[PATCH] psi: allow unprivileged users with CAP_SYS_RESOURCE to write psi files

Josh Hunt
2021-04-01T04:20:28Z

Currently only root can write files under /proc/pressure. Relax this to
allow tasks running as unprivileged users with CAP_SYS_RESOURCE to be
able to write to these files.

Signed-off-by: Josh Hunt <johunt@akamai.com>
---
kernel/sched/psi.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index b1b00e9bd7ed..98ff7baf1ba8 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1270,6 +1270,9 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf,
if (!nbytes)
return -EINVAL;

+ if (!capable(CAP_SYS_RESOURCE))
+ return -EPERM;
+
buf_size = min(nbytes, sizeof(buf));
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
@@ -1353,9 +1356,9 @@ static int __init psi_proc_init(void)
{
if (psi_enable) {
proc_mkdir("pressure", NULL);
- proc_create("pressure/io", 0, NULL, &psi_io_proc_ops);
- proc_create("pressure/memory", 0, NULL, &psi_memory_proc_ops);
- proc_create("pressure/cpu", 0, NULL, &psi_cpu_proc_ops);
+ proc_create("pressure/io", 0666, NULL, &psi_io_proc_ops);
+ proc_create("pressure/memory", 0666, NULL, &psi_memory_proc_ops);
+ proc_create("pressure/cpu", 0666, NULL, &psi_cpu_proc_ops);
}
return 0;
}
--
2.17.1