// SPDX-License-Identifier: GPL-2.0 /* * /proc/sys support */ #include <linux/init.h> #include <linux/sysctl.h> #include <linux/poll.h> #include <linux/proc_fs.h> #include <linux/printk.h> #include <linux/security.h> #include <linux/sched.h> #include <linux/cred.h> #include <linux/namei.h> #include <linux/mm.h> #include <linux/uio.h> #include <linux/module.h> #include <linux/bpf-cgroup.h> #include <linux/mount.h> #include <linux/kmemleak.h> #include "internal.h" #define list_for_each_table_entry(entry, header) … static const struct dentry_operations proc_sys_dentry_operations; static const struct file_operations proc_sys_file_operations; static const struct inode_operations proc_sys_inode_operations; static const struct file_operations proc_sys_dir_file_operations; static const struct inode_operations proc_sys_dir_operations; /* Support for permanently empty directories */ static struct ctl_table sysctl_mount_point[] = …; /** * register_sysctl_mount_point() - registers a sysctl mount point * @path: path for the mount point * * Used to create a permanently empty directory to serve as mount point. * There are some subtle but important permission checks this allows in the * case of unprivileged mounts. */ struct ctl_table_header *register_sysctl_mount_point(const char *path) { … } EXPORT_SYMBOL(…); #define sysctl_is_perm_empty_ctl_header(hptr) … #define sysctl_set_perm_empty_ctl_header(hptr) … #define sysctl_clear_perm_empty_ctl_header(hptr) … void proc_sys_poll_notify(struct ctl_table_poll *poll) { … } static struct ctl_table root_table[] = …; static struct ctl_table_root sysctl_table_root = …; static DEFINE_SPINLOCK(sysctl_lock); static void drop_sysctl_table(struct ctl_table_header *header); static int sysctl_follow_link(struct ctl_table_header **phead, struct ctl_table **pentry); static int insert_links(struct ctl_table_header *head); static void put_links(struct ctl_table_header *header); static void sysctl_print_dir(struct ctl_dir *dir) { … } static int namecmp(const char *name1, int len1, const char *name2, int len2) { … } /* Called under sysctl_lock */ static struct ctl_table *find_entry(struct ctl_table_header **phead, struct ctl_dir *dir, const char *name, int namelen) { … } static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry) { … } static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry) { … } static void init_header(struct ctl_table_header *head, struct ctl_table_root *root, struct ctl_table_set *set, struct ctl_node *node, struct ctl_table *table, size_t table_size) { … } static void erase_header(struct ctl_table_header *head) { … } static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header) { … } /* called under sysctl_lock */ static int use_table(struct ctl_table_header *p) { … } /* called under sysctl_lock */ static void unuse_table(struct ctl_table_header *p) { … } static void proc_sys_invalidate_dcache(struct ctl_table_header *head) { … } /* called under sysctl_lock, will reacquire if has to wait */ static void start_unregistering(struct ctl_table_header *p) { … } static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head) { … } static void sysctl_head_finish(struct ctl_table_header *head) { … } static struct ctl_table_set * lookup_header_set(struct ctl_table_root *root) { … } static struct ctl_table *lookup_entry(struct ctl_table_header **phead, struct ctl_dir *dir, const char *name, int namelen) { … } static struct ctl_node *first_usable_entry(struct rb_node *node) { … } static void first_entry(struct ctl_dir *dir, struct ctl_table_header **phead, struct ctl_table **pentry) { … } static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry) { … } /* * sysctl_perm does NOT grant the superuser all rights automatically, because * some sysctl variables are readonly even to root. */ static int test_perm(int mode, int op) { … } static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op) { … } static struct inode *proc_sys_make_inode(struct super_block *sb, struct ctl_table_header *head, struct ctl_table *table) { … } void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head) { … } static struct ctl_table_header *grab_header(struct inode *inode) { … } static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { … } static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter, int write) { … } static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter) { … } static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter) { … } static int proc_sys_open(struct inode *inode, struct file *filp) { … } static __poll_t proc_sys_poll(struct file *filp, poll_table *wait) { … } static bool proc_sys_fill_cache(struct file *file, struct dir_context *ctx, struct ctl_table_header *head, struct ctl_table *table) { … } static bool proc_sys_link_fill_cache(struct file *file, struct dir_context *ctx, struct ctl_table_header *head, struct ctl_table *table) { … } static int scan(struct ctl_table_header *head, struct ctl_table *table, unsigned long *pos, struct file *file, struct dir_context *ctx) { … } static int proc_sys_readdir(struct file *file, struct dir_context *ctx) { … } static int proc_sys_permission(struct mnt_idmap *idmap, struct inode *inode, int mask) { … } static int proc_sys_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { … } static int proc_sys_getattr(struct mnt_idmap *idmap, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { … } static const struct file_operations proc_sys_file_operations = …; static const struct file_operations proc_sys_dir_file_operations = …; static const struct inode_operations proc_sys_inode_operations = …; static const struct inode_operations proc_sys_dir_operations = …; static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags) { … } static int proc_sys_delete(const struct dentry *dentry) { … } static int sysctl_is_seen(struct ctl_table_header *p) { … } static int proc_sys_compare(const struct dentry *dentry, unsigned int len, const char *str, const struct qstr *name) { … } static const struct dentry_operations proc_sys_dentry_operations = …; static struct ctl_dir *find_subdir(struct ctl_dir *dir, const char *name, int namelen) { … } static struct ctl_dir *new_dir(struct ctl_table_set *set, const char *name, int namelen) { … } /** * get_subdir - find or create a subdir with the specified name. * @dir: Directory to create the subdirectory in * @name: The name of the subdirectory to find or create * @namelen: The length of name * * Takes a directory with an elevated reference count so we know that * if we drop the lock the directory will not go away. Upon success * the reference is moved from @dir to the returned subdirectory. * Upon error an error code is returned and the reference on @dir is * simply dropped. */ static struct ctl_dir *get_subdir(struct ctl_dir *dir, const char *name, int namelen) { … } static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir) { … } static int sysctl_follow_link(struct ctl_table_header **phead, struct ctl_table **pentry) { … } static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...) { … } static int sysctl_check_table_array(const char *path, struct ctl_table *table) { … } static int sysctl_check_table(const char *path, struct ctl_table_header *header) { … } static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_header *head) { … } static bool get_links(struct ctl_dir *dir, struct ctl_table_header *header, struct ctl_table_root *link_root) { … } static int insert_links(struct ctl_table_header *head) { … } /* Find the directory for the ctl_table. If one is not found create it. */ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path) { … } /** * __register_sysctl_table - register a leaf sysctl table * @set: Sysctl tree to register on * @path: The path to the directory the sysctl table is in. * * @table: the top-level table structure. This table should not be free'd * after registration. So it should not be used on stack. It can either * be a global or dynamically allocated by the caller and free'd later * after sysctl unregistration. * @table_size : The number of elements in table * * Register a sysctl table hierarchy. @table should be a filled in ctl_table * array. * * The members of the &struct ctl_table structure are used as follows: * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not * enter a sysctl file * data - a pointer to data for use by proc_handler * maxlen - the maximum size in bytes of the data * mode - the file permissions for the /proc/sys file * type - Defines the target type (described in struct definition) * proc_handler - the text handler routine (described below) * * extra1, extra2 - extra pointers usable by the proc handler routines * XXX: we should eventually modify these to use long min / max [0] * [0] https://lkml.kernel.org/[email protected] * * Leaf nodes in the sysctl tree will be represented by a single file * under /proc; non-leaf nodes are not allowed. * * There must be a proc_handler routine for any terminal nodes. * Several default handlers are available to cover common cases - * * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(), * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(), * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax() * * It is the handler's job to read the input buffer from user memory * and process it. The handler should return 0 on success. * * This routine returns %NULL on a failure to register, and a pointer * to the table header on success. */ struct ctl_table_header *__register_sysctl_table( struct ctl_table_set *set, const char *path, struct ctl_table *table, size_t table_size) { … } /** * register_sysctl_sz - register a sysctl table * @path: The path to the directory the sysctl table is in. If the path * doesn't exist we will create it for you. * @table: the table structure. The calller must ensure the life of the @table * will be kept during the lifetime use of the syctl. It must not be freed * until unregister_sysctl_table() is called with the given returned table * with this registration. If your code is non modular then you don't need * to call unregister_sysctl_table() and can instead use something like * register_sysctl_init() which does not care for the result of the syctl * registration. * @table_size: The number of elements in table. * * Register a sysctl table. @table should be a filled in ctl_table * array. A completely 0 filled entry terminates the table. * * See __register_sysctl_table for more details. */ struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table, size_t table_size) { … } EXPORT_SYMBOL(…); /** * __register_sysctl_init() - register sysctl table to path * @path: path name for sysctl base. If that path doesn't exist we will create * it for you. * @table: This is the sysctl table that needs to be registered to the path. * The caller must ensure the life of the @table will be kept during the * lifetime use of the sysctl. * @table_name: The name of sysctl table, only used for log printing when * registration fails * @table_size: The number of elements in table * * The sysctl interface is used by userspace to query or modify at runtime * a predefined value set on a variable. These variables however have default * values pre-set. Code which depends on these variables will always work even * if register_sysctl() fails. If register_sysctl() fails you'd just loose the * ability to query or modify the sysctls dynamically at run time. Chances of * register_sysctl() failing on init are extremely low, and so for both reasons * this function does not return any error as it is used by initialization code. * * Context: if your base directory does not exist it will be created for you. */ void __init __register_sysctl_init(const char *path, struct ctl_table *table, const char *table_name, size_t table_size) { … } static void put_links(struct ctl_table_header *header) { … } static void drop_sysctl_table(struct ctl_table_header *header) { … } /** * unregister_sysctl_table - unregister a sysctl table hierarchy * @header: the header returned from register_sysctl or __register_sysctl_table * * Unregisters the sysctl table and all children. proc entries may not * actually be removed until they are no longer used by anyone. */ void unregister_sysctl_table(struct ctl_table_header * header) { … } EXPORT_SYMBOL(…); void setup_sysctl_set(struct ctl_table_set *set, struct ctl_table_root *root, int (*is_seen)(struct ctl_table_set *)) { … } void retire_sysctl_set(struct ctl_table_set *set) { … } int __init proc_sys_init(void) { … } struct sysctl_alias { … }; /* * Historically some settings had both sysctl and a command line parameter. * With the generic sysctl. parameter support, we can handle them at a single * place and only keep the historical name for compatibility. This is not meant * to add brand new aliases. When adding existing aliases, consider whether * the possibly different moment of changing the value (e.g. from early_param * to the moment do_sysctl_args() is called) is an issue for the specific * parameter. */ static const struct sysctl_alias sysctl_aliases[] = …; static const char *sysctl_find_alias(char *param) { … } bool sysctl_is_alias(char *param) { … } /* Set sysctl value passed on kernel command line. */ static int process_sysctl_arg(char *param, char *val, const char *unused, void *arg) { … } void do_sysctl_args(void) { … }
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