path: root/fs/open.c
diff options
authorChristian Brauner <>2020-06-03 21:48:55 +0200
committerChristian Brauner <>2020-06-17 00:07:38 +0200
commit60997c3d45d9a67daf01c56d805ae4fec37e0bd8 (patch)
tree8f915556e039b20018e6d95ab154048a0fddf576 /fs/open.c
parent2c5db60e46ad7f03789fe7e2beedb15496930468 (diff)
close_range: add CLOSE_RANGE_UNSHARE
One of the use-cases of close_range() is to drop file descriptors just before execve(). This would usually be expressed in the sequence: unshare(CLONE_FILES); close_range(3, ~0U); as pointed out by Linus it might be desirable to have this be a part of close_range() itself under a new flag CLOSE_RANGE_UNSHARE. This expands {dup,unshare)_fd() to take a max_fds argument that indicates the maximum number of file descriptors to copy from the old struct files. When the user requests that all file descriptors are supposed to be closed via close_range(min, max) then we can cap via unshare_fd(min) and hence don't need to do any of the heavy fput() work for everything above min. The patch makes it so that if CLOSE_RANGE_UNSHARE is requested and we do in fact currently share our file descriptor table we create a new private copy. We then close all fds in the requested range and finally after we're done we install the new fd table. Suggested-by: Linus Torvalds <> Signed-off-by: Christian Brauner <>
Diffstat (limited to 'fs/open.c')
1 files changed, 1 insertions, 4 deletions
diff --git a/fs/open.c b/fs/open.c
index 073ea3c45347..5e62f18adc5b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1324,10 +1324,7 @@ SYSCALL_DEFINE1(close, unsigned int, fd)
SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
unsigned int, flags)
- if (flags)
- return -EINVAL;
- return __close_range(current->files, fd, max_fd);
+ return __close_range(fd, max_fd, flags);