From 811b0d6538b9f26f3eb0f90fe4e6118f2480ec6f Mon Sep 17 00:00:00 2001 From: Andrew Lunn Date: Fri, 26 Feb 2016 20:59:18 +0100 Subject: [PATCH] nvmem: Add flag to export NVMEM to root only Legacy AT24, AT25 EEPROMs are exported in sys so that only root can read the contents. The EEPROMs may contain sensitive information. Add a flag so the provide can indicate that NVMEM should also restrict access to root only. Signed-off-by: Andrew Lunn Acked-by: Srinivas Kandagatla Signed-off-by: Greg Kroah-Hartman --- drivers/nvmem/core.c | 57 ++++++++++++++++++++++++++++++++-- include/linux/nvmem-provider.h | 1 + 2 files changed, 56 insertions(+), 2 deletions(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index de14fae6f7f6..b03690bc8f09 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -161,6 +161,53 @@ static const struct attribute_group *nvmem_ro_dev_groups[] = { NULL, }; +/* default read/write permissions, root only */ +static struct bin_attribute bin_attr_rw_root_nvmem = { + .attr = { + .name = "nvmem", + .mode = S_IWUSR | S_IRUSR, + }, + .read = bin_attr_nvmem_read, + .write = bin_attr_nvmem_write, +}; + +static struct bin_attribute *nvmem_bin_rw_root_attributes[] = { + &bin_attr_rw_root_nvmem, + NULL, +}; + +static const struct attribute_group nvmem_bin_rw_root_group = { + .bin_attrs = nvmem_bin_rw_root_attributes, +}; + +static const struct attribute_group *nvmem_rw_root_dev_groups[] = { + &nvmem_bin_rw_root_group, + NULL, +}; + +/* read only permission, root only */ +static struct bin_attribute bin_attr_ro_root_nvmem = { + .attr = { + .name = "nvmem", + .mode = S_IRUSR, + }, + .read = bin_attr_nvmem_read, +}; + +static struct bin_attribute *nvmem_bin_ro_root_attributes[] = { + &bin_attr_ro_root_nvmem, + NULL, +}; + +static const struct attribute_group nvmem_bin_ro_root_group = { + .bin_attrs = nvmem_bin_ro_root_attributes, +}; + +static const struct attribute_group *nvmem_ro_root_dev_groups[] = { + &nvmem_bin_ro_root_group, + NULL, +}; + static void nvmem_release(struct device *dev) { struct nvmem_device *nvmem = to_nvmem_device(dev); @@ -355,8 +402,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) nvmem->read_only = of_property_read_bool(np, "read-only") | config->read_only; - nvmem->dev.groups = nvmem->read_only ? nvmem_ro_dev_groups : - nvmem_rw_dev_groups; + if (config->root_only) + nvmem->dev.groups = nvmem->read_only ? + nvmem_ro_root_dev_groups : + nvmem_rw_root_dev_groups; + else + nvmem->dev.groups = nvmem->read_only ? + nvmem_ro_dev_groups : + nvmem_rw_dev_groups; device_initialize(&nvmem->dev); diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h index 0b68caff1b3c..d24fefa0c11d 100644 --- a/include/linux/nvmem-provider.h +++ b/include/linux/nvmem-provider.h @@ -23,6 +23,7 @@ struct nvmem_config { const struct nvmem_cell_info *cells; int ncells; bool read_only; + bool root_only; }; #if IS_ENABLED(CONFIG_NVMEM) -- 2.20.1