- 11 Dec, 2014 1 commit
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Oleg Nesterov authored
The comments in zap_pid_ns_processes() are not clear, we need to explain how this code actually works. 1. "Ignore SIGCHLD" looks like optimization but it is not, we also need this for correctness. 2. The comment above sys_wait4() could tell more. EXIT_ZOMBIE child is only possible if it has exited before we ignored SIGCHLD. Or if it is traced from the parent namespace, but in this case it will be reaped by debugger after detach, sys_wait4() acts as a synchronization point. 3. The comment about TASK_DEAD (EXIT_DEAD in fact) children is outdated. Contrary to what it says we do not need to make sure they all go away after 0a01f2cc "pidns: Make the pidns proc mount/umount logic obvious". At the same time, we do need to wait for nr_hashed==init_pids, but the reasons are quite different and not obvious: setns(). Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Sterling Alexander <stalexan@redhat.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- 04 Dec, 2014 5 commits
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Al Viro authored
Signed-off-by:Al Viro <viro@zeniv.linux.org.uk>
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Al Viro authored
take struct ns_common *, for now simply wrappers around proc_{alloc,free}_inum() Signed-off-by: -
Al Viro authored
We can do that now. And kill ->inum(), while we are at it - all instances are identical. Signed-off-by: -
Al Viro authored
Signed-off-by: -
Al Viro authored
for now - just move corresponding ->proc_inum instances over there Acked-by:
"Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:
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- 02 Apr, 2014 1 commit
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Oleg Nesterov authored
pidns_get()->get_pid_ns() can hit ns == NULL. This task_struct can't go away, but task_active_pid_ns(task) is NULL if release_task(task) was already called. Alternatively we could change get_pid_ns(ns) to check ns != NULL, but it seems that other callers are fine. Signed-off-by:
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- 25 Oct, 2013 1 commit
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Al Viro authored
makes procfs ->premission() instances safety in RCU mode independent from vfsmount_lock. Signed-off-by:
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- 31 Aug, 2013 1 commit
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Eric W. Biederman authored
nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and CAP_SETGID. For the existing users it doesn't noticably simplify things and from the suggested patches I have seen it encourages people to do the wrong thing. So remove nsown_capable. Acked-by:
Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by:
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- 27 Aug, 2013 1 commit
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Andy Lutomirski authored
nsproxy.pid_ns is *not* the task's pid namespace. The name should clarify that. This makes it more obvious that setns on a pid namespace is weird -- it won't change the pid namespace shown in procfs. Signed-off-by:
Andy Lutomirski <luto@amacapital.net> Reviewed-by:
David S. Miller <davem@davemloft.net>
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- 01 May, 2013 2 commits
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David Howells authored
Split the proc namespace stuff out into linux/proc_ns.h. Signed-off-by:
David Howells <dhowells@redhat.com> cc: netdev@vger.kernel.org cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by:
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Raphael S.Carvalho authored
Move BITS_PER_PAGE from pid_namespace.c to pid_namespace.h, since we can simplify the define PID_MAP_ENTRIES by using the BITS_PER_PAGE. [akpm@linux-foundation.org: kernel/pid.c:54:1: warning: "BITS_PER_PAGE" redefined] Signed-off-by:
Raphael S.Carvalho <raphael.scarv@gmail.com> Signed-off-by:
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- 26 Mar, 2013 1 commit
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Eric W. Biederman authored
When a multi-threaded init exits and the initial thread is not the last thread to exit the initial thread hangs around as a zombie until the last thread exits. In that case zap_pid_ns_processes needs to wait until there are only 2 hashed pids in the pid namespace not one. v2. Replace thread_pid_vnr(me) == 1 with the test thread_group_leader(me) as suggested by Oleg. Cc: stable@vger.kernel.org Cc: Oleg Nesterov <oleg@redhat.com> Reported-by:Caj Larsson <caj@omnicloud.com> Signed-off-by:
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- 26 Dec, 2012 1 commit
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Eric W. Biederman authored
Oleg pointed out that in a pid namespace the sequence. - pid 1 becomes a zombie - setns(thepidns), fork,... - reaping pid 1. - The injected processes exiting. Can lead to processes attempting access their child reaper and instead following a stale pointer. That waitpid for init can return before all of the processes in the pid namespace have exited is also unfortunate. Avoid these problems by disabling the allocation of new pids in a pid namespace when init dies, instead of when the last process in a pid namespace is reaped. Pointed-out-by:
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- 15 Dec, 2012 1 commit
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Eric W. Biederman authored
Andy Lutomirski <luto@amacapital.net> found a nasty little bug in the permissions of setns. With unprivileged user namespaces it became possible to create new namespaces without privilege. However the setns calls were relaxed to only require CAP_SYS_ADMIN in the user nameapce of the targed namespace. Which made the following nasty sequence possible. pid = clone(CLONE_NEWUSER | CLONE_NEWNS); if (pid == 0) { /* child */ system("mount --bind /home/me/passwd /etc/passwd"); } else if (pid != 0) { /* parent */ char path[PATH_MAX]; snprintf(path, sizeof(path), "/proc/%u/ns/mnt"); fd = open(path, O_RDONLY); setns(fd, 0); system("su -"); } Prevent this possibility by requiring CAP_SYS_ADMIN in the current user namespace when joing all but the user namespace. Acked-by:
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- 20 Nov, 2012 1 commit
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Eric W. Biederman authored
Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by:
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- 19 Nov, 2012 6 commits
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Eric W. Biederman authored
Unsharing of the pid namespace unlike unsharing of other namespaces does not take affect immediately. Instead it affects the children created with fork and clone. The first of these children becomes the init process of the new pid namespace, the rest become oddball children of pid 0. From the point of view of the new pid namespace the process that created it is pid 0, as it's pid does not map. A couple of different semantics were considered but this one was settled on because it is easy to implement and it is usable from pam modules. The core reasons for the existence of unshare. I took a survey of the callers of pam modules and the following appears to be a representative sample of their logic. { setup stuff include pam child = fork(); if (!child) { setuid() exec /bin/bash } waitpid(child); pam and other cleanup } As you can see there is a fork to create the unprivileged user space process. Which means that the unprivileged user space process will appear as pid 1 in the new pid namespace. Further most login processes do not cope with extraneous children which means shifting the duty of reaping extraneous child process to the creator of those extraneous children makes the system more comprehensible. The practical reason for this set of pid namespace semantics is that it is simple to implement and verify they work correctly. Whereas an implementation that requres changing the struct pid on a process comes with a lot more races and pain. Not the least of which is that glibc caches getpid(). These semantics are implemented by having two notions of the pid namespace of a proces. There is task_active_pid_ns which is the pid namspace the process was created with and the pid namespace that all pids are presented to that process in. The task_active_pid_ns is stored in the struct pid of the task. Then there is the pid namespace that will be used for children that pid namespace is stored in task->nsproxy->pid_ns. Signed-off-by: -
Eric W. Biederman authored
- Pid namespaces are designed to be inescapable so verify that the passed in pid namespace is a child of the currently active pid namespace or the currently active pid namespace itself. Allowing the currently active pid namespace is important so the effects of an earlier setns can be cancelled. Signed-off-by: -
Eric W. Biederman authored
task_active_pid_ns(current) != current->ns_proxy->pid_ns will soon be allowed to support unshare and setns. The definition of creating a child pid namespace when task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that we create a child pid namespace of current->ns_proxy->pid_ns. However that leads to strange cases like trying to have a single process be init in multiple pid namespaces, which is racy and hard to think about. The definition of creating a child pid namespace when task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that we create a child pid namespace of task_active_pid_ns(current). While that seems less racy it does not provide any utility. Therefore define the semantics of creating a child pid namespace when task_active_pid_ns(current) != current->ns_proxy->pid_ns to be that the pid namespace creation fails. That is easy to implement and easy to think about. Signed-off-by: -
Eric W. Biederman authored
Looking at pid_ns->nr_hashed is a bit simpler and it works for disjoint process trees that an unshare or a join of a pid_namespace may create. Acked-by:
"Serge E. Hallyn" <serge@hallyn.com> Signed-off-by:
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Eric W. Biederman authored
Track the number of pids in the proc hash table. When the number of pids goes to 0 schedule work to unmount the kernel mount of proc. Move the mount of proc into alloc_pid when we allocate the pid for init. Remove the surprising calls of pid_ns_release proc in fork and proc_flush_task. Those code paths really shouldn't know about proc namespace implementation details and people have demonstrated several times that finding and understanding those code paths is difficult and non-obvious. Because of the call path detach pid is alwasy called with the rtnl_lock held free_pid is not allowed to sleep, so the work to unmounting proc is moved to a work queue. This has the side benefit of not blocking the entire world waiting for the unnecessary rcu_barrier in deactivate_locked_super. In the process of making the code clear and obvious this fixes a bug reported by Gao feng <gaofeng@cn.fujitsu.com> where we would leak a mount of proc during clone(CLONE_NEWPID|CLONE_NEWNET) if copy_pid_ns succeeded and copy_net_ns failed. Acked-by:
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Eric W. Biederman authored
- Capture the the user namespace that creates the pid namespace - Use that user namespace to test if it is ok to write to /proc/sys/kernel/ns_last_pid. Zhao Hongjiang <zhaohongjiang@huawei.com> noticed I was missing a put_user_ns in when destroying a pid_ns. I have foloded his patch into this one so that bisects will work properly. Acked-by:
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- 25 Oct, 2012 1 commit
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Andrew Vagin authored
'struct pid' is a "variable sized struct" - a header with an array of upids at the end. The size of the array depends on a level (depth) of pid namespaces. Now a level of pidns is not limited, so 'struct pid' can be more than one page. Looks reasonable, that it should be less than a page. MAX_PIS_NS_LEVEL is not calculated from PAGE_SIZE, because in this case it depends on architectures, config options and it will be reduced, if someone adds a new fields in struct pid or struct upid. I suggest to set MAX_PIS_NS_LEVEL = 32, because it saves ability to expand "struct pid" and it's more than enough for all known for me use-cases. When someone finds a reasonable use case, we can add a config option or a sysctl parameter. In addition it will reduce the effect of another problem, when we have many nested namespaces and the oldest one starts dying. zap_pid_ns_processe will be called for each namespace and find_vpid will be called for each process in a namespace. find_vpid will be called minimum max_level^2 / 2 times. The reason of that is that when we found a bit in pidmap, we can't determine this pidns is top for this process or it isn't. vpid is a heavy operation, so a fork bomb, which create many nested namespace, can make a system inaccessible for a long time. For example my system becomes inaccessible for a few minutes with 4000 processes. [akpm@linux-foundation.org: return -EINVAL in response to excessive nesting, not -ENOMEM] Signed-off-by:
Andrew Vagin <avagin@openvz.org> Acked-by:
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- 19 Oct, 2012 1 commit
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Cyrill Gorcunov authored
free_pid_ns() operates in a recursive fashion: free_pid_ns(parent) put_pid_ns(parent) kref_put(&ns->kref, free_pid_ns); free_pid_ns thus if there was a huge nesting of namespaces the userspace may trigger avalanche calling of free_pid_ns leading to kernel stack exhausting and a panic eventually. This patch turns the recursion into an iterative loop. Based on a patch by Andrew Vagin. [akpm@linux-foundation.org: export put_pid_ns() to modules] Signed-off-by:Cyrill Gorcunov <gorcunov@openvz.org> Cc: Andrew Vagin <avagin@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Greg KH <greg@kroah.com> Signed-off-by:
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- 17 Sep, 2012 1 commit
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Andrew Vagin authored
The kernel doesn't check the pid for negative values, so if you try to write -2 to /proc/sys/kernel/ns_last_pid, you will get a kernel panic. The crash happens because the next pid is -1, and alloc_pidmap() will try to access to a nonexistent pidmap. map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; Signed-off-by:
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- 15 Aug, 2012 1 commit
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Eric W. Biederman authored
There is a least one modular user so export free_pid_ns so modules can capture and use the pid namespace on the very rare occasion when it makes sense. Acked-by:
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- 20 Jun, 2012 1 commit
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Eric W. Biederman authored
Today we have a twofold bug. Sometimes release_task on pid == 1 in a pid namespace can run before other processes in a pid namespace have had release task called. With the result that pid_ns_release_proc can be called before the last proc_flus_task() is done using upid->ns->proc_mnt, resulting in the use of a stale pointer. This same set of circumstances can lead to waitpid(...) returning for a processes started with clone(CLONE_NEWPID) before the every process in the pid namespace has actually exited. To fix this modify zap_pid_ns_processess wait until all other processes in the pid namespace have exited, even EXIT_DEAD zombies. The delay_group_leader and related tests ensure that the thread gruop leader will be the last thread of a process group to be reaped, or to become EXIT_DEAD and self reap. With the change to zap_pid_ns_processes we get the guarantee that pid == 1 in a pid namespace will be the last task that release_task is called on. With pid == 1 being the last task to pass through release_task pid_ns_release_proc can no longer be called too early nor can wait return before all of the EXIT_DEAD tasks in a pid namespace have exited. Signed-off-by:
Pavel Emelyanov <xemul@parallels.com> Tested-by:
Andrew Wagin <avagin@gmail.com> Signed-off-by:
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- 01 Jun, 2012 2 commits
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Cyrill Gorcunov authored
For those who doesn't need C/R functionality there is no need to control last pid, ie the pid for the next fork() call. Signed-off-by:
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Eric W. Biederman authored
Force SIGCHLD handling to SIG_IGN so that signals are not generated and so that the children autoreap. This increases the parallelize and in general the speed of network namespace shutdown. Note self reaping childrean can exist past zap_pid_ns_processess but they will all be reaped before we allow the pid namespace init task with pid == 1 to be reaped. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by:
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- 29 Mar, 2012 1 commit
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Daniel Lezcano authored
In the case of a child pid namespace, rebooting the system does not really makes sense. When the pid namespace is used in conjunction with the other namespaces in order to create a linux container, the reboot syscall leads to some problems. A container can reboot the host. That can be fixed by dropping the sys_reboot capability but we are unable to correctly to poweroff/ halt/reboot a container and the container stays stuck at the shutdown time with the container's init process waiting indefinitively. After several attempts, no solution from userspace was found to reliabily handle the shutdown from a container. This patch propose to make the init process of the child pid namespace to exit with a signal status set to : SIGINT if the child pid namespace called "halt/poweroff" and SIGHUP if the child pid namespace called "reboot". When the reboot syscall is called and we are not in the initial pid namespace, we kill the pid namespace for "HALT", "POWEROFF", "RESTART", and "RESTART2". Otherwise we return EINVAL. Returning EINVAL is also an easy way to check if this feature is supported by the kernel when invoking another 'reboot' option like CAD. By this way the parent process of the child pid namespace knows if it rebooted or not and can take the right decision. Test case: ========== #include <alloca.h> #include <stdio.h> #include <sched.h> #include <unistd.h> #include <signal.h> #include <sys/reboot.h> #include <sys/types.h> #include <sys/wait.h> #include <linux/reboot.h> static int do_reboot(void *arg) { int *cmd = arg; if (reboot(*cmd)) printf("failed to reboot(%d): %m\n", *cmd); } int test_reboot(int cmd, int sig) { long stack_size = 4096; void *stack = alloca(stack_size) + stack_size; int status; pid_t ret; ret = clone(do_reboot, stack, CLONE_NEWPID | SIGCHLD, &cmd); if (ret < 0) { printf("failed to clone: %m\n"); return -1; } if (wait(&status) < 0) { printf("unexpected wait error: %m\n"); return -1; } if (!WIFSIGNALED(status)) { printf("child process exited but was not signaled\n"); return -1; } if (WTERMSIG(status) != sig) { printf("signal termination is not the one expected\n"); return -1; } return 0; } int main(int argc, char *argv[]) { int status; status = test_reboot(LINUX_REBOOT_CMD_RESTART, SIGHUP); if (status < 0) return 1; printf("reboot(LINUX_REBOOT_CMD_RESTART) succeed\n"); status = test_reboot(LINUX_REBOOT_CMD_RESTART2, SIGHUP); if (status < 0) return 1; printf("reboot(LINUX_REBOOT_CMD_RESTART2) succeed\n"); status = test_reboot(LINUX_REBOOT_CMD_HALT, SIGINT); if (status < 0) return 1; printf("reboot(LINUX_REBOOT_CMD_HALT) succeed\n"); status = test_reboot(LINUX_REBOOT_CMD_POWER_OFF, SIGINT); if (status < 0) return 1; printf("reboot(LINUX_REBOOT_CMD_POWERR_OFF) succeed\n"); status = test_reboot(LINUX_REBOOT_CMD_CAD_ON, -1); if (status >= 0) { printf("reboot(LINUX_REBOOT_CMD_CAD_ON) should have failed\n"); return 1; } printf("reboot(LINUX_REBOOT_CMD_CAD_ON) has failed as expected\n"); return 0; } [akpm@linux-foundation.org: tweak and add comments] [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by:Daniel Lezcano <daniel.lezcano@free.fr> Acked-by:
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- 23 Mar, 2012 1 commit
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Oleg Nesterov authored
Change zap_pid_ns_processes() to use SEND_SIG_FORCED, it looks more clear compared to SEND_SIG_NOINFO which relies on from_ancestor_ns logic send_signal(). It is also more efficient if we need to kill a lot of tasks because it doesn't alloc sigqueue. While at it, add the __fatal_signal_pending(task) check as a minor optimization. Signed-off-by:
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- 13 Jan, 2012 1 commit
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Pavel Emelyanov authored
The sysctl works on the current task's pid namespace, getting and setting its last_pid field. Writing is allowed for CAP_SYS_ADMIN-capable tasks thus making it possible to create a task with desired pid value. This ability is required badly for the checkpoint/restore in userspace. This approach suits all the parties for now. Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Serge Hallyn <serue@us.ibm.com> Signed-off-by:
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- 24 Mar, 2011 1 commit
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Eric W. Biederman authored
Reorganize proc_get_sb() so it can be called before the struct pid of the first process is allocated. Signed-off-by:
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- 30 Mar, 2010 1 commit
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Tejun Heo authored
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include bloc...
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- 12 Mar, 2010 1 commit
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Oleg Nesterov authored
zap_pid_ns_processes() uses force_sig(SIGKILL) to ensure SIGKILL will be delivered to sub-namespace inits as well. This is correct, but we are going to change force_sig_info() semantics. See http://bugzilla.kernel.org/show_bug.cgi?id=15395#c31 We can use send_sig_info(SEND_SIG_NOINFO) instead, since 614c517d ("signals: SEND_SIG_NOINFO should be considered as SI_FROMUSER()") SEND_SIG_NOINFO means "from user" and therefore send_signal() will get the correct from_ancestor_ns = T flag. Signed-off-by:
Serge Hallyn <serue@us.ibm.com> Acked-by:
Roland McGrath <roland@redhat.com> Signed-off-by:
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- 24 Sep, 2009 1 commit
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Sukadev Bhattiprolu authored
CLONE_PARENT was used to implement an older threading model. For consistency with the CLONE_THREAD check in copy_pid_ns(), disable CLONE_PARENT with CLONE_NEWPID, at least until the required semantics of pid namespaces are clear. Signed-off-by:
Sukadev Bhattiprolu <sukadev@us.ibm.com> Acked-by:
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- 18 Jun, 2009 2 commits
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Alexey Dobriyan authored
copy_pid_ns() is a perfect example of a case where unwinding leads to more code and makes it less clear. Watch the diffstat. Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Reviewed-by:
Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Reviewed-by:
WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by:
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Alexey Dobriyan authored
create_pid_namespace() creates everything, but caller has to assign parent pidns by hand, which is unnatural. At the moment of call new ->level has to be taken from somewhere and parent pidns is already available. Signed-off-by:
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- 03 Apr, 2009 1 commit
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Sukadev Bhattiprolu authored
send_signal() assumes that signals with SEND_SIG_PRIV are generated from within the same namespace. So any nested container-init processes become immune to the SIGKILL generated by kill_proc_info() in zap_pid_ns_processes(). Use force_sig() in zap_pid_ns_processes() instead - force_sig() clears the SIGNAL_UNKILLABLE flag ensuring the signal is processed by container-inits. Signed-off-by:
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- 03 Sep, 2008 1 commit
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Oleg Nesterov authored
We don't change pid_ns->child_reaper when the main thread of the subnamespace init exits. As Robert Rex <robert.rex@exasol.com> pointed out this is wrong. Yes, the re-parenting itself works correctly, but if the reparented task exits it needs ->parent->nsproxy->pid_ns in do_notify_parent(), and if the main thread is zombie its ->nsproxy was already cleared by exit_task_namespaces(). Introduce the new function, find_new_reaper(), which finds the new ->parent for the re-parenting and changes ->child_reaper if needed. Kill the now unneeded exit_child_reaper(). Also move the changing of ->child_reaper from zap_pid_ns_processes() to find_new_reaper(), this consolidates the games with ->child_reaper and makes it stable under tasklist_lock. Addresses http://bugzilla.kernel.org/show_bug.cgi?id=11391 Reported-by:
Robert Rex <robert.rex@exasol.com> Signed-off-by:
Oleg Nesterov <oleg@tv-sign.ru> Acked-by:
Pavel Emelyanov <xemul@openvz.org> Acked-by:
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