| Message ID | YjdVHgildbWO7diJ@localhost.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | proc: fix dentry/inode overinstantiating under /proc/${pid}/net | expand |
proc_misc_dentry_ops is a general ops for dentry under /proc, except
for "/proc/${pid}/net"，other dentries may also use there own ops too,
so I think change proc_misc_d_delete may be better?
see patch under: https://lkml.org/lkml/2022/3/17/319
Alexey Dobriyan <adobriyan@gmail.com> 于2022年3月21日周一 00:24写道：
>
> 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.
>
> Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)")
> Reported-by: hui li <juanfengpy@gmail.com>
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---
>
> fs/proc/generic.c | 4 ++++
> fs/proc/proc_net.c | 3 +++
> 2 files changed, 7 insertions(+)
>
> --- a/fs/proc/generic.c
> +++ b/fs/proc/generic.c
> @@ -448,6 +448,10 @@ 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/${pid}/net */
> + if ((*parent)->proc_dops == &proc_net_dentry_ops) {
> + pde_force_lookup(ent);
> + }
>
> out:
> return ent;
> --- a/fs/proc/proc_net.c
> +++ b/fs/proc/proc_net.c
> @@ -376,6 +376,9 @@ static __net_init int proc_net_ns_init(struct net *net)
>
> proc_set_user(netd, uid, gid);
>
> + /* Seed dentry revalidation for /proc/${pid}/net */
> + pde_force_lookup(netd);
> +
> err = -EEXIST;
> net_statd = proc_net_mkdir(net, "stat", netd);
> if (!net_statd)
On Mon, Mar 21, 2022 at 05:15:02PM +0800, hui li wrote: > Alexey Dobriyan <adobriyan@gmail.com> 于2022年3月21日周一 00:24写道： > > > > 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. > > > > Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)") > > Reported-by: hui li <juanfengpy@gmail.com> > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > > --- > > > > fs/proc/generic.c | 4 ++++ > > fs/proc/proc_net.c | 3 +++ > > 2 files changed, 7 insertions(+) > > > > --- a/fs/proc/generic.c > > +++ b/fs/proc/generic.c > > @@ -448,6 +448,10 @@ 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/${pid}/net */ > > + if ((*parent)->proc_dops == &proc_net_dentry_ops) { > > + pde_force_lookup(ent); > > + } > > > > out: > > return ent; > > --- a/fs/proc/proc_net.c > > +++ b/fs/proc/proc_net.c > > @@ -376,6 +376,9 @@ static __net_init int proc_net_ns_init(struct net *net) > > > > proc_set_user(netd, uid, gid); > > > > + /* Seed dentry revalidation for /proc/${pid}/net */ > > + pde_force_lookup(netd); > > + > > err = -EEXIST; > > net_statd = proc_net_mkdir(net, "stat", netd); > > if (!net_statd) > proc_misc_dentry_ops is a general ops for dentry under /proc, except > for "/proc/${pid}/net"，other dentries may also use there own ops too, > so I think change proc_misc_d_delete may be better? > see patch under: https://lkml.org/lkml/2022/3/17/319 I don't think so. proc_misc_d_delete covers "everything else" part under /proc/ and /proc/net which are 2 separate trees. Now /proc/net/ requires revalidation because of commit c6c75deda81344c3a95d1d1f606d5cee109e5d54 proc: fix lookup in /proc/net subdirectories after setns(2) so the bug is that the above commit was applied only partially. In particular, /proc/*/net/stat/arp_cache was created with proc_create_seq_data(), avoiding proc_net_* APIs. And there is probably the same "lookup after setns find wrong file" if you search hard enough in /proc/*/net/ This is the logic. Please test on your systems.
I see, I will test on my system. Alexey Dobriyan <adobriyan@gmail.com> 于2022年3月21日周一 18:40写道： > > On Mon, Mar 21, 2022 at 05:15:02PM +0800, hui li wrote: > > Alexey Dobriyan <adobriyan@gmail.com> 于2022年3月21日周一 00:24写道： > > > > > > When a process exits, /proc/${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/${pid}/net by inheriting > > > proc_net_dentry_ops. > > > > > > Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)") > > > Reported-by: hui li <juanfengpy@gmail.com> > > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > > > --- > > > > > > fs/proc/generic.c | 4 ++++ > > > fs/proc/proc_net.c | 3 +++ > > > 2 files changed, 7 insertions(+) > > > > > > --- a/fs/proc/generic.c > > > +++ b/fs/proc/generic.c > > > @@ -448,6 +448,10 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, > > > proc_set_user(ent, (*parent)->uid, (*parent)->gid); > > > > > > ent->proc_dops = &proc_misc_dentry_ops; > > > + /* Revalidate everything under /proc/${pid}/net */ > > > + if ((*parent)->proc_dops == &proc_net_dentry_ops) { > > > + pde_force_lookup(ent); > > > + } > > > > > > out: > > > return ent; > > > --- a/fs/proc/proc_net.c > > > +++ b/fs/proc/proc_net.c > > > @@ -376,6 +376,9 @@ static __net_init int proc_net_ns_init(struct net *net) > > > > > > proc_set_user(netd, uid, gid); > > > > > > + /* Seed dentry revalidation for /proc/${pid}/net */ > > > + pde_force_lookup(netd); > > > + > > > err = -EEXIST; > > > net_statd = proc_net_mkdir(net, "stat", netd); > > > if (!net_statd) > > > proc_misc_dentry_ops is a general ops for dentry under /proc, except > > for "/proc/${pid}/net"，other dentries may also use there own ops too, > > so I think change proc_misc_d_delete may be better? > > see patch under: https://lkml.org/lkml/2022/3/17/319 > > I don't think so. > > proc_misc_d_delete covers "everything else" part under /proc/ and > /proc/net which are 2 separate trees. Now /proc/net/ requires > revalidation because of > > commit c6c75deda81344c3a95d1d1f606d5cee109e5d54 > proc: fix lookup in /proc/net subdirectories after setns(2) > > so the bug is that the above commit was applied only partially. > In particular, /proc/*/net/stat/arp_cache was created with > proc_create_seq_data(), avoiding proc_net_* APIs. > > And there is probably the same "lookup after setns find wrong file" > if you search hard enough in /proc/*/net/ > > This is the logic. Please test on your systems.
--- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -448,6 +448,10 @@ 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/${pid}/net */ + if ((*parent)->proc_dops == &proc_net_dentry_ops) { + pde_force_lookup(ent); + } out: return ent; --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -376,6 +376,9 @@ static __net_init int proc_net_ns_init(struct net *net) proc_set_user(netd, uid, gid); + /* Seed dentry revalidation for /proc/${pid}/net */ + pde_force_lookup(netd); + err = -EEXIST; net_statd = proc_net_mkdir(net, "stat", netd); if (!net_statd)
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. Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)") Reported-by: hui li <juanfengpy@gmail.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> --- fs/proc/generic.c | 4 ++++ fs/proc/proc_net.c | 3 +++ 2 files changed, 7 insertions(+)