[PATCH RFC v3 7/7] proc: flush dcache entries from all procfs instances

2017-11-09 Thread Djalal Harouni
Flush dcache entries of a task when it terminates. The task may have
showed up in multiple procfs mounts per pid namespace, and we need to
walk the mounts and invalidate any left entires.

Cc: Kees Cook 
Cc: Greg Kroah-Hartman 
Cc: Andy Lutomirski 
Cc: Alexey Gladkov 
Signed-off-by: Djalal Harouni 
---
 fs/proc/base.c| 27 +++-
 fs/proc/inode.c   |  9 +++-
 fs/proc/root.c| 10 +
 include/linux/pid_namespace.h | 49 +++
 include/linux/proc_fs.h   |  2 ++
 5 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 88b92bc..27e52aa 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3034,7 +3034,8 @@ static const struct inode_operations 
proc_tgid_base_inode_operations = {
.permission = proc_pid_permission,
 };
 
-static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
+static void proc_flush_task_mnt_root(struct dentry *mnt_root,
+pid_t pid, pid_t tgid)
 {
struct dentry *dentry, *leader, *dir;
char buf[PROC_NUMBUF];
@@ -3043,7 +3044,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, 
pid_t pid, pid_t tgid)
name.name = buf;
name.len = snprintf(buf, sizeof(buf), "%d", pid);
/* no ->d_hash() rejects on procfs */
-   dentry = d_hash_and_lookup(mnt->mnt_root, );
+   dentry = d_hash_and_lookup(mnt_root, );
if (dentry) {
d_invalidate(dentry);
dput(dentry);
@@ -3054,7 +3055,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, 
pid_t pid, pid_t tgid)
 
name.name = buf;
name.len = snprintf(buf, sizeof(buf), "%d", tgid);
-   leader = d_hash_and_lookup(mnt->mnt_root, );
+   leader = d_hash_and_lookup(mnt_root, );
if (!leader)
goto out;
 
@@ -3109,14 +3110,30 @@ void proc_flush_task(struct task_struct *task)
int i;
struct pid *pid, *tgid;
struct upid *upid;
+   struct proc_fs_info *fs_info_entry;
+   struct pid_namespace *pid_ns;
+   struct dentry *mnt_root;
 
pid = task_pid(task);
tgid = task_tgid(task);
 
for (i = 0; i <= pid->level; i++) {
upid = >numbers[i];
-   proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
-   tgid->numbers[i].nr);
+   pid_ns = upid->ns;
+
+   pidns_proc_lock_shared(pid_ns);
+   list_for_each_entry(fs_info_entry, _ns->procfs_mounts,
+   pidns_entry) {
+   if (proc_fs_newinstance(fs_info_entry)) {
+   mnt_root = fs_info_entry->sb->s_root;
+   proc_flush_task_mnt_root(mnt_root, upid->nr,
+tgid->numbers[i].nr);
+   }
+   }
+   pidns_proc_unlock_shared(pid_ns);
+
+   mnt_root = pid_ns->proc_mnt->mnt_root;
+   proc_flush_task_mnt_root(mnt_root, upid->nr, 
tgid->numbers[i].nr);
}
 }
 
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 2707d5f..8fcf0d7 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -484,10 +484,17 @@ struct inode *proc_get_inode(struct super_block *sb, 
struct proc_dir_entry *de)
 int proc_fill_super(struct super_block *s, void *data, int silent)
 {
struct proc_fs_info *fs_info = proc_sb(s);
+   struct pid_namespace *ns = get_pid_ns(fs_info->pid_ns);
struct inode *root_inode;
int ret;
 
-   get_pid_ns(fs_info->pid_ns);
+   fs_info->sb = s;
+
+   if (proc_fs_newinstance(fs_info)) {
+   pidns_proc_lock(ns);
+   list_add_tail(_info->pidns_entry, >procfs_mounts);
+   pidns_proc_unlock(ns);
+   }
 
if (!proc_parse_options(data, fs_info))
return -EINVAL;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 5cdff69..5503799 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -259,6 +259,13 @@ static void proc_kill_sb(struct super_block *sb)
dput(fs_info->proc_self);
if (fs_info->proc_thread_self)
dput(fs_info->proc_thread_self);
+
+   if (proc_fs_newinstance(fs_info)) {
+   pidns_proc_lock(ns);
+   list_del(_info->pidns_entry);
+   pidns_proc_unlock(ns);
+   }
+
kill_anon_super(sb);
put_pid_ns(ns);
kfree(fs_info);
@@ -374,6 +381,9 @@ int pid_ns_prepare_proc(struct pid_namespace *ns)
return PTR_ERR(mnt);
 
ns->proc_mnt = mnt;
+   init_rwsem(>rw_procfs_mnts);
+   INIT_LIST_HEAD(>procfs_mounts);
+
return 0;
 }
 
diff --git a/include/linux/pid_namespace.h 

[PATCH RFC v3 7/7] proc: flush dcache entries from all procfs instances

2017-11-09 Thread Djalal Harouni
Flush dcache entries of a task when it terminates. The task may have
showed up in multiple procfs mounts per pid namespace, and we need to
walk the mounts and invalidate any left entires.

Cc: Kees Cook 
Cc: Greg Kroah-Hartman 
Cc: Andy Lutomirski 
Cc: Alexey Gladkov 
Signed-off-by: Djalal Harouni 
---
 fs/proc/base.c| 27 +++-
 fs/proc/inode.c   |  9 +++-
 fs/proc/root.c| 10 +
 include/linux/pid_namespace.h | 49 +++
 include/linux/proc_fs.h   |  2 ++
 5 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 88b92bc..27e52aa 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3034,7 +3034,8 @@ static const struct inode_operations 
proc_tgid_base_inode_operations = {
.permission = proc_pid_permission,
 };
 
-static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
+static void proc_flush_task_mnt_root(struct dentry *mnt_root,
+pid_t pid, pid_t tgid)
 {
struct dentry *dentry, *leader, *dir;
char buf[PROC_NUMBUF];
@@ -3043,7 +3044,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, 
pid_t pid, pid_t tgid)
name.name = buf;
name.len = snprintf(buf, sizeof(buf), "%d", pid);
/* no ->d_hash() rejects on procfs */
-   dentry = d_hash_and_lookup(mnt->mnt_root, );
+   dentry = d_hash_and_lookup(mnt_root, );
if (dentry) {
d_invalidate(dentry);
dput(dentry);
@@ -3054,7 +3055,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, 
pid_t pid, pid_t tgid)
 
name.name = buf;
name.len = snprintf(buf, sizeof(buf), "%d", tgid);
-   leader = d_hash_and_lookup(mnt->mnt_root, );
+   leader = d_hash_and_lookup(mnt_root, );
if (!leader)
goto out;
 
@@ -3109,14 +3110,30 @@ void proc_flush_task(struct task_struct *task)
int i;
struct pid *pid, *tgid;
struct upid *upid;
+   struct proc_fs_info *fs_info_entry;
+   struct pid_namespace *pid_ns;
+   struct dentry *mnt_root;
 
pid = task_pid(task);
tgid = task_tgid(task);
 
for (i = 0; i <= pid->level; i++) {
upid = >numbers[i];
-   proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
-   tgid->numbers[i].nr);
+   pid_ns = upid->ns;
+
+   pidns_proc_lock_shared(pid_ns);
+   list_for_each_entry(fs_info_entry, _ns->procfs_mounts,
+   pidns_entry) {
+   if (proc_fs_newinstance(fs_info_entry)) {
+   mnt_root = fs_info_entry->sb->s_root;
+   proc_flush_task_mnt_root(mnt_root, upid->nr,
+tgid->numbers[i].nr);
+   }
+   }
+   pidns_proc_unlock_shared(pid_ns);
+
+   mnt_root = pid_ns->proc_mnt->mnt_root;
+   proc_flush_task_mnt_root(mnt_root, upid->nr, 
tgid->numbers[i].nr);
}
 }
 
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 2707d5f..8fcf0d7 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -484,10 +484,17 @@ struct inode *proc_get_inode(struct super_block *sb, 
struct proc_dir_entry *de)
 int proc_fill_super(struct super_block *s, void *data, int silent)
 {
struct proc_fs_info *fs_info = proc_sb(s);
+   struct pid_namespace *ns = get_pid_ns(fs_info->pid_ns);
struct inode *root_inode;
int ret;
 
-   get_pid_ns(fs_info->pid_ns);
+   fs_info->sb = s;
+
+   if (proc_fs_newinstance(fs_info)) {
+   pidns_proc_lock(ns);
+   list_add_tail(_info->pidns_entry, >procfs_mounts);
+   pidns_proc_unlock(ns);
+   }
 
if (!proc_parse_options(data, fs_info))
return -EINVAL;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 5cdff69..5503799 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -259,6 +259,13 @@ static void proc_kill_sb(struct super_block *sb)
dput(fs_info->proc_self);
if (fs_info->proc_thread_self)
dput(fs_info->proc_thread_self);
+
+   if (proc_fs_newinstance(fs_info)) {
+   pidns_proc_lock(ns);
+   list_del(_info->pidns_entry);
+   pidns_proc_unlock(ns);
+   }
+
kill_anon_super(sb);
put_pid_ns(ns);
kfree(fs_info);
@@ -374,6 +381,9 @@ int pid_ns_prepare_proc(struct pid_namespace *ns)
return PTR_ERR(mnt);
 
ns->proc_mnt = mnt;
+   init_rwsem(>rw_procfs_mnts);
+   INIT_LIST_HEAD(>procfs_mounts);
+
return 0;
 }
 
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 66f47f1..9a7a28d 100644
--- a/include/linux/pid_namespace.h
+++