From: ebiederm@xmission.com (Eric W. Biederman)
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
Oleg Nesterov <oleg@redhat.com>, Jann Horn <jann@thejh.net>
Subject: [PATCH -1/24] exec: Don't open code get_close_on_exec
Date: Wed, 09 Dec 2020 15:42:57 -0600 [thread overview]
Message-ID: <87k0tqr6zi.fsf_-_@x220.int.ebiederm.org> (raw)
In-Reply-To: <20201209195033.GP3579531@ZenIV.linux.org.uk> (Al Viro's message of "Wed, 9 Dec 2020 19:50:33 +0000")
Al Viro pointed out that using the phrase "close_on_exec(fd,
rcu_dereference_raw(current->files->fdt))" instead of wrapping it in
rcu_read_lock(), rcu_read_unlock() is a very questionable
optimization[1].
Once wrapped with rcu_read_lock()/rcu_read_unlock() that phrase
becomes equivalent the helper function get_close_on_exec so
simplify the code and make it more robust by simply using
get_close_on_exec.
[1] https://lkml.kernel.org/r/20201207222214.GA4115853@ZenIV.linux.org.uk
Suggested-by: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
I aim to rebase my exec branch and apply this tomorrow.
fs/exec.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 547a2390baf5..9aabf6e8c904 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1808,8 +1808,7 @@ static int bprm_execve(struct linux_binprm *bprm,
* inaccessible after exec. Relies on having exclusive access to
* current->files (due to unshare_files above).
*/
- if (bprm->fdpath &&
- close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
+ if (bprm->fdpath && get_close_on_exec(fd))
bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
/* Set the unchanging part of bprm->cred */
--
2.20.1
next prev parent reply other threads:[~2020-12-09 21:44 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87r1on1v62.fsf@x220.int.ebiederm.org>
2020-11-20 23:14 ` [PATCH v2 01/24] exec: Move unshare_files to fix posix file locking during exec Eric W. Biederman
2020-11-20 23:58 ` Linus Torvalds
2020-12-07 22:22 ` Al Viro
[not found] ` <87zh2pusdw.fsf@x220.int.ebiederm.org>
2020-12-07 23:35 ` Al Viro
2020-11-20 23:14 ` [PATCH v2 02/24] exec: Simplify unshare_files Eric W. Biederman
2020-11-23 17:50 ` Oleg Nesterov
2020-11-23 18:25 ` Linus Torvalds
[not found] ` <87im9vx08i.fsf@x220.int.ebiederm.org>
[not found] ` <87pn42r0n7.fsf@x220.int.ebiederm.org>
2020-11-24 19:58 ` Linus Torvalds
2020-11-24 20:14 ` Arnd Bergmann
2020-11-24 23:44 ` Geoff Levand
2020-11-25 1:16 ` Eric W. Biederman
2020-11-27 20:29 ` Arnd Bergmann
2020-11-30 21:37 ` Eric W. Biederman
2020-12-01 9:46 ` Michael Ellerman
2020-11-25 21:51 ` [RFC][PATCH] coredump: Document coredump code exclusively used by cell spufs Eric W. Biederman
2020-12-02 15:20 ` Eric W. Biederman
2020-12-02 15:58 ` Arnd Bergmann
2020-12-07 22:32 ` [PATCH v2 02/24] exec: Simplify unshare_files Al Viro
2020-11-20 23:14 ` [PATCH v2 03/24] exec: Remove reset_files_struct Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 04/24] kcmp: In kcmp_epoll_target use fget_task Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 05/24] bpf: In bpf_task_fd_query " Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 06/24] proc/fd: In proc_fd_link " Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 07/24] file: Rename __fcheck_files to files_lookup_fd_raw Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 08/24] file: Factor files_lookup_fd_locked out of fcheck_files Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 09/24] file: Replace fcheck_files with files_lookup_fd_rcu Eric W. Biederman
2020-12-07 22:46 ` Al Viro
2020-12-07 22:49 ` Al Viro
2020-12-09 16:54 ` Al Viro
2020-12-09 17:44 ` Paul E. McKenney
2020-11-20 23:14 ` [PATCH v2 10/24] file: Rename fcheck lookup_fd_rcu Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 11/24] file: Implement task_lookup_fd_rcu Eric W. Biederman
2020-11-21 18:19 ` Cyrill Gorcunov
[not found] ` <87blfp1r8b.fsf@x220.int.ebiederm.org>
2020-11-22 13:52 ` Cyrill Gorcunov
2020-11-20 23:14 ` [PATCH v2 12/24] proc/fd: In tid_fd_mode use task_lookup_fd_rcu Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 13/24] kcmp: In get_file_raw_ptr " Eric W. Biederman
2020-11-23 21:05 ` Cyrill Gorcunov
2020-11-20 23:14 ` [PATCH v2 14/24] file: Implement task_lookup_next_fd_rcu Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 15/24] proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu Eric W. Biederman
2020-12-07 23:29 ` Al Viro
[not found] ` <877dprvs8e.fsf@x220.int.ebiederm.org>
2020-12-09 4:07 ` Al Viro
[not found] ` <877dprtxly.fsf@x220.int.ebiederm.org>
2020-12-09 14:23 ` Al Viro
2020-12-09 18:04 ` [PATCH] files: rcu free files_struct Eric W. Biederman
2020-12-09 19:13 ` Linus Torvalds
2020-12-09 19:50 ` Al Viro
2020-12-09 21:32 ` Eric W. Biederman
2020-12-10 6:13 ` Al Viro
2020-12-10 19:29 ` Eric W. Biederman
2020-12-10 21:36 ` Al Viro
2020-12-10 22:30 ` Christian Brauner
2020-12-10 22:54 ` Al Viro
2020-12-10 23:10 ` Al Viro
2020-12-09 21:42 ` Eric W. Biederman [this message]
2020-12-09 22:04 ` Eric W. Biederman
2020-12-09 19:49 ` Matthew Wilcox
2020-12-09 22:06 ` Eric W. Biederman
2020-12-09 22:58 ` Al Viro
2020-12-09 23:01 ` Linus Torvalds
2020-12-09 23:04 ` Linus Torvalds
2020-12-09 23:07 ` Matthew Wilcox
2020-12-09 23:26 ` Paul E. McKenney
2020-12-09 23:29 ` Linus Torvalds
2020-12-10 0:39 ` Paul E. McKenney
2020-12-10 0:41 ` Linus Torvalds
2020-12-10 0:57 ` Paul E. McKenney
2020-11-20 23:14 ` [PATCH v2 16/24] bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu Eric W. Biederman
2020-11-23 17:06 ` Yonghong Song
2020-11-20 23:14 ` [PATCH v2 17/24] proc/fd: In fdinfo seq_show don't use get_files_struct Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 18/24] file: Merge __fd_install into fd_install Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 19/24] file: In f_dupfd read RLIMIT_NOFILE once Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 20/24] file: Merge __alloc_fd into alloc_fd Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 21/24] file: Rename __close_fd to close_fd and remove the files parameter Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 22/24] file: Replace ksys_close with close_fd Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 23/24] file: Rename __close_fd_get_file close_fd_get_file Eric W. Biederman
2020-11-20 23:14 ` [PATCH v2 24/24] file: Remove get_files_struct Eric W. Biederman
2020-11-21 0:05 ` [PATCH v2 00/24] exec: Move unshare_files and guarantee files_struct.count is correct Linus Torvalds
2020-11-28 5:12 ` Al Viro
2020-12-07 23:56 ` Al Viro
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87k0tqr6zi.fsf_-_@x220.int.ebiederm.org \
--to=ebiederm@xmission.com \
--cc=christian.brauner@ubuntu.com \
--cc=jann@thejh.net \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).