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-rw-r--r--fs/pipe.c93
1 files changed, 65 insertions, 28 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index db6eaaba0dd8..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
@@ -1118,26 +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;
@@ -1146,20 +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)
@@ -1174,23 +1209,25 @@ 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) {
- ret = -EINVAL;
+ 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;
- }
- /*
- * The pipe needs to be at least 2 pages large to
- * guarantee POSIX behaviour.
- */
- if (arg < 2) {
- ret = -EINVAL;
+
+ if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
+ ret = -EPERM;
goto out;
}
- ret = pipe_set_size(pipe, arg);
+ ret = pipe_set_size(pipe, nr_pages);
break;
+ }
case F_GETPIPE_SZ:
- ret = pipe->buffers;
+ ret = pipe->buffers * PAGE_SIZE;
break;
default:
ret = -EINVAL;