From mboxrd@z Thu Jan 1 00:00:00 1970 From: srinivas.kandagatla@linaro.org (Srinivas Kandagatla) Date: Wed, 07 Oct 2015 18:26:02 +0100 Subject: [PATCH] nvmem: core: make default user binary file root-access only In-Reply-To: <20151007171227.GA9485@kroah.com> References: <1444235714-24365-1-git-send-email-srinivas.kandagatla@linaro.org> <20151007165046.GC12099@kroah.com> <56154FCF.6010105@linaro.org> <20151007171227.GA9485@kroah.com> Message-ID: <561555AA.5090000@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/10/15 18:12, Greg KH wrote: > On Wed, Oct 07, 2015 at 06:01:03PM +0100, Srinivas Kandagatla wrote: >> >> >> On 07/10/15 17:50, Greg KH wrote: >>> On Wed, Oct 07, 2015 at 05:35:14PM +0100, Srinivas Kandagatla wrote: >>>> As required by many providers like at24/at25/mxs-ocotp/qfprom, which would >>>> want to allow root-only to read/write the nvmem content. >>>> So making the defaults to be root-only access which can prevent normal >>>> users from reading the nvmem data. >>>> >>>> Signed-off-by: Srinivas Kandagatla >>>> --- >>>> drivers/nvmem/core.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c >>>> index 6fd4e5a..4d2e476 100644 >>>> --- a/drivers/nvmem/core.c >>>> +++ b/drivers/nvmem/core.c >>>> @@ -112,7 +112,7 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj, >>>> static struct bin_attribute bin_attr_rw_nvmem = { >>>> .attr = { >>>> .name = "nvmem", >>>> - .mode = S_IWUSR | S_IRUGO, >>>> + .mode = S_IWUSR | S_IRUSR, >>>> }, >>>> .read = bin_attr_nvmem_read, >>>> .write = bin_attr_nvmem_write, >>>> @@ -136,7 +136,7 @@ static const struct attribute_group *nvmem_rw_dev_groups[] = { >>>> static struct bin_attribute bin_attr_ro_nvmem = { >>>> .attr = { >>>> .name = "nvmem", >>>> - .mode = S_IRUGO, >>>> + .mode = S_IRUSR, >>>> }, >>>> .read = bin_attr_nvmem_read, >>>> }; >>> >>> How about using BIN_ATTR_RO() and friends instead, that way I _know_ you >>> got the permissions correct as it's impossible to get them wrong by >>> using those macros. >> Yes, that sounds good, but there are no macros for just "S_IRUSR" or >> "(S_IWUSR | S_IRUSR)" in ./include/linux/sysfs.h > > Then that means you are trying to do something "odd" and you shouldn't > be doing that :) > The requirement originally came from a discussion regarding file permissions set by at24 (drivers/mis/eeprom/at24.c) vs nvmem. at24 driver sets the permission of root-only read/write, which is different to what nvmem sets as default. So this patch was primarily make nvmem framework inline with what at24/at25 does. Other argument was regarding the content of the nvmem which could have things like keys and normal user should not be allowed read it. --srini > Use the standard attribute permissions (RO, RW), as those are the > "safest" and what you really want to be using here, as you already are. > > thanks, > > greg k-h >