/* * linux/fs/proc/inode.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #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/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 <asm/system.h> #include <asm/uaccess.h> #include "internal.h" static void proc_evict_inode(struct inode *inode) { struct proc_dir_entry *de; struct ctl_table_header *head; const struct proc_ns_operations *ns_ops; truncate_inode_pages(&inode->i_data, 0); end_writeback(inode); /* Stop tracking associated processes */ put_pid(PROC_I(inode)->pid); /* Let go of any associated proc directory entry */ de = PROC_I(inode)->pde; if (de) pde_put(de); head = PROC_I(inode)->sysctl; if (head) { rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); sysctl_head_put(head); } /* Release any associated namespace */ ns_ops = PROC_I(inode)->ns_ops; if (ns_ops && ns_ops->put) ns_ops->put(PROC_I(inode)->ns); } static struct kmem_cache * proc_inode_cachep; static struct inode *proc_alloc_inode(struct super_block *sb) { struct proc_inode *ei; struct inode *inode; ei = (struct proc_inode *)kmem_cache_alloc(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; ei->ns = NULL; ei->ns_ops = NULL; inode = &ei->vfs_inode; inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; return inode; } static void proc_i_callback(struct rcu_head *head) { struct inode *inode = container_of(head, struct inode, i_rcu); kmem_cache_free(proc_inode_cachep, PROC_I(inode)); } static void proc_destroy_inode(struct inode *inode) { call_rcu(&inode->i_rcu, proc_i_callback); } static void init_once(void *foo) { struct proc_inode *ei = (struct proc_inode *) foo; inode_init_once(&ei->vfs_inode); } void __init proc_init_inodecache(void) { proc_inode_cachep = kmem_cache_create("proc_inode_cache", sizeof(struct proc_inode), 0, (SLAB_RECLAIM_ACCOUNT| SLAB_MEM_SPREAD|SLAB_PANIC), init_once); } static int proc_show_options(struct seq_file *seq, struct dentry *root) { struct super_block *sb = root->d_sb; struct pid_namespace *pid = sb->s_fs_info; if (pid->pid_gid) seq_printf(seq, ",gid=%lu", (unsigned long)pid->pid_gid); if (pid->hide_pid != 0) seq_printf(seq, ",hidepid=%u", pid->hide_pid); return 0; } static const struct super_operations proc_sops = { .alloc_inode = proc_alloc_inode, .destroy_inode = proc_destroy_inode, .drop_inode = generic_delete_inode, .evict_inode = proc_evict_inode, .statfs = simple_statfs, .remount_fs = proc_remount, .show_options = proc_show_options, }; static void __pde_users_dec(struct proc_dir_entry *pde) { pde->pde_users--; if (pde->pde_unload_completion && pde->pde_users == 0) complete(pde->pde_unload_completion); } void pde_users_dec(struct proc_dir_entry *pde) { spin_lock(&pde->pde_unload_lock); __pde_users_dec(pde); spin_unlock(&pde->pde_unload_lock); } static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) { struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); loff_t rv = -EINVAL; loff_t (*llseek)(struct file *, loff_t, int); spin_lock(&pde->pde_unload_lock); /* * remove_proc_entry() is going to delete PDE (as part of module * cleanup sequence). No new callers into module allowed. */ if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } /* * Bump refcount so that remove_proc_entry will wail for ->llseek to * complete. */ pde->pde_users++; /* * Save function pointer under lock, to protect against ->proc_fops * NULL'ifying right after ->pde_unload_lock is dropped. */ llseek = pde->proc_fops->llseek; spin_unlock(&pde->pde_unload_lock); if (!llseek) llseek = default_llseek; rv = llseek(file, offset, whence); pde_users_dec(pde); return rv; } 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->f_path.dentry->d_inode); ssize_t rv = -EIO; ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; read = pde->proc_fops->read; spin_unlock(&pde->pde_unload_lock); if (read) rv = read(file, buf, count, ppos); pde_users_dec(pde); return rv; } 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->f_path.dentry->d_inode); ssize_t rv = -EIO; ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; write = pde->proc_fops->write; spin_unlock(&pde->pde_unload_lock); if (write) rv = write(file, buf, count, ppos); pde_users_dec(pde); return rv; } static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts) { struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); unsigned int rv = DEFAULT_POLLMASK; unsigned int (*poll)(struct file *, struct poll_table_struct *); spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; poll = pde->proc_fops->poll; spin_unlock(&pde->pde_unload_lock); if (poll) rv = poll(file, pts); pde_users_dec(pde); return rv; } static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); long rv = -ENOTTY; long (*ioctl)(struct file *, unsigned int, unsigned long); spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; ioctl = pde->proc_fops->unlocked_ioctl; spin_unlock(&pde->pde_unload_lock); if (ioctl) rv = ioctl(file, cmd, arg); pde_users_dec(pde); return rv; } #ifdef CONFIG_COMPAT static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); long rv = -ENOTTY; long (*compat_ioctl)(struct file *, unsigned int, unsigned long); spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; compat_ioctl = pde->proc_fops->compat_ioctl; spin_unlock(&pde->pde_unload_lock); if (compat_ioctl) rv = compat_ioctl(file, cmd, arg); pde_users_dec(pde); return rv; } #endif static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) { struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); int rv = -EIO; int (*mmap)(struct file *, struct vm_area_struct *); spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; mmap = pde->proc_fops->mmap; spin_unlock(&pde->pde_unload_lock); if (mmap) rv = mmap(file, vma); pde_users_dec(pde); return rv; } static int proc_reg_open(struct inode *inode, struct file *file) { struct proc_dir_entry *pde = PDE(inode); int rv = 0; int (*open)(struct inode *, struct file *); int (*release)(struct inode *, struct file *); struct pde_opener *pdeo; /* * What for, you ask? Well, we can have open, rmmod, remove_proc_entry * sequence. ->release won't be called because ->proc_fops will be * cleared. Depending on complexity of ->release, consequences vary. * * We can't wait for mercy when close will be done for real, it's * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release * by hand in remove_proc_entry(). For this, save opener's credentials * for later. */ pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL); if (!pdeo) return -ENOMEM; spin_lock(&pde->pde_unload_lock); if (!pde->proc_fops) { spin_unlock(&pde->pde_unload_lock); kfree(pdeo); return -ENOENT; } pde->pde_users++; open = pde->proc_fops->open; release = pde->proc_fops->release; spin_unlock(&pde->pde_unload_lock); if (open) rv = open(inode, file); spin_lock(&pde->pde_unload_lock); if (rv == 0 && release) { /* To know what to release. */ pdeo->inode = inode; pdeo->file = file; /* Strictly for "too late" ->release in proc_reg_release(). */ pdeo->release = release; list_add(&pdeo->lh, &pde->pde_openers); } else kfree(pdeo); __pde_users_dec(pde); spin_unlock(&pde->pde_unload_lock); return rv; } static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde, struct inode *inode, struct file *file) { struct pde_opener *pdeo; list_for_each_entry(pdeo, &pde->pde_openers, lh) { if (pdeo->inode == inode && pdeo->file == file) return pdeo; } return NULL; } static int proc_reg_release(struct inode *inode, struct file *file) { struct proc_dir_entry *pde = PDE(inode); int rv = 0; int (*release)(struct inode *, struct file *); struct pde_opener *pdeo; spin_lock(&pde->pde_unload_lock); pdeo = find_pde_opener(pde, inode, file); if (!pde->proc_fops) { /* * Can't simply exit, __fput() will think that everything is OK, * and move on to freeing struct file. remove_proc_entry() will * find slacker in opener's list and will try to do non-trivial * things with struct file. Therefore, remove opener from list. * * But if opener is removed from list, who will ->release it? */ if (pdeo) { list_del(&pdeo->lh); spin_unlock(&pde->pde_unload_lock); rv = pdeo->release(inode, file); kfree(pdeo); } else spin_unlock(&pde->pde_unload_lock); return rv; } pde->pde_users++; release = pde->proc_fops->release; if (pdeo) { list_del(&pdeo->lh); kfree(pdeo); } spin_unlock(&pde->pde_unload_lock); if (release) rv = release(inode, file); pde_users_dec(pde); return rv; } 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, #ifdef CONFIG_COMPAT .compat_ioctl = proc_reg_compat_ioctl, #endif .mmap = proc_reg_mmap, .open = proc_reg_open, .release = proc_reg_release, }; #ifdef CONFIG_COMPAT static const struct file_operations proc_reg_file_ops_no_compat = { .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, .open = proc_reg_open, .release = proc_reg_release, }; #endif struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) { struct inode * inode; inode = iget_locked(sb, de->low_ino); if (!inode) return NULL; if (inode->i_state & I_NEW) { inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; PROC_I(inode)->fd = 0; PROC_I(inode)->pde = de; 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 (de->proc_iops) inode->i_op = de->proc_iops; if (de->proc_fops) { if (S_ISREG(inode->i_mode)) { #ifdef CONFIG_COMPAT if (!de->proc_fops->compat_ioctl) inode->i_fop = &proc_reg_file_ops_no_compat; else #endif inode->i_fop = &proc_reg_file_ops; } else { inode->i_fop = de->proc_fops; } } unlock_new_inode(inode); } else pde_put(de); return inode; } int proc_fill_super(struct super_block *s) { struct inode * root_inode; s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC; s->s_blocksize = 1024; s->s_blocksize_bits = 10; s->s_magic = PROC_SUPER_MAGIC; s->s_op = &proc_sops; s->s_time_gran = 1; pde_get(&proc_root); root_inode = proc_get_inode(s, &proc_root); if (!root_inode) goto out_no_root; root_inode->i_uid = 0; root_inode->i_gid = 0; s->s_root = d_alloc_root(root_inode); if (!s->s_root) goto out_no_root; return 0; out_no_root: printk("proc_read_super: get root inode failed\n"); iput(root_inode); pde_put(&proc_root); return -ENOMEM; }