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procfs: use an enum for possible hidepid values

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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.

Link: http://lkml.kernel.org/r/1484572984-13388-2-git-send-email-djalal@gmail.com
Signed-off-by: Lafcadio Wluiki <wluikil@gmail.com>
Signed-off-by: Djalal Harouni <tixxdz@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lafcadio Wluiki 2017-02-24 15:00:23 -08:00 committed by Linus Torvalds
parent a0a07b87f3
commit 796f571b0c
4 changed files with 13 additions and 6 deletions
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8
fs/proc/base.c
View File

@ -697,11 +697,11 @@ 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
@ -1737,7 +1737,7 @@ 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,
@ -3168,7 +3168,7 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
int len;
cond_resched();
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);

2
fs/proc/inode.c
View File

@ -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;

3
fs/proc/root.c
View File

@ -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;
}

6
include/linux/pid_namespace.h
View File

@ -21,6 +21,12 @@ struct pidmap {
struct fs_pin;
enum { /* definitions for pid_namespace's hide_pid field */
HIDEPID_OFF = 0,
HIDEPID_NO_ACCESS = 1,
HIDEPID_INVISIBLE = 2,
};
struct pid_namespace {
struct kref kref;
struct pidmap pidmap[PIDMAP_ENTRIES];