Revision 9e368259ad988356c4c95150fafd1a06af095d98 authored by Andrea Arcangeli on 30 November 2018, 22:09:25 UTC, committed by Linus Torvalds on 30 November 2018, 22:56:14 UTC
Patch series "userfaultfd shmem updates". Jann found two bugs in the userfaultfd shmem MAP_SHARED backend: the lack of the VM_MAYWRITE check and the lack of i_size checks. Then looking into the above we also fixed the MAP_PRIVATE case. Hugh by source review also found a data loss source if UFFDIO_COPY is used on shmem MAP_SHARED PROT_READ mappings (the production usages incidentally run with PROT_READ|PROT_WRITE, so the data loss couldn't happen in those production usages like with QEMU). The whole patchset is marked for stable. We verified QEMU postcopy live migration with guest running on shmem MAP_PRIVATE run as well as before after the fix of shmem MAP_PRIVATE. Regardless if it's shmem or hugetlbfs or MAP_PRIVATE or MAP_SHARED, QEMU unconditionally invokes a punch hole if the guest mapping is filebacked and a MADV_DONTNEED too (needed to get rid of the MAP_PRIVATE COWs and for the anon backend). This patch (of 5): We internally used EFAULT to communicate with the caller, switch to ENOENT, so EFAULT can be used as a non internal retval. Link: http://lkml.kernel.org/r/20181126173452.26955-2-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Hugh Dickins <hughd@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jann Horn <jannh@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: <stable@vger.kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 5618cf0
root.c
// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/proc/root.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* proc root directory handling functions
*/
#include <linux/uaccess.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/stat.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/user_namespace.h>
#include <linux/mount.h>
#include <linux/pid_namespace.h>
#include <linux/parser.h>
#include <linux/cred.h>
#include "internal.h"
enum {
Opt_gid, Opt_hidepid, Opt_err,
};
static const match_table_t tokens = {
{Opt_hidepid, "hidepid=%u"},
{Opt_gid, "gid=%u"},
{Opt_err, NULL},
};
int proc_parse_options(char *options, struct pid_namespace *pid)
{
char *p;
substring_t args[MAX_OPT_ARGS];
int option;
if (!options)
return 1;
while ((p = strsep(&options, ",")) != NULL) {
int token;
if (!*p)
continue;
args[0].to = args[0].from = NULL;
token = match_token(p, tokens, args);
switch (token) {
case Opt_gid:
if (match_int(&args[0], &option))
return 0;
pid->pid_gid = make_kgid(current_user_ns(), option);
break;
case Opt_hidepid:
if (match_int(&args[0], &option))
return 0;
if (option < HIDEPID_OFF ||
option > HIDEPID_INVISIBLE) {
pr_err("proc: hidepid value must be between 0 and 2.\n");
return 0;
}
pid->hide_pid = option;
break;
default:
pr_err("proc: unrecognized mount option \"%s\" "
"or missing value\n", p);
return 0;
}
}
return 1;
}
int proc_remount(struct super_block *sb, int *flags, char *data)
{
struct pid_namespace *pid = sb->s_fs_info;
sync_filesystem(sb);
return !proc_parse_options(data, pid);
}
static struct dentry *proc_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
struct pid_namespace *ns;
if (flags & SB_KERNMOUNT) {
ns = data;
data = NULL;
} else {
ns = task_active_pid_ns(current);
}
return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
}
static void proc_kill_sb(struct super_block *sb)
{
struct pid_namespace *ns;
ns = (struct pid_namespace *)sb->s_fs_info;
if (ns->proc_self)
dput(ns->proc_self);
if (ns->proc_thread_self)
dput(ns->proc_thread_self);
kill_anon_super(sb);
put_pid_ns(ns);
}
static struct file_system_type proc_fs_type = {
.name = "proc",
.mount = proc_mount,
.kill_sb = proc_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
void __init proc_root_init(void)
{
proc_init_kmemcache();
set_proc_pid_nlink();
proc_self_init();
proc_thread_self_init();
proc_symlink("mounts", NULL, "self/mounts");
proc_net_init();
proc_mkdir("fs", NULL);
proc_mkdir("driver", NULL);
proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */
#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
/* just give it a mountpoint */
proc_create_mount_point("openprom");
#endif
proc_tty_init();
proc_mkdir("bus", NULL);
proc_sys_init();
register_filesystem(&proc_fs_type);
}
static int proc_root_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
generic_fillattr(d_inode(path->dentry), stat);
stat->nlink = proc_root.nlink + nr_processes();
return 0;
}
static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
{
if (!proc_pid_lookup(dir, dentry, flags))
return NULL;
return proc_lookup(dir, dentry, flags);
}
static int proc_root_readdir(struct file *file, struct dir_context *ctx)
{
if (ctx->pos < FIRST_PROCESS_ENTRY) {
int error = proc_readdir(file, ctx);
if (unlikely(error <= 0))
return error;
ctx->pos = FIRST_PROCESS_ENTRY;
}
return proc_pid_readdir(file, ctx);
}
/*
* The root /proc directory is special, as it has the
* <pid> directories. Thus we don't use the generic
* directory handling functions for that..
*/
static const struct file_operations proc_root_operations = {
.read = generic_read_dir,
.iterate_shared = proc_root_readdir,
.llseek = generic_file_llseek,
};
/*
* proc root can do almost nothing..
*/
static const struct inode_operations proc_root_inode_operations = {
.lookup = proc_root_lookup,
.getattr = proc_root_getattr,
};
/*
* This is the root "inode" in the /proc tree..
*/
struct proc_dir_entry proc_root = {
.low_ino = PROC_ROOT_INO,
.namelen = 5,
.mode = S_IFDIR | S_IRUGO | S_IXUGO,
.nlink = 2,
.refcnt = REFCOUNT_INIT(1),
.proc_iops = &proc_root_inode_operations,
.proc_fops = &proc_root_operations,
.parent = &proc_root,
.subdir = RB_ROOT,
.name = "/proc",
};
int pid_ns_prepare_proc(struct pid_namespace *ns)
{
struct vfsmount *mnt;
mnt = kern_mount_data(&proc_fs_type, ns);
if (IS_ERR(mnt))
return PTR_ERR(mnt);
ns->proc_mnt = mnt;
return 0;
}
void pid_ns_release_proc(struct pid_namespace *ns)
{
kern_unmount(ns->proc_mnt);
}
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...