET) = -1 ESPIPE (Illegal seek) > lseek() failed on /proc/net file: Illegal seek > lseek(13, 0, SEEK_SET) = -1 ESPIPE (Illegal seek) > lseek() failed on /proc/net file: Illegal seek > openat(AT_FDCWD, "/proc/net/udp", O_RDONLY|O_CLOEXEC) = 14 > openat(AT_FDCWD, "/proc/net/udp6", O_RDONLY|O_CLOEXEC) = 15 > lseek(14, 0, SEEK_SET) = -1 ESPIPE (Illegal seek) > lseek() failed on /proc/net file: Illegal seek > lseek(15, 0, SEEK_SET) = -1 ESPIPE (Illegal seek) > lseek() failed on /proc/net file: Illegal seek > [...] > > That's because PROC_ENTRY_proc_lseek isn't set for /proc/net entries, > and it's now mandatory for lseek(). In fact, flags aren't set at all > for those entries because pde_set_flags() isn't called for them. > > As commit d919b33dafb3 ("proc: faster open/read/close with "permanent" > files") introduced flags for procfs directory entries, along with the > pde_set_flags() helper, they weren't relevant for /proc/net entries, > so the lack of pde_set_flags() calls in proc_create_net_*() functions > was harmless. > > Now that the calls are strictly needed for lseek() functionality, > add them. > > Fixes: ff7ec8dc1b64 ("proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al") > Signed-off-by: Stefano Brivio > --- > fs/proc/generic.c | 2 +- > fs/proc/internal.h | 1 + > fs/proc/proc_net.c | 4 ++++ > 3 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > index 76e800e38c8f..57ec5e385d1b 100644 > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -561,7 +561,7 @@ struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode, > return p; > } > > -static void pde_set_flags(struct proc_dir_entry *pde) > +void pde_set_flags(struct proc_dir_entry *pde) > { > if (pde->proc_ops->proc_flags & PROC_ENTRY_PERMANENT) > pde->flags |= PROC_ENTRY_PERMANENT; > diff --git a/fs/proc/internal.h b/fs/proc/internal.h > index e737401d7383..a358974f14d2 100644 > --- a/fs/proc/internal.h > +++ b/fs/proc/internal.h > @@ -284,6 +284,7 @@ extern struct dentry *proc_lookup(struct inode *, struct dentry *, unsigned int) > struct dentry *proc_lookup_de(struct inode *, struct dentry *, struct proc_dir_entry *); > extern int proc_readdir(struct file *, struct dir_context *); > int proc_readdir_de(struct file *, struct dir_context *, struct proc_dir_entry *); > +void pde_set_flags(struct proc_dir_entry *pde); > > static inline void pde_get(struct proc_dir_entry *pde) > { > diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c > index 52f0b75cbce2..20bc7481b02c 100644 > --- a/fs/proc/proc_net.c > +++ b/fs/proc/proc_net.c > @@ -124,6 +124,7 @@ struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode, > p->proc_ops = &proc_net_seq_ops; > p->seq_ops = ops; > p->state_size = state_size; > + pde_set_flags(p); > return proc_register(parent, p); > } > EXPORT_SYMBOL_GPL(proc_create_net_data); > @@ -170,6 +171,7 @@ struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode > p->seq_ops = ops; > p->state_size = state_size; > p->write = write; > + pde_set_flags(p); > return proc_register(parent, p); > } > EXPORT_SYMBOL_GPL(proc_create_net_data_write); > @@ -217,6 +219,7 @@ struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode, > pde_force_lookup(p); > p->proc_ops = &proc_net_single_ops; > p->single_show = show; > + pde_set_flags(p); > return proc_register(parent, p); > } > EXPORT_SYMBOL_GPL(proc_create_net_single); > @@ -261,6 +264,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo > p->proc_ops = &proc_net_single_ops; > p->single_show = show; > p->write = write; > + pde_set_flags(p); > return proc_register(parent, p); > } > EXPORT_SYMBOL_GPL(proc_create_net_single_write); > -- > 2.43.0 Hi Stefano, Thanks for your patch, Lars reported this bug last week: https://lore.kernel.org/all/20250815195616.64497967@chagall.paradoxon.rec/ Jiri suggested to make pde_set_flags() part of proc_register(). I think it can help to avoid lack of pde_set_flags() calls in the future and make code clean. I have submitted a patch: https://lore.kernel.org/all/20250821105806.1453833-1-wangzijie1@honor.com