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From: Josh Triplett <[email protected]>
To: [email protected], [email protected],
	[email protected], [email protected]
Cc: Alexander Viro <[email protected]>,
	Arnd Bergmann <[email protected]>, Jens Axboe <[email protected]>
Subject: [PATCH v3 3/3] fs: pipe2: Support O_SPECIFIC_FD
Date: Tue, 7 Apr 2020 23:57:47 -0700	[thread overview]
Message-ID: <4ce301ca8ab8f6fdcc8feb05b4f7c026a203f68a.1586321767.git.josh@joshtriplett.org> (raw)
In-Reply-To: <[email protected]>

This allows the caller of pipe2 to specify one or both file descriptors
rather than having them automatically use the lowest available file
descriptor. The caller can specify either file descriptor as -1 to
allow that file descriptor to use the lowest available.

Signed-off-by: Josh Triplett <[email protected]>
---
 fs/pipe.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 16fb72e9abf7..4681a0d1d587 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -936,19 +936,19 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags)
 	int error;
 	int fdw, fdr;
 
-	if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
+	if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_SPECIFIC_FD))
 		return -EINVAL;
 
 	error = create_pipe_files(files, flags);
 	if (error)
 		return error;
 
-	error = get_unused_fd_flags(flags);
+	error = get_specific_unused_fd_flags(fd[0], flags);
 	if (error < 0)
 		goto err_read_pipe;
 	fdr = error;
 
-	error = get_unused_fd_flags(flags);
+	error = get_specific_unused_fd_flags(fd[1], flags);
 	if (error < 0)
 		goto err_fdr;
 	fdw = error;
@@ -969,7 +969,11 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags)
 int do_pipe_flags(int *fd, int flags)
 {
 	struct file *files[2];
-	int error = __do_pipe_flags(fd, files, flags);
+	int error;
+
+	if (flags & O_SPECIFIC_FD)
+		return -EINVAL;
+	error = __do_pipe_flags(fd, files, flags);
 	if (!error) {
 		fd_install(fd[0], files[0]);
 		fd_install(fd[1], files[1]);
@@ -987,6 +991,10 @@ static int do_pipe2(int __user *fildes, int flags)
 	int fd[2];
 	int error;
 
+	if (flags & O_SPECIFIC_FD)
+		if (copy_from_user(fd, fildes, sizeof(fd)))
+			return -EFAULT;
+
 	error = __do_pipe_flags(fd, files, flags);
 	if (!error) {
 		if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {
-- 
2.26.0


  parent reply	other threads:[~2020-04-08  6:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-08  6:56 [PATCH v3 0/3] Support userspace-selected fds Josh Triplett
2020-04-08  6:57 ` [PATCH v3 1/3] fs: Support setting a minimum fd for "lowest available fd" allocation Josh Triplett
2020-04-08 12:00   ` Aleksa Sarai
2020-04-09  3:17     ` Josh Triplett
2020-04-08  6:57 ` [PATCH v3 2/3] fs: openat2: Extend open_how to allow userspace-selected fds Josh Triplett
2020-04-08 12:23   ` Aleksa Sarai
2020-04-09  5:00     ` Josh Triplett
2020-04-09  8:10     ` Aleksa Sarai
2020-04-08  6:57 ` Josh Triplett [this message]
2020-04-08 12:26 ` [PATCH v3 0/3] Support " Aleksa Sarai
2020-04-09  3:19   ` Josh Triplett
  -- strict thread matches above, loose matches on Subject: below --
2020-04-04  5:57 Josh Triplett
2020-04-04  5:58 ` [PATCH v3 3/3] fs: pipe2: Support O_SPECIFIC_FD Josh Triplett

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