/* File: fs/xattr.c Extended attribute handling. Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org> Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com> Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> */ #include <linux/fs.h> #include <linux/slab.h> #include <linux/smp_lock.h> #include <linux/file.h> #include <linux/xattr.h> #include <linux/namei.h> #include <linux/security.h> #include <linux/syscalls.h> #include <linux/module.h> #include <linux/fsnotify.h> #include <asm/uaccess.h> /* * Extended attribute SET operations */ static long setxattr(struct dentry *d, char __user *name, void __user *value, size_t size, int flags) { int error; void *kvalue = NULL; char kname[XATTR_NAME_MAX + 1]; if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) return -EINVAL; error = strncpy_from_user(kname, name, sizeof(kname)); if (error == 0 || error == sizeof(kname)) error = -ERANGE; if (error < 0) return error; if (size) { if (size > XATTR_SIZE_MAX) return -E2BIG; kvalue = kmalloc(size, GFP_KERNEL); if (!kvalue) return -ENOMEM; if (copy_from_user(kvalue, value, size)) { kfree(kvalue); return -EFAULT; } } down(&d->d_inode->i_sem); error = security_inode_setxattr(d, kname, kvalue, size, flags); if (error) goto out; error = -EOPNOTSUPP; if (d->d_inode->i_op && d->d_inode->i_op->setxattr) { error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags); if (!error) { fsnotify_xattr(d); security_inode_post_setxattr(d, kname, kvalue, size, flags); } } else if (!strncmp(kname, XATTR_SECURITY_PREFIX, sizeof XATTR_SECURITY_PREFIX - 1)) { const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1; error = security_inode_setsecurity(d->d_inode, suffix, kvalue, size, flags); if (!error) fsnotify_xattr(d); } out: up(&d->d_inode->i_sem); if (kvalue) kfree(kvalue); return error; } asmlinkage long sys_setxattr(char __user *path, char __user *name, void __user *value, size_t size, int flags) { struct nameidata nd; int error; error = user_path_walk(path, &nd); if (error) return error; error = setxattr(nd.dentry, name, value, size, flags); path_release(&nd); return error; } asmlinkage long sys_lsetxattr(char __user *path, char __user *name, void __user *value, size_t size, int flags) { struct nameidata nd; int error; error = user_path_walk_link(path, &nd); if (error) return error; error = setxattr(nd.dentry, name, value, size, flags); path_release(&nd); return error; } asmlinkage long sys_fsetxattr(int fd, char __user *name, void __user *value, size_t size, int flags) { struct file *f; int error = -EBADF; f = fget(fd); if (!f) return error; error = setxattr(f->f_dentry, name, value, size, flags); fput(f); return error; } /* * Extended attribute GET operations */ static ssize_t getxattr(struct dentry *d, char __user *name, void __user *value, size_t size) { ssize_t error; void *kvalue = NULL; char kname[XATTR_NAME_MAX + 1]; error = strncpy_from_user(kname, name, sizeof(kname)); if (error == 0 || error == sizeof(kname)) error = -ERANGE; if (error < 0) return error; if (size) { if (size > XATTR_SIZE_MAX) size = XATTR_SIZE_MAX; kvalue = kmalloc(size, GFP_KERNEL); if (!kvalue) return -ENOMEM; } error = security_inode_getxattr(d, kname); if (error) goto out; error = -EOPNOTSUPP; if (d->d_inode->i_op && d->d_inode->i_op->getxattr) error = d->d_inode->i_op->getxattr(d, kname, kvalue, size); else if (!strncmp(kname, XATTR_SECURITY_PREFIX, sizeof XATTR_SECURITY_PREFIX - 1)) { const char *suffix = kname + sizeof XATTR_SECURITY_PREFIX - 1; error = security_inode_getsecurity(d->d_inode, suffix, kvalue, size); } if (error > 0) { if (size && copy_to_user(value, kvalue, error)) error = -EFAULT; } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { /* The file system tried to returned a value bigger than XATTR_SIZE_MAX bytes. Not possible. */ error = -E2BIG; } out: if (kvalue) kfree(kvalue); return error; } asmlinkage ssize_t sys_getxattr(char __user *path, char __user *name, void __user *value, size_t size) { struct nameidata nd; ssize_t error; error = user_path_walk(path, &nd); if (error) return error; error = getxattr(nd.dentry, name, value, size); path_release(&nd); return error; } asmlinkage ssize_t sys_lgetxattr(char __user *path, char __user *name, void __user *value, size_t size) { struct nameidata nd; ssize_t error; error = user_path_walk_link(path, &nd); if (error) return error; error = getxattr(nd.dentry, name, value, size); path_release(&nd); return error; } asmlinkage ssize_t sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size) { struct file *f; ssize_t error = -EBADF; f = fget(fd); if (!f) return error; error = getxattr(f->f_dentry, name, value, size); fput(f); return error; } /* * Extended attribute LIST operations */ static ssize_t listxattr(struct dentry *d, char __user *list, size_t size) { ssize_t error; char *klist = NULL; if (size) { if (size > XATTR_LIST_MAX) size = XATTR_LIST_MAX; klist = kmalloc(size, GFP_KERNEL); if (!klist) return -ENOMEM; } error = security_inode_listxattr(d); if (error) goto out; error = -EOPNOTSUPP; if (d->d_inode->i_op && d->d_inode->i_op->listxattr) { error = d->d_inode->i_op->listxattr(d, klist, size); } else { error = security_inode_listsecurity(d->d_inode, klist, size); if (size && error >= size) error = -ERANGE; } if (error > 0) { if (size && copy_to_user(list, klist, error)) error = -EFAULT; } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { /* The file system tried to returned a list bigger than XATTR_LIST_MAX bytes. Not possible. */ error = -E2BIG; } out: if (klist) kfree(klist); return error; } asmlinkage ssize_t sys_listxattr(char __user *path, char __user *list, size_t size) { struct nameidata nd; ssize_t error; error = user_path_walk(path, &nd); if (error) return error; error = listxattr(nd.dentry, list, size); path_release(&nd); return error; } asmlinkage ssize_t sys_llistxattr(char __user *path, char __user *list, size_t size) { struct nameidata nd; ssize_t error; error = user_path_walk_link(path, &nd); if (error) return error; error = listxattr(nd.dentry, list, size); path_release(&nd); return error; } asmlinkage ssize_t sys_flistxattr(int fd, char __user *list, size_t size) { struct file *f; ssize_t error = -EBADF; f = fget(fd); if (!f) return error; error = listxattr(f->f_dentry, list, size); fput(f); return error; } /* * Extended attribute REMOVE operations */ static long removexattr(struct dentry *d, char __user *name) { int error; char kname[XATTR_NAME_MAX + 1]; error = strncpy_from_user(kname, name, sizeof(kname)); if (error == 0 || error == sizeof(kname)) error = -ERANGE; if (error < 0) return error; error = -EOPNOTSUPP; if (d->d_inode->i_op && d->d_inode->i_op->removexattr) { error = security_inode_removexattr(d, kname); if (error) goto out; down(&d->d_inode->i_sem); error = d->d_inode->i_op->removexattr(d, kname); up(&d->d_inode->i_sem); if (!error) fsnotify_xattr(d); } out: return error; } asmlinkage long sys_removexattr(char __user *path, char __user *name) { struct nameidata nd; int error; error = user_path_walk(path, &nd); if (error) return error; error = removexattr(nd.dentry, name); path_release(&nd); return error; } asmlinkage long sys_lremovexattr(char __user *path, char __user *name) { struct nameidata nd; int error; error = user_path_walk_link(path, &nd); if (error) return error; error = removexattr(nd.dentry, name); path_release(&nd); return error; } asmlinkage long sys_fremovexattr(int fd, char __user *name) { struct file *f; int error = -EBADF; f = fget(fd); if (!f) return error; error = removexattr(f->f_dentry, name); fput(f); return error; } static const char * strcmp_prefix(const char *a, const char *a_prefix) { while (*a_prefix && *a == *a_prefix) { a++; a_prefix++; } return *a_prefix ? NULL : a; } /* * In order to implement different sets of xattr operations for each xattr * prefix with the generic xattr API, a filesystem should create a * null-terminated array of struct xattr_handler (one for each prefix) and * hang a pointer to it off of the s_xattr field of the superblock. * * The generic_fooxattr() functions will use this list to dispatch xattr * operations to the correct xattr_handler. */ #define for_each_xattr_handler(handlers, handler) \ for ((handler) = *(handlers)++; \ (handler) != NULL; \ (handler) = *(handlers)++) /* * Find the xattr_handler with the matching prefix. */ static struct xattr_handler * xattr_resolve_name(struct xattr_handler **handlers, const char **name) { struct xattr_handler *handler; if (!*name) return NULL; for_each_xattr_handler(handlers, handler) { const char *n = strcmp_prefix(*name, handler->prefix); if (n) { *name = n; break; } } return handler; } /* * Find the handler for the prefix and dispatch its get() operation. */ ssize_t generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) { struct xattr_handler *handler; struct inode *inode = dentry->d_inode; handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); if (!handler) return -EOPNOTSUPP; return handler->get(inode, name, buffer, size); } /* * Combine the results of the list() operation from every xattr_handler in the * list. */ ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) { struct inode *inode = dentry->d_inode; struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr; unsigned int size = 0; if (!buffer) { for_each_xattr_handler(handlers, handler) size += handler->list(inode, NULL, 0, NULL, 0); } else { char *buf = buffer; for_each_xattr_handler(handlers, handler) { size = handler->list(inode, buf, buffer_size, NULL, 0); if (size > buffer_size) return -ERANGE; buf += size; buffer_size -= size; } size = buf - buffer; } return size; } /* * Find the handler for the prefix and dispatch its set() operation. */ int generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { struct xattr_handler *handler; struct inode *inode = dentry->d_inode; if (size == 0) value = ""; /* empty EA, do not remove */ handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); if (!handler) return -EOPNOTSUPP; return handler->set(inode, name, value, size, flags); } /* * Find the handler for the prefix and dispatch its set() operation to remove * any associated extended attribute. */ int generic_removexattr(struct dentry *dentry, const char *name) { struct xattr_handler *handler; struct inode *inode = dentry->d_inode; handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); if (!handler) return -EOPNOTSUPP; return handler->set(inode, name, NULL, 0, XATTR_REPLACE); } EXPORT_SYMBOL(generic_getxattr); EXPORT_SYMBOL(generic_listxattr); EXPORT_SYMBOL(generic_setxattr); EXPORT_SYMBOL(generic_removexattr);