The patch titled
From: Jürg Billeter <j@xxxxxxxxx>
has been added to the -mm tree. Its filename is
prctl-add-pr_et_pdeathsig_proc.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/prctl-add-pr_et_pdeathsig_proc.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/prctl-add-pr_et_pdeathsig_proc.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Jürg Billeter <j@xxxxxxxxx>
Subject: prctl: add PR_[GS]ET_PDEATHSIG_PROC
PR_SET_PDEATHSIG sets a parent death signal that the calling process will
get when its parent thread dies, even when the result of getppid() doesn't
change because the calling process is reparented to a different thread in
the same parent process. When managing multiple processes, a
process-based parent death signal is much more useful. E.g., to avoid
stray child processes.
PR_SET_PDEATHSIG_PROC sets a process-based death signal. Unlike
PR_SET_PDEATHSIG, this is inherited across fork to allow killing a whole
subtree without race conditions.
This can be used for sandboxing when combined with a seccomp filter.
There have been previous attempts to support this by changing the behavior
of PR_SET_PDEATHSIG. However, that would break existing applications.
See https://marc.info/?l=linux-kernel&m=117621804801689 and
https://bugzilla.kernel.org/show_bug.cgi?id=43300
Link: http://lkml.kernel.org/r/20170929123058.48924-1-j@xxxxxxxxx
Signed-off-by: Jürg Billeter <j@xxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Filipe Brandenburger <filbranden@xxxxxxxxxx>
Cc: David Wilcox <davidvsthegiant@xxxxxxxxx>
Cc: "Adam H . Peterson" <alphaetapi@xxxxxxxxxxx>
Cc: <hansecke@xxxxxxxxx>
Cc: <linux-api@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 1 +
include/linux/sched/signal.h | 3 +++
include/uapi/linux/prctl.h | 4 ++++
kernel/cred.c | 1 +
kernel/exit.c | 4 ++++
kernel/fork.c | 2 ++
kernel/sys.c | 11 +++++++++++
security/apparmor/lsm.c | 1 +
security/selinux/hooks.c | 1 +
9 files changed, 28 insertions(+)
diff -puN fs/exec.c~prctl-add-pr_et_pdeathsig_proc fs/exec.c
--- a/fs/exec.c~prctl-add-pr_et_pdeathsig_proc
+++ a/fs/exec.c
@@ -1334,6 +1334,7 @@ void setup_new_exec(struct linux_binprm
if (bprm->secureexec) {
/* Make sure parent cannot signal privileged process. */
current->pdeath_signal = 0;
+ current->signal->pdeath_signal_proc = 0;
/*
* For secureexec, reset the stack limit to sane default to
diff -puN include/linux/sched/signal.h~prctl-add-pr_et_pdeathsig_proc include/linux/sched/signal.h
--- a/include/linux/sched/signal.h~prctl-add-pr_et_pdeathsig_proc
+++ a/include/linux/sched/signal.h
@@ -103,6 +103,9 @@ struct signal_struct {
int group_stop_count;
unsigned int flags; /* see SIGNAL_* flags below */
+ /* The signal sent when the parent dies: */
+ int pdeath_signal_proc;
+
/*
* PR_SET_CHILD_SUBREAPER marks a process, like a service
* manager, to re-parent orphan (double-forking) child processes
diff -puN include/uapi/linux/prctl.h~prctl-add-pr_et_pdeathsig_proc include/uapi/linux/prctl.h
--- a/include/uapi/linux/prctl.h~prctl-add-pr_et_pdeathsig_proc
+++ a/include/uapi/linux/prctl.h
@@ -197,4 +197,8 @@ struct prctl_mm_map {
# define PR_CAP_AMBIENT_LOWER 3
# define PR_CAP_AMBIENT_CLEAR_ALL 4
+/* Process-based variant of PDEATHSIG */
+#define PR_SET_PDEATHSIG_PROC 48
+#define PR_GET_PDEATHSIG_PROC 49
+
#endif /* _LINUX_PRCTL_H */
diff -puN kernel/cred.c~prctl-add-pr_et_pdeathsig_proc kernel/cred.c
--- a/kernel/cred.c~prctl-add-pr_et_pdeathsig_proc
+++ a/kernel/cred.c
@@ -448,6 +448,7 @@ int commit_creds(struct cred *new)
if (task->mm)
set_dumpable(task->mm, suid_dumpable);
task->pdeath_signal = 0;
+ task->signal->pdeath_signal_proc = 0;
smp_wmb();
}
diff -puN kernel/exit.c~prctl-add-pr_et_pdeathsig_proc kernel/exit.c
--- a/kernel/exit.c~prctl-add-pr_et_pdeathsig_proc
+++ a/kernel/exit.c
@@ -635,6 +635,10 @@ static void reparent_leader(struct task_
if (unlikely(p->exit_state == EXIT_DEAD))
return;
+ if (p->signal->pdeath_signal_proc)
+ group_send_sig_info(p->signal->pdeath_signal_proc,
+ SEND_SIG_NOINFO, p);
+
/* We don't want people slaying init. */
p->exit_signal = SIGCHLD;
diff -puN kernel/fork.c~prctl-add-pr_et_pdeathsig_proc kernel/fork.c
--- a/kernel/fork.c~prctl-add-pr_et_pdeathsig_proc
+++ a/kernel/fork.c
@@ -1433,6 +1433,8 @@ static int copy_signal(unsigned long clo
mutex_init(&sig->cred_guard_mutex);
+ sig->pdeath_signal_proc = current->signal->pdeath_signal_proc;
+
return 0;
}
diff -puN kernel/sys.c~prctl-add-pr_et_pdeathsig_proc kernel/sys.c
--- a/kernel/sys.c~prctl-add-pr_et_pdeathsig_proc
+++ a/kernel/sys.c
@@ -2206,6 +2206,17 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
case PR_GET_PDEATHSIG:
error = put_user(me->pdeath_signal, (int __user *)arg2);
break;
+ case PR_SET_PDEATHSIG_PROC:
+ if (!valid_signal(arg2)) {
+ error = -EINVAL;
+ break;
+ }
+ me->signal->pdeath_signal_proc = arg2;
+ break;
+ case PR_GET_PDEATHSIG_PROC:
+ error = put_user(me->signal->pdeath_signal_proc,
+ (int __user *)arg2);
+ break;
case PR_GET_DUMPABLE:
error = get_dumpable(me->mm);
break;
diff -puN security/apparmor/lsm.c~prctl-add-pr_et_pdeathsig_proc security/apparmor/lsm.c
--- a/security/apparmor/lsm.c~prctl-add-pr_et_pdeathsig_proc
+++ a/security/apparmor/lsm.c
@@ -689,6 +689,7 @@ static void apparmor_bprm_committing_cre
aa_inherit_files(bprm->cred, current->files);
current->pdeath_signal = 0;
+ current->signal->pdeath_signal_proc = 0;
/* reset soft limits and set hard limits for the new label */
__aa_transition_rlimits(label, new_ctx->label);
diff -puN security/selinux/hooks.c~prctl-add-pr_et_pdeathsig_proc security/selinux/hooks.c
--- a/security/selinux/hooks.c~prctl-add-pr_et_pdeathsig_proc
+++ a/security/selinux/hooks.c
@@ -2547,6 +2547,7 @@ static void selinux_bprm_committing_cred
/* Always clear parent death signal on SID transitions. */
current->pdeath_signal = 0;
+ current->signal->pdeath_signal_proc = 0;
/* Check whether the new SID can inherit resource limits from the old
* SID. If not, reset all soft limits to the lower of the current
_
Patches currently in -mm which might be from j@xxxxxxxxx are
prctl-add-pr_et_pdeathsig_proc.patch
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