[PATCH 1/2] procfs: use an enum for possible hidepid values

Lafcadio Wluiki
2016-10-09T14:37:35Z

(Second, rebased submission, since first submission yielded no replies.)

Previously, the hidepid parameter was checked by comparing literal
integers 0, 1, 2. Let's add a proper enum for this, to make the checking
more expressive:

0 → HIDEPID_OFF
1 → HIDEPID_NO_ACCESS
2 → HIDEPID_INVISIBLE

This changes the internal labelling only, the userspace-facing interface
remains unmodified, and still works with literal integers 0, 1, 2.

No functional changes.

Signed-off-by: Lafcadio Wluiki <wluikil@gmail.com>
---
fs/proc/base.c | 8 ++++----
fs/proc/inode.c | 2 +-
fs/proc/root.c | 3 ++-
include/linux/pid_namespace.h | 6 ++++++
4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index dc7fe5f..2680794 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -743,11 +743,11 @@ static int proc_pid_permission(struct inode *inode, int mask)
task = get_proc_task(inode);
if (!task)
return -ESRCH;
- has_perms = has_pid_permissions(pid, task, 1);
+ has_perms = has_pid_permissions(pid, task, HIDEPID_NO_ACCESS);
put_task_struct(task);

if (!has_perms) {
- if (pid->hide_pid == 2) {
+ if (pid->hide_pid == HIDEPID_INVISIBLE) {
/*
* Let's make getdents(), stat(), and open()
* consistent with each other. If a process
@@ -1705,7 +1705,7 @@ int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
stat->gid = GLOBAL_ROOT_GID;
task = pid_task(proc_pid(inode), PIDTYPE_PID);
if (task) {
- if (!has_pid_permissions(pid, task, 2)) {
+ if (!has_pid_permissions(pid, task, HIDEPID_INVISIBLE)) {
rcu_read_unlock();
/*
* This doesn't prevent learning whether PID exists,
@@ -3166,7 +3166,7 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
iter.tgid += 1, iter = next_tgid(ns, iter)) {
char name[PROC_NUMBUF];
int len;
- if (!has_pid_permissions(ns, iter.task, 2))
+ if (!has_pid_permissions(ns, iter.task, HIDEPID_INVISIBLE))
continue;

len = snprintf(name, sizeof(name), "%d", iter.tgid);
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index c1b7238..7b28103 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -107,7 +107,7 @@ static int proc_show_options(struct seq_file *seq, struct dentry *root)

if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
- if (pid->hide_pid != 0)
+ if (pid->hide_pid != HIDEPID_OFF)
seq_printf(seq, ",hidepid=%u", pid->hide_pid);

return 0;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 8d3e484..2989731 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -58,7 +58,8 @@ int proc_parse_options(char *options, struct pid_namespace *pid)
case Opt_hidepid:
if (match_int(&args[0], &option))
return 0;
- if (option < 0 || option > 2) {
+ if (option < HIDEPID_OFF ||
+ option > HIDEPID_INVISIBLE) {
pr_err("proc: hidepid value must be between 0 and 2.\n");
return 0;
}
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 34cce96..c2a989d 100644