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Thu, 30 Jul 2020 05:18:36 -0700 (PDT) Date: Thu, 30 Jul 2020 15:18:34 +0300 From: Alexey Dobriyan To: Kirill Tkhai Cc: viro@zeniv.linux.org.uk, davem@davemloft.net, ebiederm@xmission.com, akpm@linux-foundation.org, christian.brauner@ubuntu.com, areber@redhat.com, serge@hallyn.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 11/23] fs: Add /proc/namespaces/ directory Message-ID: <20200730121834.GA4490@localhost.localdomain> References: <159611007271.535980.15362304262237658692.stgit@localhost.localdomain> <159611041929.535980.14513096920129728440.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <159611041929.535980.14513096920129728440.stgit@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 30, 2020 at 03:00:19PM +0300, Kirill Tkhai wrote: > # ls /proc/namespaces/ -l > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'cgroup:[4026531835]' -> 'cgroup:[4026531835]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'ipc:[4026531839]' -> 'ipc:[4026531839]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026531840]' -> 'mnt:[4026531840]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026531861]' -> 'mnt:[4026531861]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532133]' -> 'mnt:[4026532133]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532134]' -> 'mnt:[4026532134]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532135]' -> 'mnt:[4026532135]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532136]' -> 'mnt:[4026532136]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'net:[4026531993]' -> 'net:[4026531993]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'pid:[4026531836]' -> 'pid:[4026531836]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'time:[4026531834]' -> 'time:[4026531834]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'user:[4026531837]' -> 'user:[4026531837]' > lrwxrwxrwx 1 root root 0 Jul 29 16:50 'uts:[4026531838]' -> 'uts:[4026531838]' I'd say make it '%s-%llu'. The brackets don't carry any information. And ':' forces quoting with recent coreutils. > +static int parse_namespace_dentry_name(const struct dentry *dentry, > + const char **type, unsigned int *type_len, unsigned int *inum) > +{ > + const char *p, *name; > + int count; > + > + *type = name = dentry->d_name.name; > + p = strchr(name, ':'); > + *type_len = p - name; > + if (!p || p == name) > + return -ENOENT; > + > + p += 1; > + if (sscanf(p, "[%u]%n", inum, &count) != 1 || *(p + count) != '\0' || > + *inum < PROC_NS_MIN_INO) > + return -ENOENT; sscanf is banned from lookup code due to lax whitespace rules. See commit ac7f1061c2c11bb8936b1b6a94cdb48de732f7a4 proc: fix /proc/*/map_files lookup Of course someone sneaked in 1 instance, yikes. $ grep -e scanf -n -r fs/proc/ fs/proc/base.c:1596: err = sscanf(pos, "%9s %lld %lu", clock, > +static int proc_namespaces_readdir(struct file *file, struct dir_context *ctx) > + len = snprintf(name, sizeof(name), "%s:[%u]", ns->ops->name, inum); [] -- no need.