Home » Mailing lists » Devel » [patch 0/8] mount ownership and unprivileged mount syscall (v4)
[patch 5/8] allow unprivileged bind mounts [message #18411 is a reply to message #18406] |
Fri, 20 April 2007 10:25 ![Go to previous message Go to previous message](/theme/ovz3/images/up.png) ![Go to next message Go to previous message](/theme/ovz3/images/down.png) |
Miklos Szeredi
Messages: 161 Registered: April 2007
|
Senior Member |
|
|
From: Miklos Szeredi <mszeredi@suse.cz>
Allow bind mounts to unprivileged users if the following conditions
are met:
- mountpoint is not a symlink or special file
- parent mount is owned by the user
- the number of user mounts is below the maximum
Unprivileged mounts imply MS_SETUSER, and will also have the "nosuid"
and "nodev" mount flags set.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
Index: linux/fs/namespace.c
===================================================================
--- linux.orig/fs/namespace.c 2007-04-20 11:55:09.000000000 +0200
+++ linux/fs/namespace.c 2007-04-20 11:55:10.000000000 +0200
@@ -237,11 +237,30 @@ static void dec_nr_user_mounts(void)
spin_unlock(&vfsmount_lock);
}
-static void set_mnt_user(struct vfsmount *mnt)
+static int reserve_user_mount(void)
+{
+ int err = 0;
+ spin_lock(&vfsmount_lock);
+ if (nr_user_mounts >= max_user_mounts && !capable(CAP_SYS_ADMIN))
+ err = -EPERM;
+ else
+ nr_user_mounts++;
+ spin_unlock(&vfsmount_lock);
+ return err;
+}
+
+static void __set_mnt_user(struct vfsmount *mnt)
{
BUG_ON(mnt->mnt_flags & MNT_USER);
mnt->mnt_uid = current->uid;
mnt->mnt_flags |= MNT_USER;
+ if (!capable(CAP_SYS_ADMIN))
+ mnt->mnt_flags |= MNT_NOSUID | MNT_NODEV;
+}
+
+static void set_mnt_user(struct vfsmount *mnt)
+{
+ __set_mnt_user(mnt);
spin_lock(&vfsmount_lock);
nr_user_mounts++;
spin_unlock(&vfsmount_lock);
@@ -260,9 +279,16 @@ static struct vfsmount *clone_mnt(struct
int flag)
{
struct super_block *sb = old->mnt_sb;
- struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
+ struct vfsmount *mnt;
+
+ if (flag & CL_SETUSER) {
+ int err = reserve_user_mount();
+ if (err)
+ return ERR_PTR(err);
+ }
+ mnt = alloc_vfsmnt(old->mnt_devname);
if (!mnt)
- return ERR_PTR(-ENOMEM);
+ goto alloc_failed;
mnt->mnt_flags = old->mnt_flags;
atomic_inc(&sb->s_active);
@@ -274,7 +300,7 @@ static struct vfsmount *clone_mnt(struct
/* don't copy the MNT_USER flag */
mnt->mnt_flags &= ~MNT_USER;
if (flag & CL_SETUSER)
- set_mnt_user(mnt);
+ __set_mnt_user(mnt);
if (flag & CL_SLAVE) {
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
@@ -299,6 +325,11 @@ static struct vfsmount *clone_mnt(struct
spin_unlock(&vfsmount_lock);
}
return mnt;
+
+ alloc_failed:
+ if (flag & CL_SETUSER)
+ dec_nr_user_mounts();
+ return ERR_PTR(-ENOMEM);
}
static inline void __mntput(struct vfsmount *mnt)
@@ -745,22 +776,29 @@ asmlinkage long sys_oldumount(char __use
#endif
-static int mount_is_safe(struct nameidata *nd)
+/*
+ * Conditions for unprivileged mounts are:
+ * - mountpoint is not a symlink or special file
+ * - mountpoint is in a mount owned by the user
+ */
+static bool permit_mount(struct nameidata *nd, int *flags)
{
+ struct inode *inode = nd->dentry->d_inode;
+
if (capable(CAP_SYS_ADMIN))
- return 0;
- return -EPERM;
-#ifdef notyet
- if (S_ISLNK(nd->dentry->d_inode->i_mode))
- return -EPERM;
- if (nd->dentry->d_inode->i_mode & S_ISVTX) {
- if (current->uid != nd->dentry->d_inode->i_uid)
- return -EPERM;
- }
- if (vfs_permission(nd, MAY_WRITE))
- return -EPERM;
- return 0;
-#endif
+ return true;
+
+ if (!S_ISDIR(inode->i_mode) && !S_ISREG(inode->i_mode))
+ return false;
+
+ if (!(nd->mnt->mnt_flags & MNT_USER))
+ return false;
+
+ if (nd->mnt->mnt_uid != current->uid)
+ return false;
+
+ *flags |= MS_SETUSER;
+ return true;
}
static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
@@ -981,9 +1019,10 @@ static int do_loopback(struct nameidata
int clone_flags;
struct nameidata old_nd;
struct vfsmount *mnt = NULL;
- int err = mount_is_safe(nd);
- if (err)
- return err;
+ int err;
+
+ if (!permit_mount(nd, &flags))
+ return -EPERM;
if (!old_name || !*old_name)
return -EINVAL;
err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
--
_______________________________________________
Containers mailing list
Containers@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containers
|
|
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 0/8] mount ownership and unprivileged mount syscall (v4)
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 1/8] add user mounts to the kernel
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
By: akpm on Sat, 21 April 2007 07:55
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
By: ebiederm on Sat, 21 April 2007 13:14
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
By: ebiederm on Sun, 22 April 2007 07:43
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 1/8] add user mounts to the kernel
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 2/8] allow unprivileged umount
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
By: akpm on Sat, 21 April 2007 07:55
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
By: hpa on Sat, 21 April 2007 08:01
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
By: akpm on Sat, 21 April 2007 08:36
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
By: ebiederm on Sat, 21 April 2007 12:53
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
By: ebiederm on Sat, 21 April 2007 13:29
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
By: ebiederm on Sun, 22 April 2007 07:09
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 2/8] allow unprivileged umount
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 3/8] account user mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 3/8] account user mounts
By: akpm on Sat, 21 April 2007 07:55
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 3/8] account user mounts
By: ebiederm on Sat, 21 April 2007 13:37
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 3/8] account user mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 3/8] account user mounts
By: ebiederm on Sun, 22 April 2007 07:49
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 3/8] account user mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 4/8] propagate error values from clone_mnt
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 4/8] propagate error values from clone_mnt
By: ebiederm on Sat, 21 April 2007 13:40
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 5/8] allow unprivileged bind mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 5/8] allow unprivileged bind mounts
By: ebiederm on Sat, 21 April 2007 14:00
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 5/8] allow unprivileged bind mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 6/8] put declaration of put_filesystem() in fs.h
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
By: akpm on Sat, 21 April 2007 07:55
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
By: ebiederm on Sat, 21 April 2007 14:10
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
By: ebiederm on Sat, 21 April 2007 16:57
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
By: ebiederm on Sat, 21 April 2007 21:00
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 7/8] allow unprivileged mounts
By: ebiederm on Sat, 21 April 2007 21:33
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
[patch 8/8] allow unprivileged fuse mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 8/8] allow unprivileged fuse mounts
By: akpm on Sat, 21 April 2007 07:55
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 8/8] allow unprivileged fuse mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 8/8] allow unprivileged fuse mounts
By: ebiederm on Sat, 21 April 2007 14:18
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 8/8] allow unprivileged fuse mounts
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 0/8] mount ownership and unprivileged mount syscall (v4)
By: ebiederm on Wed, 25 April 2007 01:04
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 0/8] mount ownership and unprivileged mount syscall (v4)
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 0/8] mount ownership and unprivileged mount syscall (v4)
|
![Read Message Read Message](/theme/ovz3/images/read.png) |
|
Re: [patch 0/8] mount ownership and unprivileged mount syscall (v4)
|
Goto Forum:
Current Time: Tue Jul 16 09:25:52 GMT 2024
Total time taken to generate the page: 0.02727 seconds
|