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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 <andrew@lunn.ch>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
steinar/wifi_calib_4_9_kernel
Andrew Lunn 2016-02-26 20:59:18 +01:00 committed by Greg Kroah-Hartman
parent 1bb850a1b7
commit 811b0d6538
2 changed files with 56 additions and 2 deletions
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57
drivers/nvmem/core.c
View File

@ -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);

1
include/linux/nvmem-provider.h
View File

@ -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)