@ -95,8 +95,6 @@ static struct ctl_table pty_root_table[] = {
static DEFINE_MUTEX ( allocated_ptys_lock ) ; static DEFINE_MUTEX ( allocated_ptys_lock ) ;
static struct vfsmount * devpts_mnt ;
struct pts_mount_opts { struct pts_mount_opts {
int setuid ; int setuid ;
int setgid ; int setgid ;
@ -104,7 +102,7 @@ struct pts_mount_opts {
kgid_t gid ; kgid_t gid ;
umode_t mode ; umode_t mode ;
umode_t ptmxmode ; umode_t ptmxmode ;
int newinstanc e; int reserv e;
int max ; int max ;
} ; } ;
@ -117,11 +115,9 @@ static const match_table_t tokens = {
{ Opt_uid , " uid=%u " } , { Opt_uid , " uid=%u " } ,
{ Opt_gid , " gid=%u " } , { Opt_gid , " gid=%u " } ,
{ Opt_mode , " mode=%o " } , { Opt_mode , " mode=%o " } ,
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
{ Opt_ptmxmode , " ptmxmode=%o " } , { Opt_ptmxmode , " ptmxmode=%o " } ,
{ Opt_newinstance , " newinstance " } , { Opt_newinstance , " newinstance " } ,
{ Opt_max , " max=%d " } , { Opt_max , " max=%d " } ,
# endif
{ Opt_err , NULL } { Opt_err , NULL }
} ; } ;
@ -137,15 +133,48 @@ static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
return sb - > s_fs_info ; return sb - > s_fs_info ;
} }
static inline struct super_block * pts_sb_from_inode ( struct inode * inode ) struct pts_fs_info * devpts_acquire ( struct file * filp )
{ {
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES struct pts_fs_info * result ;
if ( inode - > i_sb - > s_magic = = DEVPTS_SUPER_MAGIC ) struct path path ;
return inode - > i_sb ; struct super_block * sb ;
# endif int err ;
if ( ! devpts_mnt )
return NULL ; path = filp - > f_path ;
return devpts_mnt - > mnt_sb ; path_get ( & path ) ;
/* Has the devpts filesystem already been found? */
sb = path . mnt - > mnt_sb ;
if ( sb - > s_magic ! = DEVPTS_SUPER_MAGIC ) {
/* Is a devpts filesystem at "pts" in the same directory? */
err = path_pts ( & path ) ;
if ( err ) {
result = ERR_PTR ( err ) ;
goto out ;
}
/* Is the path the root of a devpts filesystem? */
result = ERR_PTR ( - ENODEV ) ;
sb = path . mnt - > mnt_sb ;
if ( ( sb - > s_magic ! = DEVPTS_SUPER_MAGIC ) | |
( path . mnt - > mnt_root ! = sb - > s_root ) )
goto out ;
}
/*
* pty code needs to hold extra references in case of last / dev / tty close
*/
atomic_inc ( & sb - > s_active ) ;
result = DEVPTS_SB ( sb ) ;
out :
path_put ( & path ) ;
return result ;
}
void devpts_release ( struct pts_fs_info * fsi )
{
deactivate_super ( fsi - > sb ) ;
} }
# define PARSE_MOUNT 0 # define PARSE_MOUNT 0
@ -154,9 +183,7 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode)
/*
/*
* parse_mount_options ( ) : * parse_mount_options ( ) :
* Set @ opts to mount options specified in @ data . If an option is not * Set @ opts to mount options specified in @ data . If an option is not
* specified in @ data , set it to its default value . The exception is * specified in @ data , set it to its default value .
* ' newinstance ' option which can only be set / cleared on a mount ( i . e .
* cannot be changed during remount ) .
* *
* Note : @ data may be NULL ( in which case all options are set to default ) . * Note : @ data may be NULL ( in which case all options are set to default ) .
*/ */
@ -174,9 +201,12 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
opts - > ptmxmode = DEVPTS_DEFAULT_PTMX_MODE ; opts - > ptmxmode = DEVPTS_DEFAULT_PTMX_MODE ;
opts - > max = NR_UNIX98_PTY_MAX ; opts - > max = NR_UNIX98_PTY_MAX ;
/* newinstance makes sense only on initial mount */ /* Only allow instances mounted from the initial mount
* namespace to tap the reserve pool of ptys .
*/
if ( op = = PARSE_MOUNT ) if ( op = = PARSE_MOUNT )
opts - > newinstance = 0 ; opts - > reserve =
( current - > nsproxy - > mnt_ns = = init_task . nsproxy - > mnt_ns ) ;
while ( ( p = strsep ( & data , " , " ) ) ! = NULL ) { while ( ( p = strsep ( & data , " , " ) ) ! = NULL ) {
substring_t args [ MAX_OPT_ARGS ] ; substring_t args [ MAX_OPT_ARGS ] ;
@ -211,16 +241,12 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
return - EINVAL ; return - EINVAL ;
opts - > mode = option & S_IALLUGO ; opts - > mode = option & S_IALLUGO ;
break ; break ;
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
case Opt_ptmxmode : case Opt_ptmxmode :
if ( match_octal ( & args [ 0 ] , & option ) ) if ( match_octal ( & args [ 0 ] , & option ) )
return - EINVAL ; return - EINVAL ;
opts - > ptmxmode = option & S_IALLUGO ; opts - > ptmxmode = option & S_IALLUGO ;
break ; break ;
case Opt_newinstance : case Opt_newinstance :
/* newinstance makes sense only on initial mount */
if ( op = = PARSE_MOUNT )
opts - > newinstance = 1 ;
break ; break ;
case Opt_max : case Opt_max :
if ( match_int ( & args [ 0 ] , & option ) | | if ( match_int ( & args [ 0 ] , & option ) | |
@ -228,7 +254,6 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
return - EINVAL ; return - EINVAL ;
opts - > max = option ; opts - > max = option ;
break ; break ;
# endif
default : default :
pr_err ( " called with bogus options \n " ) ; pr_err ( " called with bogus options \n " ) ;
return - EINVAL ; return - EINVAL ;
@ -238,7 +263,6 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
return 0 ; return 0 ;
} }
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
static int mknod_ptmx ( struct super_block * sb ) static int mknod_ptmx ( struct super_block * sb )
{ {
int mode ; int mode ;
@ -305,12 +329,6 @@ static void update_ptmx_mode(struct pts_fs_info *fsi)
inode - > i_mode = S_IFCHR | fsi - > mount_opts . ptmxmode ; inode - > i_mode = S_IFCHR | fsi - > mount_opts . ptmxmode ;
} }
} }
# else
static inline void update_ptmx_mode ( struct pts_fs_info * fsi )
{
return ;
}
# endif
static int devpts_remount ( struct super_block * sb , int * flags , char * data ) static int devpts_remount ( struct super_block * sb , int * flags , char * data )
{ {
@ -344,11 +362,9 @@ static int devpts_show_options(struct seq_file *seq, struct dentry *root)
seq_printf ( seq , " ,gid=%u " , seq_printf ( seq , " ,gid=%u " ,
from_kgid_munged ( & init_user_ns , opts - > gid ) ) ; from_kgid_munged ( & init_user_ns , opts - > gid ) ) ;
seq_printf ( seq , " ,mode=%03o " , opts - > mode ) ; seq_printf ( seq , " ,mode=%03o " , opts - > mode ) ;
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
seq_printf ( seq , " ,ptmxmode=%03o " , opts - > ptmxmode ) ; seq_printf ( seq , " ,ptmxmode=%03o " , opts - > ptmxmode ) ;
if ( opts - > max < NR_UNIX98_PTY_MAX ) if ( opts - > max < NR_UNIX98_PTY_MAX )
seq_printf ( seq , " ,max=%d " , opts - > max ) ; seq_printf ( seq , " ,max=%d " , opts - > max ) ;
# endif
return 0 ; return 0 ;
} }
@ -410,40 +426,11 @@ fail:
return - ENOMEM ; return - ENOMEM ;
} }
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
static int compare_init_pts_sb ( struct super_block * s , void * p )
{
if ( devpts_mnt )
return devpts_mnt - > mnt_sb = = s ;
return 0 ;
}
/*
/*
* devpts_mount ( ) * devpts_mount ( )
* *
* If the ' - o newinstance ' mount option was specified , mount a new * Mount a new ( private ) instance of devpts . PTYs created in this
* ( private ) instance of devpts . PTYs created in this instance are * instance are independent of the PTYs in other devpts instances .
* independent of the PTYs in other devpts instances .
*
* If the ' - o newinstance ' option was not specified , mount / remount the
* initial kernel mount of devpts . This type of mount gives the
* legacy , single - instance semantics .
*
* The ' newinstance ' option is needed to support multiple namespace
* semantics in devpts while preserving backward compatibility of the
* current ' single - namespace ' semantics . i . e all mounts of devpts
* without the ' newinstance ' mount option should bind to the initial
* kernel mount , like mount_single ( ) .
*
* Mounts with ' newinstance ' option create a new , private namespace .
*
* NOTE :
*
* For single - mount semantics , devpts cannot use mount_single ( ) ,
* because mount_single ( ) / sget ( ) find and use the super - block from
* the most recent mount of devpts . But that recent mount may be a
* ' newinstance ' mount and mount_single ( ) would pick the newinstance
* super - block instead of the initial super - block .
*/ */
static struct dentry * devpts_mount ( struct file_system_type * fs_type , static struct dentry * devpts_mount ( struct file_system_type * fs_type ,
int flags , const char * dev_name , void * data ) int flags , const char * dev_name , void * data )
@ -456,18 +443,7 @@ static struct dentry *devpts_mount(struct file_system_type *fs_type,
if ( error ) if ( error )
return ERR_PTR ( error ) ; return ERR_PTR ( error ) ;
/* Require newinstance for all user namespace mounts to ensure
s = sget ( fs_type , NULL , set_anon_super , flags , NULL ) ;
* 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
s = sget ( fs_type , compare_init_pts_sb , set_anon_super , flags ,
NULL ) ;
if ( IS_ERR ( s ) ) if ( IS_ERR ( s ) )
return ERR_CAST ( s ) ; return ERR_CAST ( s ) ;
@ -491,18 +467,6 @@ out_undo_sget:
return ERR_PTR ( error ) ; return ERR_PTR ( error ) ;
} }
# else
/*
* This supports only the legacy single - instance semantics ( no
* multiple - instance semantics )
*/
static struct dentry * devpts_mount ( struct file_system_type * fs_type , int flags ,
const char * dev_name , void * data )
{
return mount_single ( fs_type , flags , data , devpts_fill_super ) ;
}
# endif
static void devpts_kill_sb ( struct super_block * sb ) static void devpts_kill_sb ( struct super_block * sb )
{ {
struct pts_fs_info * fsi = DEVPTS_SB ( sb ) ; struct pts_fs_info * fsi = DEVPTS_SB ( sb ) ;
@ -516,9 +480,7 @@ static struct file_system_type devpts_fs_type = {
. name = " devpts " , . name = " devpts " ,
. mount = devpts_mount , . mount = devpts_mount ,
. kill_sb = devpts_kill_sb , . kill_sb = devpts_kill_sb ,
# ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
. fs_flags = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT , . fs_flags = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT ,
# endif
} ; } ;
/*
/*
@ -531,16 +493,13 @@ int devpts_new_index(struct pts_fs_info *fsi)
int index ; int index ;
int ida_ret ; int ida_ret ;
if ( ! fsi )
return - ENODEV ;
retry : retry :
if ( ! ida_pre_get ( & fsi - > allocated_ptys , GFP_KERNEL ) ) if ( ! ida_pre_get ( & fsi - > allocated_ptys , GFP_KERNEL ) )
return - ENOMEM ; return - ENOMEM ;
mutex_lock ( & allocated_ptys_lock ) ; mutex_lock ( & allocated_ptys_lock ) ;
if ( pty_count > = pty_limit - if ( pty_count > = ( pty_limit -
( fsi - > mount_opts . newinstance ? pty_reserve : 0 ) ) { ( fsi - > mount_opts . reserve ? 0 : pty_reserve ) ) ) {
mutex_unlock ( & allocated_ptys_lock ) ; mutex_unlock ( & allocated_ptys_lock ) ;
return - ENOSPC ; return - ENOSPC ;
} }
@ -571,30 +530,6 @@ void devpts_kill_index(struct pts_fs_info *fsi, int idx)
mutex_unlock ( & allocated_ptys_lock ) ; mutex_unlock ( & allocated_ptys_lock ) ;
} }
/*
* pty code needs to hold extra references in case of last / dev / tty close
*/
struct pts_fs_info * devpts_get_ref ( struct inode * ptmx_inode , struct file * file )
{
struct super_block * sb ;
struct pts_fs_info * fsi ;
sb = pts_sb_from_inode ( ptmx_inode ) ;
if ( ! sb )
return NULL ;
fsi = DEVPTS_SB ( sb ) ;
if ( ! fsi )
return NULL ;
atomic_inc ( & sb - > s_active ) ;
return fsi ;
}
void devpts_put_ref ( struct pts_fs_info * fsi )
{
deactivate_super ( fsi - > sb ) ;
}
/**
/**
* devpts_pty_new - - create a new inode in / dev / pts / * devpts_pty_new - - create a new inode in / dev / pts /
* @ ptmx_inode : inode of the master * @ ptmx_inode : inode of the master
@ -607,16 +542,12 @@ void devpts_put_ref(struct pts_fs_info *fsi)
struct dentry * devpts_pty_new ( struct pts_fs_info * fsi , int index , void * priv ) struct dentry * devpts_pty_new ( struct pts_fs_info * fsi , int index , void * priv )
{ {
struct dentry * dentry ; struct dentry * dentry ;
struct super_block * sb ; struct super_block * sb = fsi - > sb ;
struct inode * inode ; struct inode * inode ;
struct dentry * root ; struct dentry * root ;
struct pts_mount_opts * opts ; struct pts_mount_opts * opts ;
char s [ 12 ] ; char s [ 12 ] ;
if ( ! fsi )
return ERR_PTR ( - ENODEV ) ;
sb = fsi - > sb ;
root = sb - > s_root ; root = sb - > s_root ;
opts = & fsi - > mount_opts ; opts = & fsi - > mount_opts ;
@ -676,20 +607,8 @@ void devpts_pty_kill(struct dentry *dentry)
static int __init init_devpts_fs ( void ) static int __init init_devpts_fs ( void )
{ {
int err = register_filesystem ( & devpts_fs_type ) ; int err = register_filesystem ( & devpts_fs_type ) ;
struct ctl_table_header * table ;
if ( ! err ) { if ( ! err ) {
struct vfsmount * mnt ; register_sysctl_table ( pty_root_table ) ;
table = register_sysctl_table ( pty_root_table ) ;
mnt = kern_mount ( & devpts_fs_type ) ;
if ( IS_ERR ( mnt ) ) {
err = PTR_ERR ( mnt ) ;
unregister_filesystem ( & devpts_fs_type ) ;
unregister_sysctl_table ( table ) ;
} else {
devpts_mnt = mnt ;
}
} }
return err ; return err ;
} }
Eric W. Biederman
9 years ago
committed by