user/sven/linux.git/kernel/pid_namespace.c, branch v3.4.58

pidns: add reboot_pid_ns() to handle the reboot syscall

2012-03-29T00:14:36Z

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 #include #include #include #include #include #include #include #include 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 Acked-by: Serge Hallyn Tested-by: Serge Hallyn Reviewed-by: Oleg Nesterov Cc: Michael Kerrisk Cc: "Eric W. Biederman" Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

signal: zap_pid_ns_processes: s/SEND_SIG_NOINFO/SEND_SIG_FORCED/

2012-03-23T23:58:41Z

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: Oleg Nesterov Cc: Tejun Heo Cc: Anton Vorontsov Cc: "Eric W. Biederman" Cc: KOSAKI Motohiro Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sysctl: add the kernel.ns_last_pid control

2012-01-13T04:13:11Z

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: Pavel Emelyanov Acked-by: Tejun Heo Cc: Oleg Nesterov Cc: Cyrill Gorcunov Cc: "Eric W. Biederman" Cc: Serge Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pidns: call pid_ns_prepare_proc() from create_pid_namespace()

2011-03-24T02:46:58Z

Reorganize proc_get_sb() so it can be called before the struct pid of the first process is allocated. Signed-off-by: Eric W. Biederman Signed-off-by: Daniel Lezcano Cc: Oleg Nesterov Cc: Alexey Dobriyan Acked-by: Serge E. Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32Z

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 blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo Guess-its-ok-by: Christoph Lameter Cc: Ingo Molnar Cc: Lee Schermerhorn

pid_ns: zap_pid_ns_processes: use SEND_SIG_NOINFO instead of force_sig()

2010-03-12T23:52:40Z

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 614c517d7c00af1b26ded20646b329397d6f51a1 ("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: Oleg Nesterov Acked-by: Serge Hallyn Acked-by: Linus Torvalds Acked-by: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pidns: deny CLONE_PARENT|CLONE_NEWPID combination

2009-09-24T14:21:04Z

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 Acked-by: Roland McGrath Acked-by: Serge Hallyn Cc: Oren Laadan Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pidns: rewrite copy_pid_ns()

2009-06-18T20:03:55Z

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 Cc: Pavel Emelyanov Cc: "Eric W. Biederman" Reviewed-by: Serge Hallyn Acked-by: Sukadev Bhattiprolu Reviewed-by: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pidns: make create_pid_namespace() accept parent pidns

2009-06-18T20:03:55Z

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: Alexey Dobriyan Cc: Pavel Emelyanov Cc: "Eric W. Biederman" Acked-by: Serge Hallyn Acked-by: Sukadev Bhattiprolu Reviewed-by: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

signals: zap_pid_ns_process() should use force_sig()

2009-04-03T02:04:58Z

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: Sukadev Bhattiprolu Cc: Oleg Nesterov Cc: Roland McGrath Cc: "Eric W. Biederman" Cc: Daniel Lezcano Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds