The code to copy file descriptors was duplicated in pidfd_getfd. Rather than continue to duplicate it, this hoists the code out of kernel/pid.c and uses the newly added file_receive helper.
Earlier, when this was implemented there was some back-and-forth about how the semantics should work around copying around file descriptors [1], and it was decided that the default behaviour should be to not modify cgroup data. As a matter of least surprise, this approach follows the default semantics as presented by SCM_RIGHTS. In the future, a flag can be added to avoid manipulating the cgroup data on copy. [1]: https://lore.kernel.org/lkml/[email protected]/ Signed-off-by: Sargun Dhillon <[email protected]> Suggested-by: Kees Cook <[email protected]> Cc: Al Viro <[email protected]> Cc: Christian Brauner <[email protected]> Cc: Daniel Wagner <[email protected]> Cc: David S. Miller <[email protected]> Cc: Jann Horn <[email protected]> Cc: John Fastabend <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Tycho Andersen <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] --- kernel/pid.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/kernel/pid.c b/kernel/pid.c index c835b844aca7..1642cf940aa1 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -606,7 +606,7 @@ static int pidfd_getfd(struct pid *pid, int fd) { struct task_struct *task; struct file *file; - int ret; + int ret, err; task = get_pid_task(pid, PIDTYPE_PID); if (!task) @@ -617,18 +617,16 @@ static int pidfd_getfd(struct pid *pid, int fd) if (IS_ERR(file)) return PTR_ERR(file); - ret = security_file_receive(file); - if (ret) { - fput(file); - return ret; - } - ret = get_unused_fd_flags(O_CLOEXEC); - if (ret < 0) - fput(file); - else - fd_install(ret, file); + if (ret >= 0) { + err = file_receive(ret, file); + if (err) { + put_unused_fd(ret); + ret = err; + } + } + fput(file); return ret; } -- 2.25.1
