Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : /*
       3             :  * descriptor table internals; you almost certainly want file.h instead.
       4             :  */
       5             : 
       6             : #ifndef __LINUX_FDTABLE_H
       7             : #define __LINUX_FDTABLE_H
       8             : 
       9             : #include <linux/posix_types.h>
      10             : #include <linux/compiler.h>
      11             : #include <linux/spinlock.h>
      12             : #include <linux/rcupdate.h>
      13             : #include <linux/nospec.h>
      14             : #include <linux/types.h>
      15             : #include <linux/init.h>
      16             : #include <linux/fs.h>
      17             : 
      18             : #include <linux/atomic.h>
      19             : 
      20             : /*
      21             :  * The default fd array needs to be at least BITS_PER_LONG,
      22             :  * as this is the granularity returned by copy_fdset().
      23             :  */
      24             : #define NR_OPEN_DEFAULT BITS_PER_LONG
      25             : #define NR_OPEN_MAX ~0U
      26             : 
      27             : struct fdtable {
      28             :         unsigned int max_fds;
      29             :         struct file __rcu **fd;      /* current fd array */
      30             :         unsigned long *close_on_exec;
      31             :         unsigned long *open_fds;
      32             :         unsigned long *full_fds_bits;
      33             :         struct rcu_head rcu;
      34             : };
      35             : 
      36           0 : static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
      37             : {
      38           0 :         return test_bit(fd, fdt->close_on_exec);
      39             : }
      40             : 
      41           0 : static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
      42             : {
      43           0 :         return test_bit(fd, fdt->open_fds);
      44             : }
      45             : 
      46             : /*
      47             :  * Open file table structure
      48             :  */
      49             : struct files_struct {
      50             :   /*
      51             :    * read mostly part
      52             :    */
      53             :         atomic_t count;
      54             :         bool resize_in_progress;
      55             :         wait_queue_head_t resize_wait;
      56             : 
      57             :         struct fdtable __rcu *fdt;
      58             :         struct fdtable fdtab;
      59             :   /*
      60             :    * written part on a separate cache line in SMP
      61             :    */
      62             :         spinlock_t file_lock ____cacheline_aligned_in_smp;
      63             :         unsigned int next_fd;
      64             :         unsigned long close_on_exec_init[1];
      65             :         unsigned long open_fds_init[1];
      66             :         unsigned long full_fds_bits_init[1];
      67             :         struct file __rcu * fd_array[NR_OPEN_DEFAULT];
      68             : };
      69             : 
      70             : struct file_operations;
      71             : struct vfsmount;
      72             : struct dentry;
      73             : 
      74             : #define rcu_dereference_check_fdtable(files, fdtfd) \
      75             :         rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
      76             : 
      77             : #define files_fdtable(files) \
      78             :         rcu_dereference_check_fdtable((files), (files)->fdt)
      79             : 
      80             : /*
      81             :  * The caller must ensure that fd table isn't shared or hold rcu or file lock
      82             :  */
      83             : static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd)
      84             : {
      85           0 :         struct fdtable *fdt = rcu_dereference_raw(files->fdt);
      86             : 
      87           0 :         if (fd < fdt->max_fds) {
      88           0 :                 fd = array_index_nospec(fd, fdt->max_fds);
      89           0 :                 return rcu_dereference_raw(fdt->fd[fd]);
      90             :         }
      91             :         return NULL;
      92             : }
      93             : 
      94             : static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd)
      95             : {
      96             :         RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
      97             :                            "suspicious rcu_dereference_check() usage");
      98           0 :         return files_lookup_fd_raw(files, fd);
      99             : }
     100             : 
     101             : static inline struct file *files_lookup_fd_rcu(struct files_struct *files, unsigned int fd)
     102             : {
     103             :         RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
     104             :                            "suspicious rcu_dereference_check() usage");
     105           0 :         return files_lookup_fd_raw(files, fd);
     106             : }
     107             : 
     108             : static inline struct file *lookup_fd_rcu(unsigned int fd)
     109             : {
     110           0 :         return files_lookup_fd_rcu(current->files, fd);
     111             : }
     112             : 
     113             : struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd);
     114             : struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *fd);
     115             : 
     116             : struct task_struct;
     117             : 
     118             : void put_files_struct(struct files_struct *fs);
     119             : int unshare_files(void);
     120             : struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy;
     121             : void do_close_on_exec(struct files_struct *);
     122             : int iterate_fd(struct files_struct *, unsigned,
     123             :                 int (*)(const void *, struct file *, unsigned),
     124             :                 const void *);
     125             : 
     126             : extern int close_fd(unsigned int fd);
     127             : extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
     128             : extern struct file *close_fd_get_file(unsigned int fd);
     129             : extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
     130             :                       struct files_struct **new_fdp);
     131             : 
     132             : extern struct kmem_cache *files_cachep;
     133             : 
     134             : #endif /* __LINUX_FDTABLE_H */