/* * linux/fs/file_table.c * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu) */ #include <linux/string.h>#include <linux/slab.h>#include <linux/file.h>#include <linux/fdtable.h>#include <linux/init.h>#include <linux/module.h>#include <linux/fs.h>#include <linux/security.h>#include <linux/eventpoll.h>#include <linux/rcupdate.h>#include <linux/mount.h>#include <linux/capability.h>#include <linux/cdev.h>#include <linux/fsnotify.h>#include <linux/sysctl.h>#include <linux/lglock.h>#include <linux/percpu_counter.h>#include <linux/percpu.h>#include <linux/ima.h> #include <linux/atomic.h> #include "internal.h" /* sysctl tunables... */struct files_stat_struct files_stat = { .max_files = NR_FILE}; DEFINE_LGLOCK(files_lglock); /* SLAB cache for file structures */static struct kmem_cache *filp_cachep __read_mostly; static struct percpu_counter nr_files __cacheline_aligned_in_smp; static inline void file_free_rcu(struct rcu_head *head){ struct file *f = container_of(head, struct file, f_u.fu_rcuhead); put_cred(f->f_cred); kmem_cache_free(filp_cachep, f);} static inline void file_free(struct file *f){ percpu_counter_dec(&nr_files); file_check_state(f); call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);} /* * Return the total number of open files in the system */static long get_nr_files(void){ return percpu_counter_read_positive(&nr_files);} /* * Return the maximum number of open files in the system */unsigned long get_max_files(void){ return files_stat.max_files;}EXPORT_SYMBOL_GPL(get_max_files); /* * Handle nr_files sysctl */#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)int proc_nr_files(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos){ files_stat.nr_files = get_nr_files(); return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);}#elseint proc_nr_files(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos){ return -ENOSYS;}#endif /* Find an unused file structure and return a pointer to it. * Returns NULL, if there are no more free file structures or * we run out of memory. * * Be very careful using this. You are responsible for * getting write access to any mount that you might assign * to this filp, if it is opened for write. If this is not * done, you will imbalance int the mount's writer count * and a warning at __fput() time. */struct file *get_empty_filp(void){ const struct cred *cred = current_cred(); static long old_max; struct file * f; /* * Privileged users can go above max_files */ if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) { /* * percpu_counters are inaccurate. Do an expensive check before * we go and fail. */ if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files) goto over; } f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL); if (f == NULL) goto fail; percpu_counter_inc(&nr_files); f->f_cred = get_cred(cred); if (security_file_alloc(f)) goto fail_sec; INIT_LIST_HEAD(&f->f_u.fu_list); atomic_long_set(&f->f_count, 1); rwlock_init(&f->f_owner.lock); spin_lock_init(&f->f_lock); eventpoll_init_file(f); /* f->f_version: 0 */ return f; over: /* Ran out of filps - report that */ if (get_nr_files() > old_max) { pr_info("VFS: file-max limit %lu reached\n", get_max_files()); old_max = get_nr_files(); } goto fail; fail_sec: file_free(f);fail: return NULL;} /** * alloc_file - allocate and initialize a 'struct file' * @mnt: the vfsmount on which the file will reside * @dentry: the dentry representing the new file * @mode: the mode with which the new file will be opened * @fop: the 'struct file_operations' for the new file * * Use this instead of get_empty_filp() to get a new * 'struct file'. Do so because of the same initialization * pitfalls reasons listed for init_file(). This is a * preferred interface to using init_file(). * * If all the callers of init_file() are eliminated, its * code should be moved into this function. */struct file *alloc_file(struct path *path, fmode_t mode, const struct file_operations *fop){ struct file *file; file = get_empty_filp(); if (!file) return NULL; file->f_path = *path; file->f_mapping = path->dentry->d_inode->i_mapping; file->f_mode = mode; file->f_op = fop; /* * These mounts don't really matter in practice * for r/o bind mounts. They aren't userspace- * visible. We do this for consistency, and so * that we can do debugging checks at __fput() */ if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) { file_take_write(file); WARN_ON(mnt_clone_write(path->mnt)); } if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) i_readcount_inc(path->dentry->d_inode); return file;}EXPORT_SYMBOL(alloc_file); /** * drop_file_write_access - give up ability to write to a file * @file: the file to which we will stop writing * * This is a central place which will give up the ability * to write to @file, along with access to write through * its vfsmount. */static void drop_file_write_access(struct file *file){ struct vfsmount *mnt = file->f_path.mnt; struct dentry *dentry = file->f_path.dentry; struct inode *inode = dentry->d_inode; put_write_access(inode); if (special_file(inode->i_mode)) return; if (file_check_writeable(file) != 0) return; mnt_drop_write(mnt); file_release_write(file);} /* the real guts of fput() - releasing the last reference to file */static void __fput(struct file *file){ struct dentry *dentry = file->f_path.dentry; struct vfsmount *mnt = file->f_path.mnt; struct inode *inode = dentry->d_inode; might_sleep(); fsnotify_close(file); /* * The function eventpoll_release() should be the first called * in the file cleanup chain. */ eventpoll_release(file); locks_remove_flock(file); if (unlikely(file->f_flags & FASYNC)) { if (file->f_op && file->f_op->fasync) file->f_op->fasync(-1, file, 0); } if (file->f_op && file->f_op->release) file->f_op->release(inode, file); security_file_free(file); ima_file_free(file); if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL && !(file->f_mode & FMODE_PATH))) { cdev_put(inode->i_cdev); } fops_put(file->f_op); put_pid(file->f_owner.pid); file_sb_list_del(file); if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) i_readcount_dec(inode); if (file->f_mode & FMODE_WRITE) drop_file_write_access(file); file->f_path.dentry = NULL; file->f_path.mnt = NULL; file_free(file); dput(dentry); mntput(mnt);} void fput(struct file *file){ if (atomic_long_dec_and_test(&file->f_count)) __fput(file);} EXPORT_SYMBOL(fput); struct file *fget(unsigned int fd){ struct file *file; struct files_struct *files = current->files; rcu_read_lock(); file = fcheck_files(files, fd); if (file) { /* File object ref couldn't be taken */ if (file->f_mode & FMODE_PATH || !atomic_long_inc_not_zero(&file->f_count)) file = NULL; } rcu_read_unlock(); return file;} EXPORT_SYMBOL(fget); struct file *fget_raw(unsigned int fd){ struct file *file; struct files_struct *files = current->files; rcu_read_lock(); file = fcheck_files(files, fd); if (file) { /* File object ref couldn't be taken */ if (!atomic_long_inc_not_zero(&file->f_count)) file = NULL; } rcu_read_unlock(); return file;} EXPORT_SYMBOL(fget_raw); /* * Lightweight file lookup - no refcnt increment if fd table isn't shared. * * You can use this instead of fget if you satisfy all of the following * conditions: * 1) You must call fput_light before exiting the syscall and returning control * to userspace (i.e. you cannot remember the returned struct file * after * returning to userspace). * 2) You must not call filp_close on the returned struct file * in between * calls to fget_light and fput_light. * 3) You must not clone the current task in between the calls to fget_light * and fput_light. * * The fput_needed flag returned by fget_light should be passed to the * corresponding fput_light. */struct file *fget_light(unsigned int fd, int *fput_needed){ struct file *file; struct files_struct *files = current->files; *fput_needed = 0; if (atomic_read(&files->count) == 1) { file = fcheck_files(files, fd); if (file && (file->f_mode & FMODE_PATH)) file = NULL; } else { rcu_read_lock(); file = fcheck_files(files, fd); if (file) { if (!(file->f_mode & FMODE_PATH) && atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ file = NULL; } rcu_read_unlock(); } return file;} struct file *fget_raw_light(unsigned int fd, int *fput_needed){ struct file *file; struct files_struct *files = current->files; *fput_needed = 0; if (atomic_read(&files->count) == 1) { file = fcheck_files(files, fd); } else { rcu_read_lock(); file = fcheck_files(files, fd); if (file) { if (atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ file = NULL; } rcu_read_unlock(); } return file;} void put_filp(struct file *file){ if (atomic_long_dec_and_test(&file->f_count)) { security_file_free(file); file_sb_list_del(file); file_free(file); }} static inline int file_list_cpu(struct file *file){#ifdef CONFIG_SMP return file->f_sb_list_cpu;#else return smp_processor_id();#endif} /* helper for file_sb_list_add to reduce ifdefs */static inline void __file_sb_list_add(struct file *file, struct super_block *sb){ struct list_head *list;#ifdef CONFIG_SMP int cpu; cpu = smp_processor_id(); file->f_sb_list_cpu = cpu; list = per_cpu_ptr(sb->s_files, cpu);#else list = &sb->s_files;#endif list_add(&file->f_u.fu_list, list);} /** * file_sb_list_add - add a file to the sb's file list * @file: file to add * @sb: sb to add it to * * Use this function to associate a file with the superblock of the inode it * refers to. */void file_sb_list_add(struct file *file, struct super_block *sb){ lg_local_lock(&files_lglock); __file_sb_list_add(file, sb); lg_local_unlock(&files_lglock);} /** * file_sb_list_del - remove a file from the sb's file list * @file: file to remove * @sb: sb to remove it from * * Use this function to remove a file from its superblock. */void file_sb_list_del(struct file *file){ if (!list_empty(&file->f_u.fu_list)) { lg_local_lock_cpu(&files_lglock, file_list_cpu(file)); list_del_init(&file->f_u.fu_list); lg_local_unlock_cpu(&files_lglock, file_list_cpu(file)); }} #ifdef CONFIG_SMP /* * These macros iterate all files on all CPUs for a given superblock. * files_lglock must be held globally. */#define do_file_list_for_each_entry(__sb, __file) \{ \ int i; \ for_each_possible_cpu(i) { \ struct list_head *list; \ list = per_cpu_ptr((__sb)->s_files, i); \ list_for_each_entry((__file), list, f_u.fu_list) #define while_file_list_for_each_entry \ } \} #else #define do_file_list_for_each_entry(__sb, __file) \{ \ struct list_head *list; \ list = &(sb)->s_files; \ list_for_each_entry((__file), list, f_u.fu_list) #define while_file_list_for_each_entry \} #endif /** * mark_files_ro - mark all files read-only * @sb: superblock in question * * All files are marked read-only. We don't care about pending * delete files so this should be used in 'force' mode only. */void mark_files_ro(struct super_block *sb){ struct file *f; retry: lg_global_lock(&files_lglock); do_file_list_for_each_entry(sb, f) { struct vfsmount *mnt; if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) continue; if (!file_count(f)) continue; if (!(f->f_mode & FMODE_WRITE)) continue; spin_lock(&f->f_lock); f->f_mode &= ~FMODE_WRITE; spin_unlock(&f->f_lock); if (file_check_writeable(f) != 0) continue;Lines 1–500 of 529. Load more
/* * linux/fs/file_table.c * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu) */ #include <linux/string.h> #include <linux/slab.h> #include <linux/file.h> #include <linux/fdtable.h> #include <linux/init.h> #include <linux/module.h> #include <linux/fs.h> #include <linux/security.h> #include <linux/eventpoll.h> #include <linux/rcupdate.h> #include <linux/mount.h> #include <linux/capability.h> #include <linux/cdev.h> #include <linux/fsnotify.h> #include <linux/sysctl.h> #include <linux/lglock.h> #include <linux/percpu_counter.h> #include <linux/percpu.h> #include <linux/ima.h> #include <linux/atomic.h> #include "internal.h" /* sysctl tunables... */ struct files_stat_struct files_stat = { .max_files = NR_FILE }; DEFINE_LGLOCK(files_lglock); /* SLAB cache for file structures */ static struct kmem_cache *filp_cachep __read_mostly; static struct percpu_counter nr_files __cacheline_aligned_in_smp; static inline void file_free_rcu(struct rcu_head *head) { struct file *f = container_of(head, struct file, f_u.fu_rcuhead); put_cred(f->f_cred); kmem_cache_free(filp_cachep, f); } static inline void file_free(struct file *f) { percpu_counter_dec(&nr_files); file_check_state(f); call_rcu(&f->f_u.fu_rcuhead, file_free_rcu); } /* * Return the total number of open files in the system */ static long get_nr_files(void) { return percpu_counter_read_positive(&nr_files); } /* * Return the maximum number of open files in the system */ unsigned long get_max_files(void) { return files_stat.max_files; } EXPORT_SYMBOL_GPL(get_max_files); /* * Handle nr_files sysctl */ #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) int proc_nr_files(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { files_stat.nr_files = get_nr_files(); return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); } #else int proc_nr_files(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } #endif /* Find an unused file structure and return a pointer to it. * Returns NULL, if there are no more free file structures or * we run out of memory. * * Be very careful using this. You are responsible for * getting write access to any mount that you might assign * to this filp, if it is opened for write. If this is not * done, you will imbalance int the mount's writer count * and a warning at __fput() time. */ struct file *get_empty_filp(void) { const struct cred *cred = current_cred(); static long old_max; struct file * f; /* * Privileged users can go above max_files */ if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) { /* * percpu_counters are inaccurate. Do an expensive check before * we go and fail. */ if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files) goto over; } f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL); if (f == NULL) goto fail; percpu_counter_inc(&nr_files); f->f_cred = get_cred(cred); if (security_file_alloc(f)) goto fail_sec; INIT_LIST_HEAD(&f->f_u.fu_list); atomic_long_set(&f->f_count, 1); rwlock_init(&f->f_owner.lock); spin_lock_init(&f->f_lock); eventpoll_init_file(f); /* f->f_version: 0 */ return f; over: /* Ran out of filps - report that */ if (get_nr_files() > old_max) { pr_info("VFS: file-max limit %lu reached\n", get_max_files()); old_max = get_nr_files(); } goto fail; fail_sec: file_free(f); fail: return NULL; } /** * alloc_file - allocate and initialize a 'struct file' * @mnt: the vfsmount on which the file will reside * @dentry: the dentry representing the new file * @mode: the mode with which the new file will be opened * @fop: the 'struct file_operations' for the new file * * Use this instead of get_empty_filp() to get a new * 'struct file'. Do so because of the same initialization * pitfalls reasons listed for init_file(). This is a * preferred interface to using init_file(). * * If all the callers of init_file() are eliminated, its * code should be moved into this function. */ struct file *alloc_file(struct path *path, fmode_t mode, const struct file_operations *fop) { struct file *file; file = get_empty_filp(); if (!file) return NULL; file->f_path = *path; file->f_mapping = path->dentry->d_inode->i_mapping; file->f_mode = mode; file->f_op = fop; /* * These mounts don't really matter in practice * for r/o bind mounts. They aren't userspace- * visible. We do this for consistency, and so * that we can do debugging checks at __fput() */ if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) { file_take_write(file); WARN_ON(mnt_clone_write(path->mnt)); } if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) i_readcount_inc(path->dentry->d_inode); return file; } EXPORT_SYMBOL(alloc_file); /** * drop_file_write_access - give up ability to write to a file * @file: the file to which we will stop writing * * This is a central place which will give up the ability * to write to @file, along with access to write through * its vfsmount. */ static void drop_file_write_access(struct file *file) { struct vfsmount *mnt = file->f_path.mnt; struct dentry *dentry = file->f_path.dentry; struct inode *inode = dentry->d_inode; put_write_access(inode); if (special_file(inode->i_mode)) return; if (file_check_writeable(file) != 0) return; mnt_drop_write(mnt); file_release_write(file); } /* the real guts of fput() - releasing the last reference to file */ static void __fput(struct file *file) { struct dentry *dentry = file->f_path.dentry; struct vfsmount *mnt = file->f_path.mnt; struct inode *inode = dentry->d_inode; might_sleep(); fsnotify_close(file); /* * The function eventpoll_release() should be the first called * in the file cleanup chain. */ eventpoll_release(file); locks_remove_flock(file); if (unlikely(file->f_flags & FASYNC)) { if (file->f_op && file->f_op->fasync) file->f_op->fasync(-1, file, 0); } if (file->f_op && file->f_op->release) file->f_op->release(inode, file); security_file_free(file); ima_file_free(file); if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL && !(file->f_mode & FMODE_PATH))) { cdev_put(inode->i_cdev); } fops_put(file->f_op); put_pid(file->f_owner.pid); file_sb_list_del(file); if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) i_readcount_dec(inode); if (file->f_mode & FMODE_WRITE) drop_file_write_access(file); file->f_path.dentry = NULL; file->f_path.mnt = NULL; file_free(file); dput(dentry); mntput(mnt); } void fput(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) __fput(file); } EXPORT_SYMBOL(fput); struct file *fget(unsigned int fd) { struct file *file; struct files_struct *files = current->files; rcu_read_lock(); file = fcheck_files(files, fd); if (file) { /* File object ref couldn't be taken */ if (file->f_mode & FMODE_PATH || !atomic_long_inc_not_zero(&file->f_count)) file = NULL; } rcu_read_unlock(); return file; } EXPORT_SYMBOL(fget); struct file *fget_raw(unsigned int fd) { struct file *file; struct files_struct *files = current->files; rcu_read_lock(); file = fcheck_files(files, fd); if (file) { /* File object ref couldn't be taken */ if (!atomic_long_inc_not_zero(&file->f_count)) file = NULL; } rcu_read_unlock(); return file; } EXPORT_SYMBOL(fget_raw); /* * Lightweight file lookup - no refcnt increment if fd table isn't shared. * * You can use this instead of fget if you satisfy all of the following * conditions: * 1) You must call fput_light before exiting the syscall and returning control * to userspace (i.e. you cannot remember the returned struct file * after * returning to userspace). * 2) You must not call filp_close on the returned struct file * in between * calls to fget_light and fput_light. * 3) You must not clone the current task in between the calls to fget_light * and fput_light. * * The fput_needed flag returned by fget_light should be passed to the * corresponding fput_light. */ struct file *fget_light(unsigned int fd, int *fput_needed) { struct file *file; struct files_struct *files = current->files; *fput_needed = 0; if (atomic_read(&files->count) == 1) { file = fcheck_files(files, fd); if (file && (file->f_mode & FMODE_PATH)) file = NULL; } else { rcu_read_lock(); file = fcheck_files(files, fd); if (file) { if (!(file->f_mode & FMODE_PATH) && atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ file = NULL; } rcu_read_unlock(); } return file; } struct file *fget_raw_light(unsigned int fd, int *fput_needed) { struct file *file; struct files_struct *files = current->files; *fput_needed = 0; if (atomic_read(&files->count) == 1) { file = fcheck_files(files, fd); } else { rcu_read_lock(); file = fcheck_files(files, fd); if (file) { if (atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ file = NULL; } rcu_read_unlock(); } return file; } void put_filp(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) { security_file_free(file); file_sb_list_del(file); file_free(file); } } static inline int file_list_cpu(struct file *file) { #ifdef CONFIG_SMP return file->f_sb_list_cpu; #else return smp_processor_id(); #endif } /* helper for file_sb_list_add to reduce ifdefs */ static inline void __file_sb_list_add(struct file *file, struct super_block *sb) { struct list_head *list; #ifdef CONFIG_SMP int cpu; cpu = smp_processor_id(); file->f_sb_list_cpu = cpu; list = per_cpu_ptr(sb->s_files, cpu); #else list = &sb->s_files; #endif list_add(&file->f_u.fu_list, list); } /** * file_sb_list_add - add a file to the sb's file list * @file: file to add * @sb: sb to add it to * * Use this function to associate a file with the superblock of the inode it * refers to. */ void file_sb_list_add(struct file *file, struct super_block *sb) { lg_local_lock(&files_lglock); __file_sb_list_add(file, sb); lg_local_unlock(&files_lglock); } /** * file_sb_list_del - remove a file from the sb's file list * @file: file to remove * @sb: sb to remove it from * * Use this function to remove a file from its superblock. */ void file_sb_list_del(struct file *file) { if (!list_empty(&file->f_u.fu_list)) { lg_local_lock_cpu(&files_lglock, file_list_cpu(file)); list_del_init(&file->f_u.fu_list); lg_local_unlock_cpu(&files_lglock, file_list_cpu(file)); } } #ifdef CONFIG_SMP /* * These macros iterate all files on all CPUs for a given superblock. * files_lglock must be held globally. */ #define do_file_list_for_each_entry(__sb, __file) \ { \ int i; \ for_each_possible_cpu(i) { \ struct list_head *list; \ list = per_cpu_ptr((__sb)->s_files, i); \ list_for_each_entry((__file), list, f_u.fu_list) #define while_file_list_for_each_entry \ } \ } #else #define do_file_list_for_each_entry(__sb, __file) \ { \ struct list_head *list; \ list = &(sb)->s_files; \ list_for_each_entry((__file), list, f_u.fu_list) #define while_file_list_for_each_entry \ } #endif /** * mark_files_ro - mark all files read-only * @sb: superblock in question * * All files are marked read-only. We don't care about pending * delete files so this should be used in 'force' mode only. */ void mark_files_ro(struct super_block *sb) { struct file *f; retry: lg_global_lock(&files_lglock); do_file_list_for_each_entry(sb, f) { struct vfsmount *mnt; if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) continue; if (!file_count(f)) continue; if (!(f->f_mode & FMODE_WRITE)) continue; spin_lock(&f->f_lock); f->f_mode &= ~FMODE_WRITE; spin_unlock(&f->f_lock); if (file_check_writeable(f) != 0) continue;