/* * linux/fs/ext2/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/fs.h> #include "ext2.h" #include "xattr.h" #include "acl.h" /* * Convert from filesystem to in-memory representation. */ static struct posix_acl * ext2_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(ext2_acl_header)) return ERR_PTR(-EINVAL); if (((ext2_acl_header *)value)->a_version != cpu_to_le32(EXT2_ACL_VERSION)) return ERR_PTR(-EINVAL); value = (char *)value + sizeof(ext2_acl_header); count = ext2_acl_count(size); if (count < 0) return ERR_PTR(-EINVAL); if (count == 0) return NULL; acl = posix_acl_alloc(count, GFP_KERNEL); if (!acl) return ERR_PTR(-ENOMEM); for (n=0; n < count; n++) { ext2_acl_entry *entry = (ext2_acl_entry *)value; if ((char *)value + sizeof(ext2_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(ext2_acl_entry_short); acl->a_entries[n].e_id = ACL_UNDEFINED_ID; break; case ACL_USER: case ACL_GROUP: value = (char *)value + sizeof(ext2_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 * ext2_acl_to_disk(const struct posix_acl *acl, size_t *size) { ext2_acl_header *ext_acl; char *e; size_t n; *size = ext2_acl_size(acl->a_count); ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) + acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL); if (!ext_acl) return ERR_PTR(-ENOMEM); ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION); e = (char *)ext_acl + sizeof(ext2_acl_header); for (n=0; n < acl->a_count; n++) { ext2_acl_entry *entry = (ext2_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(ext2_acl_entry); break; case ACL_USER_OBJ: case ACL_GROUP_OBJ: case ACL_MASK: case ACL_OTHER: e += sizeof(ext2_acl_entry_short); break; default: goto fail; } } return (char *)ext_acl; fail: kfree(ext_acl); return ERR_PTR(-EINVAL); } static inline struct posix_acl * ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl) { struct posix_acl *acl = EXT2_ACL_NOT_CACHED; spin_lock(&inode->i_lock); if (*i_acl != EXT2_ACL_NOT_CACHED) acl = posix_acl_dup(*i_acl); spin_unlock(&inode->i_lock); return acl; } static inline void ext2_iset_acl(struct inode *inode, struct posix_acl **i_acl, struct posix_acl *acl) { spin_lock(&inode->i_lock); if (*i_acl != EXT2_ACL_NOT_CACHED) posix_acl_release(*i_acl); *i_acl = posix_acl_dup(acl); spin_unlock(&inode->i_lock); } /* * inode->i_sem: don't care */ static struct posix_acl * ext2_get_acl(struct inode *inode, int type) { struct ext2_inode_info *ei = EXT2_I(inode); int name_index; char *value = NULL; struct posix_acl *acl; int retval; if (!test_opt(inode->i_sb, POSIX_ACL)) return NULL; switch(type) { case ACL_TYPE_ACCESS: acl = ext2_iget_acl(inode, &ei->i_acl); if (acl != EXT2_ACL_NOT_CACHED) return acl; name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS; break; case ACL_TYPE_DEFAULT: acl = ext2_iget_acl(inode, &ei->i_default_acl); if (acl != EXT2_ACL_NOT_CACHED) return acl; name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT; break; default: return ERR_PTR(-EINVAL); } retval = ext2_xattr_get(inode, name_index, "", NULL, 0); if (retval > 0) { value = kmalloc(retval, GFP_KERNEL); if (!value) return ERR_PTR(-ENOMEM); retval = ext2_xattr_get(inode, name_index, "", value, retval); } if (retval > 0) acl = ext2_acl_from_disk(value, retval); else if (retval == -ENODATA || retval == -ENOSYS) acl = NULL; else acl = ERR_PTR(retval); kfree(value); if (!IS_ERR(acl)) { switch(type) { case ACL_TYPE_ACCESS: ext2_iset_acl(inode, &ei->i_acl, acl); break; case ACL_TYPE_DEFAULT: ext2_iset_acl(inode, &ei->i_default_acl, acl); break; } } return acl; } /* * inode->i_sem: down */ static int ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl) { struct ext2_inode_info *ei = EXT2_I(inode); int name_index; void *value = NULL; size_t size; int error; if (S_ISLNK(inode->i_mode)) return -EOPNOTSUPP; if (!test_opt(inode->i_sb, POSIX_ACL)) return 0; switch(type) { case ACL_TYPE_ACCESS: name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS; if (acl) { mode_t mode = inode->i_mode; error = posix_acl_equiv_mode(acl, &mode); if (error < 0) return error; else { inode->i_mode = mode; mark_inode_dirty(inode); if (error == 0) acl = NULL; } } break; case ACL_TYPE_DEFAULT: name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT; if (!S_ISDIR(inode->i_mode)) return acl ? -EACCES : 0; break; default: return -EINVAL; } if (acl) { value = ext2_acl_to_disk(acl, &size); if (IS_ERR(value)) return (int)PTR_ERR(value); } error = ext2_xattr_set(inode, name_index, "", value, size, 0); kfree(value); if (!error) { switch(type) { case ACL_TYPE_ACCESS: ext2_iset_acl(inode, &ei->i_acl, acl); break; case ACL_TYPE_DEFAULT: ext2_iset_acl(inode, &ei->i_default_acl, acl); break; } } return error; } static int ext2_check_acl(struct inode *inode, int mask) { struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS); if (IS_ERR(acl)) return PTR_ERR(acl); if (acl) { int error = posix_acl_permission(inode, acl, mask); posix_acl_release(acl); return error; } return -EAGAIN; } int ext2_permission(struct inode *inode, int mask, struct nameidata *nd) { return generic_permission(inode, mask, ext2_check_acl); } /* * Initialize the ACLs of a new inode. Called from ext2_new_inode. * * dir->i_sem: down * inode->i_sem: up (access to inode is still exclusive) */ int ext2_init_acl(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 = ext2_get_acl(dir, ACL_TYPE_DEFAULT); if (IS_ERR(acl)) return PTR_ERR(acl); } if (!acl) inode->i_mode &= ~current->fs->umask; } if (test_opt(inode->i_sb, POSIX_ACL) && acl) { struct posix_acl *clone; mode_t mode; if (S_ISDIR(inode->i_mode)) { error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl); if (error) goto cleanup; } clone = posix_acl_clone(acl, GFP_KERNEL); error = -ENOMEM; if (!clone) goto cleanup; mode = inode->i_mode; error = posix_acl_create_masq(clone, &mode); if (error >= 0) { inode->i_mode = mode; if (error > 0) { /* This is an extended ACL */ error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone); } } posix_acl_release(clone); } 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_sem: down */ int ext2_acl_chmod(struct inode *inode) { struct posix_acl *acl, *clone; int error; if (!test_opt(inode->i_sb, POSIX_ACL)) return 0; if (S_ISLNK(inode->i_mode)) return -EOPNOTSUPP; acl = ext2_get_acl(inode, ACL_TYPE_ACCESS); if (IS_ERR(acl) || !acl) return PTR_ERR(acl); clone = posix_acl_clone(acl, GFP_KERNEL); posix_acl_release(acl); if (!clone) return -ENOMEM; error = posix_acl_chmod_masq(clone, inode->i_mode); if (!error) error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone); posix_acl_release(clone); return error; } /* * Extended attribut handlers */ static size_t ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size, const char *name, size_t name_len) { const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); if (!test_opt(inode->i_sb, POSIX_ACL)) return 0; if (list && size <= list_size) memcpy(list, POSIX_ACL_XATTR_ACCESS, size); return size; } static size_t ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size, const char *name, size_t name_len) { const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); if (!test_opt(inode->i_sb, POSIX_ACL)) return 0; if (list && size <= list_size) memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); return size; } static int ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size) { struct posix_acl *acl; int error; if (!test_opt(inode->i_sb, POSIX_ACL)) return -EOPNOTSUPP; acl = ext2_get_acl(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 ext2_xattr_get_acl_access(struct inode *inode, const char *name, void *buffer, size_t size) { if (strcmp(name, "") != 0) return -EINVAL; return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size); } static int ext2_xattr_get_acl_default(struct inode *inode, const char *name, void *buffer, size_t size) { if (strcmp(name, "") != 0) return -EINVAL; return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size); } static int ext2_xattr_set_acl(struct inode *inode, int type, const void *value, size_t size) { struct posix_acl *acl; int error; if (!test_opt(inode->i_sb, POSIX_ACL)) return -EOPNOTSUPP; if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER)) 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; error = ext2_set_acl(inode, type, acl); release_and_out: posix_acl_release(acl); return error; } static int ext2_xattr_set_acl_access(struct inode *inode, const char *name, const void *value, size_t size, int flags) { if (strcmp(name, "") != 0) return -EINVAL; return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size); } static int ext2_xattr_set_acl_default(struct inode *inode, const char *name, const void *value, size_t size, int flags) { if (strcmp(name, "") != 0) return -EINVAL; return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size); } struct xattr_handler ext2_xattr_acl_access_handler = { .prefix = POSIX_ACL_XATTR_ACCESS, .list = ext2_xattr_list_acl_access, .get = ext2_xattr_get_acl_access, .set = ext2_xattr_set_acl_access, }; struct xattr_handler ext2_xattr_acl_default_handler = { .prefix = POSIX_ACL_XATTR_DEFAULT, .list = ext2_xattr_list_acl_default, .get = ext2_xattr_get_acl_default, .set = ext2_xattr_set_acl_default, };