Commit eadee0ce authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 

Pull more vfs updates from Al Viro:
 "Embarrassing braino fix + pipe page accounting + fixing an eyesore in
  find_filesystem() (checking that s1 is equal to prefix of s2 of given
  length can be done in many ways, but "compare strlen(s1) with length
  and then do strncmp()" is not a good one...)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  [regression] fix braino in fs/dlm/user.c
  pipe: limit the per-user amount of pages allocated in pipes
  find_filesystem(): simplify comparison
parents 6fb11e65 117aa41e

Documentation/sysctl/fs.txt

+23 −0
Original line number Diff line number Diff line
@@ -32,6 +32,8 @@ Currently, these files are in /proc/sys/fs: 
- nr_open

- overflowuid

- overflowgid

- pipe-user-pages-hard

- pipe-user-pages-soft

- protected_hardlinks

- protected_symlinks

- suid_dumpable
@@ -159,6 +161,27 @@ The default is 65534. 


==============================================================



pipe-user-pages-hard:



Maximum total number of pages a non-privileged user may allocate for pipes.

Once this limit is reached, no new pipes may be allocated until usage goes

below the limit again. When set to 0, no limit is applied, which is the default

setting.



==============================================================



pipe-user-pages-soft:



Maximum total number of pages a non-privileged user may allocate for pipes

before the pipe size gets limited to a single page. Once this limit is reached,

new pipes will be limited to a single page in size for this user in order to

limit total memory usage, and trying to increase them using fcntl() will be

denied until usage goes below the limit again. The default value allows to

allocate up to 1024 pipes at their default size. When set to 0, no limit is

applied.



==============================================================



protected_hardlinks:



A long-standing class of security issues is the hardlink-based

fs/dlm/user.c

+1 −1
Original line number Diff line number Diff line
@@ -516,7 +516,7 @@ static ssize_t device_write(struct file *file, const char __user *buf, 
		return -EINVAL;



	kbuf = memdup_user_nul(buf, count);

	if (!IS_ERR(kbuf))

	if (IS_ERR(kbuf))

		return PTR_ERR(kbuf);



	if (check_version(kbuf)) {

fs/filesystems.c

+3 −3
Original line number Diff line number Diff line
@@ -47,8 +47,8 @@ static struct file_system_type **find_filesystem(const char *name, unsigned len) 
{

	struct file_system_type **p;

	for (p = &file_systems; *p; p = &(*p)->next)

		if (strlen((*p)->name) == len &&

		    strncmp((*p)->name, name, len) == 0)

		if (strncmp((*p)->name, name, len) == 0 &&

		    !(*p)->name[len])

			break;

	return p;

}

fs/pipe.c

+45 −2
Original line number Diff line number Diff line
@@ -38,6 +38,12 @@ unsigned int pipe_max_size = 1048576; 
 */

unsigned int pipe_min_size = PAGE_SIZE;



/* Maximum allocatable pages per user. Hard limit is unset by default, soft

 * matches default values.

 */

unsigned long pipe_user_pages_hard;

unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;



/*

 * We use a start+len construction, which provides full use of the 

 * allocated memory.
@@ -583,20 +589,49 @@ pipe_fasync(int fd, struct file *filp, int on) 
	return retval;

}



static void account_pipe_buffers(struct pipe_inode_info *pipe,

                                 unsigned long old, unsigned long new)

{

	atomic_long_add(new - old, &pipe->user->pipe_bufs);

}



static bool too_many_pipe_buffers_soft(struct user_struct *user)

{

	return pipe_user_pages_soft &&

	       atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_soft;

}



static bool too_many_pipe_buffers_hard(struct user_struct *user)

{

	return pipe_user_pages_hard &&

	       atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_hard;

}



struct pipe_inode_info *alloc_pipe_info(void)

{

	struct pipe_inode_info *pipe;



	pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);

	if (pipe) {

		pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);

		unsigned long pipe_bufs = PIPE_DEF_BUFFERS;

		struct user_struct *user = get_current_user();



		if (!too_many_pipe_buffers_hard(user)) {

			if (too_many_pipe_buffers_soft(user))

				pipe_bufs = 1;

			pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * pipe_bufs, GFP_KERNEL);

		}



		if (pipe->bufs) {

			init_waitqueue_head(&pipe->wait);

			pipe->r_counter = pipe->w_counter = 1;

			pipe->buffers = PIPE_DEF_BUFFERS;

			pipe->buffers = pipe_bufs;

			pipe->user = user;

			account_pipe_buffers(pipe, 0, pipe_bufs);

			mutex_init(&pipe->mutex);

			return pipe;

		}

		free_uid(user);

		kfree(pipe);

	}
@@ -607,6 +642,8 @@ void free_pipe_info(struct pipe_inode_info *pipe) 
{

	int i;



	account_pipe_buffers(pipe, pipe->buffers, 0);

	free_uid(pipe->user);

	for (i = 0; i < pipe->buffers; i++) {

		struct pipe_buffer *buf = pipe->bufs + i;

		if (buf->ops)
@@ -998,6 +1035,7 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) 
			memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));

	}



	account_pipe_buffers(pipe, pipe->buffers, nr_pages);

	pipe->curbuf = 0;

	kfree(pipe->bufs);

	pipe->bufs = bufs;
@@ -1069,6 +1107,11 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) 
		if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {

			ret = -EPERM;

			goto out;

		} else if ((too_many_pipe_buffers_hard(pipe->user) ||

			    too_many_pipe_buffers_soft(pipe->user)) &&

		           !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {

			ret = -EPERM;

			goto out;

		}

		ret = pipe_set_size(pipe, nr_pages);

		break;

include/linux/pipe_fs_i.h

+4 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ struct pipe_buffer { 
 *	@fasync_readers: reader side fasync

 *	@fasync_writers: writer side fasync

 *	@bufs: the circular array of pipe buffers

 *	@user: the user who created this pipe

 **/

struct pipe_inode_info {

	struct mutex mutex;
@@ -57,6 +58,7 @@ struct pipe_inode_info { 
	struct fasync_struct *fasync_readers;

	struct fasync_struct *fasync_writers;

	struct pipe_buffer *bufs;

	struct user_struct *user;

};



/*
@@ -123,6 +125,8 @@ void pipe_unlock(struct pipe_inode_info *); 
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);



extern unsigned int pipe_max_size, pipe_min_size;

extern unsigned long pipe_user_pages_hard;

extern unsigned long pipe_user_pages_soft;

int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);

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