Re: [PATCH RFC v3 2/7] proc: move /proc/{self|thread-self} dentries to proc_fs_info

[Djalal Harouni]

On Fri, Nov 10, 2017 at 11:31 AM, Alexey Dobriyan  wrote:
> On 11/9/17, Djalal Harouni  wrote:
>
>>  struct proc_fs_info {
>>   struct pid_namespace *pid_ns;
>> + struct dentry *proc_self; /* For /proc/self/ */
>> + struct dentry *proc_thread_self; /* For /proc/thread-self/ */
>
> These are redundant comments.

I can remove them, but actually the area is so difficult and
uncommented that I won't mind extra comments...

Thanks!

-- 
tixxdz

Re: [PATCH RFC v3 2/7] proc: move /proc/{self|thread-self} dentries to proc_fs_info

[Djalal Harouni]

On Fri, Nov 10, 2017 at 11:31 AM, Alexey Dobriyan  wrote:
> On 11/9/17, Djalal Harouni  wrote:
>
>>  struct proc_fs_info {
>>   struct pid_namespace *pid_ns;
>> + struct dentry *proc_self; /* For /proc/self/ */
>> + struct dentry *proc_thread_self; /* For /proc/thread-self/ */
>
> These are redundant comments.

I can remove them, but actually the area is so difficult and
uncommented that I won't mind extra comments...

Thanks!

-- 
tixxdz

Re: [PATCH RFC v3 2/7] proc: move /proc/{self|thread-self} dentries to proc_fs_info

[Alexey Dobriyan]

On 11/9/17, Djalal Harouni  wrote:

>  struct proc_fs_info {
>   struct pid_namespace *pid_ns;
> + struct dentry *proc_self; /* For /proc/self/ */
> + struct dentry *proc_thread_self; /* For /proc/thread-self/ */

These are redundant comments.

Re: [PATCH RFC v3 2/7] proc: move /proc/{self|thread-self} dentries to proc_fs_info

[Alexey Dobriyan]

On 11/9/17, Djalal Harouni  wrote:

>  struct proc_fs_info {
>   struct pid_namespace *pid_ns;
> + struct dentry *proc_self; /* For /proc/self/ */
> + struct dentry *proc_thread_self; /* For /proc/thread-self/ */

These are redundant comments.

[PATCH RFC v3 2/7] proc: move /proc/{self|thread-self} dentries to proc_fs_info

[Djalal Harouni]

This is a preparation patch that moves /proc/{self|thread-self} dentries
to be stored inside procfs proc_fs_info struct instead of making them
per PID namespace. Since we want to support multiple procfs instances we
need to make sure that these dentries are also per-superblock instead of
per-pidns, and we want to make sure that unmounting a private procfs
won't clash with other procfs mounts.

Cc: Kees Cook 
Cc: Greg Kroah-Hartman 
Suggested-by: Andy Lutomirski 
Signed-off-by: Alexey Gladkov 
Signed-off-by: Djalal Harouni 
---
 fs/proc/base.c| 4 ++--
 fs/proc/root.c| 8 
 fs/proc/self.c| 3 +--
 fs/proc/thread_self.c | 5 ++---
 include/linux/pid_namespace.h | 4 +---
 include/linux/proc_fs.h   | 2 ++
 6 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 5fc2006..0d9b4214 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3214,13 +3214,13 @@ int proc_pid_readdir(struct file *file, struct 
dir_context *ctx)
return 0;
 
if (pos == TGID_OFFSET - 2) {
-   struct inode *inode = d_inode(ns->proc_self);
+   struct inode *inode = d_inode(fs_info->proc_self);
if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
return 0;
ctx->pos = pos = pos + 1;
}
if (pos == TGID_OFFSET - 1) {
-   struct inode *inode = d_inode(ns->proc_thread_self);
+   struct inode *inode = d_inode(fs_info->proc_thread_self);
if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
return 0;
ctx->pos = pos = pos + 1;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 43e2639..b225ae5 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -166,10 +166,10 @@ static void proc_kill_sb(struct super_block *sb)
struct proc_fs_info *fs_info = proc_sb(sb);
struct pid_namespace *ns = fs_info->pid_ns;
 
-   if (ns->proc_self)
-   dput(ns->proc_self);
-   if (ns->proc_thread_self)
-   dput(ns->proc_thread_self);
+   if (fs_info->proc_self)
+   dput(fs_info->proc_self);
+   if (fs_info->proc_thread_self)
+   dput(fs_info->proc_thread_self);
kill_anon_super(sb);
put_pid_ns(ns);
kfree(fs_info);
diff --git a/fs/proc/self.c b/fs/proc/self.c
index f773301..8a67cf0 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -37,7 +37,6 @@ int proc_setup_self(struct super_block *s)
 {
struct inode *root_inode = d_inode(s->s_root);
struct proc_fs_info *fs_info = proc_sb(s);
-   struct pid_namespace *ns = fs_info->pid_ns;
struct dentry *self;
 
inode_lock(root_inode);
@@ -64,7 +63,7 @@ int proc_setup_self(struct super_block *s)
pr_err("proc_fill_super: can't allocate /proc/self\n");
return PTR_ERR(self);
}
-   ns->proc_self = self;
+   fs_info->proc_self = self;
return 0;
 }
 
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index 578887b..6e3225f 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -37,7 +37,6 @@ static unsigned thread_self_inum;
 int proc_setup_thread_self(struct super_block *s)
 {
struct proc_fs_info *fs_info = proc_sb(s);
-   struct pid_namespace *ns = fs_info->pid_ns;
struct inode *root_inode = d_inode(s->s_root);
struct dentry *thread_self;
 
@@ -62,10 +61,10 @@ int proc_setup_thread_self(struct super_block *s)
}
inode_unlock(root_inode);
if (IS_ERR(thread_self)) {
-   pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
+   pr_err("proc_fill_super: can't allocate /proc/thread-self\n");
return PTR_ERR(thread_self);
}
-   ns->proc_thread_self = thread_self;
+   fs_info->proc_thread_self = thread_self;
return 0;
 }
 
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 49538b1..f91a8bf 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -31,9 +31,7 @@ struct pid_namespace {
unsigned int level;
struct pid_namespace *parent;
 #ifdef CONFIG_PROC_FS
-   struct vfsmount *proc_mnt;
-   struct dentry *proc_self;
-   struct dentry *proc_thread_self;
+   struct vfsmount *proc_mnt; /* Internal proc mounted during each new 
pidns */
 #endif
 #ifdef CONFIG_BSD_PROCESS_ACCT
struct fs_pin *bacct;
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 9a3f6e9..8f89069 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -10,6 +10,8 @@
 
 struct proc_fs_info {
struct pid_namespace *pid_ns;
+   struct dentry *proc_self; /* For /proc/self/ */
+   struct dentry 

[PATCH RFC v3 2/7] proc: move /proc/{self|thread-self} dentries to proc_fs_info

[Djalal Harouni]

This is a preparation patch that moves /proc/{self|thread-self} dentries
to be stored inside procfs proc_fs_info struct instead of making them
per PID namespace. Since we want to support multiple procfs instances we
need to make sure that these dentries are also per-superblock instead of
per-pidns, and we want to make sure that unmounting a private procfs
won't clash with other procfs mounts.

Cc: Kees Cook 
Cc: Greg Kroah-Hartman 
Suggested-by: Andy Lutomirski 
Signed-off-by: Alexey Gladkov 
Signed-off-by: Djalal Harouni 
---
 fs/proc/base.c| 4 ++--
 fs/proc/root.c| 8 
 fs/proc/self.c| 3 +--
 fs/proc/thread_self.c | 5 ++---
 include/linux/pid_namespace.h | 4 +---
 include/linux/proc_fs.h   | 2 ++
 6 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 5fc2006..0d9b4214 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3214,13 +3214,13 @@ int proc_pid_readdir(struct file *file, struct 
dir_context *ctx)
return 0;
 
if (pos == TGID_OFFSET - 2) {
-   struct inode *inode = d_inode(ns->proc_self);
+   struct inode *inode = d_inode(fs_info->proc_self);
if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
return 0;
ctx->pos = pos = pos + 1;
}
if (pos == TGID_OFFSET - 1) {
-   struct inode *inode = d_inode(ns->proc_thread_self);
+   struct inode *inode = d_inode(fs_info->proc_thread_self);
if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
return 0;
ctx->pos = pos = pos + 1;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 43e2639..b225ae5 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -166,10 +166,10 @@ static void proc_kill_sb(struct super_block *sb)
struct proc_fs_info *fs_info = proc_sb(sb);
struct pid_namespace *ns = fs_info->pid_ns;
 
-   if (ns->proc_self)
-   dput(ns->proc_self);
-   if (ns->proc_thread_self)
-   dput(ns->proc_thread_self);
+   if (fs_info->proc_self)
+   dput(fs_info->proc_self);
+   if (fs_info->proc_thread_self)
+   dput(fs_info->proc_thread_self);
kill_anon_super(sb);
put_pid_ns(ns);
kfree(fs_info);
diff --git a/fs/proc/self.c b/fs/proc/self.c
index f773301..8a67cf0 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -37,7 +37,6 @@ int proc_setup_self(struct super_block *s)
 {
struct inode *root_inode = d_inode(s->s_root);
struct proc_fs_info *fs_info = proc_sb(s);
-   struct pid_namespace *ns = fs_info->pid_ns;
struct dentry *self;
 
inode_lock(root_inode);
@@ -64,7 +63,7 @@ int proc_setup_self(struct super_block *s)
pr_err("proc_fill_super: can't allocate /proc/self\n");
return PTR_ERR(self);
}
-   ns->proc_self = self;
+   fs_info->proc_self = self;
return 0;
 }
 
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index 578887b..6e3225f 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -37,7 +37,6 @@ static unsigned thread_self_inum;
 int proc_setup_thread_self(struct super_block *s)
 {
struct proc_fs_info *fs_info = proc_sb(s);
-   struct pid_namespace *ns = fs_info->pid_ns;
struct inode *root_inode = d_inode(s->s_root);
struct dentry *thread_self;
 
@@ -62,10 +61,10 @@ int proc_setup_thread_self(struct super_block *s)
}
inode_unlock(root_inode);
if (IS_ERR(thread_self)) {
-   pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
+   pr_err("proc_fill_super: can't allocate /proc/thread-self\n");
return PTR_ERR(thread_self);
}
-   ns->proc_thread_self = thread_self;
+   fs_info->proc_thread_self = thread_self;
return 0;
 }
 
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 49538b1..f91a8bf 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -31,9 +31,7 @@ struct pid_namespace {
unsigned int level;
struct pid_namespace *parent;
 #ifdef CONFIG_PROC_FS
-   struct vfsmount *proc_mnt;
-   struct dentry *proc_self;
-   struct dentry *proc_thread_self;
+   struct vfsmount *proc_mnt; /* Internal proc mounted during each new 
pidns */
 #endif
 #ifdef CONFIG_BSD_PROCESS_ACCT
struct fs_pin *bacct;
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 9a3f6e9..8f89069 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -10,6 +10,8 @@
 
 struct proc_fs_info {
struct pid_namespace *pid_ns;
+   struct dentry *proc_self; /* For /proc/self/ */
+   struct dentry *proc_thread_self; /* For /proc/thread-self/ */
 };
 
 struct proc_dir_entry;
-- 
2.7.4