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1// SPDX-License-Identifier: GPL-2.02/*3 * /proc/sys support4 */5#include <linux/init.h>6#include <linux/sysctl.h>7#include <linux/poll.h>8#include <linux/proc_fs.h>9#include <linux/printk.h>10#include <linux/security.h>11#include <linux/sched.h>12#include <linux/cred.h>13#include <linux/namei.h>14#include <linux/mm.h>15#include <linux/uio.h>16#include <linux/module.h>17#include <linux/bpf-cgroup.h>18#include <linux/mount.h>19#include <linux/kmemleak.h>20#include "internal.h"21 22#define list_for_each_table_entry(entry, header) \23 entry = header->ctl_table; \24 for (size_t i = 0 ; i < header->ctl_table_size; ++i, entry++)25 26static const struct dentry_operations proc_sys_dentry_operations;27static const struct file_operations proc_sys_file_operations;28static const struct inode_operations proc_sys_inode_operations;29static const struct file_operations proc_sys_dir_file_operations;30static const struct inode_operations proc_sys_dir_operations;31 32/*33 * Support for permanently empty directories.34 * Must be non-empty to avoid sharing an address with other tables.35 */36static struct ctl_table sysctl_mount_point[] = {37 { }38};39 40/**41 * register_sysctl_mount_point() - registers a sysctl mount point42 * @path: path for the mount point43 *44 * Used to create a permanently empty directory to serve as mount point.45 * There are some subtle but important permission checks this allows in the46 * case of unprivileged mounts.47 */48struct ctl_table_header *register_sysctl_mount_point(const char *path)49{50 return register_sysctl_sz(path, sysctl_mount_point, 0);51}52EXPORT_SYMBOL(register_sysctl_mount_point);53 54#define sysctl_is_perm_empty_ctl_header(hptr) \55 (hptr->type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)56#define sysctl_set_perm_empty_ctl_header(hptr) \57 (hptr->type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)58#define sysctl_clear_perm_empty_ctl_header(hptr) \59 (hptr->type = SYSCTL_TABLE_TYPE_DEFAULT)60 61void proc_sys_poll_notify(struct ctl_table_poll *poll)62{63 if (!poll)64 return;65 66 atomic_inc(&poll->event);67 wake_up_interruptible(&poll->wait);68}69 70static struct ctl_table root_table[] = {71 {72 .procname = "",73 .mode = S_IFDIR|S_IRUGO|S_IXUGO,74 },75};76static struct ctl_table_root sysctl_table_root = {77 .default_set.dir.header = {78 {{.count = 1,79 .nreg = 1,80 .ctl_table = root_table }},81 .ctl_table_arg = root_table,82 .root = &sysctl_table_root,83 .set = &sysctl_table_root.default_set,84 },85};86 87static DEFINE_SPINLOCK(sysctl_lock);88 89static HWJS_SUSPENDS void drop_sysctl_table(struct ctl_table_header *header);90static HWJS_SUSPENDS int sysctl_follow_link(struct ctl_table_header **phead,91 struct ctl_table **pentry);92static HWJS_SUSPENDS int insert_links(struct ctl_table_header *head);93static HWJS_SUSPENDS void put_links(struct ctl_table_header *header);94 95static void sysctl_print_dir(struct ctl_dir *dir)96{97 if (dir->header.parent)98 sysctl_print_dir(dir->header.parent);99 pr_cont("%s/", dir->header.ctl_table[0].procname);100}101 102static int namecmp(const char *name1, int len1, const char *name2, int len2)103{104 int cmp;105 106 cmp = memcmp(name1, name2, min(len1, len2));107 if (cmp == 0)108 cmp = len1 - len2;109 return cmp;110}111 112/* Called under sysctl_lock */113static struct ctl_table *find_entry(struct ctl_table_header **phead,114 struct ctl_dir *dir, const char *name, int namelen)115{116 struct ctl_table_header *head;117 struct ctl_table *entry;118 struct rb_node *node = dir->root.rb_node;119 120 while (node)121 {122 struct ctl_node *ctl_node;123 const char *procname;124 int cmp;125 126 ctl_node = rb_entry(node, struct ctl_node, node);127 head = ctl_node->header;128 entry = &head->ctl_table[ctl_node - head->node];129 procname = entry->procname;130 131 cmp = namecmp(name, namelen, procname, strlen(procname));132 if (cmp < 0)133 node = node->rb_left;134 else if (cmp > 0)135 node = node->rb_right;136 else {137 *phead = head;138 return entry;139 }140 }141 return NULL;142}143 144static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)145{146 struct rb_node *node = &head->node[entry - head->ctl_table].node;147 struct rb_node **p = &head->parent->root.rb_node;148 struct rb_node *parent = NULL;149 const char *name = entry->procname;150 int namelen = strlen(name);151 152 while (*p) {153 struct ctl_table_header *parent_head;154 struct ctl_table *parent_entry;155 struct ctl_node *parent_node;156 const char *parent_name;157 int cmp;158 159 parent = *p;160 parent_node = rb_entry(parent, struct ctl_node, node);161 parent_head = parent_node->header;162 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];163 parent_name = parent_entry->procname;164 165 cmp = namecmp(name, namelen, parent_name, strlen(parent_name));166 if (cmp < 0)167 p = &(*p)->rb_left;168 else if (cmp > 0)169 p = &(*p)->rb_right;170 else {171 pr_err("sysctl duplicate entry: ");172 sysctl_print_dir(head->parent);173 pr_cont("%s\n", entry->procname);174 return -EEXIST;175 }176 }177 178 rb_link_node(node, parent, p);179 rb_insert_color(node, &head->parent->root);180 return 0;181}182 183static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)184{185 struct rb_node *node = &head->node[entry - head->ctl_table].node;186 187 rb_erase(node, &head->parent->root);188}189 190static void init_header(struct ctl_table_header *head,191 struct ctl_table_root *root, struct ctl_table_set *set,192 struct ctl_node *node, struct ctl_table *table, size_t table_size)193{194 head->ctl_table = table;195 head->ctl_table_size = table_size;196 head->ctl_table_arg = table;197 head->used = 0;198 head->count = 1;199 head->nreg = 1;200 head->unregistering = NULL;201 head->root = root;202 head->set = set;203 head->parent = NULL;204 head->node = node;205 INIT_HLIST_HEAD(&head->inodes);206 if (node) {207 struct ctl_table *entry;208 209 list_for_each_table_entry(entry, head) {210 node->header = head;211 node++;212 }213 }214 if (table == sysctl_mount_point)215 sysctl_set_perm_empty_ctl_header(head);216}217 218static void erase_header(struct ctl_table_header *head)219{220 struct ctl_table *entry;221 222 list_for_each_table_entry(entry, head)223 erase_entry(head, entry);224}225 226static HWJS_SUSPENDS int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)227{228 struct ctl_table *entry;229 struct ctl_table_header *dir_h = &dir->header;230 int err;231 232 233 /* Is this a permanently empty directory? */234 if (sysctl_is_perm_empty_ctl_header(dir_h))235 return -EROFS;236 237 /* Am I creating a permanently empty directory? */238 if (sysctl_is_perm_empty_ctl_header(header)) {239 if (!RB_EMPTY_ROOT(&dir->root))240 return -EINVAL;241 sysctl_set_perm_empty_ctl_header(dir_h);242 }243 244 dir_h->nreg++;245 header->parent = dir;246 err = insert_links(header);247 if (err)248 goto fail_links;249 list_for_each_table_entry(entry, header) {250 err = insert_entry(header, entry);251 if (err)252 goto fail;253 }254 return 0;255fail:256 erase_header(header);257 put_links(header);258fail_links:259 if (header->ctl_table == sysctl_mount_point)260 sysctl_clear_perm_empty_ctl_header(dir_h);261 header->parent = NULL;262 drop_sysctl_table(dir_h);263 return err;264}265 266/* called under sysctl_lock */267static int use_table(struct ctl_table_header *p)268{269 if (unlikely(p->unregistering))270 return 0;271 p->used++;272 return 1;273}274 275/* called under sysctl_lock */276static HWJS_SUSPENDS void unuse_table(struct ctl_table_header *p)277{278 if (!--p->used)279 if (unlikely(p->unregistering))280 complete(p->unregistering);281}282 283static void proc_sys_invalidate_dcache(struct ctl_table_header *head)284{285 proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);286}287 288/* called under sysctl_lock, will reacquire if has to wait */289static void start_unregistering(struct ctl_table_header *p)290{291 /*292 * if p->used is 0, nobody will ever touch that entry again;293 * we'll eliminate all paths to it before dropping sysctl_lock294 */295 if (unlikely(p->used)) {296 struct completion wait;297 init_completion(&wait);298 p->unregistering = &wait;299 spin_unlock(&sysctl_lock);300 wait_for_completion(&wait);301 } else {302 /* anything non-NULL; we'll never dereference it */303 p->unregistering = ERR_PTR(-EINVAL);304 spin_unlock(&sysctl_lock);305 }306 /*307 * Invalidate dentries for unregistered sysctls: namespaced sysctls308 * can have duplicate names and contaminate dcache very badly.309 */310 proc_sys_invalidate_dcache(p);311 /*312 * do not remove from the list until nobody holds it; walking the313 * list in do_sysctl() relies on that.314 */315 spin_lock(&sysctl_lock);316 erase_header(p);317}318 319static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)320{321 BUG_ON(!head);322 spin_lock(&sysctl_lock);323 if (!use_table(head))324 head = ERR_PTR(-ENOENT);325 spin_unlock(&sysctl_lock);326 return head;327}328 329static HWJS_SUSPENDS void sysctl_head_finish(struct ctl_table_header *head)330{331 if (!head)332 return;333 spin_lock(&sysctl_lock);334 unuse_table(head);335 spin_unlock(&sysctl_lock);336}337 338static struct ctl_table_set *339lookup_header_set(struct ctl_table_root *root)340{341 struct ctl_table_set *set = &root->default_set;342 if (root->lookup)343 set = root->lookup(root);344 return set;345}346 347static struct ctl_table *lookup_entry(struct ctl_table_header **phead,348 struct ctl_dir *dir,349 const char *name, int namelen)350{351 struct ctl_table_header *head;352 struct ctl_table *entry;353 354 spin_lock(&sysctl_lock);355 entry = find_entry(&head, dir, name, namelen);356 if (entry && use_table(head))357 *phead = head;358 else359 entry = NULL;360 spin_unlock(&sysctl_lock);361 return entry;362}363 364static struct ctl_node *first_usable_entry(struct rb_node *node)365{366 struct ctl_node *ctl_node;367 368 for (;node; node = rb_next(node)) {369 ctl_node = rb_entry(node, struct ctl_node, node);370 if (use_table(ctl_node->header))371 return ctl_node;372 }373 return NULL;374}375 376static void first_entry(struct ctl_dir *dir,377 struct ctl_table_header **phead, struct ctl_table **pentry)378{379 struct ctl_table_header *head = NULL;380 struct ctl_table *entry = NULL;381 struct ctl_node *ctl_node;382 383 spin_lock(&sysctl_lock);384 ctl_node = first_usable_entry(rb_first(&dir->root));385 spin_unlock(&sysctl_lock);386 if (ctl_node) {387 head = ctl_node->header;388 entry = &head->ctl_table[ctl_node - head->node];389 }390 *phead = head;391 *pentry = entry;392}393 394static HWJS_SUSPENDS void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)395{396 struct ctl_table_header *head = *phead;397 struct ctl_table *entry = *pentry;398 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];399 400 spin_lock(&sysctl_lock);401 unuse_table(head);402 403 ctl_node = first_usable_entry(rb_next(&ctl_node->node));404 spin_unlock(&sysctl_lock);405 head = NULL;406 if (ctl_node) {407 head = ctl_node->header;408 entry = &head->ctl_table[ctl_node - head->node];409 }410 *phead = head;411 *pentry = entry;412}413 414/*415 * sysctl_perm does NOT grant the superuser all rights automatically, because416 * some sysctl variables are readonly even to root.417 */418 419static int test_perm(int mode, int op)420{421 if (uid_eq(current_euid(), GLOBAL_ROOT_UID))422 mode >>= 6;423 else if (in_egroup_p(GLOBAL_ROOT_GID))424 mode >>= 3;425 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)426 return 0;427 return -EACCES;428}429 430static HWJS_SUSPENDS int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)431{432 struct ctl_table_root *root = head->root;433 int mode;434 435 if (root->permissions)436 mode = root->permissions(head, table);437 else438 mode = table->mode;439 440 return test_perm(mode, op);441}442 443static HWJS_SUSPENDS struct inode *proc_sys_make_inode(struct super_block *sb,444 struct ctl_table_header *head, struct ctl_table *table)445{446 struct ctl_table_root *root = head->root;447 struct inode *inode;448 struct proc_inode *ei;449 450 inode = new_inode(sb);451 if (!inode)452 return ERR_PTR(-ENOMEM);453 454 inode->i_ino = get_next_ino();455 456 ei = PROC_I(inode);457 458 spin_lock(&sysctl_lock);459 if (unlikely(head->unregistering)) {460 spin_unlock(&sysctl_lock);461 iput(inode);462 return ERR_PTR(-ENOENT);463 }464 ei->sysctl = head;465 ei->sysctl_entry = table;466 hlist_add_head_rcu(&ei->sibling_inodes, &head->inodes);467 head->count++;468 spin_unlock(&sysctl_lock);469 470 simple_inode_init_ts(inode);471 inode->i_mode = table->mode;472 if (!S_ISDIR(table->mode)) {473 inode->i_mode |= S_IFREG;474 inode->i_op = &proc_sys_inode_operations;475 inode->i_fop = &proc_sys_file_operations;476 } else {477 inode->i_mode |= S_IFDIR;478 inode->i_op = &proc_sys_dir_operations;479 inode->i_fop = &proc_sys_dir_file_operations;480 if (sysctl_is_perm_empty_ctl_header(head))481 make_empty_dir_inode(inode);482 }483 484 inode->i_uid = GLOBAL_ROOT_UID;485 inode->i_gid = GLOBAL_ROOT_GID;486 if (root->set_ownership)487 root->set_ownership(head, &inode->i_uid, &inode->i_gid);488 489 return inode;490}491 492void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)493{494 spin_lock(&sysctl_lock);495 hlist_del_init_rcu(&PROC_I(inode)->sibling_inodes);496 if (!--head->count)497 kfree_rcu(head, rcu);498 spin_unlock(&sysctl_lock);499}500 501static struct ctl_table_header *grab_header(struct inode *inode)502{503 struct ctl_table_header *head = PROC_I(inode)->sysctl;504 if (!head)505 head = &sysctl_table_root.default_set.dir.header;506 return sysctl_head_grab(head);507}508 509static HWJS_SUSPENDS struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,510 unsigned int flags)511{512 struct ctl_table_header *head = grab_header(dir);513 struct ctl_table_header *h = NULL;514 const struct qstr *name = &dentry->d_name;515 struct ctl_table *p;516 struct inode *inode;517 struct dentry *err = ERR_PTR(-ENOENT);518 struct ctl_dir *ctl_dir;519 int ret;520 521 if (IS_ERR(head))522 return ERR_CAST(head);523 524 ctl_dir = container_of(head, struct ctl_dir, header);525 526 p = lookup_entry(&h, ctl_dir, name->name, name->len);527 if (!p)528 goto out;529 530 if (S_ISLNK(p->mode)) {531 ret = sysctl_follow_link(&h, &p);532 err = ERR_PTR(ret);533 if (ret)534 goto out;535 }536 537 d_set_d_op(dentry, &proc_sys_dentry_operations);538 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);539 err = d_splice_alias(inode, dentry);540 541out:542 if (h)543 sysctl_head_finish(h);544 sysctl_head_finish(head);545 return err;546}547 548static HWJS_SUSPENDS ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,549 int write)550{551 struct inode *inode = file_inode(iocb->ki_filp);552 struct ctl_table_header *head = grab_header(inode);553 struct ctl_table *table = PROC_I(inode)->sysctl_entry;554 size_t count = iov_iter_count(iter);555 char *kbuf;556 ssize_t error;557 558 if (IS_ERR(head))559 return PTR_ERR(head);560 561 /*562 * At this point we know that the sysctl was not unregistered563 * and won't be until we finish.564 */565 error = -EPERM;566 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))567 goto out;568 569 /* if that can happen at all, it should be -EINVAL, not -EISDIR */570 error = -EINVAL;571 if (!table->proc_handler)572 goto out;573 574 /* don't even try if the size is too large */575 error = -ENOMEM;576 if (count >= KMALLOC_MAX_SIZE)577 goto out;578 kbuf = kvzalloc(count + 1, GFP_KERNEL);579 if (!kbuf)580 goto out;581 582 if (write) {583 error = -EFAULT;584 if (!copy_from_iter_full(kbuf, count, iter))585 goto out_free_buf;586 kbuf[count] = '\0';587 }588 589 error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count,590 &iocb->ki_pos);591 if (error)592 goto out_free_buf;593 594 /* careful: calling conventions are nasty here */595 error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos);596 if (error)597 goto out_free_buf;598 599 if (!write) {600 error = -EFAULT;601 if (copy_to_iter(kbuf, count, iter) < count)602 goto out_free_buf;603 }604 605 error = count;606out_free_buf:607 kvfree(kbuf);608out:609 sysctl_head_finish(head);610 611 return error;612}613 614static HWJS_SUSPENDS ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter)615{616 return proc_sys_call_handler(iocb, iter, 0);617}618 619static HWJS_SUSPENDS ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter)620{621 return proc_sys_call_handler(iocb, iter, 1);622}623 624static HWJS_SUSPENDS int proc_sys_open(struct inode *inode, struct file *filp)625{626 struct ctl_table_header *head = grab_header(inode);627 struct ctl_table *table = PROC_I(inode)->sysctl_entry;628 629 /* sysctl was unregistered */630 if (IS_ERR(head))631 return PTR_ERR(head);632 633 if (table->poll)634 filp->private_data = proc_sys_poll_event(table->poll);635 636 sysctl_head_finish(head);637 638 return 0;639}640 641static HWJS_SUSPENDS __poll_t proc_sys_poll(struct file *filp, poll_table *wait)642{643 struct inode *inode = file_inode(filp);644 struct ctl_table_header *head = grab_header(inode);645 struct ctl_table *table = PROC_I(inode)->sysctl_entry;646 __poll_t ret = DEFAULT_POLLMASK;647 unsigned long event;648 649 /* sysctl was unregistered */650 if (IS_ERR(head))651 return EPOLLERR | EPOLLHUP;652 653 if (!table->proc_handler)654 goto out;655 656 if (!table->poll)657 goto out;658 659 event = (unsigned long)filp->private_data;660 poll_wait(filp, &table->poll->wait, wait);661 662 if (event != atomic_read(&table->poll->event)) {663 filp->private_data = proc_sys_poll_event(table->poll);664 ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;665 }666 667out:668 sysctl_head_finish(head);669 670 return ret;671}672 673static HWJS_SUSPENDS bool proc_sys_fill_cache(struct file *file,674 struct dir_context *ctx,675 struct ctl_table_header *head,676 struct ctl_table *table)677{678 struct dentry *child, *dir = file->f_path.dentry;679 struct inode *inode;680 struct qstr qname;681 ino_t ino = 0;682 unsigned type = DT_UNKNOWN;683 684 qname.name = table->procname;685 qname.len = strlen(table->procname);686 qname.hash = full_name_hash(dir, qname.name, qname.len);687 688 child = d_lookup(dir, &qname);689 if (!child) {690 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);691 child = d_alloc_parallel(dir, &qname, &wq);692 if (IS_ERR(child))693 return false;694 if (d_in_lookup(child)) {695 struct dentry *res;696 d_set_d_op(child, &proc_sys_dentry_operations);697 inode = proc_sys_make_inode(dir->d_sb, head, table);698 res = d_splice_alias(inode, child);699 d_lookup_done(child);700 if (unlikely(res)) {701 if (IS_ERR(res)) {702 dput(child);703 return false;704 }705 dput(child);706 child = res;707 }708 }709 }710 inode = d_inode(child);711 ino = inode->i_ino;712 type = inode->i_mode >> 12;713 dput(child);714 return dir_emit(ctx, qname.name, qname.len, ino, type);715}716 717static HWJS_SUSPENDS bool proc_sys_link_fill_cache(struct file *file,718 struct dir_context *ctx,719 struct ctl_table_header *head,720 struct ctl_table *table)721{722 bool ret = true;723 724 head = sysctl_head_grab(head);725 if (IS_ERR(head))726 return false;727 728 /* It is not an error if we can not follow the link ignore it */729 if (sysctl_follow_link(&head, &table))730 goto out;731 732 ret = proc_sys_fill_cache(file, ctx, head, table);733out:734 sysctl_head_finish(head);735 return ret;736}737 738static HWJS_SUSPENDS int scan(struct ctl_table_header *head, struct ctl_table *table,739 unsigned long *pos, struct file *file,740 struct dir_context *ctx)741{742 bool res;743 744 if ((*pos)++ < ctx->pos)745 return true;746 747 if (unlikely(S_ISLNK(table->mode)))748 res = proc_sys_link_fill_cache(file, ctx, head, table);749 else750 res = proc_sys_fill_cache(file, ctx, head, table);751 752 if (res)753 ctx->pos = *pos;754 755 return res;756}757 758static HWJS_SUSPENDS int proc_sys_readdir(struct file *file, struct dir_context *ctx)759{760 struct ctl_table_header *head = grab_header(file_inode(file));761 struct ctl_table_header *h = NULL;762 struct ctl_table *entry;763 struct ctl_dir *ctl_dir;764 unsigned long pos;765 766 if (IS_ERR(head))767 return PTR_ERR(head);768 769 ctl_dir = container_of(head, struct ctl_dir, header);770 771 if (!dir_emit_dots(file, ctx))772 goto out;773 774 pos = 2;775 776 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {777 if (!scan(h, entry, &pos, file, ctx)) {778 sysctl_head_finish(h);779 break;780 }781 }782out:783 sysctl_head_finish(head);784 return 0;785}786 787static HWJS_SUSPENDS int proc_sys_permission(struct mnt_idmap *idmap,788 struct inode *inode, int mask)789{790 /*791 * sysctl entries that are not writeable,792 * are _NOT_ writeable, capabilities or not.793 */794 struct ctl_table_header *head;795 struct ctl_table *table;796 int error;797 798 /* Executable files are not allowed under /proc/sys/ */799 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))800 return -EACCES;801 802 head = grab_header(inode);803 if (IS_ERR(head))804 return PTR_ERR(head);805 806 table = PROC_I(inode)->sysctl_entry;807 if (!table) /* global root - r-xr-xr-x */808 error = mask & MAY_WRITE ? -EACCES : 0;809 else /* Use the permissions on the sysctl table entry */810 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);811 812 sysctl_head_finish(head);813 return error;814}815 816static int proc_sys_setattr(struct mnt_idmap *idmap,817 struct dentry *dentry, struct iattr *attr)818{819 struct inode *inode = d_inode(dentry);820 int error;821 822 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))823 return -EPERM;824 825 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);826 if (error)827 return error;828 829 setattr_copy(&nop_mnt_idmap, inode, attr);830 return 0;831}832 833static HWJS_SUSPENDS int proc_sys_getattr(struct mnt_idmap *idmap,834 const struct path *path, struct kstat *stat,835 u32 request_mask, unsigned int query_flags)836{837 struct inode *inode = d_inode(path->dentry);838 struct ctl_table_header *head = grab_header(inode);839 struct ctl_table *table = PROC_I(inode)->sysctl_entry;840 841 if (IS_ERR(head))842 return PTR_ERR(head);843 844 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);845 if (table)846 stat->mode = (stat->mode & S_IFMT) | table->mode;847 848 sysctl_head_finish(head);849 return 0;850}851 852static const struct file_operations proc_sys_file_operations = {853 .open = proc_sys_open,854 .poll = proc_sys_poll,855 .read_iter = proc_sys_read,856 .write_iter = proc_sys_write,857 .splice_read = copy_splice_read,858 .splice_write = iter_file_splice_write,859 .llseek = default_llseek,860};861 862static const struct file_operations proc_sys_dir_file_operations = {863 .read = generic_read_dir,864 .iterate_shared = proc_sys_readdir,865 .llseek = generic_file_llseek,866};867 868static const struct inode_operations proc_sys_inode_operations = {869 .permission = proc_sys_permission,870 .setattr = proc_sys_setattr,871 .getattr = proc_sys_getattr,872};873 874static const struct inode_operations proc_sys_dir_operations = {875 .lookup = proc_sys_lookup,876 .permission = proc_sys_permission,877 .setattr = proc_sys_setattr,878 .getattr = proc_sys_getattr,879};880 881static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)882{883 if (flags & LOOKUP_RCU)884 return -ECHILD;885 return !PROC_I(d_inode(dentry))->sysctl->unregistering;886}887 888static int proc_sys_delete(const struct dentry *dentry)889{890 return !!PROC_I(d_inode(dentry))->sysctl->unregistering;891}892 893static int sysctl_is_seen(struct ctl_table_header *p)894{895 struct ctl_table_set *set = p->set;896 int res;897 spin_lock(&sysctl_lock);898 if (p->unregistering)899 res = 0;900 else if (!set->is_seen)901 res = 1;902 else903 res = set->is_seen(set);904 spin_unlock(&sysctl_lock);905 return res;906}907 908static int proc_sys_compare(const struct dentry *dentry,909 unsigned int len, const char *str, const struct qstr *name)910{911 struct ctl_table_header *head;912 struct inode *inode;913 914 /* Although proc doesn't have negative dentries, rcu-walk means915 * that inode here can be NULL */916 /* AV: can it, indeed? */917 inode = d_inode_rcu(dentry);918 if (!inode)919 return 1;920 if (name->len != len)921 return 1;922 if (memcmp(name->name, str, len))923 return 1;924 head = rcu_dereference(PROC_I(inode)->sysctl);925 return !head || !sysctl_is_seen(head);926}927 928static const struct dentry_operations proc_sys_dentry_operations = {929 .d_revalidate = proc_sys_revalidate,930 .d_delete = proc_sys_delete,931 .d_compare = proc_sys_compare,932};933 934static struct ctl_dir *find_subdir(struct ctl_dir *dir,935 const char *name, int namelen)936{937 struct ctl_table_header *head;938 struct ctl_table *entry;939 940 entry = find_entry(&head, dir, name, namelen);941 if (!entry)942 return ERR_PTR(-ENOENT);943 if (!S_ISDIR(entry->mode))944 return ERR_PTR(-ENOTDIR);945 return container_of(head, struct ctl_dir, header);946}947 948static struct ctl_dir *new_dir(struct ctl_table_set *set,949 const char *name, int namelen)950{951 struct ctl_table *table;952 struct ctl_dir *new;953 struct ctl_node *node;954 char *new_name;955 956 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +957 sizeof(struct ctl_table) + namelen + 1,958 GFP_KERNEL);959 if (!new)960 return NULL;961 962 node = (struct ctl_node *)(new + 1);963 table = (struct ctl_table *)(node + 1);964 new_name = (char *)(table + 1);965 memcpy(new_name, name, namelen);966 table[0].procname = new_name;967 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;968 init_header(&new->header, set->dir.header.root, set, node, table, 1);969 970 return new;971}972 973/**974 * get_subdir - find or create a subdir with the specified name.975 * @dir: Directory to create the subdirectory in976 * @name: The name of the subdirectory to find or create977 * @namelen: The length of name978 *979 * Takes a directory with an elevated reference count so we know that980 * if we drop the lock the directory will not go away. Upon success981 * the reference is moved from @dir to the returned subdirectory.982 * Upon error an error code is returned and the reference on @dir is983 * simply dropped.984 */985static HWJS_SUSPENDS struct ctl_dir *get_subdir(struct ctl_dir *dir,986 const char *name, int namelen)987{988 struct ctl_table_set *set = dir->header.set;989 struct ctl_dir *subdir, *new = NULL;990 int err;991 992 spin_lock(&sysctl_lock);993 subdir = find_subdir(dir, name, namelen);994 if (!IS_ERR(subdir))995 goto found;996 if (PTR_ERR(subdir) != -ENOENT)997 goto failed;998 999 spin_unlock(&sysctl_lock);1000 new = new_dir(set, name, namelen);1001 spin_lock(&sysctl_lock);1002 subdir = ERR_PTR(-ENOMEM);1003 if (!new)1004 goto failed;1005 1006 /* Was the subdir added while we dropped the lock? */1007 subdir = find_subdir(dir, name, namelen);1008 if (!IS_ERR(subdir))1009 goto found;1010 if (PTR_ERR(subdir) != -ENOENT)1011 goto failed;1012 1013 /* Nope. Use the our freshly made directory entry. */1014 err = insert_header(dir, &new->header);1015 subdir = ERR_PTR(err);1016 if (err)1017 goto failed;1018 subdir = new;1019found:1020 subdir->header.nreg++;1021failed:1022 if (IS_ERR(subdir)) {1023 pr_err("sysctl could not get directory: ");1024 sysctl_print_dir(dir);1025 pr_cont("%*.*s %ld\n", namelen, namelen, name,1026 PTR_ERR(subdir));1027 }1028 drop_sysctl_table(&dir->header);1029 if (new)1030 drop_sysctl_table(&new->header);1031 spin_unlock(&sysctl_lock);1032 return subdir;1033}1034 1035static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)1036{1037 struct ctl_dir *parent;1038 const char *procname;1039 if (!dir->header.parent)1040 return &set->dir;1041 parent = xlate_dir(set, dir->header.parent);1042 if (IS_ERR(parent))1043 return parent;1044 procname = dir->header.ctl_table[0].procname;1045 return find_subdir(parent, procname, strlen(procname));1046}1047 1048static HWJS_SUSPENDS int sysctl_follow_link(struct ctl_table_header **phead,1049 struct ctl_table **pentry)1050{1051 struct ctl_table_header *head;1052 struct ctl_table_root *root;1053 struct ctl_table_set *set;1054 struct ctl_table *entry;1055 struct ctl_dir *dir;1056 int ret;1057 1058 spin_lock(&sysctl_lock);1059 root = (*pentry)->data;1060 set = lookup_header_set(root);1061 dir = xlate_dir(set, (*phead)->parent);1062 if (IS_ERR(dir))1063 ret = PTR_ERR(dir);1064 else {1065 const char *procname = (*pentry)->procname;1066 head = NULL;1067 entry = find_entry(&head, dir, procname, strlen(procname));1068 ret = -ENOENT;1069 if (entry && use_table(head)) {1070 unuse_table(*phead);1071 *phead = head;1072 *pentry = entry;1073 ret = 0;1074 }1075 }1076 1077 spin_unlock(&sysctl_lock);1078 return ret;1079}1080 1081static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)1082{1083 struct va_format vaf;1084 va_list args;1085 1086 va_start(args, fmt);1087 vaf.fmt = fmt;1088 vaf.va = &args;1089 1090 pr_err("sysctl table check failed: %s/%s %pV\n",1091 path, table->procname, &vaf);1092 1093 va_end(args);1094 return -EINVAL;1095}1096 1097static int sysctl_check_table_array(const char *path, struct ctl_table *table)1098{1099 unsigned int extra;1100 int err = 0;1101 1102 if ((table->proc_handler == proc_douintvec) ||1103 (table->proc_handler == proc_douintvec_minmax)) {1104 if (table->maxlen != sizeof(unsigned int))1105 err |= sysctl_err(path, table, "array not allowed");1106 }1107 1108 if (table->proc_handler == proc_dou8vec_minmax) {1109 if (table->maxlen != sizeof(u8))1110 err |= sysctl_err(path, table, "array not allowed");1111 1112 if (table->extra1) {1113 extra = *(unsigned int *) table->extra1;1114 if (extra > 255U)1115 err |= sysctl_err(path, table,1116 "range value too large for proc_dou8vec_minmax");1117 }1118 if (table->extra2) {1119 extra = *(unsigned int *) table->extra2;1120 if (extra > 255U)1121 err |= sysctl_err(path, table,1122 "range value too large for proc_dou8vec_minmax");1123 }1124 }1125 1126 if (table->proc_handler == proc_dobool) {1127 if (table->maxlen != sizeof(bool))1128 err |= sysctl_err(path, table, "array not allowed");1129 }1130 1131 return err;1132}1133 1134static int sysctl_check_table(const char *path, struct ctl_table_header *header)1135{1136 struct ctl_table *entry;1137 int err = 0;1138 list_for_each_table_entry(entry, header) {1139 if (!entry->procname)1140 err |= sysctl_err(path, entry, "procname is null");1141 if ((entry->proc_handler == proc_dostring) ||1142 (entry->proc_handler == proc_dobool) ||1143 (entry->proc_handler == proc_dointvec) ||1144 (entry->proc_handler == proc_douintvec) ||1145 (entry->proc_handler == proc_douintvec_minmax) ||1146 (entry->proc_handler == proc_dointvec_minmax) ||1147 (entry->proc_handler == proc_dou8vec_minmax) ||1148 (entry->proc_handler == proc_dointvec_jiffies) ||1149 (entry->proc_handler == proc_dointvec_userhz_jiffies) ||1150 (entry->proc_handler == proc_dointvec_ms_jiffies) ||1151 (entry->proc_handler == proc_doulongvec_minmax) ||1152 (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {1153 if (!entry->data)1154 err |= sysctl_err(path, entry, "No data");1155 if (!entry->maxlen)1156 err |= sysctl_err(path, entry, "No maxlen");1157 else1158 err |= sysctl_check_table_array(path, entry);1159 }1160 if (!entry->proc_handler)1161 err |= sysctl_err(path, entry, "No proc_handler");1162 1163 if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode)1164 err |= sysctl_err(path, entry, "bogus .mode 0%o",1165 entry->mode);1166 }1167 return err;1168}1169 1170static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_header *head)1171{1172 struct ctl_table *link_table, *entry, *link;1173 struct ctl_table_header *links;1174 struct ctl_node *node;1175 char *link_name;1176 int name_bytes;1177 1178 name_bytes = 0;1179 list_for_each_table_entry(entry, head) {1180 name_bytes += strlen(entry->procname) + 1;1181 }1182 1183 links = kzalloc(sizeof(struct ctl_table_header) +1184 sizeof(struct ctl_node)*head->ctl_table_size +1185 sizeof(struct ctl_table)*head->ctl_table_size +1186 name_bytes,1187 GFP_KERNEL);1188 1189 if (!links)1190 return NULL;1191 1192 node = (struct ctl_node *)(links + 1);1193 link_table = (struct ctl_table *)(node + head->ctl_table_size);1194 link_name = (char *)(link_table + head->ctl_table_size);1195 link = link_table;1196 1197 list_for_each_table_entry(entry, head) {1198 int len = strlen(entry->procname) + 1;1199 memcpy(link_name, entry->procname, len);1200 link->procname = link_name;1201 link->mode = S_IFLNK|S_IRWXUGO;1202 link->data = head->root;1203 link_name += len;1204 link++;1205 }1206 init_header(links, dir->header.root, dir->header.set, node, link_table,1207 head->ctl_table_size);1208 links->nreg = head->ctl_table_size;1209 1210 return links;1211}1212 1213static bool get_links(struct ctl_dir *dir,1214 struct ctl_table_header *header,1215 struct ctl_table_root *link_root)1216{1217 struct ctl_table_header *tmp_head;1218 struct ctl_table *entry, *link;1219 1220 if (header->ctl_table_size == 0 ||1221 sysctl_is_perm_empty_ctl_header(header))1222 return true;1223 1224 /* Are there links available for every entry in table? */1225 list_for_each_table_entry(entry, header) {1226 const char *procname = entry->procname;1227 link = find_entry(&tmp_head, dir, procname, strlen(procname));1228 if (!link)1229 return false;1230 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))1231 continue;1232 if (S_ISLNK(link->mode) && (link->data == link_root))1233 continue;1234 return false;1235 }1236 1237 /* The checks passed. Increase the registration count on the links */1238 list_for_each_table_entry(entry, header) {1239 const char *procname = entry->procname;1240 link = find_entry(&tmp_head, dir, procname, strlen(procname));1241 tmp_head->nreg++;1242 }1243 return true;1244}1245 1246static HWJS_SUSPENDS int insert_links(struct ctl_table_header *head)1247{1248 struct ctl_table_set *root_set = &sysctl_table_root.default_set;1249 struct ctl_dir *core_parent;1250 struct ctl_table_header *links;1251 int err;1252 1253 if (head->set == root_set)1254 return 0;1255 1256 core_parent = xlate_dir(root_set, head->parent);1257 if (IS_ERR(core_parent))1258 return 0;1259 1260 if (get_links(core_parent, head, head->root))1261 return 0;1262 1263 core_parent->header.nreg++;1264 spin_unlock(&sysctl_lock);1265 1266 links = new_links(core_parent, head);1267 1268 spin_lock(&sysctl_lock);1269 err = -ENOMEM;1270 if (!links)1271 goto out;1272 1273 err = 0;1274 if (get_links(core_parent, head, head->root)) {1275 kfree(links);1276 goto out;1277 }1278 1279 err = insert_header(core_parent, links);1280 if (err)1281 kfree(links);1282out:1283 drop_sysctl_table(&core_parent->header);1284 return err;1285}1286 1287/* Find the directory for the ctl_table. If one is not found create it. */1288static HWJS_SUSPENDS struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)1289{1290 const char *name, *nextname;1291 1292 for (name = path; name; name = nextname) {1293 int namelen;1294 nextname = strchr(name, '/');1295 if (nextname) {1296 namelen = nextname - name;1297 nextname++;1298 } else {1299 namelen = strlen(name);1300 }1301 if (namelen == 0)1302 continue;1303 1304 /*1305 * namelen ensures if name is "foo/bar/yay" only foo is1306 * registered first. We traverse as if using mkdir -p and1307 * return a ctl_dir for the last directory entry.1308 */1309 dir = get_subdir(dir, name, namelen);1310 if (IS_ERR(dir))1311 break;1312 }1313 return dir;1314}1315 1316/**1317 * __register_sysctl_table - register a leaf sysctl table1318 * @set: Sysctl tree to register on1319 * @path: The path to the directory the sysctl table is in.1320 *1321 * @table: the top-level table structure. This table should not be free'd1322 * after registration. So it should not be used on stack. It can either1323 * be a global or dynamically allocated by the caller and free'd later1324 * after sysctl unregistration.1325 * @table_size : The number of elements in table1326 *1327 * Register a sysctl table hierarchy. @table should be a filled in ctl_table1328 * array.1329 *1330 * The members of the &struct ctl_table structure are used as follows:1331 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not1332 * enter a sysctl file1333 * data - a pointer to data for use by proc_handler1334 * maxlen - the maximum size in bytes of the data1335 * mode - the file permissions for the /proc/sys file1336 * type - Defines the target type (described in struct definition)1337 * proc_handler - the text handler routine (described below)1338 *1339 * extra1, extra2 - extra pointers usable by the proc handler routines1340 * XXX: we should eventually modify these to use long min / max [0]1341 * [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org1342 *1343 * Leaf nodes in the sysctl tree will be represented by a single file1344 * under /proc; non-leaf nodes are not allowed.1345 *1346 * There must be a proc_handler routine for any terminal nodes.1347 * Several default handlers are available to cover common cases -1348 *1349 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),1350 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),1351 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()1352 *1353 * It is the handler's job to read the input buffer from user memory1354 * and process it. The handler should return 0 on success.1355 *1356 * This routine returns %NULL on a failure to register, and a pointer1357 * to the table header on success.1358 */1359struct ctl_table_header *__register_sysctl_table(1360 struct ctl_table_set *set,1361 const char *path, struct ctl_table *table, size_t table_size)1362{1363 struct ctl_table_root *root = set->dir.header.root;1364 struct ctl_table_header *header;1365 struct ctl_dir *dir;1366 struct ctl_node *node;1367 1368 header = kzalloc(sizeof(struct ctl_table_header) +1369 sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);1370 if (!header)1371 return NULL;1372 1373 node = (struct ctl_node *)(header + 1);1374 init_header(header, root, set, node, table, table_size);1375 if (sysctl_check_table(path, header))1376 goto fail;1377 1378 spin_lock(&sysctl_lock);1379 dir = &set->dir;1380 /* Reference moved down the directory tree get_subdir */1381 dir->header.nreg++;1382 spin_unlock(&sysctl_lock);1383 1384 dir = sysctl_mkdir_p(dir, path);1385 if (IS_ERR(dir))1386 goto fail;1387 spin_lock(&sysctl_lock);1388 if (insert_header(dir, header))1389 goto fail_put_dir_locked;1390 1391 drop_sysctl_table(&dir->header);1392 spin_unlock(&sysctl_lock);1393 1394 return header;1395 1396fail_put_dir_locked:1397 drop_sysctl_table(&dir->header);1398 spin_unlock(&sysctl_lock);1399fail:1400 kfree(header);1401 return NULL;1402}1403 1404/**1405 * register_sysctl_sz - register a sysctl table1406 * @path: The path to the directory the sysctl table is in. If the path1407 * doesn't exist we will create it for you.1408 * @table: the table structure. The calller must ensure the life of the @table1409 * will be kept during the lifetime use of the syctl. It must not be freed1410 * until unregister_sysctl_table() is called with the given returned table1411 * with this registration. If your code is non modular then you don't need1412 * to call unregister_sysctl_table() and can instead use something like1413 * register_sysctl_init() which does not care for the result of the syctl1414 * registration.1415 * @table_size: The number of elements in table.1416 *1417 * Register a sysctl table. @table should be a filled in ctl_table1418 * array. A completely 0 filled entry terminates the table.1419 *1420 * See __register_sysctl_table for more details.1421 */1422struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table,1423 size_t table_size)1424{1425 return __register_sysctl_table(&sysctl_table_root.default_set,1426 path, table, table_size);1427}1428EXPORT_SYMBOL(register_sysctl_sz);1429 1430/**1431 * __register_sysctl_init() - register sysctl table to path1432 * @path: path name for sysctl base. If that path doesn't exist we will create1433 * it for you.1434 * @table: This is the sysctl table that needs to be registered to the path.1435 * The caller must ensure the life of the @table will be kept during the1436 * lifetime use of the sysctl.1437 * @table_name: The name of sysctl table, only used for log printing when1438 * registration fails1439 * @table_size: The number of elements in table1440 *1441 * The sysctl interface is used by userspace to query or modify at runtime1442 * a predefined value set on a variable. These variables however have default1443 * values pre-set. Code which depends on these variables will always work even1444 * if register_sysctl() fails. If register_sysctl() fails you'd just loose the1445 * ability to query or modify the sysctls dynamically at run time. Chances of1446 * register_sysctl() failing on init are extremely low, and so for both reasons1447 * this function does not return any error as it is used by initialization code.1448 *1449 * Context: if your base directory does not exist it will be created for you.1450 */1451void __init __register_sysctl_init(const char *path, struct ctl_table *table,1452 const char *table_name, size_t table_size)1453{1454 struct ctl_table_header *hdr = register_sysctl_sz(path, table, table_size);1455 1456 if (unlikely(!hdr)) {1457 pr_err("failed when register_sysctl_sz %s to %s\n", table_name, path);1458 return;1459 }1460 kmemleak_not_leak(hdr);1461}1462 1463static HWJS_SUSPENDS void put_links(struct ctl_table_header *header)1464{1465 struct ctl_table_set *root_set = &sysctl_table_root.default_set;1466 struct ctl_table_root *root = header->root;1467 struct ctl_dir *parent = header->parent;1468 struct ctl_dir *core_parent;1469 struct ctl_table *entry;1470 1471 if (header->set == root_set)1472 return;1473 1474 core_parent = xlate_dir(root_set, parent);1475 if (IS_ERR(core_parent))1476 return;1477 1478 list_for_each_table_entry(entry, header) {1479 struct ctl_table_header *link_head;1480 struct ctl_table *link;1481 const char *name = entry->procname;1482 1483 link = find_entry(&link_head, core_parent, name, strlen(name));1484 if (link &&1485 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||1486 (S_ISLNK(link->mode) && (link->data == root)))) {1487 drop_sysctl_table(link_head);1488 }1489 else {1490 pr_err("sysctl link missing during unregister: ");1491 sysctl_print_dir(parent);1492 pr_cont("%s\n", name);1493 }1494 }1495}1496 1497static HWJS_SUSPENDS void drop_sysctl_table(struct ctl_table_header *header)1498{1499 struct ctl_dir *parent = header->parent;1500 1501 if (--header->nreg)1502 return;1503 1504 if (parent) {1505 put_links(header);1506 start_unregistering(header);1507 }1508 1509 if (!--header->count)1510 kfree_rcu(header, rcu);1511 1512 if (parent)1513 drop_sysctl_table(&parent->header);1514}1515 1516/**1517 * unregister_sysctl_table - unregister a sysctl table hierarchy1518 * @header: the header returned from register_sysctl or __register_sysctl_table1519 *1520 * Unregisters the sysctl table and all children. proc entries may not1521 * actually be removed until they are no longer used by anyone.1522 */1523void unregister_sysctl_table(struct ctl_table_header * header)1524{1525 might_sleep();1526 1527 if (header == NULL)1528 return;1529 1530 spin_lock(&sysctl_lock);1531 drop_sysctl_table(header);1532 spin_unlock(&sysctl_lock);1533}1534EXPORT_SYMBOL(unregister_sysctl_table);1535 1536void setup_sysctl_set(struct ctl_table_set *set,1537 struct ctl_table_root *root,1538 int (*is_seen)(struct ctl_table_set *))1539{1540 memset(set, 0, sizeof(*set));1541 set->is_seen = is_seen;1542 init_header(&set->dir.header, root, set, NULL, root_table, 1);1543}1544 1545void retire_sysctl_set(struct ctl_table_set *set)1546{1547 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));1548}1549 1550int __init proc_sys_init(void)1551{1552 struct proc_dir_entry *proc_sys_root;1553 1554 proc_sys_root = proc_mkdir("sys", NULL);1555 proc_sys_root->proc_iops = &proc_sys_dir_operations;1556 proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;1557 proc_sys_root->nlink = 0;1558 1559 return sysctl_init_bases();1560}1561 1562struct sysctl_alias {1563 const char *kernel_param;1564 const char *sysctl_param;1565};1566 1567/*1568 * Historically some settings had both sysctl and a command line parameter.1569 * With the generic sysctl. parameter support, we can handle them at a single1570 * place and only keep the historical name for compatibility. This is not meant1571 * to add brand new aliases. When adding existing aliases, consider whether1572 * the possibly different moment of changing the value (e.g. from early_param1573 * to the moment do_sysctl_args() is called) is an issue for the specific1574 * parameter.1575 */1576static const struct sysctl_alias sysctl_aliases[] = {1577 {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },1578 {"hung_task_panic", "kernel.hung_task_panic" },1579 {"numa_zonelist_order", "vm.numa_zonelist_order" },1580 {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },1581 { }1582};1583 1584static const char *sysctl_find_alias(char *param)1585{1586 const struct sysctl_alias *alias;1587 1588 for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {1589 if (strcmp(alias->kernel_param, param) == 0)1590 return alias->sysctl_param;1591 }1592 1593 return NULL;1594}1595 1596bool sysctl_is_alias(char *param)1597{1598 const char *alias = sysctl_find_alias(param);1599 1600 return alias != NULL;1601}1602 1603/* Set sysctl value passed on kernel command line. */1604static int process_sysctl_arg(char *param, char *val,1605 const char *unused, void *arg)1606{1607 char *path;1608 struct vfsmount **proc_mnt = arg;1609 struct file_system_type *proc_fs_type;1610 struct file *file;1611 int len;1612 int err;1613 loff_t pos = 0;1614 ssize_t wret;1615 1616 if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {1617 param += sizeof("sysctl") - 1;1618 1619 if (param[0] != '/' && param[0] != '.')1620 return 0;1621 1622 param++;1623 } else {1624 param = (char *) sysctl_find_alias(param);1625 if (!param)1626 return 0;1627 }1628 1629 if (!val)1630 return -EINVAL;1631 len = strlen(val);1632 if (len == 0)1633 return -EINVAL;1634 1635 /*1636 * To set sysctl options, we use a temporary mount of proc, look up the1637 * respective sys/ file and write to it. To avoid mounting it when no1638 * options were given, we mount it only when the first sysctl option is1639 * found. Why not a persistent mount? There are problems with a1640 * persistent mount of proc in that it forces userspace not to use any1641 * proc mount options.1642 */1643 if (!*proc_mnt) {1644 proc_fs_type = get_fs_type("proc");1645 if (!proc_fs_type) {1646 pr_err("Failed to find procfs to set sysctl from command line\n");1647 return 0;1648 }1649 *proc_mnt = kern_mount(proc_fs_type);1650 put_filesystem(proc_fs_type);1651 if (IS_ERR(*proc_mnt)) {1652 pr_err("Failed to mount procfs to set sysctl from command line\n");1653 return 0;1654 }1655 }1656 1657 path = kasprintf(GFP_KERNEL, "sys/%s", param);1658 if (!path)1659 panic("%s: Failed to allocate path for %s\n", __func__, param);1660 strreplace(path, '.', '/');1661 1662 file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0);1663 if (IS_ERR(file)) {1664 err = PTR_ERR(file);1665 if (err == -ENOENT)1666 pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",1667 param, val);1668 else if (err == -EACCES)1669 pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",1670 param, val);1671 else1672 pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",1673 file, param, val);1674 goto out;1675 }1676 wret = kernel_write(file, val, len, &pos);1677 if (wret < 0) {1678 err = wret;1679 if (err == -EINVAL)1680 pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",1681 param, val);1682 else1683 pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",1684 ERR_PTR(err), param, val);1685 } else if (wret != len) {1686 pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",1687 wret, len, path, param, val);1688 }1689 1690 err = filp_close(file, NULL);1691 if (err)1692 pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",1693 ERR_PTR(err), param, val);1694out:1695 kfree(path);1696 return 0;1697}1698 1699void do_sysctl_args(void)1700{1701 char *command_line;1702 struct vfsmount *proc_mnt = NULL;1703 1704 command_line = kstrdup(saved_command_line, GFP_KERNEL);1705 if (!command_line)1706 panic("%s: Failed to allocate copy of command line\n", __func__);1707 1708 parse_args("Setting sysctl args", command_line,1709 NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg);1710 1711 if (proc_mnt)1712 kern_unmount(proc_mnt);1713 1714 kfree(command_line);1715}1716