| From ed66f991bb19d94cae5d38f77de81f96aac7813f Mon Sep 17 00:00:00 2001 |
| From: Kees Cook <keescook@chromium.org> |
| Date: Thu, 2 Jul 2020 13:47:20 -0700 |
| Subject: module: Refactor section attr into bin attribute |
| |
| From: Kees Cook <keescook@chromium.org> |
| |
| commit ed66f991bb19d94cae5d38f77de81f96aac7813f upstream. |
| |
| In order to gain access to the open file's f_cred for kallsym visibility |
| permission checks, refactor the module section attributes to use the |
| bin_attribute instead of attribute interface. Additionally removes the |
| redundant "name" struct member. |
| |
| Cc: stable@vger.kernel.org |
| Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Tested-by: Jessica Yu <jeyu@kernel.org> |
| Acked-by: Jessica Yu <jeyu@kernel.org> |
| Signed-off-by: Kees Cook <keescook@chromium.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/module.c | 45 ++++++++++++++++++++++++--------------------- |
| 1 file changed, 24 insertions(+), 21 deletions(-) |
| |
| --- a/kernel/module.c |
| +++ b/kernel/module.c |
| @@ -1507,8 +1507,7 @@ static inline bool sect_empty(const Elf_ |
| } |
| |
| struct module_sect_attr { |
| - struct module_attribute mattr; |
| - char *name; |
| + struct bin_attribute battr; |
| unsigned long address; |
| }; |
| |
| @@ -1518,11 +1517,16 @@ struct module_sect_attrs { |
| struct module_sect_attr attrs[0]; |
| }; |
| |
| -static ssize_t module_sect_show(struct module_attribute *mattr, |
| - struct module_kobject *mk, char *buf) |
| +static ssize_t module_sect_read(struct file *file, struct kobject *kobj, |
| + struct bin_attribute *battr, |
| + char *buf, loff_t pos, size_t count) |
| { |
| struct module_sect_attr *sattr = |
| - container_of(mattr, struct module_sect_attr, mattr); |
| + container_of(battr, struct module_sect_attr, battr); |
| + |
| + if (pos != 0) |
| + return -EINVAL; |
| + |
| return sprintf(buf, "0x%px\n", kptr_restrict < 2 ? |
| (void *)sattr->address : NULL); |
| } |
| @@ -1532,7 +1536,7 @@ static void free_sect_attrs(struct modul |
| unsigned int section; |
| |
| for (section = 0; section < sect_attrs->nsections; section++) |
| - kfree(sect_attrs->attrs[section].name); |
| + kfree(sect_attrs->attrs[section].battr.attr.name); |
| kfree(sect_attrs); |
| } |
| |
| @@ -1541,42 +1545,41 @@ static void add_sect_attrs(struct module |
| unsigned int nloaded = 0, i, size[2]; |
| struct module_sect_attrs *sect_attrs; |
| struct module_sect_attr *sattr; |
| - struct attribute **gattr; |
| + struct bin_attribute **gattr; |
| |
| /* Count loaded sections and allocate structures */ |
| for (i = 0; i < info->hdr->e_shnum; i++) |
| if (!sect_empty(&info->sechdrs[i])) |
| nloaded++; |
| size[0] = ALIGN(struct_size(sect_attrs, attrs, nloaded), |
| - sizeof(sect_attrs->grp.attrs[0])); |
| - size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.attrs[0]); |
| + sizeof(sect_attrs->grp.bin_attrs[0])); |
| + size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.bin_attrs[0]); |
| sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL); |
| if (sect_attrs == NULL) |
| return; |
| |
| /* Setup section attributes. */ |
| sect_attrs->grp.name = "sections"; |
| - sect_attrs->grp.attrs = (void *)sect_attrs + size[0]; |
| + sect_attrs->grp.bin_attrs = (void *)sect_attrs + size[0]; |
| |
| sect_attrs->nsections = 0; |
| sattr = §_attrs->attrs[0]; |
| - gattr = §_attrs->grp.attrs[0]; |
| + gattr = §_attrs->grp.bin_attrs[0]; |
| for (i = 0; i < info->hdr->e_shnum; i++) { |
| Elf_Shdr *sec = &info->sechdrs[i]; |
| if (sect_empty(sec)) |
| continue; |
| + sysfs_bin_attr_init(&sattr->battr); |
| sattr->address = sec->sh_addr; |
| - sattr->name = kstrdup(info->secstrings + sec->sh_name, |
| - GFP_KERNEL); |
| - if (sattr->name == NULL) |
| + sattr->battr.attr.name = |
| + kstrdup(info->secstrings + sec->sh_name, GFP_KERNEL); |
| + if (sattr->battr.attr.name == NULL) |
| goto out; |
| sect_attrs->nsections++; |
| - sysfs_attr_init(&sattr->mattr.attr); |
| - sattr->mattr.show = module_sect_show; |
| - sattr->mattr.store = NULL; |
| - sattr->mattr.attr.name = sattr->name; |
| - sattr->mattr.attr.mode = S_IRUSR; |
| - *(gattr++) = &(sattr++)->mattr.attr; |
| + sattr->battr.read = module_sect_read; |
| + sattr->battr.size = 3 /* "0x", "\n" */ + (BITS_PER_LONG / 4); |
| + sattr->battr.attr.mode = 0400; |
| + *(gattr++) = &(sattr++)->battr; |
| } |
| *gattr = NULL; |
| |
| @@ -1666,7 +1669,7 @@ static void add_notes_attrs(struct modul |
| continue; |
| if (info->sechdrs[i].sh_type == SHT_NOTE) { |
| sysfs_bin_attr_init(nattr); |
| - nattr->attr.name = mod->sect_attrs->attrs[loaded].name; |
| + nattr->attr.name = mod->sect_attrs->attrs[loaded].battr.attr.name; |
| nattr->attr.mode = S_IRUGO; |
| nattr->size = info->sechdrs[i].sh_size; |
| nattr->private = (void *) info->sechdrs[i].sh_addr; |