proc: remove kernel.maps_protect

After commit 831830b5a2b5d413407adf380ef62fe17d6fcbf2 aka
"restrict reading from /proc/<pid>/maps to those who share ->mm or can ptrace"
sysctl stopped being relevant because commit moved security checks from ->show
time to ->start time (mm_for_maps()).

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Kees Cook <kees.cook@canonical.com>

4 files changed, 1 insertions, 25 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c1332dd..b5918ae 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -148,9 +148,6 @@ static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
 	return count;
 }
 
-int maps_protect;
-EXPORT_SYMBOL(maps_protect);
-
 static struct fs_struct *get_fs_struct(struct task_struct *task)
 {
 	struct fs_struct *fs;
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 4422023..3bfb7b8 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -45,8 +45,6 @@ do {						\
 extern int nommu_vma_show(struct seq_file *, struct vm_area_struct *);
 #endif
 
-extern int maps_protect;
-
 extern int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
 				struct pid *pid, struct task_struct *task);
 extern int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 73d1891..4806830 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -210,9 +210,6 @@ static int show_map(struct seq_file *m, void *v)
 	dev_t dev = 0;
 	int len;
 
-	if (maps_protect && !ptrace_may_access(task, PTRACE_MODE_READ))
-		return -EACCES;
-
 	if (file) {
 		struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 		dev = inode->i_sb->s_dev;
@@ -742,22 +739,11 @@ const struct file_operations proc_pagemap_operations = {
 #ifdef CONFIG_NUMA
 extern int show_numa_map(struct seq_file *m, void *v);
 
-static int show_numa_map_checked(struct seq_file *m, void *v)
-{
-	struct proc_maps_private *priv = m->private;
-	struct task_struct *task = priv->task;
-
-	if (maps_protect && !ptrace_may_access(task, PTRACE_MODE_READ))
-		return -EACCES;
-
-	return show_numa_map(m, v);
-}
-
 static const struct seq_operations proc_pid_numa_maps_op = {
         .start  = m_start,
         .next   = m_next,
         .stop   = m_stop,
-        .show   = show_numa_map_checked
+        .show   = show_numa_map,
 };
 
 static int numa_maps_open(struct inode *inode, struct file *file)
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 5d84e71..219bd79e 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -110,11 +110,6 @@ int task_statm(struct mm_struct *mm, int *shared, int *text,
 static int show_map(struct seq_file *m, void *_vml)
 {
 	struct vm_list_struct *vml = _vml;
-	struct proc_maps_private *priv = m->private;
-	struct task_struct *task = priv->task;
-
-	if (maps_protect && !ptrace_may_access(task, PTRACE_MODE_READ))
-		return -EACCES;
 
 	return nommu_vma_show(m, vml->vma);
 }