From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=fail (p=none dis=none) header.from=honor.com Received: from mta21.hihonor.com (mta21.hihonor.com [81.70.160.142]) by passt.top (Postfix) with ESMTPS id B05F85A0279 for ; Sat, 23 Aug 2025 03:53:53 +0200 (CEST) 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: 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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.144.23.14] X-ClientProxiedBy: w001.hihonor.com (10.68.25.235) To a011.hihonor.com (10.68.31.243) X-MailFrom: wangzijie1@honor.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation Message-ID-Hash: WBZJRLUUS3XNZPG4B2L547ATILDPXIUV X-Message-ID-Hash: WBZJRLUUS3XNZPG4B2L547ATILDPXIUV X-Mailman-Approved-At: Sat, 23 Aug 2025 10:24:00 +0200 CC: adobriyan@gmail.com, akpm@linux-foundation.org, ast@kernel.org, brauner@kernel.org, kirill.shutemov@linux.intel.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, passt-dev@passt.top, rick.p.edgecombe@intel.com, viro@zeniv.linux.org.uk, wangzijie1@honor.com, jirislaby@kernel.org X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: > 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