The patch titled
unprivileged mounts: account user mounts
has been added to the -mm tree. Its filename is
unprivileged-mounts-account-user-mounts.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: unprivileged mounts: account user mounts
From: Miklos Szeredi <mszeredi@xxxxxxx>
Add sysctl variables for accounting and limiting the number of user
mounts.
The maximum number of user mounts is set to 1024 by default. This
won't in itself enable user mounts, setting a mount to be owned by a
user is first needed
[akpm]
- don't use enumerated sysctls
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Ram Pai <linuxram@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.txt | 9 +++++++++
fs/namespace.c | 24 ++++++++++++++++++++++++
include/linux/fs.h | 3 +++
kernel/sysctl.c | 16 ++++++++++++++++
4 files changed, 52 insertions(+)
diff -puN Documentation/filesystems/proc.txt~unprivileged-mounts-account-user-mounts Documentation/filesystems/proc.txt
--- a/Documentation/filesystems/proc.txt~unprivileged-mounts-account-user-mounts
+++ a/Documentation/filesystems/proc.txt
@@ -923,6 +923,15 @@ reaches aio-max-nr then io_setup will fa
raising aio-max-nr does not result in the pre-allocation or re-sizing
of any kernel data structures.
+nr_user_mounts and max_user_mounts
+----------------------------------
+
+These represent the number of "user" mounts and the maximum number of
+"user" mounts respectively. User mounts may be created by
+unprivileged users. User mounts may also be created with sysadmin
+privileges on behalf of a user, in which case nr_user_mounts may
+exceed max_user_mounts.
+
2.2 /proc/sys/fs/binfmt_misc - Miscellaneous binary formats
-----------------------------------------------------------
diff -puN fs/namespace.c~unprivileged-mounts-account-user-mounts fs/namespace.c
--- a/fs/namespace.c~unprivileged-mounts-account-user-mounts
+++ a/fs/namespace.c
@@ -39,6 +39,9 @@ static int hash_mask __read_mostly, hash
static struct kmem_cache *mnt_cache __read_mostly;
static struct rw_semaphore namespace_sem;
+int nr_user_mounts;
+int max_user_mounts = 1024;
+
/* /sys/fs */
decl_subsys(fs, NULL, NULL);
EXPORT_SYMBOL_GPL(fs_subsys);
@@ -227,11 +230,30 @@ static struct vfsmount *skip_mnt_tree(st
return p;
}
+static void dec_nr_user_mounts(void)
+{
+ spin_lock(&vfsmount_lock);
+ nr_user_mounts--;
+ spin_unlock(&vfsmount_lock);
+}
+
static void set_mnt_user(struct vfsmount *mnt)
{
BUG_ON(mnt->mnt_flags & MNT_USER);
mnt->mnt_uid = current->fsuid;
mnt->mnt_flags |= MNT_USER;
+ spin_lock(&vfsmount_lock);
+ nr_user_mounts++;
+ spin_unlock(&vfsmount_lock);
+}
+
+static void clear_mnt_user(struct vfsmount *mnt)
+{
+ if (mnt->mnt_flags & MNT_USER) {
+ mnt->mnt_uid = 0;
+ mnt->mnt_flags &= ~MNT_USER;
+ dec_nr_user_mounts();
+ }
}
static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
@@ -283,6 +305,7 @@ static inline void __mntput(struct vfsmo
{
struct super_block *sb = mnt->mnt_sb;
dput(mnt->mnt_root);
+ clear_mnt_user(mnt);
free_vfsmnt(mnt);
deactivate_super(sb);
}
@@ -1009,6 +1032,7 @@ static int do_remount(struct nameidata *
down_write(&sb->s_umount);
err = do_remount_sb(sb, flags, data, 0);
if (!err) {
+ clear_mnt_user(nd->mnt);
nd->mnt->mnt_flags = mnt_flags;
if (flags & MS_SETUSER)
set_mnt_user(nd->mnt);
diff -puN include/linux/fs.h~unprivileged-mounts-account-user-mounts include/linux/fs.h
--- a/include/linux/fs.h~unprivileged-mounts-account-user-mounts
+++ a/include/linux/fs.h
@@ -50,6 +50,9 @@ extern struct inodes_stat_t inodes_stat;
extern int leases_enable, lease_break_time;
+extern int nr_user_mounts;
+extern int max_user_mounts;
+
#ifdef CONFIG_DNOTIFY
extern int dir_notify_enable;
#endif
diff -puN kernel/sysctl.c~unprivileged-mounts-account-user-mounts kernel/sysctl.c
--- a/kernel/sysctl.c~unprivileged-mounts-account-user-mounts
+++ a/kernel/sysctl.c
@@ -1026,6 +1026,22 @@ static ctl_table fs_table[] = {
#endif
#endif
{
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "nr_user_mounts",
+ .data = &nr_user_mounts,
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = &proc_dointvec,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "max_user_mounts",
+ .data = &max_user_mounts,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
.ctl_name = KERN_SETUID_DUMPABLE,
.procname = "suid_dumpable",
.data = &suid_dumpable,
_
Patches currently in -mm which might be from mszeredi@xxxxxxx are
split-mmap.patch
only-allow-nonlinear-vmas-for-ram-backed-filesystems.patch
fix-quadratic-behavior-of-shrink_dcache_parent.patch
mm-shrink-parent-dentries-when-shrinking-slab.patch
add-filesystem-subtype-support.patch
add-file-position-info-to-proc.patch
check-privileges-before-setting-mount-propagation.patch
consolidate-generic_writepages-and-mpage_writepages.patch
unprivileged-mounts-add-user-mounts-to-the-kernel.patch
unprivileged-mounts-allow-unprivileged-umount.patch
unprivileged-mounts-account-user-mounts.patch
unprivileged-mounts-propagate-error-values-from-clone_mnt.patch
unprivileged-mounts-allow-unprivileged-bind-mounts.patch
unprivileged-mounts-put-declaration-of-put_filesystem-in-fsh.patch
unprivileged-mounts-allow-unprivileged-mounts.patch
unprivileged-mounts-allow-unprivileged-fuse-mounts.patch
unprivileged-mounts-propagation-inherit-owner-from-parent.patch
unprivileged-mounts-add-no-submounts-flag.patch
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