Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
fs/pidfs.c | 42 +++++++++++++++++++++++++++++++++++++
include/linux/pidfs.h | 29 +++++++++++++++++++++++++
kernel/signal.c | 49 ++++++++++++-------------------------------
3 files changed, 84 insertions(+), 36 deletions(-)
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 80675b6bf884..de7e9e6bbd22 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -22,6 +22,48 @@
#include "internal.h"
#include "mount.h"
+struct pid_fd pidfd_get(int fd)
+{
+ struct fd f;
+ struct pid *pid;
+
+ /* handle PIDFD_SELF_* cases */
+ if (fd < 0) {
+ if (fd == PIDFD_SELF_THREAD)
+ return (struct pid_fd){ .fd = EMPTY_FD, .pid = get_task_pid(current, PIDTYPE_PID) };
+ if (fd == PIDFD_SELF_THREAD_GROUP)
+ return (struct pid_fd){ .fd = EMPTY_FD, .pid = get_task_pid(current, PIDTYPE_TGID) };
+ return (struct pid_fd){ .fd = EMPTY_FD, .pid = ERR_PTR(-EBADF) };
+ }
+
+ /* handle the regular case */
+ f = fdget(fd);
+ if (!fd_file(f))
+ return (struct pid_fd){ .fd = EMPTY_FD, .pid = ERR_PTR(-EBADF) };
+
+ pid = pidfd_pid(fd_file(f));
+ if (IS_ERR(pid)) {
+ fdput(f);
+ return (struct pid_fd) { .fd = EMPTY_FD, .pid = pid };
+ }
+
+ return (struct pid_fd) { .fd = f, pid = pid } ;
+}
+
+void pidfd_put(struct pid_fd fd)
+{
+ /*
+ * Handle PIDFD_SELF_* where the struct pid hasn't been attached
+ * to a file.
+ */
+ if (fd_empty(fd.fd) && pidfd_valid(fd))
+ put_pid(fd.pid);
+
+ /* Can call unconditionally safely. */
+ fdput(fd.fd);
+
+}
+
#ifdef CONFIG_PROC_FS
/**
* pidfd_show_fdinfo - print information about a pidfd
diff --git a/include/linux/pidfs.h b/include/linux/pidfs.h
index 75bdf9807802..ad86b69ee1ea 100644
--- a/include/linux/pidfs.h
+++ b/include/linux/pidfs.h
@@ -2,6 +2,35 @@
#ifndef _LINUX_PID_FS_H
#define _LINUX_PID_FS_H
+#include <linux/file.h>
+#include <linux/cleanup.h>
+
+#define PIDFD_SELF PIDFD_SELF_THREAD
+#define PIDFD_SELF_PROCESS PIDFD_SELF_THREAD_GROUP
+
+#define PIDFD_SELF_THREAD -10000 /* Current thread. */
+#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */
+
+struct pid_fd {
+ struct fd fd;
+ struct pid *pid;
+};
+
+static inline struct pid *pid_fd_pid(struct pid_fd pfd)
+{
+ return pfd.pid;
+}
+
+static inline bool pidfd_valid(struct pid_fd pfd)
+{
+ return !IS_ERR(pid_fd_pid(pfd));
+}
+
+struct pid_fd pidfd_get(int fd);
+void pidfd_put(struct pid_fd fd);
+
+DEFINE_CLASS(pid_fd, struct pid_fd, pidfd_put(_T), pidfd_get(fd), int fd)
+
struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags);
void __init pidfs_init(void);
diff --git a/kernel/signal.c b/kernel/signal.c
index 4344860ffcac..16b10e726038 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -47,6 +47,7 @@
#include <linux/cgroup.h>
#include <linux/audit.h>
#include <linux/sysctl.h>
+#include <linux/pidfs.h>
#include <uapi/linux/pidfd.h>
#define CREATE_TRACE_POINTS
@@ -3875,17 +3876,6 @@ static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
return copy_siginfo_from_user(kinfo, info);
}
-static struct pid *pidfd_to_pid(const struct file *file)
-{
- struct pid *pid;
-
- pid = pidfd_pid(file);
- if (!IS_ERR(pid))
- return pid;
-
- return tgid_pidfd_to_pid(file);
-}
-
#define PIDFD_SEND_SIGNAL_FLAGS \
(PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \
PIDFD_SIGNAL_PROCESS_GROUP)
@@ -3908,7 +3898,6 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
siginfo_t __user *, info, unsigned int, flags)
{
int ret;
- struct fd f;
struct pid *pid;
kernel_siginfo_t kinfo;
enum pid_type type;
@@ -3921,25 +3910,18 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1)
return -EINVAL;
- f = fdget(pidfd);
- if (!fd_file(f))
- return -EBADF;
-
- /* Is this a pidfd? */
- pid = pidfd_to_pid(fd_file(f));
- if (IS_ERR(pid)) {
- ret = PTR_ERR(pid);
- goto err;
- }
+ CLASS(pid_fd, pid_fd)(pidfd);
+ if (!pidfd_valid(pid_fd))
+ return PTR_ERR(pid_fd_pid(pid_fd));
- ret = -EINVAL;
+ pid = pid_fd_pid(pid_fd);
if (!access_pidfd_pidns(pid))
- goto err;
+ return -EINVAL;
switch (flags) {
case 0:
/* Infer scope from the type of pidfd. */
- if (fd_file(f)->f_flags & PIDFD_THREAD)
+ if (pidfd > 0 && fd_file(pid_fd.fd)->f_flags & PIDFD_THREAD)
type = PIDTYPE_PID;
else
type = PIDTYPE_TGID;
@@ -3958,28 +3940,23 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
if (info) {
ret = copy_siginfo_from_user_any(&kinfo, info);
if (unlikely(ret))
- goto err;
+ return ret;
- ret = -EINVAL;
if (unlikely(sig != kinfo.si_signo))
- goto err;
+ return -EINVAL;
/* Only allow sending arbitrary signals to yourself. */
- ret = -EPERM;
if ((task_pid(current) != pid || type > PIDTYPE_TGID) &&
(kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
- goto err;
+ return -EPERM;
} else {
prepare_kill_siginfo(sig, &kinfo, type);
}
if (type == PIDTYPE_PGID)
- ret = kill_pgrp_info(sig, &kinfo, pid);
- else
- ret = kill_pid_info_type(sig, &kinfo, pid, type);
-err:
- fdput(f);
- return ret;
+ return kill_pgrp_info(sig, &kinfo, pid);
+
+ return kill_pid_info_type(sig, &kinfo, pid, type);
}
static int
--
2.45.2
--ft377c7j3f5pvc3c--
