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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 03/27] containers: Provide /proc/containers From: David Howells To: keyrings@vger.kernel.org, trond.myklebust@hammerspace.com, sfrench@samba.org Cc: linux-security-module@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, rgb@redhat.com, dhowells@redhat.com, linux-kernel@vger.kernel.org Date: Fri, 15 Feb 2019 16:07:41 +0000 Message-ID: <155024686175.21651.6141317051029384847.stgit@warthog.procyon.org.uk> In-Reply-To: <155024683432.21651.14153938339749694146.stgit@warthog.procyon.org.uk> References: <155024683432.21651.14153938339749694146.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Fri, 15 Feb 2019 16:07:44 +0000 (UTC) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Provide /proc/containers to view the current container and all the containers created within it: # ./foo-container NAME USE FL OWNER GROUP 141 01 0 0 foo-test 1 04 0 0 I'm not sure whether this is really desirable, though. Signed-off-by: David Howells --- kernel/container.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 110 insertions(+) diff --git a/kernel/container.c b/kernel/container.c index ca4012632cfa..1d2cb1c1e9b1 100644 --- a/kernel/container.c +++ b/kernel/container.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "namespaces.h" struct container init_container = { @@ -69,6 +70,108 @@ void put_container(struct container *c) } } +static void *container_proc_start(struct seq_file *m, loff_t *_pos) +{ + struct container *c = m->private; + struct list_head *p; + loff_t pos = *_pos; + + spin_lock(&c->lock); + + if (pos <= 1) { + *_pos = 1; + return (void *)1UL; /* Banner on first line */ + } + + if (pos == 2) + return m->private; /* Current container on second line */ + + /* Subordinate containers thereafter */ + p = c->children.next; + pos--; + for (pos--; pos > 0 && p != &c->children; pos--) { + p = p->next; + } + + if (p == &c->children) + return NULL; + return container_of(p, struct container, child_link); +} + +static void *container_proc_next(struct seq_file *m, void *v, loff_t *_pos) +{ + struct container *c = m->private, *vc = v; + struct list_head *p; + loff_t pos = *_pos; + + pos++; + *_pos = pos; + if (pos == 2) + return c; /* Current container on second line */ + + if (pos == 3) + p = &c->children; + else + p = &vc->child_link; + p = p->next; + if (p == &c->children) + return NULL; + return container_of(p, struct container, child_link); +} + +static void container_proc_stop(struct seq_file *m, void *v) +{ + struct container *c = m->private; + + spin_unlock(&c->lock); +} + +static int container_proc_show(struct seq_file *m, void *v) +{ + struct user_namespace *uns = current_user_ns(); + struct container *c = v; + const char *name; + + if (v == (void *)1UL) { + seq_puts(m, "NAME ID USE FL OWNER GROUP\n"); + return 0; + } + + name = (c == m->private) ? "" : c->name; + seq_printf(m, "%-24s %12llu %3u %02lx %5d %5d\n", + name, c->id, refcount_read(&c->usage), c->flags, + from_kuid_munged(uns, c->cred->uid), + from_kgid_munged(uns, c->cred->gid)); + + return 0; +} + +static const struct seq_operations container_proc_ops = { + .start = container_proc_start, + .next = container_proc_next, + .stop = container_proc_stop, + .show = container_proc_show, +}; + +static int container_proc_open(struct inode *inode, struct file *file) +{ + struct seq_file *m; + int ret = seq_open(file, &container_proc_ops); + + if (ret == 0) { + m = file->private_data; + m->private = current->container; + } + return ret; +} + +static const struct file_operations container_proc_fops = { + .open = container_proc_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + /* * Allow the user to poll for the container dying. */ @@ -345,4 +448,11 @@ SYSCALL_DEFINE5(container_create, return fd; } +static int __init init_container_fs(void) +{ + proc_create("containers", 0, NULL, &container_proc_fops); + return 0; +} +fs_initcall(init_container_fs); + #endif /* CONFIG_CONTAINERS */