diff options
Diffstat (limited to 'patches/linux-sched-implement-adopt-system-call.patch.txt')
| -rw-r--r-- | patches/linux-sched-implement-adopt-system-call.patch.txt | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/patches/linux-sched-implement-adopt-system-call.patch.txt b/patches/linux-sched-implement-adopt-system-call.patch.txt new file mode 100644 index 0000000..f8c6ec1 --- /dev/null +++ b/patches/linux-sched-implement-adopt-system-call.patch.txt @@ -0,0 +1,132 @@ +From 2d9f1781c6cdec8d74f44f98624af2eacbd21810 Mon Sep 17 00:00:00 2001 +From: Vito Caputo <vcaputo@gnugeneration.com> +Date: Mon, 10 Jun 2013 17:28:49 -0700 +Subject: [PATCH 1/1] sched: implement adopt() system call + + This implements a proposed facility for adopting a process + by another. The immediate use case is programs like GNU + screen which lose their parent-child relationship when + detached. Using this sytem call on reattach, the relation + can be restored, which is particularly of use to those + taking advantage of the /proc/$pid/task/$pid/children list + provided by CONFIG_CHECKPOINT_RESTORE. + + This implementation applies permission checks similar to + that of kill(), in addition to preventing the adoption of + an ancestor process. + + I have tested it and use the change myself to complement + process subtree monitoring, without which I lose all + visibility of the descendants of my screen sessions on + reattach. + +Signed-off-by: Vito Caputo <vcaputo@gnugeneration.com> +--- + arch/x86/syscalls/syscall_32.tbl | 1 + + arch/x86/syscalls/syscall_64.tbl | 1 + + include/linux/syscalls.h | 2 ++ + kernel/exit.c | 59 ++++++++++++++++++++++++++++++++++++++ + 4 files changed, 63 insertions(+) + +diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl +index aabfb83..d219781 100644 +--- a/arch/x86/syscalls/syscall_32.tbl ++++ b/arch/x86/syscalls/syscall_32.tbl +@@ -357,3 +357,4 @@ + 348 i386 process_vm_writev sys_process_vm_writev compat_sys_process_vm_writev + 349 i386 kcmp sys_kcmp + 350 i386 finit_module sys_finit_module ++351 i386 adopt sys_adopt +diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl +index 38ae65d..6345ebf 100644 +--- a/arch/x86/syscalls/syscall_64.tbl ++++ b/arch/x86/syscalls/syscall_64.tbl +@@ -320,6 +320,7 @@ + 311 64 process_vm_writev sys_process_vm_writev + 312 common kcmp sys_kcmp + 313 common finit_module sys_finit_module ++314 common adopt sys_adopt + + # + # x32-specific system call numbers start at 512 to avoid cache impact +diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h +index 4147d70..3997cde 100644 +--- a/include/linux/syscalls.h ++++ b/include/linux/syscalls.h +@@ -841,4 +841,6 @@ asmlinkage long sys_process_vm_writev(pid_t pid, + asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type, + unsigned long idx1, unsigned long idx2); + asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags); ++ ++asmlinkage long sys_adopt(pid_t upid); + #endif +diff --git a/kernel/exit.c b/kernel/exit.c +index af2eb3c..5b554c8 100644 +--- a/kernel/exit.c ++++ b/kernel/exit.c +@@ -1681,3 +1681,62 @@ SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) + } + + #endif ++ ++/* ++ * sys_adopt() adopts the process specified as upid by the current ++ * process if permitted. This is linux-specific and provided so ++ * programs such as GNU screen may restore the parent-child ++ * relationship lost in detaching when reattaching. ++ */ ++SYSCALL_DEFINE1(adopt, pid_t, upid) ++{ ++ long ret = -ENOENT; ++ struct pid *pid; ++ ++ if ((pid = find_get_pid(upid))) { ++ struct task_struct *p; ++ ++ rcu_read_lock(); ++ write_lock_irq(&tasklist_lock); ++ p = pid_task(pid, PIDTYPE_PID); ++ if (p) { ++ struct task_struct *t; ++ const struct cred *cred = current_cred(); ++ const struct cred *tcred = __task_cred(p); ++ ++ if (!uid_eq(cred->euid, tcred->suid) && ++ !uid_eq(cred->euid, tcred->uid) && ++ !uid_eq(cred->uid, tcred->suid) && ++ !uid_eq(cred->uid, tcred->uid) && ++ !ns_capable(cred->user_ns, CAP_KILL)) { ++ ret = -EPERM; ++ goto out_unlock; ++ } ++ ++ ++ /* upid cannot be current nor an ancestor of current */ ++ for (t = current;; t = t->real_parent) { ++ if (t == p) { ++ ret = -EINVAL; ++ goto out_unlock; ++ } ++ if (is_global_init(t)) ++ break; ++ } ++ ++ t = p; ++ do { ++ t->real_parent = current; ++ } while_each_thread(p, t); ++ ++ list_move_tail(&p->sibling, &p->real_parent->children); ++ ret = 0; ++ } /* else { ret = -ENOENT } */ ++out_unlock: ++ write_unlock_irq(&tasklist_lock); ++ rcu_read_unlock(); ++ put_pid(pid); ++ } /* else { ret = -ENOENT } */ ++ ++ return ret; ++} +-- +1.7.10.4 + |