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proc: revalidate directories created with proc_net_mkdir()

PATCH In review Alexey Dobriyan 3 participants 4 messages Jul 6, 2019 – Jul 7, 2019

Subsystems (3)
Networking Network drivers Proc filesystem
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Alexey Dobriyan

author
#0 lore raw

PATCH 1/2 proc: revalidate directories created with proc_net_mkdir()

/proc/net directories may contain content which depends on net namespace. Such dentries should be revalidated after setns(CLONE_NEWNET).

See

	commit 1fde6f21d90f8ba5da3cb9c54ca991ed72696c43
	proc: fix /proc/net/* after setns(2)

The patch is all about "pde_force_lookup()" line.

	[redid original patch --adobriyan]
Reported-by "Hallsmark, Per" <[email protected]>
Signed-off-by Alexey Dobriyan <[email protected]>

---

 fs/proc/generic.c       |   25 ++++++++++++++++++-------
 fs/proc/internal.h      |    3 +++
 fs/proc/proc_net.c      |   17 +++++++++++++++++
 include/linux/proc_fs.h |   16 ++++++++--------
 4 files changed, 46 insertions(+), 15 deletions(-)
fs/proc/generic.c +18 -7
@@ -459,26 +459,37 @@ struct proc_dir_entry *proc_symlink(const char *name,
 }
 EXPORT_SYMBOL(proc_symlink);
 
-struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
-		struct proc_dir_entry *parent, void *data)
+struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
+				   struct proc_dir_entry **parent, void *data)
 {
 	struct proc_dir_entry *ent;
 
 	if (mode == 0)
 		mode = S_IRUGO | S_IXUGO;
 
-	ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
+	ent = __proc_create(parent, name, S_IFDIR | mode, 2);
 	if (ent) {
 		ent->data = data;
 		ent->proc_fops = &proc_dir_operations;
 		ent->proc_iops = &proc_dir_inode_operations;
-		parent->nlink++;
-		ent = proc_register(parent, ent);
-		if (!ent)
-			parent->nlink--;
 	}
 	return ent;
 }
+
+struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
+		struct proc_dir_entry *parent, void *data)
+{
+	struct proc_dir_entry *pde;
+
+	pde = _proc_mkdir(name, mode, &parent, data);
+	if (!pde)
+		return NULL;
+	parent->nlink++;
+	pde = proc_register(parent, pde);
+	if (!pde)
+		parent->nlink--;
+	return pde;
+}
 EXPORT_SYMBOL_GPL(proc_mkdir_data);
 
 struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
fs/proc/internal.h +3 -0
@@ -299,3 +299,6 @@ extern unsigned long task_statm(struct mm_struct *,
 				unsigned long *, unsigned long *,
 				unsigned long *, unsigned long *);
 extern void task_mem(struct seq_file *, struct mm_struct *);
+
+struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
+				   struct proc_dir_entry **parent, void *data);
fs/proc/proc_net.c +17 -0
@@ -251,6 +251,23 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
 }
 EXPORT_SYMBOL_GPL(proc_create_net_single_write);
 
+struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
+				      struct proc_dir_entry *parent)
+{
+	struct proc_dir_entry *pde;
+
+	pde = _proc_mkdir(name, 0, &parent, net);
+	if (!pde)
+		return NULL;
+	pde_force_lookup(pde);
+	parent->nlink++;
+	pde = proc_register(parent, pde);
+	if (!pde)
+		parent->nlink++;
+	return pde;
+}
+EXPORT_SYMBOL_GPL(proc_net_mkdir);
+
 static struct net *get_proc_task_net(struct inode *dir)
 {
 	struct task_struct *task;
include/linux/proc_fs.h +8 -8
@@ -8,6 +8,7 @@
 #include <linux/types.h>
 #include <linux/fs.h>
 
+struct net;
 struct proc_dir_entry;
 struct seq_file;
 struct seq_operations;

@@ -73,6 +74,8 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
 						    int (*show)(struct seq_file *, void *),
 						    proc_write_t write,
 						    void *data);
+struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name, struct proc_dir_entry *parent);
+
 extern struct pid *tgid_pidfd_to_pid(const struct file *file);
 
 #else /* CONFIG_PROC_FS */

@@ -115,6 +118,11 @@ static inline int remove_proc_subtree(const char *name, struct proc_dir_entry *p
 #define proc_create_net(name, mode, parent, state_size, ops) ({NULL;})
 #define proc_create_net_single(name, mode, parent, show, data) ({NULL;})
 
+static inline struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name, struct proc_dir_entry *parent)
+{
+	return NULL;
+}
+
 static inline struct pid *tgid_pidfd_to_pid(const struct file *file)
 {
 	return ERR_PTR(-EBADF);

@@ -122,14 +130,6 @@ static inline struct pid *tgid_pidfd_to_pid(const struct file *file)
 
 #endif /* CONFIG_PROC_FS */
 
-struct net;
-
-static inline struct proc_dir_entry *proc_net_mkdir(
-	struct net *net, const char *name, struct proc_dir_entry *parent)
-{
-	return proc_mkdir_data(name, 0, parent, net);
-}
-
 struct ns_common;
 int open_related_ns(struct ns_common *ns,
 		   struct ns_common *(*get_ns)(struct ns_common *ns));
#1 lore raw

fs/proc/generic.c struct proc_dir_entry *proc_symlink(const char *name, · line 463

Quoted 2 lines · Alexey Dobriyan
fs/proc/generic.c +2 -0
+struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
+				   struct proc_dir_entry **parent, void *data)

Two underscores, please...

fs/proc/proc_net.c struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo · line 266

Quoted 4 lines
fs/proc/proc_net.c +4 -0
+	parent->nlink++;
+	pde = proc_register(parent, pde);
+	if (!pde)
+		parent->nlink++;

Really?

author
#2 lore raw
Quoted 5 lines · Al Viro

fs/proc/generic.c struct proc_dir_entry *proc_symlink(const char *name, · line 463

Quoted 2 lines · Alexey Dobriyan
fs/proc/generic.c +2 -0
+struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
+				   struct proc_dir_entry **parent, void *data)

Two underscores, please...

Second underscore is more typing, I never understood it.

Quoted 6 lines

fs/proc/proc_net.c struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo · line 266

Quoted 4 lines
fs/proc/proc_net.c +4 -0
+	parent->nlink++;
+	pde = proc_register(parent, pde);
+	if (!pde)
+		parent->nlink++;

Really?

And ->nlink is a separate bug.

maintainer
#3 lore raw

From: Alexey Dobriyan <[email protected]>
Date: Sun, 7 Jul 2019 11:03:51 +0300

Quoted 8 lines · Al Viro
Quoted 5 lines · Alexey Dobriyan

fs/proc/generic.c struct proc_dir_entry *proc_symlink(const char *name, · line 463

Quoted 2 lines
fs/proc/generic.c +2 -0
+struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
+				   struct proc_dir_entry **parent, void *data)

Two underscores, please...

Second underscore is more typing, I never understood it.

Canonicalness is not about understanding, it's about being consistent with the rest of the tree.

Just do it please...