subject:"\[PATCH review 4\/6\] userns\: Allow the userns root to mount of devpts"

Re: [PATCH review 4/6] userns: Allow the userns root to mount of devpts

2013-01-26 Thread Serge E. Hallyn

Quoting Eric W. Biederman (ebied...@xmission.com):
> 
> - The context in which devpts is mounted has no effect on the creation
>   of ptys as the /dev/ptmx interface has been used by unprivileged
>   users for many years.
> 
> - Only support unprivileged mounts in combination with the newinstance
>   option to ensure that mounting of /dev/pts in a user namespace will
>   not allow the options of an existing mount of devpts to be modified.
> 
> - Create /dev/pts/ptmx as the root user in the user namespace that
>   mounts devpts so that it's permissions to be changed.
> 
> Signed-off-by: "Eric W. Biederman" 

Acked-by: Serge Hallyn 

> ---
>  fs/devpts/inode.c |   18 ++
>  1 files changed, 18 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
> index 472e6be..073d30b 100644
> --- a/fs/devpts/inode.c
> +++ b/fs/devpts/inode.c
> @@ -243,6 +243,13 @@ static int mknod_ptmx(struct super_block *sb)
>   struct dentry *root = sb->s_root;
>   struct pts_fs_info *fsi = DEVPTS_SB(sb);
>   struct pts_mount_opts *opts = >mount_opts;
> + kuid_t root_uid;
> + kgid_t root_gid;
> +
> + root_uid = make_kuid(current_user_ns(), 0);
> + root_gid = make_kgid(current_user_ns(), 0);
> + if (!uid_valid(root_uid) || !gid_valid(root_gid))
> + return -EINVAL;
>  
>   mutex_lock(>d_inode->i_mutex);
>  
> @@ -273,6 +280,8 @@ static int mknod_ptmx(struct super_block *sb)
>  
>   mode = S_IFCHR|opts->ptmxmode;
>   init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
> + inode->i_uid = root_uid;
> + inode->i_gid = root_gid;
>  
>   d_add(dentry, inode);
>  
> @@ -438,6 +447,12 @@ static struct dentry *devpts_mount(struct 
> file_system_type *fs_type,
>   if (error)
>   return ERR_PTR(error);
>  
> + /* Require newinstance for all user namespace mounts to ensure
> +  * the mount options are not changed.
> +  */
> + if ((current_user_ns() != _user_ns) && !opts.newinstance)
> + return ERR_PTR(-EINVAL);
> +
>   if (opts.newinstance)
>   s = sget(fs_type, NULL, set_anon_super, flags, NULL);
>   else
> @@ -491,6 +506,9 @@ static struct file_system_type devpts_fs_type = {
>   .name   = "devpts",
>   .mount  = devpts_mount,
>   .kill_sb= devpts_kill_sb,
> +#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
> + .fs_flags   = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
> +#endif
>  };
>  
>  /*
> -- 
> 1.7.5.4
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Re: [PATCH review 4/6] userns: Allow the userns root to mount of devpts

2013-01-26 Thread Serge E. Hallyn

Quoting Eric W. Biederman (ebied...@xmission.com):
 
 - The context in which devpts is mounted has no effect on the creation
   of ptys as the /dev/ptmx interface has been used by unprivileged
   users for many years.
 
 - Only support unprivileged mounts in combination with the newinstance
   option to ensure that mounting of /dev/pts in a user namespace will
   not allow the options of an existing mount of devpts to be modified.
 
 - Create /dev/pts/ptmx as the root user in the user namespace that
   mounts devpts so that it's permissions to be changed.
 
 Signed-off-by: Eric W. Biederman ebied...@xmission.com

Acked-by: Serge Hallyn serge.hal...@canonical.com

 ---
  fs/devpts/inode.c |   18 ++
  1 files changed, 18 insertions(+), 0 deletions(-)
 
 diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
 index 472e6be..073d30b 100644
 --- a/fs/devpts/inode.c
 +++ b/fs/devpts/inode.c
 @@ -243,6 +243,13 @@ static int mknod_ptmx(struct super_block *sb)
   struct dentry *root = sb-s_root;
   struct pts_fs_info *fsi = DEVPTS_SB(sb);
   struct pts_mount_opts *opts = fsi-mount_opts;
 + kuid_t root_uid;
 + kgid_t root_gid;
 +
 + root_uid = make_kuid(current_user_ns(), 0);
 + root_gid = make_kgid(current_user_ns(), 0);
 + if (!uid_valid(root_uid) || !gid_valid(root_gid))
 + return -EINVAL;
  
   mutex_lock(root-d_inode-i_mutex);
  
 @@ -273,6 +280,8 @@ static int mknod_ptmx(struct super_block *sb)
  
   mode = S_IFCHR|opts-ptmxmode;
   init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
 + inode-i_uid = root_uid;
 + inode-i_gid = root_gid;
  
   d_add(dentry, inode);
  
 @@ -438,6 +447,12 @@ static struct dentry *devpts_mount(struct 
 file_system_type *fs_type,
   if (error)
   return ERR_PTR(error);
  
 + /* Require newinstance for all user namespace mounts to ensure
 +  * the mount options are not changed.
 +  */
 + if ((current_user_ns() != init_user_ns)  !opts.newinstance)
 + return ERR_PTR(-EINVAL);
 +
   if (opts.newinstance)
   s = sget(fs_type, NULL, set_anon_super, flags, NULL);
   else
 @@ -491,6 +506,9 @@ static struct file_system_type devpts_fs_type = {
   .name   = devpts,
   .mount  = devpts_mount,
   .kill_sb= devpts_kill_sb,
 +#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
 + .fs_flags   = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
 +#endif
  };
  
  /*
 -- 
 1.7.5.4
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[PATCH review 4/6] userns: Allow the userns root to mount of devpts

2013-01-25 Thread Eric W. Biederman


- The context in which devpts is mounted has no effect on the creation
  of ptys as the /dev/ptmx interface has been used by unprivileged
  users for many years.

- Only support unprivileged mounts in combination with the newinstance
  option to ensure that mounting of /dev/pts in a user namespace will
  not allow the options of an existing mount of devpts to be modified.

- Create /dev/pts/ptmx as the root user in the user namespace that
  mounts devpts so that it's permissions to be changed.

Signed-off-by: "Eric W. Biederman" 
---
 fs/devpts/inode.c |   18 ++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 472e6be..073d30b 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -243,6 +243,13 @@ static int mknod_ptmx(struct super_block *sb)
struct dentry *root = sb->s_root;
struct pts_fs_info *fsi = DEVPTS_SB(sb);
struct pts_mount_opts *opts = >mount_opts;
+   kuid_t root_uid;
+   kgid_t root_gid;
+
+   root_uid = make_kuid(current_user_ns(), 0);
+   root_gid = make_kgid(current_user_ns(), 0);
+   if (!uid_valid(root_uid) || !gid_valid(root_gid))
+   return -EINVAL;
 
mutex_lock(>d_inode->i_mutex);
 
@@ -273,6 +280,8 @@ static int mknod_ptmx(struct super_block *sb)
 
mode = S_IFCHR|opts->ptmxmode;
init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
+   inode->i_uid = root_uid;
+   inode->i_gid = root_gid;
 
d_add(dentry, inode);
 
@@ -438,6 +447,12 @@ static struct dentry *devpts_mount(struct file_system_type 
*fs_type,
if (error)
return ERR_PTR(error);
 
+   /* Require newinstance for all user namespace mounts to ensure
+* the mount options are not changed.
+*/
+   if ((current_user_ns() != _user_ns) && !opts.newinstance)
+   return ERR_PTR(-EINVAL);
+
if (opts.newinstance)
s = sget(fs_type, NULL, set_anon_super, flags, NULL);
else
@@ -491,6 +506,9 @@ static struct file_system_type devpts_fs_type = {
.name   = "devpts",
.mount  = devpts_mount,
.kill_sb= devpts_kill_sb,
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+   .fs_flags   = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
+#endif
 };
 
 /*
-- 
1.7.5.4

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[PATCH review 4/6] userns: Allow the userns root to mount of devpts

2013-01-25 Thread Eric W. Biederman


- The context in which devpts is mounted has no effect on the creation
  of ptys as the /dev/ptmx interface has been used by unprivileged
  users for many years.

- Only support unprivileged mounts in combination with the newinstance
  option to ensure that mounting of /dev/pts in a user namespace will
  not allow the options of an existing mount of devpts to be modified.

- Create /dev/pts/ptmx as the root user in the user namespace that
  mounts devpts so that it's permissions to be changed.

Signed-off-by: Eric W. Biederman ebied...@xmission.com
---
 fs/devpts/inode.c |   18 ++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 472e6be..073d30b 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -243,6 +243,13 @@ static int mknod_ptmx(struct super_block *sb)
struct dentry *root = sb-s_root;
struct pts_fs_info *fsi = DEVPTS_SB(sb);
struct pts_mount_opts *opts = fsi-mount_opts;
+   kuid_t root_uid;
+   kgid_t root_gid;
+
+   root_uid = make_kuid(current_user_ns(), 0);
+   root_gid = make_kgid(current_user_ns(), 0);
+   if (!uid_valid(root_uid) || !gid_valid(root_gid))
+   return -EINVAL;
 
mutex_lock(root-d_inode-i_mutex);
 
@@ -273,6 +280,8 @@ static int mknod_ptmx(struct super_block *sb)
 
mode = S_IFCHR|opts-ptmxmode;
init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
+   inode-i_uid = root_uid;
+   inode-i_gid = root_gid;
 
d_add(dentry, inode);
 
@@ -438,6 +447,12 @@ static struct dentry *devpts_mount(struct file_system_type 
*fs_type,
if (error)
return ERR_PTR(error);
 
+   /* Require newinstance for all user namespace mounts to ensure
+* the mount options are not changed.
+*/
+   if ((current_user_ns() != init_user_ns)  !opts.newinstance)
+   return ERR_PTR(-EINVAL);
+
if (opts.newinstance)
s = sget(fs_type, NULL, set_anon_super, flags, NULL);
else
@@ -491,6 +506,9 @@ static struct file_system_type devpts_fs_type = {
.name   = devpts,
.mount  = devpts_mount,
.kill_sb= devpts_kill_sb,
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+   .fs_flags   = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
+#endif
 };
 
 /*
-- 
1.7.5.4

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Re: [PATCH review 4/6] userns: Allow the userns root to mount of devpts

Re: [PATCH review 4/6] userns: Allow the userns root to mount of devpts

[PATCH review 4/6] userns: Allow the userns root to mount of devpts

[PATCH review 4/6] userns: Allow the userns root to mount of devpts

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