v4.19.13 snapshot.
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
new file mode 100644
index 0000000..fc5306a
--- /dev/null
+++ b/fs/proc/inode.c
@@ -0,0 +1,537 @@
+// 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/magic.h>
+
+#include <linux/uaccess.h>
+
+#include "internal.h"
+
+static void proc_evict_inode(struct inode *inode)
+{
+ struct proc_dir_entry *de;
+ struct ctl_table_header *head;
+
+ truncate_inode_pages_final(&inode->i_data);
+ clear_inode(inode);
+
+ /* Stop tracking associated processes */
+ put_pid(PROC_I(inode)->pid);
+
+ /* Let go of any associated proc directory entry */
+ de = PDE(inode);
+ if (de)
+ pde_put(de);
+
+ head = PROC_I(inode)->sysctl;
+ if (head) {
+ RCU_INIT_POINTER(PROC_I(inode)->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;
+ struct inode *inode;
+
+ ei = 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_ops = NULL;
+ inode = &ei->vfs_inode;
+ 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_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);
+}
+
+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 (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
+ seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
+ if (pid->hide_pid != HIDEPID_OFF)
+ 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,
+};
+
+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);
+}
+
+/* pde is locked on entry, unlocked on exit */
+static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
+{
+ /*
+ * 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.
+ *
+ * Therefore, first process to enter this function does ->release() and
+ * signals its completion to the other process which does nothing.
+ */
+ 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_fops->release(file_inode(file), file);
+ spin_lock(&pde->pde_unload_lock);
+ /* After ->release. */
+ 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 (use_pde(pde)) {
+ loff_t (*llseek)(struct file *, loff_t, int);
+ llseek = pde->proc_fops->llseek;
+ if (!llseek)
+ llseek = default_llseek;
+ rv = llseek(file, offset, whence);
+ unuse_pde(pde);
+ }
+ return rv;
+}
+
+static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
+ struct proc_dir_entry *pde = PDE(file_inode(file));
+ ssize_t rv = -EIO;
+ if (use_pde(pde)) {
+ read = pde->proc_fops->read;
+ if (read)
+ rv = read(file, buf, count, ppos);
+ unuse_pde(pde);
+ }
+ return rv;
+}
+
+static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+ ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
+ struct proc_dir_entry *pde = PDE(file_inode(file));
+ ssize_t rv = -EIO;
+ if (use_pde(pde)) {
+ write = pde->proc_fops->write;
+ if (write)
+ rv = write(file, buf, count, ppos);
+ unuse_pde(pde);
+ }
+ return rv;
+}
+
+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;
+ __poll_t (*poll)(struct file *, struct poll_table_struct *);
+ if (use_pde(pde)) {
+ poll = pde->proc_fops->poll;
+ if (poll)
+ rv = poll(file, pts);
+ unuse_pde(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_inode(file));
+ long rv = -ENOTTY;
+ long (*ioctl)(struct file *, unsigned int, unsigned long);
+ if (use_pde(pde)) {
+ ioctl = pde->proc_fops->unlocked_ioctl;
+ if (ioctl)
+ rv = ioctl(file, cmd, arg);
+ unuse_pde(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_inode(file));
+ long rv = -ENOTTY;
+ long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
+ if (use_pde(pde)) {
+ compat_ioctl = pde->proc_fops->compat_ioctl;
+ if (compat_ioctl)
+ rv = compat_ioctl(file, cmd, arg);
+ unuse_pde(pde);
+ }
+ return rv;
+}
+#endif
+
+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;
+ int (*mmap)(struct file *, struct vm_area_struct *);
+ if (use_pde(pde)) {
+ mmap = pde->proc_fops->mmap;
+ if (mmap)
+ rv = mmap(file, vma);
+ unuse_pde(pde);
+ }
+ return rv;
+}
+
+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 (use_pde(pde)) {
+ typeof(proc_reg_get_unmapped_area) *get_area;
+
+ get_area = pde->proc_fops->get_unmapped_area;
+#ifdef CONFIG_MMU
+ if (!get_area)
+ get_area = current->mm->get_unmapped_area;
+#endif
+
+ if (get_area)
+ rv = get_area(file, orig_addr, len, pgoff, flags);
+ else
+ rv = orig_addr;
+ 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;
+ int (*open)(struct inode *, struct file *);
+ int (*release)(struct inode *, struct file *);
+ struct pde_opener *pdeo;
+
+ /*
+ * 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_fops->release;
+ if (release) {
+ pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
+ if (!pdeo) {
+ rv = -ENOMEM;
+ goto out_unuse;
+ }
+ }
+
+ open = pde->proc_fops->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;
+ 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,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = proc_reg_compat_ioctl,
+#endif
+ .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_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,
+ .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_pseudo(sb);
+
+ if (inode) {
+ inode->i_ino = de->low_ino;
+ inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(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);
+ WARN_ON(!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;
+ }
+ }
+ } else
+ pde_put(de);
+ return inode;
+}
+
+int proc_fill_super(struct super_block *s, void *data, int silent)
+{
+ struct pid_namespace *ns = get_pid_ns(s->s_fs_info);
+ struct inode *root_inode;
+ int ret;
+
+ if (!proc_parse_options(data, ns))
+ return -EINVAL;
+
+ /* User space would break if executables or devices appear on proc */
+ s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
+ s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_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;
+
+ /*
+ * procfs isn't actually a stacking filesystem; however, there is
+ * too much magic going on inside it to permit stacking things on
+ * top of it
+ */
+ s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
+
+ pde_get(&proc_root);
+ root_inode = proc_get_inode(s, &proc_root);
+ if (!root_inode) {
+ pr_err("proc_fill_super: get root inode failed\n");
+ return -ENOMEM;
+ }
+
+ s->s_root = d_make_root(root_inode);
+ if (!s->s_root) {
+ pr_err("proc_fill_super: allocate dentry failed\n");
+ return -ENOMEM;
+ }
+
+ ret = proc_setup_self(s);
+ if (ret) {
+ return ret;
+ }
+ return proc_setup_thread_self(s);
+}