Commit dbcdb504 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds
Browse files

proc: add and remove /proc entry create checks 



* remove proc_create(NULL, ...) check, let it oops

* warn about proc_create("", ...) and proc_create("very very long name", ...)
  proc code keeps length as u8, no 256+ name length possible

* warn about proc_create("123", ...)
  /proc/$PID and /proc/misc namespaces are separate things,
  but dumb module might create funky a-la $PID entry.

* remove post mortem strchr('/') check
  Triggering it implies either strchr() is buggy or memory corruption.
  It should be VFS check anyway.

In reality, none of these checks will ever trigger,
it is preparation for the next patch.

Based on patch from Al Viro.

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
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 ccf94f1b

fs/proc/base.c

+2 −2
Original line number Diff line number Diff line
@@ -2785,7 +2785,7 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign 
	unsigned tgid;

	struct pid_namespace *ns;



	tgid = name_to_int(dentry);

	tgid = name_to_int(&dentry->d_name);

	if (tgid == ~0U)

		goto out;
@@ -3033,7 +3033,7 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry 
	if (!leader)

		goto out_no_task;



	tid = name_to_int(dentry);

	tid = name_to_int(&dentry->d_name);

	if (tid == ~0U)

		goto out;

fs/proc/fd.c

+1 −1
Original line number Diff line number Diff line
@@ -206,7 +206,7 @@ static struct dentry *proc_lookupfd_common(struct inode *dir, 
{

	struct task_struct *task = get_proc_task(dir);

	int result = -ENOENT;

	unsigned fd = name_to_int(dentry);

	unsigned fd = name_to_int(&dentry->d_name);



	if (!task)

		goto out_no_task;

fs/proc/generic.c

+15 −15
Original line number Diff line number Diff line
@@ -330,28 +330,28 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, 
					  nlink_t nlink)

{

	struct proc_dir_entry *ent = NULL;

	const char *fn = name;

	unsigned int len;



	/* make sure name is valid */

	if (!name || !strlen(name))

		goto out;

	const char *fn;

	struct qstr qstr;



	if (xlate_proc_name(name, parent, &fn) != 0)

		goto out;

	qstr.name = fn;

	qstr.len = strlen(fn);

	if (qstr.len == 0 || qstr.len >= 256) {

		WARN(1, "name len %u\n", qstr.len);

		return NULL;

	}

	if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {

		WARN(1, "create '/proc/%s' by hand\n", qstr.name);

		return NULL;

	}



	/* At this point there must not be any '/' characters beyond *fn */

	if (strchr(fn, '/'))

		goto out;



	len = strlen(fn);



	ent = kzalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);

	ent = kzalloc(sizeof(struct proc_dir_entry) + qstr.len + 1, GFP_KERNEL);

	if (!ent)

		goto out;



	memcpy(ent->name, fn, len + 1);

	ent->namelen = len;

	memcpy(ent->name, fn, qstr.len + 1);

	ent->namelen = qstr.len;

	ent->mode = mode;

	ent->nlink = nlink;

	atomic_set(&ent->count, 1);

fs/proc/internal.h

+3 −3
Original line number Diff line number Diff line
@@ -112,10 +112,10 @@ static inline int task_dumpable(struct task_struct *task) 
	return 0;

}



static inline unsigned name_to_int(struct dentry *dentry)

static inline unsigned name_to_int(const struct qstr *qstr)

{

	const char *name = dentry->d_name.name;

	int len = dentry->d_name.len;

	const char *name = qstr->name;

	int len = qstr->len;

	unsigned n = 0;



	if (len > 1 && *name == '0')

CRA Git | Maintained and supported by SUSTech CRA and CCSE