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| author |   Tejun Heo <tj@kernel.org> | 2015-09-18 17:54:23 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2015-09-18 17:54:23 -0400 |
| commit | 7dbdb199d3bf88f043ea17e97113eb28d5b100bc (patch) | |
| tree | 648451cd5f719dafe1c01a18cf2a7903d6166f93 /kernel/cgroup.c | |
| parent | cgroup: replace "cgroup.populated" with "cgroup.events" (diff) | |
| download | linux-dev-7dbdb199d3bf88f043ea17e97113eb28d5b100bc.tar.xz linux-dev-7dbdb199d3bf88f043ea17e97113eb28d5b100bc.zip | |
cgroup: replace cftype->mode with CFTYPE_WORLD_WRITABLE
cftype->mode allows controllers to give arbitrary permissions to
interface knobs. Except for "cgroup.event_control", the existing uses
are spurious.
* Some explicitly specify S_IRUGO | S_IWUSR even though that's the
default.
* "cpuset.memory_pressure" specifies S_IRUGO while also setting a
write callback which returns -EACCES. All it needs to do is simply
not setting a write callback.
"cgroup.event_control" uses cftype->mode to make the file
world-writable. It's a misdesigned interface and we don't want
controllers to be tweaking interface file permissions in general.
This patch removes cftype->mode and all its spurious uses and
implements CFTYPE_WORLD_WRITABLE for "cgroup.event_control" which is
marked as compatibility-only.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 75eba25d8dfd..5031edc6f077 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1139,23 +1139,21 @@ static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, * cgroup_file_mode - deduce file mode of a control file * @cft: the control file in question * - * returns cft->mode if ->mode is not 0 - * returns S_IRUGO|S_IWUSR if it has both a read and a write handler - * returns S_IRUGO if it has only a read handler - * returns S_IWUSR if it has only a write hander + * S_IRUGO for read, S_IWUSR for write. */ static umode_t cgroup_file_mode(const struct cftype *cft) { umode_t mode = 0; - if (cft->mode) - return cft->mode; - if (cft->read_u64 || cft->read_s64 || cft->seq_show) mode |= S_IRUGO; - if (cft->write_u64 || cft->write_s64 || cft->write) - mode |= S_IWUSR; + if (cft->write_u64 || cft->write_s64 || cft->write) { + if (cft->flags & CFTYPE_WORLD_WRITABLE) + mode |= S_IWUGO; + else + mode |= S_IWUSR; + } return mode; } @@ -4371,7 +4369,6 @@ static struct cftype cgroup_dfl_base_files[] = { .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_PROCS, .write = cgroup_procs_write, - .mode = S_IRUGO | S_IWUSR, }, { .name = "cgroup.controllers", @@ -4406,7 +4403,6 @@ static struct cftype cgroup_legacy_base_files[] = { .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_PROCS, .write = cgroup_procs_write, - .mode = S_IRUGO | S_IWUSR, }, { .name = "cgroup.clone_children", @@ -4426,7 +4422,6 @@ static struct cftype cgroup_legacy_base_files[] = { .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_TASKS, .write = cgroup_tasks_write, - .mode = S_IRUGO | S_IWUSR, }, { .name = "notify_on_release", |