cregit-Linux how code gets into the kernel

Release 4.17 fs/proc/inode.c

Directory: fs/proc
// 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); } }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro4041.67%315.79%
Linus Torvalds (pre-git)2930.21%631.58%
Linus Torvalds88.33%15.26%
Mark Fasheh77.29%15.26%
Eric W. Biedermann44.17%210.53%
Konstantin Khlebnikov33.12%15.26%
Alexander Kuleshov11.04%15.26%
Jan Kara11.04%15.26%
Alexey Dobriyan11.04%15.26%
Johannes Weiner11.04%15.26%
Monam Agarwal11.04%15.26%
Total96100.00%19100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro5154.26%228.57%
Linus Torvalds3436.17%114.29%
Eric W. Biedermann88.51%342.86%
Christoph Lameter11.06%114.29%
Total94100.00%7100.00%


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)); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro1850.00%150.00%
Nicholas Piggin1850.00%150.00%
Total36100.00%2100.00%


static void proc_destroy_inode(struct inode *inode) { call_rcu(&inode->i_rcu, proc_i_callback); }

Contributors

PersonTokensPropCommitsCommitProp
Nicholas Piggin21100.00%1100.00%
Total21100.00%1100.00%


static void init_once(void *foo) { struct proc_inode *ei = (struct proc_inode *) foo; inode_init_once(&ei->vfs_inode); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro2790.00%150.00%
Christoph Lameter310.00%150.00%
Total30100.00%2100.00%


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(struct proc_dir_entry), 0, SLAB_PANIC, offsetof(struct proc_dir_entry, inline_name), sizeof_field(struct proc_dir_entry, inline_name), NULL); }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan6065.93%550.00%
Al Viro2426.37%110.00%
Paul Jackson44.40%220.00%
Vladimir Davydov22.20%110.00%
Andrew Morton11.10%110.00%
Total91100.00%10100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Vasiliy Kulikov7183.53%250.00%
Eric W. Biedermann1315.29%125.00%
Lafcadio Wluiki11.18%125.00%
Total85100.00%4100.00%

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)); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro2187.50%266.67%
Alexey Dobriyan312.50%133.33%
Total24100.00%3100.00%


static void unuse_pde(struct proc_dir_entry *pde) { if (unlikely(atomic_dec_return(&pde->in_use) == BIAS)) complete(pde->pde_unload_completion); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro1854.55%240.00%
Alexey Dobriyan1339.39%240.00%
Linus Torvalds (pre-git)26.06%120.00%
Total33100.00%5100.00%

/* 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); } }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro12080.54%225.00%
Alexey Dobriyan2919.46%675.00%
Total149100.00%8100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro9789.81%350.00%
Alexey Dobriyan1110.19%350.00%
Total108100.00%6100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan6365.62%114.29%
Al Viro1515.62%342.86%
Linus Torvalds (pre-git)1515.62%228.57%
Eric W. Biedermann33.12%114.29%
Total96100.00%7100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan7269.23%125.00%
Al Viro2322.12%250.00%
Linus Torvalds (pre-git)98.65%125.00%
Total104100.00%4100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan8479.25%150.00%
Al Viro2220.75%150.00%
Total106100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan6574.71%228.57%
Al Viro2225.29%571.43%
Total87100.00%7100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan8690.53%125.00%
Al Viro88.42%250.00%
Arnd Bergmann11.05%125.00%
Total95100.00%4100.00%

#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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan8791.58%133.33%
Al Viro88.42%266.67%
Total95100.00%3100.00%

#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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan8090.91%133.33%
Al Viro89.09%266.67%
Total88100.00%3100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan8569.67%120.00%
Jan Beulich2318.85%120.00%
Daisuke Hatayama1411.48%360.00%
Total122100.00%5100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan20192.20%685.71%
Al Viro177.80%114.29%
Total218100.00%7100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan6885.00%360.00%
Al Viro1215.00%240.00%
Total80100.00%5100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro15100.00%1100.00%
Total15100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro62100.00%4100.00%
Total62100.00%4100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan11048.03%213.33%
Linus Torvalds3414.85%213.33%
David S. Miller2410.48%16.67%
David Howells177.42%16.67%
Eric W. Biedermann177.42%16.67%
Linus Torvalds (pre-git)73.06%213.33%
Al Viro73.06%213.33%
Miklos Szeredi41.75%16.67%
Krzysztof Sachanowicz41.75%16.67%
Deepa Dinamani41.75%16.67%
Denis V. Lunev10.44%16.67%
Total229100.00%15100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Eric W. Biedermann6232.46%420.00%
Linus Torvalds (pre-git)5227.23%525.00%
Maxim Patlasov3819.90%15.00%
Linus Torvalds126.28%315.00%
Al Viro84.19%210.00%
Andrew Morton73.66%210.00%
Alexey Dobriyan63.14%210.00%
Andi Kleen63.14%15.00%
Total191100.00%20100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Alexey Dobriyan121546.22%1916.96%
Al Viro68125.90%2017.86%
Linus Torvalds (pre-git)1545.86%1412.50%
Eric W. Biedermann1074.07%119.82%
Linus Torvalds913.46%87.14%
Vasiliy Kulikov903.42%21.79%
David S. Miller772.93%10.89%
Nicholas Piggin391.48%10.89%
Maxim Patlasov381.45%10.89%
Jan Beulich230.87%10.89%
David Howells200.76%21.79%
Daisuke Hatayama140.53%32.68%
Andrew Morton110.42%32.68%
Art Haas100.38%10.89%
Andi Kleen90.34%21.79%
Mark Fasheh70.27%10.89%
Christoph Lameter60.23%32.68%
Paul Jackson40.15%21.79%
Krzysztof Sachanowicz40.15%10.89%
Deepa Dinamani40.15%10.89%
Miklos Szeredi40.15%10.89%
Adrian Bunk30.11%10.89%
Konstantin Khlebnikov30.11%10.89%
Tejun Heo30.11%10.89%
Vladimir Davydov20.08%10.89%
Lafcadio Wluiki10.04%10.89%
Denis V. Lunev10.04%10.89%
Dave Jones10.04%10.89%
Alexander Kuleshov10.04%10.89%
Jan Kara10.04%10.89%
Greg Kroah-Hartman10.04%10.89%
Arnd Bergmann10.04%10.89%
Monam Agarwal10.04%10.89%
Josef 'Jeff' Sipek10.04%10.89%
Johannes Weiner10.04%10.89%
Total2629100.00%112100.00%
Directory: fs/proc
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