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Message-Id: <20180930234628.25528-3-laurent@vivier.eu>
Date: Mon, 1 Oct 2018 01:46:28 +0200
From: Laurent Vivier <laurent@...ier.eu>
To: linux-kernel@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
James Bottomley <James.Bottomley@...senPartnership.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
linux-api@...r.kernel.org, Eric Biederman <ebiederm@...ssion.com>,
Dmitry Safonov <dima@...sta.com>,
Andrei Vagin <avagin@...nvz.org>,
containers@...ts.linux-foundation.org,
Laurent Vivier <laurent@...ier.eu>
Subject: [RFC 2/2] binfmt_misc: move data to binfmt_namespace
Signed-off-by: Laurent Vivier <laurent@...ier.eu>
---
fs/binfmt_misc.c | 50 +++++++++++++++++---------------
include/linux/binfmt_namespace.h | 12 ++++++++
kernel/binfmt_namespace.c | 11 +++++++
3 files changed, 49 insertions(+), 24 deletions(-)
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index aa4a7a23ff99..c6148b2bdd19 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -25,6 +25,7 @@
#include <linux/syscalls.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
+#include <linux/binfmt_namespace.h>
#include "internal.h"
@@ -38,9 +39,6 @@ enum {
VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
};
-static LIST_HEAD(entries);
-static int enabled = 1;
-
enum {Enabled, Magic};
#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
#define MISC_FMT_OPEN_BINARY (1 << 30)
@@ -60,10 +58,7 @@ typedef struct {
struct file *interp_file;
} Node;
-static DEFINE_RWLOCK(entries_lock);
static struct file_system_type bm_fs_type;
-static struct vfsmount *bm_mnt;
-static int entry_count;
/*
* Max length of the register string. Determined by:
@@ -91,7 +86,7 @@ static Node *check_file(struct linux_binprm *bprm)
struct list_head *l;
/* Walk all the registered handlers. */
- list_for_each(l, &entries) {
+ list_for_each(l, &binfmt_ns(entries)) {
Node *e = list_entry(l, Node, list);
char *s;
int j;
@@ -135,15 +130,15 @@ static int load_misc_binary(struct linux_binprm *bprm)
int fd_binary = -1;
retval = -ENOEXEC;
- if (!enabled)
+ if (!binfmt_ns(enabled))
return retval;
/* to keep locking time low, we copy the interpreter string */
- read_lock(&entries_lock);
+ read_lock(&binfmt_ns(entries_lock));
fmt = check_file(bprm);
if (fmt)
dget(fmt->dentry);
- read_unlock(&entries_lock);
+ read_unlock(&binfmt_ns(entries_lock));
if (!fmt)
return retval;
@@ -613,15 +608,15 @@ static void kill_node(Node *e)
{
struct dentry *dentry;
- write_lock(&entries_lock);
+ write_lock(&binfmt_ns(entries_lock));
list_del_init(&e->list);
- write_unlock(&entries_lock);
+ write_unlock(&binfmt_ns(entries_lock));
dentry = e->dentry;
drop_nlink(d_inode(dentry));
d_drop(dentry);
dput(dentry);
- simple_release_fs(&bm_mnt, &entry_count);
+ simple_release_fs(&binfmt_ns(bm_mnt), &binfmt_ns(entry_count));
}
/* /<entry> */
@@ -716,7 +711,8 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
if (!inode)
goto out2;
- err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
+ err = simple_pin_fs(&bm_fs_type, &binfmt_ns(bm_mnt),
+ &binfmt_ns(entry_count));
if (err) {
iput(inode);
inode = NULL;
@@ -730,7 +726,8 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
if (IS_ERR(f)) {
err = PTR_ERR(f);
pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
- simple_release_fs(&bm_mnt, &entry_count);
+ simple_release_fs(&binfmt_ns(bm_mnt),
+ &binfmt_ns(entry_count));
iput(inode);
inode = NULL;
goto out2;
@@ -743,9 +740,9 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
inode->i_fop = &bm_entry_operations;
d_instantiate(dentry, inode);
- write_lock(&entries_lock);
- list_add(&e->list, &entries);
- write_unlock(&entries_lock);
+ write_lock(&binfmt_ns(entries_lock));
+ list_add(&e->list, &binfmt_ns(entries));
+ write_unlock(&binfmt_ns(entries_lock));
err = 0;
out2:
@@ -770,7 +767,7 @@ static const struct file_operations bm_register_operations = {
static ssize_t
bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
- char *s = enabled ? "enabled\n" : "disabled\n";
+ char *s = binfmt_ns(enabled) ? "enabled\n" : "disabled\n";
return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
}
@@ -784,19 +781,20 @@ static ssize_t bm_status_write(struct file *file, const char __user *buffer,
switch (res) {
case 1:
/* Disable all handlers. */
- enabled = 0;
+ binfmt_ns(enabled) = 0;
break;
case 2:
/* Enable all handlers. */
- enabled = 1;
+ binfmt_ns(enabled) = 1;
break;
case 3:
/* Delete all handlers. */
root = file_inode(file)->i_sb->s_root;
inode_lock(d_inode(root));
- while (!list_empty(&entries))
- kill_node(list_first_entry(&entries, Node, list));
+ while (!list_empty(&binfmt_ns(entries)))
+ kill_node(list_first_entry(&binfmt_ns(entries),
+ Node, list));
inode_unlock(d_inode(root));
break;
@@ -838,7 +836,10 @@ static int bm_fill_super(struct super_block *sb, void *data, int silent)
static struct dentry *bm_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
- return mount_single(fs_type, flags, data, bm_fill_super);
+ struct binfmt_namespace *binfmt_ns = current->nsproxy->binfmt_ns;
+
+ return mount_ns(fs_type, flags, data, binfmt_ns, binfmt_ns->user_ns,
+ bm_fill_super);
}
static struct linux_binfmt misc_format = {
@@ -849,6 +850,7 @@ static struct linux_binfmt misc_format = {
static struct file_system_type bm_fs_type = {
.owner = THIS_MODULE,
.name = "binfmt_misc",
+ .fs_flags = FS_USERNS_MOUNT,
.mount = bm_mount,
.kill_sb = kill_litter_super,
};
diff --git a/include/linux/binfmt_namespace.h b/include/linux/binfmt_namespace.h
index 8688869ee254..550357ab4f62 100644
--- a/include/linux/binfmt_namespace.h
+++ b/include/linux/binfmt_namespace.h
@@ -7,12 +7,24 @@ extern struct user_namespace init_user_ns;
struct binfmt_namespace {
struct kref kref;
+
+ struct list_head entries;
+ rwlock_t entries_lock;
+ int enabled;
+ struct vfsmount *bm_mnt;
+ int entry_count;
+
+ /* user_ns which owns the binfmt_misc ns */
+
struct user_namespace *user_ns;
struct ucounts *ucounts;
+
struct ns_common ns;
} __randomize_layout;
extern struct binfmt_namespace init_binfmt_ns;
+#define binfmt_ns(a) (current->nsproxy->binfmt_ns->a)
+
#ifdef CONFIG_BINFMT_NS
static inline void get_binfmt_ns(struct binfmt_namespace *ns)
{
diff --git a/kernel/binfmt_namespace.c b/kernel/binfmt_namespace.c
index 63a80bcd70df..22be49beee08 100644
--- a/kernel/binfmt_namespace.c
+++ b/kernel/binfmt_namespace.c
@@ -48,6 +48,12 @@ static struct binfmt_namespace *clone_binfmt_ns(struct user_namespace *user_ns,
if (err)
goto fail_free;
+ INIT_LIST_HEAD(&ns->entries);
+ ns->enabled = 1;
+ rwlock_init(&ns->entries_lock);
+ ns->bm_mnt = NULL;
+ ns->entry_count = 0;
+
ns->ucounts = ucounts;
ns->ns.ops = &binfmtns_operations;
ns->user_ns = get_user_ns(user_ns);
@@ -140,6 +146,9 @@ const struct proc_ns_operations binfmtns_operations = {
struct binfmt_namespace init_binfmt_ns = {
.kref = KREF_INIT(2),
.user_ns = &init_user_ns,
+ .enabled = 1,
+ .entry_count = 0,
+ .bm_mnt = NULL,
.ns.inum = PROC_BINFMT_INIT_INO,
#ifdef CONFIG_BINFMT_NS
.ns.ops = &binfmtns_operations,
@@ -148,6 +157,8 @@ struct binfmt_namespace init_binfmt_ns = {
static int __init binfmt_ns_init(void)
{
+ INIT_LIST_HEAD(&init_binfmt_ns.entries);
+ rwlock_init(&init_binfmt_ns.entries_lock);
return 0;
}
subsys_initcall(binfmt_ns_init);
--
2.17.1
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