/* * /proc/sys support */ #include <linux/init.h> #include <linux/sysctl.h> #include <linux/proc_fs.h> #include <linux/security.h> #include <linux/namei.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; static struct inode *proc_sys_make_inode(struct super_block *sb, struct ctl_table_header *head, struct ctl_table *table) { struct inode *inode; struct proc_inode *ei; inode = new_inode(sb); if (!inode) goto out; inode->i_ino = get_next_ino(); sysctl_head_get(head); ei = PROC_I(inode); ei->sysctl = head; ei->sysctl_entry = table; inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */ inode->i_mode = table->mode; if (!table->child) { 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_nlink = 0; inode->i_op = &proc_sys_dir_operations; inode->i_fop = &proc_sys_dir_file_operations; } out: return inode; } static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name) { int len; for ( ; p->procname; p++) { if (!p->procname) continue; len = strlen(p->procname); if (len != name->len) continue; if (memcmp(p->procname, name->name, len) != 0) continue; /* I have a match */ return p; } return NULL; } static struct ctl_table_header *grab_header(struct inode *inode) { if (PROC_I(inode)->sysctl) return sysctl_head_grab(PROC_I(inode)->sysctl); else return sysctl_head_next(NULL); } static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) { struct ctl_table_header *head = grab_header(dir); struct ctl_table *table = PROC_I(dir)->sysctl_entry; struct ctl_table_header *h = NULL; struct qstr *name = &dentry->d_name; struct ctl_table *p; struct inode *inode; struct dentry *err = ERR_PTR(-ENOENT); if (IS_ERR(head)) return ERR_CAST(head); if (table && !table->child) { WARN_ON(1); goto out; } table = table ? table->child : head->ctl_table; p = find_in_table(table, name); if (!p) { for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { if (h->attached_to != table) continue; p = find_in_table(h->attached_by, name); if (p) break; } } if (!p) goto out; err = ERR_PTR(-ENOMEM); inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); if (h) sysctl_head_finish(h); if (!inode) goto out; err = NULL; d_set_d_op(dentry, &proc_sys_dentry_operations); d_add(dentry, inode); out: sysctl_head_finish(head); return err; } static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf, size_t count, loff_t *ppos, int write) { struct inode *inode = filp->f_path.dentry->d_inode; struct ctl_table_header *head = grab_header(inode); struct ctl_table *table = PROC_I(inode)->sysctl_entry; ssize_t error; size_t res; if (IS_ERR(head)) return PTR_ERR(head); /* * At this point we know that the sysctl was not unregistered * and won't be until we finish. */ error = -EPERM; if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ)) goto out; /* if that can happen at all, it should be -EINVAL, not -EISDIR */ error = -EINVAL; if (!table->proc_handler) goto out; /* careful: calling conventions are nasty here */ res = count; error = table->proc_handler(table, write, buf, &res, ppos); if (!error) error = res; out: sysctl_head_finish(head); return error; } static ssize_t proc_sys_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0); } static ssize_t proc_sys_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1); } static int proc_sys_fill_cache(struct file *filp, void *dirent, filldir_t filldir, struct ctl_table_header *head, struct ctl_table *table) { struct dentry *child, *dir = filp->f_path.dentry; struct inode *inode; struct qstr qname; ino_t ino = 0; unsigned type = DT_UNKNOWN; qname.name = table->procname; qname.len = strlen(table->procname); qname.hash = full_name_hash(qname.name, qname.len); child = d_lookup(dir, &qname); if (!child) { child = d_alloc(dir, &qname); if (child) { inode = proc_sys_make_inode(dir->d_sb, head, table); if (!inode) { dput(child); return -ENOMEM; } else { d_set_d_op(child, &proc_sys_dentry_operations); d_add(child, inode); } } else { return -ENOMEM; } } inode = child->d_inode; ino = inode->i_ino; type = inode->i_mode >> 12; dput(child); return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type); } static int scan(struct ctl_table_header *head, ctl_table *table, unsigned long *pos, struct file *file, void *dirent, filldir_t filldir) { for (; table->procname; table++, (*pos)++) { int res; /* Can't do anything without a proc name */ if (!table->procname) continue; if (*pos < file->f_pos) continue; res = proc_sys_fill_cache(file, dirent, filldir, head, table); if (res) return res; file->f_pos = *pos + 1; } return 0; } static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir) { struct dentry *dentry = filp->f_path.dentry; struct inode *inode = dentry->d_inode; struct ctl_table_header *head = grab_header(inode); struct ctl_table *table = PROC_I(inode)->sysctl_entry; struct ctl_table_header *h = NULL; unsigned long pos; int ret = -EINVAL; if (IS_ERR(head)) return PTR_ERR(head); if (table && !table->child) { WARN_ON(1); goto out; } table = table ? table->child : head->ctl_table; ret = 0; /* Avoid a switch here: arm builds fail with missing __cmpdi2 */ if (filp->f_pos == 0) { if (filldir(dirent, ".", 1, filp->f_pos, inode->i_ino, DT_DIR) < 0) goto out; filp->f_pos++; } if (filp->f_pos == 1) { if (filldir(dirent, "..", 2, filp->f_pos, parent_ino(dentry), DT_DIR) < 0) goto out; filp->f_pos++; } pos = 2; ret = scan(head, table, &pos, filp, dirent, filldir); if (ret) goto out; for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { if (h->attached_to != table) continue; ret = scan(h, h->attached_by, &pos, filp, dirent, filldir); if (ret) { sysctl_head_finish(h); break; } } ret = 1; out: sysctl_head_finish(head); return ret; } static int proc_sys_permission(struct inode *inode, int mask,unsigned int flags) { /* * sysctl entries that are not writeable, * are _NOT_ writeable, capabilities or not. */ struct ctl_table_header *head; struct ctl_table *table; int error; if (flags & IPERM_FLAG_RCU) return -ECHILD; /* Executable files are not allowed under /proc/sys/ */ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) return -EACCES; head = grab_header(inode); if (IS_ERR(head)) return PTR_ERR(head); table = PROC_I(inode)->sysctl_entry; if (!table) /* global root - r-xr-xr-x */ error = mask & MAY_WRITE ? -EACCES : 0; else /* Use the permissions on the sysctl table entry */ error = sysctl_perm(head->root, table, mask); sysctl_head_finish(head); return error; } static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; int error; if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) return -EPERM; error = inode_change_ok(inode, attr); if (error) return error; if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size != i_size_read(inode)) { error = vmtruncate(inode, attr->ia_size); if (error) return error; } setattr_copy(inode, attr); mark_inode_dirty(inode); return 0; } static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { struct inode *inode = dentry->d_inode; struct ctl_table_header *head = grab_header(inode); struct ctl_table *table = PROC_I(inode)->sysctl_entry; if (IS_ERR(head)) return PTR_ERR(head); generic_fillattr(inode, stat); if (table) stat->mode = (stat->mode & S_IFMT) | table->mode; sysctl_head_finish(head); return 0; } static const struct file_operations proc_sys_file_operations = { .read = proc_sys_read, .write = proc_sys_write, .llseek = default_llseek, }; static const struct file_operations proc_sys_dir_file_operations = { .readdir = proc_sys_readdir, .llseek = generic_file_llseek, }; static const struct inode_operations proc_sys_inode_operations = { .permission = proc_sys_permission, .setattr = proc_sys_setattr, .getattr = proc_sys_getattr, }; static const struct inode_operations proc_sys_dir_operations = { .lookup = proc_sys_lookup, .permission = proc_sys_permission, .setattr = proc_sys_setattr, .getattr = proc_sys_getattr, }; static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd) { if (nd->flags & LOOKUP_RCU) return -ECHILD; return !PROC_I(dentry->d_inode)->sysctl->unregistering; } static int proc_sys_delete(const struct dentry *dentry) { return !!PROC_I(dentry->d_inode)->sysctl->unregistering; } static int proc_sys_compare(const struct dentry *parent, const struct inode *pinode, const struct dentry *dentry, const struct inode *inode, unsigned int len, const char *str, const struct qstr *name) { /* Although proc doesn't have negative dentries, rcu-walk means * that inode here can be NULL */ if (!inode) return 0; if (name->len != len) return 1; if (memcmp(name->name, str, len)) return 1; return !sysctl_is_seen(PROC_I(inode)->sysctl); } static const struct dentry_operations proc_sys_dentry_operations = { .d_revalidate = proc_sys_revalidate, .d_delete = proc_sys_delete, .d_compare = proc_sys_compare, }; int __init proc_sys_init(void) { struct proc_dir_entry *proc_sys_root; proc_sys_root = proc_mkdir("sys", NULL); proc_sys_root->proc_iops = &proc_sys_dir_operations; proc_sys_root->proc_fops = &proc_sys_dir_file_operations; proc_sys_root->nlink = 0; return 0; }