提交 eadee0ce 编写于 作者: L Linus Torvalds

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
......@@ -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
......
......@@ -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)) {
......
......@@ -46,9 +46,9 @@ void put_filesystem(struct file_system_type *fs)
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)
for (p = &file_systems; *p; p = &(*p)->next)
if (strncmp((*p)->name, name, len) == 0 &&
!(*p)->name[len])
break;
return p;
}
......
......@@ -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;
......
......@@ -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 *);
......
......@@ -835,6 +835,7 @@ struct user_struct {
#endif
unsigned long locked_shm; /* How many pages of mlocked shm ? */
unsigned long unix_inflight; /* How many files in flight in unix sockets */
atomic_long_t pipe_bufs; /* how many pages are allocated in pipe buffers */
#ifdef CONFIG_KEYS
struct key *uid_keyring; /* UID specific keyring */
......
......@@ -1757,6 +1757,20 @@ static struct ctl_table fs_table[] = {
.proc_handler = &pipe_proc_fn,
.extra1 = &pipe_min_size,
},
{
.procname = "pipe-user-pages-hard",
.data = &pipe_user_pages_hard,
.maxlen = sizeof(pipe_user_pages_hard),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
},
{
.procname = "pipe-user-pages-soft",
.data = &pipe_user_pages_soft,
.maxlen = sizeof(pipe_user_pages_soft),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
},
{ }
};
......
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