proc: fix dentry/inode overinstantiating under /proc/${pid}/net

[ Upstream commit 7055197705709c59b8ab77e6a5c7d46d61edd96e ]

When a process exits, /proc/${pid}, and /proc/${pid}/net dentries are
flushed.  However some leaf dentries like /proc/${pid}/net/arp_cache
aren't.  That's because respective PDEs have proc_misc_d_revalidate() hook
which returns 1 and leaves dentries/inodes in the LRU.

Force revalidation/lookup on everything under /proc/${pid}/net by
inheriting proc_net_dentry_ops.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/YjdVHgildbWO7diJ@localhost.localdomain
Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: hui li <juanfengpy@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 5b78739e60e406c75abfc7677f41ea5c5806b554..d32f69aaaa36f555d1b14f31a4fd064bbf05c92f 100644 (file)
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -448,6 +448,9 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
        proc_set_user(ent, (*parent)->uid, (*parent)->gid);
 
        ent->proc_dops = &proc_misc_dentry_ops;
+       /* Revalidate everything under /proc/${pid}/net */
+       if ((*parent)->proc_dops == &proc_net_dentry_ops)
+               pde_force_lookup(ent);
 
 out:
        return ent;

diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 15c2e55d2ed2c4b8b00209ecf9b18caa1a47f1b7..123e3c9d8674b486489402c86f9d62efad22534f 100644 (file)
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -363,6 +363,9 @@ static __net_init int proc_net_ns_init(struct net *net)
 
        proc_set_user(netd, uid, gid);
 
+       /* Seed dentry revalidation for /proc/${pid}/net */
+       pde_force_lookup(netd);
+
        err = -EEXIST;
        net_statd = proc_net_mkdir(net, "stat", netd);
        if (!net_statd)