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proc: fix /proc/net/* after setns(2)

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/proc entries under /proc/net/* can't be cached into dcache because
setns(2) can change current net namespace.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: avoid vim miscolorization]
[adobriyan@gmail.com: write test, add dummy ->d_revalidate hook: necessary if /proc/net/* is pinned at setns time]
  Link: http://lkml.kernel.org/r/20190108192350.GA12034@avx2
Link: http://lkml.kernel.org/r/20190107162336.GA9239@avx2
Fixes: 1da4d377f9 ("proc: revalidate misc dentries")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: Mateusz Stępień <mateusz.stepien@netrounds.com>
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
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>
This commit is contained in:
Alexey Dobriyan
2019-02-01 14:20:01 -08:00
committed by Linus Torvalds
parent 1723058eab
commit 1fde6f21d9
6 changed files with 155 additions and 1 deletions
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20
fs/proc/proc_net.c
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@@ -38,6 +38,22 @@ static struct net *get_proc_net(const struct inode *inode)
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;
@@ -90,6 +106,7 @@ struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_seq_fops;
p->seq_ops = ops;
p->state_size = state_size;
@@ -133,6 +150,7 @@ struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_seq_fops;
p->seq_ops = ops;
p->state_size = state_size;
@@ -181,6 +199,7 @@ struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_single_fops;
p->single_show = show;
return proc_register(parent, p);
@@ -223,6 +242,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_single_fops;
p->single_show = show;
p->write = write;