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nvmet: model_number must be immutable once set

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In case we have already established connection to nvmf target, it
shouldn't be allowed to change the model_number. E.g. if someone will
identify ctrl and get model_number of "my_model" later on will change
the model_numbel via configfs to "my_new_model" this will break the NVMe
specification for "Get Log Page – Persistent Event Log" that refers to
Model Number as: "This field contains the same value as reported in the
Model Number field of the Identify Controller data structure, bytes
63:24."

Although it doesn't mentioned explicitly that this field can't be
changed, we can assume it.

So allow setting this field only once: using configfs or in the first
identify ctrl operation.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Max Gurtovoy
2021-02-17 17:19:40 +00:00
committed by Christoph Hellwig
parent 32feb6de47
commit d9f273b758
4 changed files with 50 additions and 45 deletions
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50
drivers/nvme/target/configfs.c
View File

@@ -1118,16 +1118,12 @@ static ssize_t nvmet_subsys_attr_model_show(struct config_item *item,
char *page)
{
struct nvmet_subsys *subsys = to_subsys(item);
struct nvmet_subsys_model *subsys_model;
char *model = NVMET_DEFAULT_CTRL_MODEL;
int ret;
rcu_read_lock();
subsys_model = rcu_dereference(subsys->model);
if (subsys_model)
model = subsys_model->number;
ret = snprintf(page, PAGE_SIZE, "%s\n", model);
rcu_read_unlock();
mutex_lock(&subsys->lock);
ret = snprintf(page, PAGE_SIZE, "%s\n", subsys->model_number ?
subsys->model_number : NVMET_DEFAULT_CTRL_MODEL);
mutex_unlock(&subsys->lock);
return ret;
}
@@ -1138,14 +1134,17 @@ static bool nvmet_is_ascii(const char c)
return c >= 0x20 && c <= 0x7e;
}
static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
const char *page, size_t count)
static ssize_t nvmet_subsys_attr_model_store_locked(struct nvmet_subsys *subsys,
const char *page, size_t count)
{
struct nvmet_subsys *subsys = to_subsys(item);
struct nvmet_subsys_model *new_model;
char *new_model_number;
int pos = 0, len;
if (subsys->model_number) {
pr_err("Can't set model number. %s is already assigned\n",
subsys->model_number);
return -EINVAL;
}
len = strcspn(page, "\n");
if (!len)
return -EINVAL;
@@ -1155,28 +1154,25 @@ static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
return -EINVAL;
}
new_model_number = kmemdup_nul(page, len, GFP_KERNEL);
if (!new_model_number)
subsys->model_number = kmemdup_nul(page, len, GFP_KERNEL);
if (!subsys->model_number)
return -ENOMEM;
return count;
}
new_model = kzalloc(sizeof(*new_model) + len + 1, GFP_KERNEL);
if (!new_model) {
kfree(new_model_number);
return -ENOMEM;
}
memcpy(new_model->number, new_model_number, len);
static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
const char *page, size_t count)
{
struct nvmet_subsys *subsys = to_subsys(item);
ssize_t ret;
down_write(&nvmet_config_sem);
mutex_lock(&subsys->lock);
new_model = rcu_replace_pointer(subsys->model, new_model,
mutex_is_locked(&subsys->lock));
ret = nvmet_subsys_attr_model_store_locked(subsys, page, count);
mutex_unlock(&subsys->lock);
up_write(&nvmet_config_sem);
kfree_rcu(new_model, rcuhead);
kfree(new_model_number);
return count;
return ret;
}
CONFIGFS_ATTR(nvmet_subsys_, attr_model);