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Commit 1fde6f21 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds
Browse files

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

/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: 1da4d377 ("proc: revalidate misc dentries")
Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Reported-by: default avatarMateusz Stępień <mateusz.stepien@netrounds.com>
Reported-by: default avatarAhmad Fatoum <a.fatoum@pengutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1723058e

fs/proc/generic.c

+3 −1
Original line number Diff line number Diff line
@@ -256,7 +256,7 @@ struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry, 
		inode = proc_get_inode(dir->i_sb, de);

		if (!inode)

			return ERR_PTR(-ENOMEM);

		d_set_d_op(dentry, &proc_misc_dentry_ops);

		d_set_d_op(dentry, de->proc_dops);

		return d_splice_alias(inode, dentry);

	}

	read_unlock(&proc_subdir_lock);
@@ -429,6 +429,8 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, 
	INIT_LIST_HEAD(&ent->pde_openers);

	proc_set_user(ent, (*parent)->uid, (*parent)->gid);



	ent->proc_dops = &proc_misc_dentry_ops;



out:

	return ent;

}

fs/proc/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ struct proc_dir_entry { 
	struct completion *pde_unload_completion;

	const struct inode_operations *proc_iops;

	const struct file_operations *proc_fops;

	const struct dentry_operations *proc_dops;

	union {

		const struct seq_operations *seq_ops;

		int (*single_show)(struct seq_file *, void *);

fs/proc/proc_net.c

+20 −0
Original line number Diff line number Diff line
@@ -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;

tools/testing/selftests/proc/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -10,4 +10,5 @@ 
/proc-uptime-002

/read

/self

/setns-dcache

/thread-self

tools/testing/selftests/proc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ TEST_GEN_PROGS += proc-uptime-001 
TEST_GEN_PROGS += proc-uptime-002

TEST_GEN_PROGS += read

TEST_GEN_PROGS += self

TEST_GEN_PROGS += setns-dcache

TEST_GEN_PROGS += thread-self



include ../lib.mk