// SPDX-License-Identifier: GPL-2.0/* * /proc/sys support */#include <linux/init.h>#include <linux/sysctl.h>#include <linux/poll.h>#include <linux/proc_fs.h>#include <linux/printk.h>#include <linux/security.h>#include <linux/sched.h>#include <linux/cred.h>#include <linux/namei.h>#include <linux/mm.h>#include <linux/module.h>#include <linux/bpf-cgroup.h>#include "internal.h" static const struct dentry_operations proc_sys_dentry_operations;static const struct file_operations proc_sys_file_operations;static const struct inode_operations proc_sys_inode_operations;static const struct file_operations proc_sys_dir_file_operations;static const struct inode_operations proc_sys_dir_operations; /* Support for permanently empty directories */ struct ctl_table sysctl_mount_point[] = { { }}; static bool is_empty_dir(struct ctl_table_header *head){ return head->ctl_table[0].child == sysctl_mount_point;} static void set_empty_dir(struct ctl_dir *dir){ dir->header.ctl_table[0].child = sysctl_mount_point;} static void clear_empty_dir(struct ctl_dir *dir) { dir->header.ctl_table[0].child = NULL;} void proc_sys_poll_notify(struct ctl_table_poll *poll){ if (!poll) return; atomic_inc(&poll->event); wake_up_interruptible(&poll->wait);} static struct ctl_table root_table[] = { { .procname = "", .mode = S_IFDIR|S_IRUGO|S_IXUGO, }, { }};static struct ctl_table_root sysctl_table_root = { .default_set.dir.header = { {{.count = 1, .nreg = 1, .ctl_table = root_table }}, .ctl_table_arg = root_table, .root = &sysctl_table_root, .set = &sysctl_table_root.default_set, },}; static DEFINE_SPINLOCK(sysctl_lock); static void drop_sysctl_table(struct ctl_table_header *header);static int sysctl_follow_link(struct ctl_table_header **phead, struct ctl_table **pentry);static int insert_links(struct ctl_table_header *head);static void put_links(struct ctl_table_header *header); static void sysctl_print_dir(struct ctl_dir *dir){ if (dir->header.parent) sysctl_print_dir(dir->header.parent); pr_cont("%s/", dir->header.ctl_table[0].procname);} static int namecmp(const char *name1, int len1, const char *name2, int len2){ int minlen; int cmp; minlen = len1; if (minlen > len2) minlen = len2; cmp = memcmp(name1, name2, minlen); if (cmp == 0) cmp = len1 - len2; return cmp;} /* Called under sysctl_lock */static struct ctl_table *find_entry(struct ctl_table_header **phead, struct ctl_dir *dir, const char *name, int namelen){ struct ctl_table_header *head; struct ctl_table *entry; struct rb_node *node = dir->root.rb_node; while (node) { struct ctl_node *ctl_node; const char *procname; int cmp; ctl_node = rb_entry(node, struct ctl_node, node); head = ctl_node->header; entry = &head->ctl_table[ctl_node - head->node]; procname = entry->procname; cmp = namecmp(name, namelen, procname, strlen(procname)); if (cmp < 0) node = node->rb_left; else if (cmp > 0) node = node->rb_right; else { *phead = head; return entry; } } return NULL;} static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry){ struct rb_node *node = &head->node[entry - head->ctl_table].node; struct rb_node **p = &head->parent->root.rb_node; struct rb_node *parent = NULL; const char *name = entry->procname; int namelen = strlen(name); while (*p) { struct ctl_table_header *parent_head; struct ctl_table *parent_entry; struct ctl_node *parent_node; const char *parent_name; int cmp; parent = *p; parent_node = rb_entry(parent, struct ctl_node, node); parent_head = parent_node->header; parent_entry = &parent_head->ctl_table[parent_node - parent_head->node]; parent_name = parent_entry->procname; cmp = namecmp(name, namelen, parent_name, strlen(parent_name)); if (cmp < 0) p = &(*p)->rb_left; else if (cmp > 0) p = &(*p)->rb_right; else { pr_err("sysctl duplicate entry: "); sysctl_print_dir(head->parent); pr_cont("/%s\n", entry->procname); return -EEXIST; } } rb_link_node(node, parent, p); rb_insert_color(node, &head->parent->root); return 0;} static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry){ struct rb_node *node = &head->node[entry - head->ctl_table].node; rb_erase(node, &head->parent->root);} static void init_header(struct ctl_table_header *head, struct ctl_table_root *root, struct ctl_table_set *set, struct ctl_node *node, struct ctl_table *table){ head->ctl_table = table; head->ctl_table_arg = table; head->used = 0; head->count = 1; head->nreg = 1; head->unregistering = NULL; head->root = root; head->set = set; head->parent = NULL; head->node = node; INIT_HLIST_HEAD(&head->inodes); if (node) { struct ctl_table *entry; for (entry = table; entry->procname; entry++, node++) node->header = head; }} static void erase_header(struct ctl_table_header *head){ struct ctl_table *entry; for (entry = head->ctl_table; entry->procname; entry++) erase_entry(head, entry);} static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header){ struct ctl_table *entry; int err; /* Is this a permanently empty directory? */ if (is_empty_dir(&dir->header)) return -EROFS; /* Am I creating a permanently empty directory? */ if (header->ctl_table == sysctl_mount_point) { if (!RB_EMPTY_ROOT(&dir->root)) return -EINVAL; set_empty_dir(dir); } dir->header.nreg++; header->parent = dir; err = insert_links(header); if (err) goto fail_links; for (entry = header->ctl_table; entry->procname; entry++) { err = insert_entry(header, entry); if (err) goto fail; } return 0;fail: erase_header(header); put_links(header);fail_links: if (header->ctl_table == sysctl_mount_point) clear_empty_dir(dir); header->parent = NULL; drop_sysctl_table(&dir->header); return err;} /* called under sysctl_lock */static int use_table(struct ctl_table_header *p){ if (unlikely(p->unregistering)) return 0; p->used++; return 1;} /* called under sysctl_lock */static void unuse_table(struct ctl_table_header *p){ if (!--p->used) if (unlikely(p->unregistering)) complete(p->unregistering);} static void proc_sys_prune_dcache(struct ctl_table_header *head){ struct inode *inode; struct proc_inode *ei; struct hlist_node *node; struct super_block *sb; rcu_read_lock(); for (;;) { node = hlist_first_rcu(&head->inodes); if (!node) break; ei = hlist_entry(node, struct proc_inode, sysctl_inodes); spin_lock(&sysctl_lock); hlist_del_init_rcu(&ei->sysctl_inodes); spin_unlock(&sysctl_lock); inode = &ei->vfs_inode; sb = inode->i_sb; if (!atomic_inc_not_zero(&sb->s_active)) continue; inode = igrab(inode); rcu_read_unlock(); if (unlikely(!inode)) { deactivate_super(sb); rcu_read_lock(); continue; } d_prune_aliases(inode); iput(inode); deactivate_super(sb); rcu_read_lock(); } rcu_read_unlock();} /* called under sysctl_lock, will reacquire if has to wait */static void start_unregistering(struct ctl_table_header *p){ /* * if p->used is 0, nobody will ever touch that entry again; * we'll eliminate all paths to it before dropping sysctl_lock */ if (unlikely(p->used)) { struct completion wait; init_completion(&wait); p->unregistering = &wait; spin_unlock(&sysctl_lock); wait_for_completion(&wait); } else { /* anything non-NULL; we'll never dereference it */ p->unregistering = ERR_PTR(-EINVAL); spin_unlock(&sysctl_lock); } /* * Prune dentries for unregistered sysctls: namespaced sysctls * can have duplicate names and contaminate dcache very badly. */ proc_sys_prune_dcache(p); /* * do not remove from the list until nobody holds it; walking the * list in do_sysctl() relies on that. */ spin_lock(&sysctl_lock); erase_header(p);} static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head){ BUG_ON(!head); spin_lock(&sysctl_lock); if (!use_table(head)) head = ERR_PTR(-ENOENT); spin_unlock(&sysctl_lock); return head;} static void sysctl_head_finish(struct ctl_table_header *head){ if (!head) return; spin_lock(&sysctl_lock); unuse_table(head); spin_unlock(&sysctl_lock);} static struct ctl_table_set *lookup_header_set(struct ctl_table_root *root){ struct ctl_table_set *set = &root->default_set; if (root->lookup) set = root->lookup(root); return set;} static struct ctl_table *lookup_entry(struct ctl_table_header **phead, struct ctl_dir *dir, const char *name, int namelen){ struct ctl_table_header *head; struct ctl_table *entry; spin_lock(&sysctl_lock); entry = find_entry(&head, dir, name, namelen); if (entry && use_table(head)) *phead = head; else entry = NULL; spin_unlock(&sysctl_lock); return entry;} static struct ctl_node *first_usable_entry(struct rb_node *node){ struct ctl_node *ctl_node; for (;node; node = rb_next(node)) { ctl_node = rb_entry(node, struct ctl_node, node); if (use_table(ctl_node->header)) return ctl_node; } return NULL;} static void first_entry(struct ctl_dir *dir, struct ctl_table_header **phead, struct ctl_table **pentry){ struct ctl_table_header *head = NULL; struct ctl_table *entry = NULL; struct ctl_node *ctl_node; spin_lock(&sysctl_lock); ctl_node = first_usable_entry(rb_first(&dir->root)); spin_unlock(&sysctl_lock); if (ctl_node) { head = ctl_node->header; entry = &head->ctl_table[ctl_node - head->node]; } *phead = head; *pentry = entry;} static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry){ struct ctl_table_header *head = *phead; struct ctl_table *entry = *pentry; struct ctl_node *ctl_node = &head->node[entry - head->ctl_table]; spin_lock(&sysctl_lock); unuse_table(head); ctl_node = first_usable_entry(rb_next(&ctl_node->node)); spin_unlock(&sysctl_lock); head = NULL; if (ctl_node) { head = ctl_node->header; entry = &head->ctl_table[ctl_node - head->node]; } *phead = head; *pentry = entry;} /* * sysctl_perm does NOT grant the superuser all rights automatically, because * some sysctl variables are readonly even to root. */ static int test_perm(int mode, int op){ if (uid_eq(current_euid(), GLOBAL_ROOT_UID)) mode >>= 6; else if (in_egroup_p(GLOBAL_ROOT_GID)) mode >>= 3; if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0) return 0; return -EACCES;} static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op){ struct ctl_table_root *root = head->root; int mode; if (root->permissions) mode = root->permissions(head, table); else mode = table->mode; return test_perm(mode, op);} static struct inode *proc_sys_make_inode(struct super_block *sb, struct ctl_table_header *head, struct ctl_table *table){ struct ctl_table_root *root = head->root; struct inode *inode; struct proc_inode *ei; inode = new_inode(sb); if (!inode) return ERR_PTR(-ENOMEM); inode->i_ino = get_next_ino(); ei = PROC_I(inode); spin_lock(&sysctl_lock); if (unlikely(head->unregistering)) { spin_unlock(&sysctl_lock); iput(inode); return ERR_PTR(-ENOENT); } ei->sysctl = head; ei->sysctl_entry = table; hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes); head->count++; spin_unlock(&sysctl_lock); inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); inode->i_mode = table->mode; if (!S_ISDIR(table->mode)) { inode->i_mode |= S_IFREG; inode->i_op = &proc_sys_inode_operations; inode->i_fop = &proc_sys_file_operations; } else { inode->i_mode |= S_IFDIR; inode->i_op = &proc_sys_dir_operations; inode->i_fop = &proc_sys_dir_file_operations; if (is_empty_dir(head)) make_empty_dir_inode(inode); } if (root->set_ownership)Lines 1–500 of 1719. 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// SPDX-License-Identifier: GPL-2.0 /* * /proc/sys support */ #include <linux/init.h> #include <linux/sysctl.h> #include <linux/poll.h> #include <linux/proc_fs.h> #include <linux/printk.h> #include <linux/security.h> #include <linux/sched.h> #include <linux/cred.h> #include <linux/namei.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/bpf-cgroup.h> #include "internal.h" static const struct dentry_operations proc_sys_dentry_operations; static const struct file_operations proc_sys_file_operations; static const struct inode_operations proc_sys_inode_operations; static const struct file_operations proc_sys_dir_file_operations; static const struct inode_operations proc_sys_dir_operations; /* Support for permanently empty directories */ struct ctl_table sysctl_mount_point[] = { { } }; static bool is_empty_dir(struct ctl_table_header *head) { return head->ctl_table[0].child == sysctl_mount_point; } static void set_empty_dir(struct ctl_dir *dir) { dir->header.ctl_table[0].child = sysctl_mount_point; } static void clear_empty_dir(struct ctl_dir *dir) { dir->header.ctl_table[0].child = NULL; } void proc_sys_poll_notify(struct ctl_table_poll *poll) { if (!poll) return; atomic_inc(&poll->event); wake_up_interruptible(&poll->wait); } static struct ctl_table root_table[] = { { .procname = "", .mode = S_IFDIR|S_IRUGO|S_IXUGO, }, { } }; static struct ctl_table_root sysctl_table_root = { .default_set.dir.header = { {{.count = 1, .nreg = 1, .ctl_table = root_table }}, .ctl_table_arg = root_table, .root = &sysctl_table_root, .set = &sysctl_table_root.default_set, }, }; static DEFINE_SPINLOCK(sysctl_lock); static void drop_sysctl_table(struct ctl_table_header *header); static int sysctl_follow_link(struct ctl_table_header **phead, struct ctl_table **pentry); static int insert_links(struct ctl_table_header *head); static void put_links(struct ctl_table_header *header); static void sysctl_print_dir(struct ctl_dir *dir) { if (dir->header.parent) sysctl_print_dir(dir->header.parent); pr_cont("%s/", dir->header.ctl_table[0].procname); } static int namecmp(const char *name1, int len1, const char *name2, int len2) { int minlen; int cmp; minlen = len1; if (minlen > len2) minlen = len2; cmp = memcmp(name1, name2, minlen); if (cmp == 0) cmp = len1 - len2; return cmp; } /* Called under sysctl_lock */ static struct ctl_table *find_entry(struct ctl_table_header **phead, struct ctl_dir *dir, const char *name, int namelen) { struct ctl_table_header *head; struct ctl_table *entry; struct rb_node *node = dir->root.rb_node; while (node) { struct ctl_node *ctl_node; const char *procname; int cmp; ctl_node = rb_entry(node, struct ctl_node, node); head = ctl_node->header; entry = &head->ctl_table[ctl_node - head->node]; procname = entry->procname; cmp = namecmp(name, namelen, procname, strlen(procname)); if (cmp < 0) node = node->rb_left; else if (cmp > 0) node = node->rb_right; else { *phead = head; return entry; } } return NULL; } static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry) { struct rb_node *node = &head->node[entry - head->ctl_table].node; struct rb_node **p = &head->parent->root.rb_node; struct rb_node *parent = NULL; const char *name = entry->procname; int namelen = strlen(name); while (*p) { struct ctl_table_header *parent_head; struct ctl_table *parent_entry; struct ctl_node *parent_node; const char *parent_name; int cmp; parent = *p; parent_node = rb_entry(parent, struct ctl_node, node); parent_head = parent_node->header; parent_entry = &parent_head->ctl_table[parent_node - parent_head->node]; parent_name = parent_entry->procname; cmp = namecmp(name, namelen, parent_name, strlen(parent_name)); if (cmp < 0) p = &(*p)->rb_left; else if (cmp > 0) p = &(*p)->rb_right; else { pr_err("sysctl duplicate entry: "); sysctl_print_dir(head->parent); pr_cont("/%s\n", entry->procname); return -EEXIST; } } rb_link_node(node, parent, p); rb_insert_color(node, &head->parent->root); return 0; } static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry) { struct rb_node *node = &head->node[entry - head->ctl_table].node; rb_erase(node, &head->parent->root); } static void init_header(struct ctl_table_header *head, struct ctl_table_root *root, struct ctl_table_set *set, struct ctl_node *node, struct ctl_table *table) { head->ctl_table = table; head->ctl_table_arg = table; head->used = 0; head->count = 1; head->nreg = 1; head->unregistering = NULL; head->root = root; head->set = set; head->parent = NULL; head->node = node; INIT_HLIST_HEAD(&head->inodes); if (node) { struct ctl_table *entry; for (entry = table; entry->procname; entry++, node++) node->header = head; } } static void erase_header(struct ctl_table_header *head) { struct ctl_table *entry; for (entry = head->ctl_table; entry->procname; entry++) erase_entry(head, entry); } static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header) { struct ctl_table *entry; int err; /* Is this a permanently empty directory? */ if (is_empty_dir(&dir->header)) return -EROFS; /* Am I creating a permanently empty directory? */ if (header->ctl_table == sysctl_mount_point) { if (!RB_EMPTY_ROOT(&dir->root)) return -EINVAL; set_empty_dir(dir); } dir->header.nreg++; header->parent = dir; err = insert_links(header); if (err) goto fail_links; for (entry = header->ctl_table; entry->procname; entry++) { err = insert_entry(header, entry); if (err) goto fail; } return 0; fail: erase_header(header); put_links(header); fail_links: if (header->ctl_table == sysctl_mount_point) clear_empty_dir(dir); header->parent = NULL; drop_sysctl_table(&dir->header); return err; } /* called under sysctl_lock */ static int use_table(struct ctl_table_header *p) { if (unlikely(p->unregistering)) return 0; p->used++; return 1; } /* called under sysctl_lock */ static void unuse_table(struct ctl_table_header *p) { if (!--p->used) if (unlikely(p->unregistering)) complete(p->unregistering); } static void proc_sys_prune_dcache(struct ctl_table_header *head) { struct inode *inode; struct proc_inode *ei; struct hlist_node *node; struct super_block *sb; rcu_read_lock(); for (;;) { node = hlist_first_rcu(&head->inodes); if (!node) break; ei = hlist_entry(node, struct proc_inode, sysctl_inodes); spin_lock(&sysctl_lock); hlist_del_init_rcu(&ei->sysctl_inodes); spin_unlock(&sysctl_lock); inode = &ei->vfs_inode; sb = inode->i_sb; if (!atomic_inc_not_zero(&sb->s_active)) continue; inode = igrab(inode); rcu_read_unlock(); if (unlikely(!inode)) { deactivate_super(sb); rcu_read_lock(); continue; } d_prune_aliases(inode); iput(inode); deactivate_super(sb); rcu_read_lock(); } rcu_read_unlock(); } /* called under sysctl_lock, will reacquire if has to wait */ static void start_unregistering(struct ctl_table_header *p) { /* * if p->used is 0, nobody will ever touch that entry again; * we'll eliminate all paths to it before dropping sysctl_lock */ if (unlikely(p->used)) { struct completion wait; init_completion(&wait); p->unregistering = &wait; spin_unlock(&sysctl_lock); wait_for_completion(&wait); } else { /* anything non-NULL; we'll never dereference it */ p->unregistering = ERR_PTR(-EINVAL); spin_unlock(&sysctl_lock); } /* * Prune dentries for unregistered sysctls: namespaced sysctls * can have duplicate names and contaminate dcache very badly. */ proc_sys_prune_dcache(p); /* * do not remove from the list until nobody holds it; walking the * list in do_sysctl() relies on that. */ spin_lock(&sysctl_lock); erase_header(p); } static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head) { BUG_ON(!head); spin_lock(&sysctl_lock); if (!use_table(head)) head = ERR_PTR(-ENOENT); spin_unlock(&sysctl_lock); return head; } static void sysctl_head_finish(struct ctl_table_header *head) { if (!head) return; spin_lock(&sysctl_lock); unuse_table(head); spin_unlock(&sysctl_lock); } static struct ctl_table_set * lookup_header_set(struct ctl_table_root *root) { struct ctl_table_set *set = &root->default_set; if (root->lookup) set = root->lookup(root); return set; } static struct ctl_table *lookup_entry(struct ctl_table_header **phead, struct ctl_dir *dir, const char *name, int namelen) { struct ctl_table_header *head; struct ctl_table *entry; spin_lock(&sysctl_lock); entry = find_entry(&head, dir, name, namelen); if (entry && use_table(head)) *phead = head; else entry = NULL; spin_unlock(&sysctl_lock); return entry; } static struct ctl_node *first_usable_entry(struct rb_node *node) { struct ctl_node *ctl_node; for (;node; node = rb_next(node)) { ctl_node = rb_entry(node, struct ctl_node, node); if (use_table(ctl_node->header)) return ctl_node; } return NULL; } static void first_entry(struct ctl_dir *dir, struct ctl_table_header **phead, struct ctl_table **pentry) { struct ctl_table_header *head = NULL; struct ctl_table *entry = NULL; struct ctl_node *ctl_node; spin_lock(&sysctl_lock); ctl_node = first_usable_entry(rb_first(&dir->root)); spin_unlock(&sysctl_lock); if (ctl_node) { head = ctl_node->header; entry = &head->ctl_table[ctl_node - head->node]; } *phead = head; *pentry = entry; } static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry) { struct ctl_table_header *head = *phead; struct ctl_table *entry = *pentry; struct ctl_node *ctl_node = &head->node[entry - head->ctl_table]; spin_lock(&sysctl_lock); unuse_table(head); ctl_node = first_usable_entry(rb_next(&ctl_node->node)); spin_unlock(&sysctl_lock); head = NULL; if (ctl_node) { head = ctl_node->header; entry = &head->ctl_table[ctl_node - head->node]; } *phead = head; *pentry = entry; } /* * sysctl_perm does NOT grant the superuser all rights automatically, because * some sysctl variables are readonly even to root. */ static int test_perm(int mode, int op) { if (uid_eq(current_euid(), GLOBAL_ROOT_UID)) mode >>= 6; else if (in_egroup_p(GLOBAL_ROOT_GID)) mode >>= 3; if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0) return 0; return -EACCES; } static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op) { struct ctl_table_root *root = head->root; int mode; if (root->permissions) mode = root->permissions(head, table); else mode = table->mode; return test_perm(mode, op); } static struct inode *proc_sys_make_inode(struct super_block *sb, struct ctl_table_header *head, struct ctl_table *table) { struct ctl_table_root *root = head->root; struct inode *inode; struct proc_inode *ei; inode = new_inode(sb); if (!inode) return ERR_PTR(-ENOMEM); inode->i_ino = get_next_ino(); ei = PROC_I(inode); spin_lock(&sysctl_lock); if (unlikely(head->unregistering)) { spin_unlock(&sysctl_lock); iput(inode); return ERR_PTR(-ENOENT); } ei->sysctl = head; ei->sysctl_entry = table; hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes); head->count++; spin_unlock(&sysctl_lock); inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); inode->i_mode = table->mode; if (!S_ISDIR(table->mode)) { inode->i_mode |= S_IFREG; inode->i_op = &proc_sys_inode_operations; inode->i_fop = &proc_sys_file_operations; } else { inode->i_mode |= S_IFDIR; inode->i_op = &proc_sys_dir_operations; inode->i_fop = &proc_sys_dir_file_operations; if (is_empty_dir(head)) make_empty_dir_inode(inode); } if (root->set_ownership)