| Message ID | 2cfcef13-2315-6bbe-4eda-ee019c870ce8@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Herbert Xu |
| Headers | show |
Hi Harald, > Hello PrasannaKumar > > here is now a version which combines patch 2 and patch 3 together > according to your suggestions: > > ========== cut ========== > > From: Harald Freudenberger <freude@linux.vnet.ibm.com> > Date: Fri, 30 Jun 2017 17:06:40 +0200 > Subject: [PATCH 2/2] crypto: hwrng remember rng chosen by user > > When a user chooses a rng source via sysfs attribute > this rng should be sticky, even when other sources > with better quality to register. This patch introduces > a simple way to remember the user's choice. This is > reflected by a new sysfs attribute file 'rng_selected' > which shows if the current rng has been chosen by > userspace. The new attribute file shows '1' for user > selected rng and '0' otherwise. > > Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com> > --- > drivers/char/hw_random/core.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c > index e9dda16..9701ac7 100644 > --- a/drivers/char/hw_random/core.c > +++ b/drivers/char/hw_random/core.c > @@ -28,6 +28,8 @@ > #define RNG_MODULE_NAME "hw_random" > > static struct hwrng *current_rng; > +/* the current rng has been explicitly chosen by user via sysfs */ > +static int cur_rng_set_by_user; > static struct task_struct *hwrng_fill; > /* list of registered rngs, sorted decending by quality */ > static LIST_HEAD(rng_list); > @@ -304,6 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev, > list_for_each_entry(rng, &rng_list, list) { > if (sysfs_streq(rng->name, buf)) { > err = 0; > + cur_rng_set_by_user = 1; > if (rng != current_rng) > err = set_current_rng(rng); > break; > @@ -352,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device *dev, > return strlen(buf); > } > > +static ssize_t hwrng_attr_selected_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user); > +} > + > static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, > hwrng_attr_current_show, > hwrng_attr_current_store); > static DEVICE_ATTR(rng_available, S_IRUGO, > hwrng_attr_available_show, > NULL); > +static DEVICE_ATTR(rng_selected, S_IRUGO, > + hwrng_attr_selected_show, > + NULL); > > static struct attribute *rng_dev_attrs[] = { > &dev_attr_rng_current.attr, > &dev_attr_rng_available.attr, > + &dev_attr_rng_selected.attr, > NULL > }; > > @@ -444,10 +458,12 @@ int hwrng_register(struct hwrng *rng) > > old_rng = current_rng; > err = 0; > - if (!old_rng || (rng->quality > old_rng->quality)) { > + if (!old_rng || > + (!cur_rng_set_by_user && rng->quality > old_rng->quality)) { > /* > * Set new rng as current as the new rng source > - * provides better entropy quality. > + * provides better entropy quality and was not > + * chosen by userspace. > */ > err = set_current_rng(rng); > if (err) > @@ -479,6 +495,7 @@ void hwrng_unregister(struct hwrng *rng) > list_del(&rng->list); > if (current_rng == rng) { > drop_current_rng(); > + cur_rng_set_by_user = 0; > /* rng_list is sorted by quality, use the best (=first) one */ > if (!list_empty(&rng_list)) { > struct hwrng *new_rng; > -- > 2.7.4 > > ========== cut ========== > Good work, patch looks good to me. Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>. I am wondering if you want to make a v2 of the whole series. You can just put your patch 1 and 2 and send it again with description. Requiring a v2 depends on how Herbert prefers to take patches in. Herbert, Do you prefer a v2 of the patch series or you can take this version of patch 2? Note: If you are re-posting this patch as v2 please add my reviewed by tag for both the patches. Regards, PrasannaKumar
========== cut ========== From: Harald Freudenberger <freude@linux.vnet.ibm.com> Date: Fri, 30 Jun 2017 17:06:40 +0200 Subject: [PATCH 2/2] crypto: hwrng remember rng chosen by user When a user chooses a rng source via sysfs attribute this rng should be sticky, even when other sources with better quality to register. This patch introduces a simple way to remember the user's choice. This is reflected by a new sysfs attribute file 'rng_selected' which shows if the current rng has been chosen by userspace. The new attribute file shows '1' for user selected rng and '0' otherwise. Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com> --- drivers/char/hw_random/core.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index e9dda16..9701ac7 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -28,6 +28,8 @@ #define RNG_MODULE_NAME "hw_random" static struct hwrng *current_rng; +/* the current rng has been explicitly chosen by user via sysfs */ +static int cur_rng_set_by_user; static struct task_struct *hwrng_fill; /* list of registered rngs, sorted decending by quality */ static LIST_HEAD(rng_list); @@ -304,6 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev, list_for_each_entry(rng, &rng_list, list) { if (sysfs_streq(rng->name, buf)) { err = 0; + cur_rng_set_by_user = 1; if (rng != current_rng) err = set_current_rng(rng); break; @@ -352,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device *dev, return strlen(buf); } +static ssize_t hwrng_attr_selected_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user); +} + static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, hwrng_attr_current_show, hwrng_attr_current_store); static DEVICE_ATTR(rng_available, S_IRUGO, hwrng_attr_available_show, NULL); +static DEVICE_ATTR(rng_selected, S_IRUGO, + hwrng_attr_selected_show, + NULL); static struct attribute *rng_dev_attrs[] = { &dev_attr_rng_current.attr, &dev_attr_rng_available.attr, + &dev_attr_rng_selected.attr, NULL }; @@ -444,10 +458,12 @@ int hwrng_register(struct hwrng *rng) old_rng = current_rng; err = 0; - if (!old_rng || (rng->quality > old_rng->quality)) { + if (!old_rng || + (!cur_rng_set_by_user && rng->quality > old_rng->quality)) { /* * Set new rng as current as the new rng source - * provides better entropy quality. + * provides better entropy quality and was not + * chosen by userspace. */ err = set_current_rng(rng); if (err) @@ -479,6 +495,7 @@ void hwrng_unregister(struct hwrng *rng) list_del(&rng->list); if (current_rng == rng) { drop_current_rng(); + cur_rng_set_by_user = 0; /* rng_list is sorted by quality, use the best (=first) one */ if (!list_empty(&rng_list)) { struct hwrng *new_rng;