From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: proc: fix lookup in /proc/net subdirectories after setns(2)
commit 1fde6f21d90f8ba5da3cb9c54ca991ed72696c43
proc: fix /proc/net/* after setns(2)
only forced revalidation of regular files under /proc/net/
However, /proc/net/ is unusual in the sense of /proc/net/foo handlers
take netns pointer from parent directory which is old netns.
Steps to reproduce:
(void)open("/proc/net/sctp/snmp", O_RDONLY);
unshare(CLONE_NEWNET);
int fd = open("/proc/net/sctp/snmp", O_RDONLY);
read(fd, &c, 1);
Read will read wrong data from original netns.
Patch forces lookup on every directory under /proc/net .
Link: https://lkml.kernel.org/r/20201205160916.GA109739@localhost.localdomain
Fixes: 1da4d377f943 ("proc: revalidate misc dentries")
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Reported-by: "Rantala, Tommi T. (Nokia - FI/Espoo)" <tommi.t.rantala@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/generic.c | 24 ++++++++++++++++++++++--
fs/proc/internal.h | 7 +++++++
fs/proc/proc_net.c | 16 ----------------
include/linux/proc_fs.h | 8 +++++++-
4 files changed, 36 insertions(+), 19 deletions(-)
--- a/fs/proc/generic.c~proc-fix-lookup-in-proc-net-subdirectories-after-setns2
+++ a/fs/proc/generic.c
@@ -349,6 +349,16 @@ static const struct file_operations proc
.iterate_shared = proc_readdir,
};
+static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ return 0;
+}
+
+const struct dentry_operations proc_net_dentry_ops = {
+ .d_revalidate = proc_net_d_revalidate,
+ .d_delete = always_delete_dentry,
+};
+
/*
* proc directories can do almost nothing..
*/
@@ -471,8 +481,8 @@ struct proc_dir_entry *proc_symlink(cons
}
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, bool force_lookup)
{
struct proc_dir_entry *ent;
@@ -484,10 +494,20 @@ struct proc_dir_entry *proc_mkdir_data(c
ent->data = data;
ent->proc_dir_ops = &proc_dir_operations;
ent->proc_iops = &proc_dir_inode_operations;
+ if (force_lookup) {
+ pde_force_lookup(ent);
+ }
ent = proc_register(parent, ent);
}
return ent;
}
+EXPORT_SYMBOL_GPL(_proc_mkdir);
+
+struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
+ struct proc_dir_entry *parent, void *data)
+{
+ return _proc_mkdir(name, mode, parent, data, false);
+}
EXPORT_SYMBOL_GPL(proc_mkdir_data);
struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
--- a/fs/proc/internal.h~proc-fix-lookup-in-proc-net-subdirectories-after-setns2
+++ a/fs/proc/internal.h
@@ -310,3 +310,10 @@ extern unsigned long task_statm(struct m
unsigned long *, unsigned long *,
unsigned long *, unsigned long *);
extern void task_mem(struct seq_file *, struct mm_struct *);
+
+extern const struct dentry_operations proc_net_dentry_ops;
+static inline void pde_force_lookup(struct proc_dir_entry *pde)
+{
+ /* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */
+ pde->proc_dops = &proc_net_dentry_ops;
+}
--- a/fs/proc/proc_net.c~proc-fix-lookup-in-proc-net-subdirectories-after-setns2
+++ a/fs/proc/proc_net.c
@@ -39,22 +39,6 @@ static struct net *get_proc_net(const st
return maybe_get_net(PDE_NET(PDE(inode)));
}
-static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
-{
- return 0;
-}
-
-static const struct dentry_operations proc_net_dentry_ops = {
- .d_revalidate = proc_net_d_revalidate,
- .d_delete = always_delete_dentry,
-};
-
-static void pde_force_lookup(struct proc_dir_entry *pde)
-{
- /* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */
- pde->proc_dops = &proc_net_dentry_ops;
-}
-
static int seq_open_net(struct inode *inode, struct file *file)
{
unsigned int state_size = PDE(inode)->state_size;
--- a/include/linux/proc_fs.h~proc-fix-lookup-in-proc-net-subdirectories-after-setns2
+++ a/include/linux/proc_fs.h
@@ -80,6 +80,7 @@ extern void proc_flush_pid(struct pid *)
extern struct proc_dir_entry *proc_symlink(const char *,
struct proc_dir_entry *, const char *);
+struct proc_dir_entry *_proc_mkdir(const char *, umode_t, struct proc_dir_entry *, void *, bool);
extern struct proc_dir_entry *proc_mkdir(const char *, struct proc_dir_entry *);
extern struct proc_dir_entry *proc_mkdir_data(const char *, umode_t,
struct proc_dir_entry *, void *);
@@ -162,6 +163,11 @@ static inline struct proc_dir_entry *pro
static inline struct proc_dir_entry *proc_mkdir(const char *name,
struct proc_dir_entry *parent) {return NULL;}
static inline struct proc_dir_entry *proc_create_mount_point(const char *name) { return NULL; }
+static inline struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
+ struct proc_dir_entry *parent, void *data, bool force_lookup)
+{
+ return NULL;
+}
static inline struct proc_dir_entry *proc_mkdir_data(const char *name,
umode_t mode, struct proc_dir_entry *parent, void *data) { return NULL; }
static inline struct proc_dir_entry *proc_mkdir_mode(const char *name,
@@ -199,7 +205,7 @@ 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);
+ return _proc_mkdir(name, 0, parent, net, true);
}
struct ns_common;
_
