proc: fix lookup in /proc/net subdirectories after setns(2)
Commit 1fde6f21d90f ("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@gmail.com>
Reported-by: "Rantala, Tommi T. (Nokia - FI/Espoo)" <tommi.t.rantala@nokia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index b846632..6c0a05f 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -349,6 +349,16 @@ static const struct file_operations proc_dir_operations = {
.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(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, bool force_lookup)
{
struct proc_dir_entry *ent;
@@ -484,10 +494,20 @@ struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
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,