On 11/20/20 9:38 PM, Bjorn Andersson wrote: > 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"? I would have to look into that, but can that be changed dynamically? Also, note that the enforcement is only on the writes/stores which impact the state-machine, but not the reads/shows. For PRU usecases, we will be setting this dynamically. regards Suman > > 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 >>
