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nvmem: Add flag to export NVMEM to root only

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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>
This commit is contained in:
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)