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Subject[PATCH v2 2/8] pipe: move limit checking logic into pipe_set_size()
Date
This is a preparatory patch for following work. Move the F_SETPIPE_SZ
limit-checking logic from pipe_fcntl() into pipe_set_size(). This
simplifies the code a little, and allows for reworking required in
a later patch that fixes the limit checking in pipe_set_size()

Cc: Willy Tarreau <w@1wt.eu>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: socketpair@gmail.com
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
---
fs/pipe.c | 41 ++++++++++++++++++-----------------------
1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 7d7c21e..4b98fd0 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1026,9 +1026,24 @@ static inline unsigned int round_pipe_size(unsigned int size)
* 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 nr_pages)
+static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
{
struct pipe_buffer *bufs;
+ unsigned int size, nr_pages;
+
+ size = round_pipe_size(arg);
+ nr_pages = size >> PAGE_SHIFT;
+
+ if (!nr_pages)
+ return -EINVAL;
+
+ if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size)
+ return -EPERM;
+
+ if ((too_many_pipe_buffers_hard(pipe->user) ||
+ too_many_pipe_buffers_soft(pipe->user)) &&
+ !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
+ return -EPERM;

/*
* We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
@@ -1112,28 +1127,9 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
__pipe_lock(pipe);

switch (cmd) {
- 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;
- } 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);
+ case F_SETPIPE_SZ:
+ ret = pipe_set_size(pipe, arg);
break;
- }
case F_GETPIPE_SZ:
ret = pipe->buffers * PAGE_SIZE;
break;
@@ -1142,7 +1138,6 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
break;
}

-out:
__pipe_unlock(pipe);
return ret;
}
--
2.5.5
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