On Fri 20 Nov 21:01 CST 2020, Suman Anna wrote: > The remoteproc framework provides sysfs interfaces for changing > the firmware name and for starting/stopping a remote processor > through the sysfs files 'state' and 'firmware'. The 'recovery' > sysfs file can also be used similarly to control the error recovery > state machine of a remoteproc. These interfaces are currently > allowed irrespective of how the remoteprocs were booted (like > remoteproc self auto-boot, remoteproc client-driven boot etc). > These interfaces can adversely affect a remoteproc and its clients > especially when a remoteproc is being controlled by a remoteproc > client driver(s). Also, not all remoteproc drivers may want to > support the sysfs interfaces by default. > > Add support to deny the sysfs state/firmware/recovery change by > introducing a state flag 'deny_sysfs_ops' that the individual > remoteproc drivers can set based on their usage needs. The default > behavior is to allow the sysfs operations as before. > This makes sense, but can't we implement attribute_group->is_visible to simply hide these entries from userspace instead of leaving them "broken"? Regards, Bjorn > Signed-off-by: Suman Anna <s-anna@xxxxxx> > --- > v2: revised to account for the 'recovery' sysfs file as well, patch > description updated accordingly > v1: https://patchwork.kernel.org/project/linux-remoteproc/patch/20180915003725.17549-5-s-anna@xxxxxx/ > > drivers/remoteproc/remoteproc_sysfs.c | 12 ++++++++++++ > include/linux/remoteproc.h | 2 ++ > 2 files changed, 14 insertions(+) > > diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c > index bd2950a246c9..3fd18a71c188 100644 > --- a/drivers/remoteproc/remoteproc_sysfs.c > +++ b/drivers/remoteproc/remoteproc_sysfs.c > @@ -49,6 +49,10 @@ static ssize_t recovery_store(struct device *dev, > { > struct rproc *rproc = to_rproc(dev); > > + /* restrict sysfs operations if not allowed by remoteproc drivers */ > + if (rproc->deny_sysfs_ops) > + return -EPERM; > + > if (sysfs_streq(buf, "enabled")) { > /* change the flag and begin the recovery process if needed */ > rproc->recovery_disabled = false; > @@ -158,6 +162,10 @@ static ssize_t firmware_store(struct device *dev, > char *p; > int err, len = count; > > + /* restrict sysfs operations if not allowed by remoteproc drivers */ > + if (rproc->deny_sysfs_ops) > + return -EPERM; > + > err = mutex_lock_interruptible(&rproc->lock); > if (err) { > dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, err); > @@ -225,6 +233,10 @@ static ssize_t state_store(struct device *dev, > struct rproc *rproc = to_rproc(dev); > int ret = 0; > > + /* restrict sysfs operations if not allowed by remoteproc drivers */ > + if (rproc->deny_sysfs_ops) > + return -EPERM; > + > if (sysfs_streq(buf, "start")) { > if (rproc->state == RPROC_RUNNING) > return -EBUSY; > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h > index 3fa3ba6498e8..dbc3767f7d0e 100644 > --- a/include/linux/remoteproc.h > +++ b/include/linux/remoteproc.h > @@ -508,6 +508,7 @@ struct rproc_dump_segment { > * @has_iommu: flag to indicate if remote processor is behind an MMU > * @auto_boot: flag to indicate if remote processor should be auto-started > * @autonomous: true if an external entity has booted the remote processor > + * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery > * @dump_segments: list of segments in the firmware > * @nb_vdev: number of vdev currently handled by rproc > * @char_dev: character device of the rproc > @@ -545,6 +546,7 @@ struct rproc { > bool has_iommu; > bool auto_boot; > bool autonomous; > + bool deny_sysfs_ops; > struct list_head dump_segments; > int nb_vdev; > u8 elf_class; > -- > 2.28.0 >
