diff options
Diffstat (limited to 'fs/proc/inode.c')
| -rw-r--r-- | fs/proc/inode.c | 704 |
1 files changed, 704 insertions, 0 deletions
diff --git a/fs/proc/inode.c b/fs/proc/inode.c new file mode 100644 index 000000000..532dc9d24 --- /dev/null +++ b/fs/proc/inode.c @@ -0,0 +1,704 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/proc/inode.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/cache.h> +#include <linux/time.h> +#include <linux/proc_fs.h> +#include <linux/kernel.h> +#include <linux/pid_namespace.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/stat.h> +#include <linux/completion.h> +#include <linux/poll.h> +#include <linux/printk.h> +#include <linux/file.h> +#include <linux/limits.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/sysctl.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/mount.h> +#include <linux/bug.h> + +#include "internal.h" + +static void proc_evict_inode(struct inode *inode) +{ + struct proc_dir_entry *de; + struct ctl_table_header *head; + struct proc_inode *ei = PROC_I(inode); + + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + + /* Stop tracking associated processes */ + if (ei->pid) { + proc_pid_evict_inode(ei); + ei->pid = NULL; + } + + /* Let go of any associated proc directory entry */ + de = ei->pde; + if (de) { + pde_put(de); + ei->pde = NULL; + } + + head = ei->sysctl; + if (head) { + RCU_INIT_POINTER(ei->sysctl, NULL); + proc_sys_evict_inode(inode, head); + } +} + +static struct kmem_cache *proc_inode_cachep __ro_after_init; +static struct kmem_cache *pde_opener_cache __ro_after_init; + +static struct inode *proc_alloc_inode(struct super_block *sb) +{ + struct proc_inode *ei; + + ei = alloc_inode_sb(sb, proc_inode_cachep, GFP_KERNEL); + if (!ei) + return NULL; + ei->pid = NULL; + ei->fd = 0; + ei->op.proc_get_link = NULL; + ei->pde = NULL; + ei->sysctl = NULL; + ei->sysctl_entry = NULL; + INIT_HLIST_NODE(&ei->sibling_inodes); + ei->ns_ops = NULL; + return &ei->vfs_inode; +} + +static void proc_free_inode(struct inode *inode) +{ + kmem_cache_free(proc_inode_cachep, PROC_I(inode)); +} + +static void init_once(void *foo) +{ + struct proc_inode *ei = (struct proc_inode *) foo; + + inode_init_once(&ei->vfs_inode); +} + +void __init proc_init_kmemcache(void) +{ + proc_inode_cachep = kmem_cache_create("proc_inode_cache", + sizeof(struct proc_inode), + 0, (SLAB_RECLAIM_ACCOUNT| + SLAB_MEM_SPREAD|SLAB_ACCOUNT| + SLAB_PANIC), + init_once); + pde_opener_cache = + kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0, + SLAB_ACCOUNT|SLAB_PANIC, NULL); + proc_dir_entry_cache = kmem_cache_create_usercopy( + "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC, + offsetof(struct proc_dir_entry, inline_name), + SIZEOF_PDE_INLINE_NAME, NULL); + BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE); +} + +void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock) +{ + struct inode *inode; + struct proc_inode *ei; + struct hlist_node *node; + struct super_block *old_sb = NULL; + + rcu_read_lock(); + for (;;) { + struct super_block *sb; + node = hlist_first_rcu(inodes); + if (!node) + break; + ei = hlist_entry(node, struct proc_inode, sibling_inodes); + spin_lock(lock); + hlist_del_init_rcu(&ei->sibling_inodes); + spin_unlock(lock); + + inode = &ei->vfs_inode; + sb = inode->i_sb; + if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active)) + continue; + inode = igrab(inode); + rcu_read_unlock(); + if (sb != old_sb) { + if (old_sb) + deactivate_super(old_sb); + old_sb = sb; + } + if (unlikely(!inode)) { + rcu_read_lock(); + continue; + } + + if (S_ISDIR(inode->i_mode)) { + struct dentry *dir = d_find_any_alias(inode); + if (dir) { + d_invalidate(dir); + dput(dir); + } + } else { + struct dentry *dentry; + while ((dentry = d_find_alias(inode))) { + d_invalidate(dentry); + dput(dentry); + } + } + iput(inode); + + rcu_read_lock(); + } + rcu_read_unlock(); + if (old_sb) + deactivate_super(old_sb); +} + +static inline const char *hidepid2str(enum proc_hidepid v) +{ + switch (v) { + case HIDEPID_OFF: return "off"; + case HIDEPID_NO_ACCESS: return "noaccess"; + case HIDEPID_INVISIBLE: return "invisible"; + case HIDEPID_NOT_PTRACEABLE: return "ptraceable"; + } + WARN_ONCE(1, "bad hide_pid value: %d\n", v); + return "unknown"; +} + +static int proc_show_options(struct seq_file *seq, struct dentry *root) +{ + struct proc_fs_info *fs_info = proc_sb_info(root->d_sb); + + if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID)) + seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid)); + if (fs_info->hide_pid != HIDEPID_OFF) + seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid)); + if (fs_info->pidonly != PROC_PIDONLY_OFF) + seq_printf(seq, ",subset=pid"); + + return 0; +} + +const struct super_operations proc_sops = { + .alloc_inode = proc_alloc_inode, + .free_inode = proc_free_inode, + .drop_inode = generic_delete_inode, + .evict_inode = proc_evict_inode, + .statfs = simple_statfs, + .show_options = proc_show_options, +}; + +enum {BIAS = -1U<<31}; + +static inline int use_pde(struct proc_dir_entry *pde) +{ + return likely(atomic_inc_unless_negative(&pde->in_use)); +} + +static void unuse_pde(struct proc_dir_entry *pde) +{ + if (unlikely(atomic_dec_return(&pde->in_use) == BIAS)) + complete(pde->pde_unload_completion); +} + +/* + * At most 2 contexts can enter this function: the one doing the last + * close on the descriptor and whoever is deleting PDE itself. + * + * First to enter calls ->proc_release hook and signals its completion + * to the second one which waits and then does nothing. + * + * PDE is locked on entry, unlocked on exit. + */ +static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) + __releases(&pde->pde_unload_lock) +{ + /* + * close() (proc_reg_release()) can't delete an entry and proceed: + * ->release hook needs to be available at the right moment. + * + * rmmod (remove_proc_entry() et al) can't delete an entry and proceed: + * "struct file" needs to be available at the right moment. + */ + if (pdeo->closing) { + /* somebody else is doing that, just wait */ + DECLARE_COMPLETION_ONSTACK(c); + pdeo->c = &c; + spin_unlock(&pde->pde_unload_lock); + wait_for_completion(&c); + } else { + struct file *file; + struct completion *c; + + pdeo->closing = true; + spin_unlock(&pde->pde_unload_lock); + + file = pdeo->file; + pde->proc_ops->proc_release(file_inode(file), file); + + spin_lock(&pde->pde_unload_lock); + /* Strictly after ->proc_release, see above. */ + list_del(&pdeo->lh); + c = pdeo->c; + spin_unlock(&pde->pde_unload_lock); + if (unlikely(c)) + complete(c); + kmem_cache_free(pde_opener_cache, pdeo); + } +} + +void proc_entry_rundown(struct proc_dir_entry *de) +{ + DECLARE_COMPLETION_ONSTACK(c); + /* Wait until all existing callers into module are done. */ + de->pde_unload_completion = &c; + if (atomic_add_return(BIAS, &de->in_use) != BIAS) + wait_for_completion(&c); + + /* ->pde_openers list can't grow from now on. */ + + spin_lock(&de->pde_unload_lock); + while (!list_empty(&de->pde_openers)) { + struct pde_opener *pdeo; + pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh); + close_pdeo(de, pdeo); + spin_lock(&de->pde_unload_lock); + } + spin_unlock(&de->pde_unload_lock); +} + +static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + loff_t rv = -EINVAL; + + if (pde_is_permanent(pde)) { + return pde->proc_ops->proc_lseek(file, offset, whence); + } else if (use_pde(pde)) { + rv = pde->proc_ops->proc_lseek(file, offset, whence); + unuse_pde(pde); + } + return rv; +} + +static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter) +{ + struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp)); + ssize_t ret; + + if (pde_is_permanent(pde)) + return pde->proc_ops->proc_read_iter(iocb, iter); + + if (!use_pde(pde)) + return -EIO; + ret = pde->proc_ops->proc_read_iter(iocb, iter); + unuse_pde(pde); + return ret; +} + +static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos) +{ + typeof_member(struct proc_ops, proc_read) read; + + read = pde->proc_ops->proc_read; + if (read) + return read(file, buf, count, ppos); + return -EIO; +} + +static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + ssize_t rv = -EIO; + + if (pde_is_permanent(pde)) { + return pde_read(pde, file, buf, count, ppos); + } else if (use_pde(pde)) { + rv = pde_read(pde, file, buf, count, ppos); + unuse_pde(pde); + } + return rv; +} + +static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos) +{ + typeof_member(struct proc_ops, proc_write) write; + + write = pde->proc_ops->proc_write; + if (write) + return write(file, buf, count, ppos); + return -EIO; +} + +static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + ssize_t rv = -EIO; + + if (pde_is_permanent(pde)) { + return pde_write(pde, file, buf, count, ppos); + } else if (use_pde(pde)) { + rv = pde_write(pde, file, buf, count, ppos); + unuse_pde(pde); + } + return rv; +} + +static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts) +{ + typeof_member(struct proc_ops, proc_poll) poll; + + poll = pde->proc_ops->proc_poll; + if (poll) + return poll(file, pts); + return DEFAULT_POLLMASK; +} + +static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + __poll_t rv = DEFAULT_POLLMASK; + + if (pde_is_permanent(pde)) { + return pde_poll(pde, file, pts); + } else if (use_pde(pde)) { + rv = pde_poll(pde, file, pts); + unuse_pde(pde); + } + return rv; +} + +static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg) +{ + typeof_member(struct proc_ops, proc_ioctl) ioctl; + + ioctl = pde->proc_ops->proc_ioctl; + if (ioctl) + return ioctl(file, cmd, arg); + return -ENOTTY; +} + +static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + long rv = -ENOTTY; + + if (pde_is_permanent(pde)) { + return pde_ioctl(pde, file, cmd, arg); + } else if (use_pde(pde)) { + rv = pde_ioctl(pde, file, cmd, arg); + unuse_pde(pde); + } + return rv; +} + +#ifdef CONFIG_COMPAT +static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg) +{ + typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl; + + compat_ioctl = pde->proc_ops->proc_compat_ioctl; + if (compat_ioctl) + return compat_ioctl(file, cmd, arg); + return -ENOTTY; +} + +static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + long rv = -ENOTTY; + if (pde_is_permanent(pde)) { + return pde_compat_ioctl(pde, file, cmd, arg); + } else if (use_pde(pde)) { + rv = pde_compat_ioctl(pde, file, cmd, arg); + unuse_pde(pde); + } + return rv; +} +#endif + +static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma) +{ + typeof_member(struct proc_ops, proc_mmap) mmap; + + mmap = pde->proc_ops->proc_mmap; + if (mmap) + return mmap(file, vma); + return -EIO; +} + +static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + int rv = -EIO; + + if (pde_is_permanent(pde)) { + return pde_mmap(pde, file, vma); + } else if (use_pde(pde)) { + rv = pde_mmap(pde, file, vma); + unuse_pde(pde); + } + return rv; +} + +static unsigned long +pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr, + unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + typeof_member(struct proc_ops, proc_get_unmapped_area) get_area; + + get_area = pde->proc_ops->proc_get_unmapped_area; +#ifdef CONFIG_MMU + if (!get_area) + get_area = current->mm->get_unmapped_area; +#endif + if (get_area) + return get_area(file, orig_addr, len, pgoff, flags); + return orig_addr; +} + +static unsigned long +proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, + unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + unsigned long rv = -EIO; + + if (pde_is_permanent(pde)) { + return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags); + } else if (use_pde(pde)) { + rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags); + unuse_pde(pde); + } + return rv; +} + +static int proc_reg_open(struct inode *inode, struct file *file) +{ + struct proc_dir_entry *pde = PDE(inode); + int rv = 0; + typeof_member(struct proc_ops, proc_open) open; + typeof_member(struct proc_ops, proc_release) release; + struct pde_opener *pdeo; + + if (!pde->proc_ops->proc_lseek) + file->f_mode &= ~FMODE_LSEEK; + + if (pde_is_permanent(pde)) { + open = pde->proc_ops->proc_open; + if (open) + rv = open(inode, file); + return rv; + } + + /* + * Ensure that + * 1) PDE's ->release hook will be called no matter what + * either normally by close()/->release, or forcefully by + * rmmod/remove_proc_entry. + * + * 2) rmmod isn't blocked by opening file in /proc and sitting on + * the descriptor (including "rmmod foo </proc/foo" scenario). + * + * Save every "struct file" with custom ->release hook. + */ + if (!use_pde(pde)) + return -ENOENT; + + release = pde->proc_ops->proc_release; + if (release) { + pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL); + if (!pdeo) { + rv = -ENOMEM; + goto out_unuse; + } + } + + open = pde->proc_ops->proc_open; + if (open) + rv = open(inode, file); + + if (release) { + if (rv == 0) { + /* To know what to release. */ + pdeo->file = file; + pdeo->closing = false; + pdeo->c = NULL; + spin_lock(&pde->pde_unload_lock); + list_add(&pdeo->lh, &pde->pde_openers); + spin_unlock(&pde->pde_unload_lock); + } else + kmem_cache_free(pde_opener_cache, pdeo); + } + +out_unuse: + unuse_pde(pde); + return rv; +} + +static int proc_reg_release(struct inode *inode, struct file *file) +{ + struct proc_dir_entry *pde = PDE(inode); + struct pde_opener *pdeo; + + if (pde_is_permanent(pde)) { + typeof_member(struct proc_ops, proc_release) release; + + release = pde->proc_ops->proc_release; + if (release) { + return release(inode, file); + } + return 0; + } + + spin_lock(&pde->pde_unload_lock); + list_for_each_entry(pdeo, &pde->pde_openers, lh) { + if (pdeo->file == file) { + close_pdeo(pde, pdeo); + return 0; + } + } + spin_unlock(&pde->pde_unload_lock); + return 0; +} + +static const struct file_operations proc_reg_file_ops = { + .llseek = proc_reg_llseek, + .read = proc_reg_read, + .write = proc_reg_write, + .poll = proc_reg_poll, + .unlocked_ioctl = proc_reg_unlocked_ioctl, + .mmap = proc_reg_mmap, + .get_unmapped_area = proc_reg_get_unmapped_area, + .open = proc_reg_open, + .release = proc_reg_release, +}; + +static const struct file_operations proc_iter_file_ops = { + .llseek = proc_reg_llseek, + .read_iter = proc_reg_read_iter, + .write = proc_reg_write, + .splice_read = copy_splice_read, + .poll = proc_reg_poll, + .unlocked_ioctl = proc_reg_unlocked_ioctl, + .mmap = proc_reg_mmap, + .get_unmapped_area = proc_reg_get_unmapped_area, + .open = proc_reg_open, + .release = proc_reg_release, +}; + +#ifdef CONFIG_COMPAT +static const struct file_operations proc_reg_file_ops_compat = { + .llseek = proc_reg_llseek, + .read = proc_reg_read, + .write = proc_reg_write, + .poll = proc_reg_poll, + .unlocked_ioctl = proc_reg_unlocked_ioctl, + .compat_ioctl = proc_reg_compat_ioctl, + .mmap = proc_reg_mmap, + .get_unmapped_area = proc_reg_get_unmapped_area, + .open = proc_reg_open, + .release = proc_reg_release, +}; + +static const struct file_operations proc_iter_file_ops_compat = { + .llseek = proc_reg_llseek, + .read_iter = proc_reg_read_iter, + .splice_read = copy_splice_read, + .write = proc_reg_write, + .poll = proc_reg_poll, + .unlocked_ioctl = proc_reg_unlocked_ioctl, + .compat_ioctl = proc_reg_compat_ioctl, + .mmap = proc_reg_mmap, + .get_unmapped_area = proc_reg_get_unmapped_area, + .open = proc_reg_open, + .release = proc_reg_release, +}; +#endif + +static void proc_put_link(void *p) +{ + unuse_pde(p); +} + +static const char *proc_get_link(struct dentry *dentry, + struct inode *inode, + struct delayed_call *done) +{ + struct proc_dir_entry *pde = PDE(inode); + if (!use_pde(pde)) + return ERR_PTR(-EINVAL); + set_delayed_call(done, proc_put_link, pde); + return pde->data; +} + +const struct inode_operations proc_link_inode_operations = { + .get_link = proc_get_link, +}; + +struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) +{ + struct inode *inode = new_inode(sb); + + if (!inode) { + pde_put(de); + return NULL; + } + + inode->i_private = de->data; + inode->i_ino = de->low_ino; + inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode); + PROC_I(inode)->pde = de; + if (is_empty_pde(de)) { + make_empty_dir_inode(inode); + return inode; + } + + if (de->mode) { + inode->i_mode = de->mode; + inode->i_uid = de->uid; + inode->i_gid = de->gid; + } + if (de->size) + inode->i_size = de->size; + if (de->nlink) + set_nlink(inode, de->nlink); + + if (S_ISREG(inode->i_mode)) { + inode->i_op = de->proc_iops; + if (de->proc_ops->proc_read_iter) + inode->i_fop = &proc_iter_file_ops; + else + inode->i_fop = &proc_reg_file_ops; +#ifdef CONFIG_COMPAT + if (de->proc_ops->proc_compat_ioctl) { + if (de->proc_ops->proc_read_iter) + inode->i_fop = &proc_iter_file_ops_compat; + else + inode->i_fop = &proc_reg_file_ops_compat; + } +#endif + } else if (S_ISDIR(inode->i_mode)) { + inode->i_op = de->proc_iops; + inode->i_fop = de->proc_dir_ops; + } else if (S_ISLNK(inode->i_mode)) { + inode->i_op = de->proc_iops; + inode->i_fop = NULL; + } else { + BUG(); + } + return inode; +} |