/* * linux/fs/ext4/acl.c * * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de> */ #include <linux/init.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/capability.h> #include <linux/fs.h> #include "ext4_jbd2.h" #include "ext4.h" #include "xattr.h" #include "acl.h" /* * Convert from filesystem to in-memory representation. */ static struct posix_acl * ext4_acl_from_disk(const void *value, size_t size) { const char *end = (char *)value + size; int n, count; struct posix_acl *acl; if (!value) return NULL; if (size < sizeof(ext4_acl_header)) return ERR_PTR(-EINVAL); if (((ext4_acl_header *)value)->a_version != cpu_to_le32(EXT4_ACL_VERSION)) return ERR_PTR(-EINVAL); value = (char *)value + sizeof(ext4_acl_header); count = ext4_acl_count(size); if (count < 0) return ERR_PTR(-EINVAL); if (count == 0) return NULL; acl = posix_acl_alloc(count, GFP_NOFS); if (!acl) return ERR_PTR(-ENOMEM); for (n = 0; n < count; n++) { ext4_acl_entry *entry = (ext4_acl_entry *)value; if ((char *)value + sizeof(ext4_acl_entry_short) > end) goto fail; acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag); acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm); switch (acl->a_entries[n].e_tag) { case ACL_USER_OBJ: case ACL_GROUP_OBJ: case ACL_MASK: case ACL_OTHER: value = (char *)value + sizeof(ext4_acl_entry_short); acl->a_entries[n].e_id = ACL_UNDEFINED_ID; break; case ACL_USER: case ACL_GROUP: value = (char *)value + sizeof(ext4_acl_entry); if ((char *)value > end) goto fail; acl->a_entries[n].e_id = le32_to_cpu(entry->e_id); break; default: goto fail; } } if (value != end) goto fail; return acl; fail: posix_acl_release(acl); return ERR_PTR(-EINVAL); } /* * Convert from in-memory to filesystem representation. */ static void * ext4_acl_to_disk(const struct posix_acl *acl, size_t *size) { ext4_acl_header *ext_acl; char *e; size_t n; *size = ext4_acl_size(acl->a_count); ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count * sizeof(ext4_acl_entry), GFP_NOFS); if (!ext_acl) return ERR_PTR(-ENOMEM); ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION); e = (char *)ext_acl + sizeof(ext4_acl_header); for (n = 0; n < acl->a_count; n++) { ext4_acl_entry *entry = (ext4_acl_entry *)e; entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag); entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm); switch (acl->a_entries[n].e_tag) { case ACL_USER: case ACL_GROUP: entry->e_id = cpu_to_le32(acl->a_entries[n].e_id); e += sizeof(ext4_acl_entry); break; case ACL_USER_OBJ: case ACL_GROUP_OBJ: case ACL_MASK: case ACL_OTHER: e += sizeof(ext4_acl_entry_short); break; default: goto fail; } } return (char *)ext_acl; fail: kfree(ext_acl); return ERR_PTR(-EINVAL); } /* * Inode operation get_posix_acl(). * * inode->i_mutex: don't care */ struct posix_acl * ext4_get_acl(struct inode *inode, int type) { int name_index; char *value = NULL; struct posix_acl *acl; int retval; if (!test_opt(inode->i_sb, POSIX_ACL)) return NULL; acl = get_cached_acl(inode, type); if (acl != ACL_NOT_CACHED) return acl; switch (type) { case ACL_TYPE_ACCESS: name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; break; case ACL_TYPE_DEFAULT: name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; break; default: BUG(); } retval = ext4_xattr_get(inode, name_index, "", NULL, 0); if (retval > 0) { value = kmalloc(retval, GFP_NOFS); if (!value) return ERR_PTR(-ENOMEM); retval = ext4_xattr_get(inode, name_index, "", value, retval); } if (retval > 0) acl = ext4_acl_from_disk(value, retval); else if (retval == -ENODATA || retval == -ENOSYS) acl = NULL; else acl = ERR_PTR(retval); kfree(value); if (!IS_ERR(acl)) set_cached_acl(inode, type, acl); return acl; } /* * Set the access or default ACL of an inode. * * inode->i_mutex: down unless called from ext4_new_inode */ static int ext4_set_acl(handle_t *handle, struct inode *inode, int type, struct posix_acl *acl) { int name_index; void *value = NULL; size_t size = 0; int error; if (S_ISLNK(inode->i_mode)) return -EOPNOTSUPP; switch (type) { case ACL_TYPE_ACCESS: name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; if (acl) { error = posix_acl_equiv_mode(acl, &inode->i_mode); if (error < 0) return error; else { inode->i_ctime = ext4_current_time(inode); ext4_mark_inode_dirty(handle, inode); if (error == 0) acl = NULL; } } break; case ACL_TYPE_DEFAULT: name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; if (!S_ISDIR(inode->i_mode)) return acl ? -EACCES : 0; break; default: return -EINVAL; } if (acl) { value = ext4_acl_to_disk(acl, &size); if (IS_ERR(value)) return (int)PTR_ERR(value); } error = ext4_xattr_set_handle(handle, inode, name_index, "", value, size, 0); kfree(value); if (!error) set_cached_acl(inode, type, acl); return error; } /* * Initialize the ACLs of a new inode. Called from ext4_new_inode. * * dir->i_mutex: down * inode->i_mutex: up (access to inode is still exclusive) */ int ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) { struct posix_acl *acl = NULL; int error = 0; if (!S_ISLNK(inode->i_mode)) { if (test_opt(dir->i_sb, POSIX_ACL)) { acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT); if (IS_ERR(acl)) return PTR_ERR(acl); } if (!acl) inode->i_mode &= ~current_umask(); } if (test_opt(inode->i_sb, POSIX_ACL) && acl) { if (S_ISDIR(inode->i_mode)) { error = ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT, acl); if (error) goto cleanup; } error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode); if (error < 0) return error; if (error > 0) { /* This is an extended ACL */ error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl); } } cleanup: posix_acl_release(acl); return error; } /* * Does chmod for an inode that may have an Access Control List. The * inode->i_mode field must be updated to the desired value by the caller * before calling this function. * Returns 0 on success, or a negative error number. * * We change the ACL rather than storing some ACL entries in the file * mode permission bits (which would be more efficient), because that * would break once additional permissions (like ACL_APPEND, ACL_DELETE * for directories) are added. There are no more bits available in the * file mode. * * inode->i_mutex: down */ int ext4_acl_chmod(struct inode *inode) { struct posix_acl *acl; handle_t *handle; int retries = 0; int error; if (S_ISLNK(inode->i_mode)) return -EOPNOTSUPP; if (!test_opt(inode->i_sb, POSIX_ACL)) return 0; acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); if (IS_ERR(acl) || !acl) return PTR_ERR(acl); error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode); if (error) return error; retry: handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); if (IS_ERR(handle)) { error = PTR_ERR(handle); ext4_std_error(inode->i_sb, error); goto out; } error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl); ext4_journal_stop(handle); if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) goto retry; out: posix_acl_release(acl); return error; } /* * Extended attribute handlers */ static size_t ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len, const char *name, size_t name_len, int type) { const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); if (!test_opt(dentry->d_sb, POSIX_ACL)) return 0; if (list && size <= list_len) memcpy(list, POSIX_ACL_XATTR_ACCESS, size); return size; } static size_t ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len, const char *name, size_t name_len, int type) { const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); if (!test_opt(dentry->d_sb, POSIX_ACL)) return 0; if (list && size <= list_len) memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); return size; } static int ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer, size_t size, int type) { struct posix_acl *acl; int error; if (strcmp(name, "") != 0) return -EINVAL; if (!test_opt(dentry->d_sb, POSIX_ACL)) return -EOPNOTSUPP; acl = ext4_get_acl(dentry->d_inode, type); if (IS_ERR(acl)) return PTR_ERR(acl); if (acl == NULL) return -ENODATA; error = posix_acl_to_xattr(acl, buffer, size); posix_acl_release(acl); return error; } static int ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value, size_t size, int flags, int type) { struct inode *inode = dentry->d_inode; handle_t *handle; struct posix_acl *acl; int error, retries = 0; if (strcmp(name, "") != 0) return -EINVAL; if (!test_opt(inode->i_sb, POSIX_ACL)) return -EOPNOTSUPP; if (!inode_owner_or_capable(inode)) return -EPERM; if (value) { acl = posix_acl_from_xattr(value, size); if (IS_ERR(acl)) return PTR_ERR(acl); else if (acl) { error = posix_acl_valid(acl); if (error) goto release_and_out; } } else acl = NULL; retry: handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); if (IS_ERR(handle)) return PTR_ERR(handle); error = ext4_set_acl(handle, inode, type, acl); ext4_journal_stop(handle); if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) goto retry; release_and_out: posix_acl_release(acl); return error; } const struct xattr_handler ext4_xattr_acl_access_handler = { .prefix = POSIX_ACL_XATTR_ACCESS, .flags = ACL_TYPE_ACCESS, .list = ext4_xattr_list_acl_access, .get = ext4_xattr_get_acl, .set = ext4_xattr_set_acl, }; const struct xattr_handler ext4_xattr_acl_default_handler = { .prefix = POSIX_ACL_XATTR_DEFAULT, .flags = ACL_TYPE_DEFAULT, .list = ext4_xattr_list_acl_default, .get = ext4_xattr_get_acl, .set = ext4_xattr_set_acl, };