diff options
Diffstat (limited to 'fs/pipe.c')
| -rw-r--r-- | fs/pipe.c | 102 |
1 files changed, 75 insertions, 27 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index d79872eba09a..279eef96c51c 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -26,9 +26,14 @@ /* * The max size that a non-root user is allowed to grow the pipe. Can - * be set by root in /proc/sys/fs/pipe-max-pages + * be set by root in /proc/sys/fs/pipe-max-size */ -unsigned int pipe_max_pages = PIPE_DEF_BUFFERS * 16; +unsigned int pipe_max_size = 1048576; + +/* + * Minimum pipe size, as required by POSIX + */ +unsigned int pipe_min_size = PAGE_SIZE; /* * We use a start+len construction, which provides full use of the @@ -230,6 +235,7 @@ void *generic_pipe_buf_map(struct pipe_inode_info *pipe, return kmap(buf->page); } +EXPORT_SYMBOL(generic_pipe_buf_map); /** * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer @@ -249,6 +255,7 @@ void generic_pipe_buf_unmap(struct pipe_inode_info *pipe, } else kunmap(buf->page); } +EXPORT_SYMBOL(generic_pipe_buf_unmap); /** * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer @@ -279,6 +286,7 @@ int generic_pipe_buf_steal(struct pipe_inode_info *pipe, return 1; } +EXPORT_SYMBOL(generic_pipe_buf_steal); /** * generic_pipe_buf_get - get a reference to a &struct pipe_buffer @@ -294,6 +302,7 @@ void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { page_cache_get(buf->page); } +EXPORT_SYMBOL(generic_pipe_buf_get); /** * generic_pipe_buf_confirm - verify contents of the pipe buffer @@ -309,6 +318,7 @@ int generic_pipe_buf_confirm(struct pipe_inode_info *info, { return 0; } +EXPORT_SYMBOL(generic_pipe_buf_confirm); /** * generic_pipe_buf_release - put a reference to a &struct pipe_buffer @@ -323,6 +333,7 @@ void generic_pipe_buf_release(struct pipe_inode_info *pipe, { page_cache_release(buf->page); } +EXPORT_SYMBOL(generic_pipe_buf_release); static const struct pipe_buf_operations anon_pipe_buf_ops = { .can_merge = 1, @@ -1112,26 +1123,20 @@ SYSCALL_DEFINE1(pipe, int __user *, fildes) * Allocate a new array of pipe buffers and copy the info over. Returns the * pipe size if successful, or return -ERROR on error. */ -static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) +static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) { struct pipe_buffer *bufs; /* - * Must be a power-of-2 currently - */ - if (!is_power_of_2(arg)) - return -EINVAL; - - /* * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't * expect a lot of shrink+grow operations, just free and allocate * again like we would do for growing. If the pipe currently * contains more buffers than arg, then return busy. */ - if (arg < pipe->nrbufs) + if (nr_pages < pipe->nrbufs) return -EBUSY; - bufs = kcalloc(arg, sizeof(struct pipe_buffer), GFP_KERNEL); + bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL); if (unlikely(!bufs)) return -ENOMEM; @@ -1140,20 +1145,56 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) * and adjust the indexes. */ if (pipe->nrbufs) { - const unsigned int tail = pipe->nrbufs & (pipe->buffers - 1); - const unsigned int head = pipe->nrbufs - tail; + unsigned int tail; + unsigned int head; + tail = pipe->curbuf + pipe->nrbufs; + if (tail < pipe->buffers) + tail = 0; + else + tail &= (pipe->buffers - 1); + + head = pipe->nrbufs - tail; if (head) memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer)); if (tail) - memcpy(bufs + head, pipe->bufs + pipe->curbuf, tail * sizeof(struct pipe_buffer)); + memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer)); } pipe->curbuf = 0; kfree(pipe->bufs); pipe->bufs = bufs; - pipe->buffers = arg; - return arg; + pipe->buffers = nr_pages; + return nr_pages * PAGE_SIZE; +} + +/* + * Currently we rely on the pipe array holding a power-of-2 number + * of pages. + */ +static inline unsigned int round_pipe_size(unsigned int size) +{ + unsigned long nr_pages; + + nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; + return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; +} + +/* + * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax + * will return an error. + */ +int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, + size_t *lenp, loff_t *ppos) +{ + int ret; + + ret = proc_dointvec_minmax(table, write, buf, lenp, ppos); + if (ret < 0 || !write) + return ret; + + pipe_max_size = round_pipe_size(pipe_max_size); + return ret; } long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) @@ -1168,25 +1209,32 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) mutex_lock(&pipe->inode->i_mutex); switch (cmd) { - case F_SETPIPE_SZ: - if (!capable(CAP_SYS_ADMIN) && arg > pipe_max_pages) - return -EINVAL; - /* - * The pipe needs to be at least 2 pages large to - * guarantee POSIX behaviour. - */ - if (arg < 2) - return -EINVAL; - ret = pipe_set_size(pipe, arg); + case F_SETPIPE_SZ: { + unsigned int size, nr_pages; + + size = round_pipe_size(arg); + nr_pages = size >> PAGE_SHIFT; + + ret = -EINVAL; + if (!nr_pages) + goto out; + + if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) { + ret = -EPERM; + goto out; + } + ret = pipe_set_size(pipe, nr_pages); break; + } case F_GETPIPE_SZ: - ret = pipe->buffers; + ret = pipe->buffers * PAGE_SIZE; break; default: ret = -EINVAL; break; } +out: mutex_unlock(&pipe->inode->i_mutex); return ret; } |