- 27 May, 2010 40 commits
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Akinobu Mita authored
By the previous modification, the cpu notifier can return encapsulate errno value. This converts the cpu notifiers for topology. Signed-off-by:
Akinobu Mita <akinobu.mita@gmail.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Akinobu Mita authored
By the previous modification, the cpu notifier can return encapsulate errno value. This converts the cpu notifiers for msr, cpuid, and therm_throt. Signed-off-by:
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Akinobu Mita authored
This changes notifier_from_errno(0) to be NOTIFY_OK instead of NOTIFY_STOP_MASK | NOTIFY_OK. Currently, the notifiers which return encapsulated errno value have to do something like this: err = do_something(); // returns -errno if (err) return notifier_from_errno(err); else return NOTIFY_OK; This change makes the above code simple: err = do_something(); // returns -errno return return notifier_from_errno(err); Signed-off-by:
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Akinobu Mita authored
Currently, onlining or offlining a CPU failure by one of the cpu notifiers error always cause -EINVAL error. (i.e. writing 0 or 1 to /sys/devices/system/cpu/cpuX/online gets EINVAL) To get better error reporting rather than always getting -EINVAL, This changes cpu_notify() to return -errno value with notifier_to_errno() and fix the callers. Now that cpu notifiers can return encapsulate errno value. Currently, all cpu hotplug notifiers return NOTIFY_OK, NOTIFY_BAD, or NOTIFY_DONE. So cpu_notify() can returns 0 or -EPERM with this change for now. (notifier_to_errno(NOTIFY_OK) == 0, notifier_to_errno(NOTIFY_DONE) == 0, notifier_to_errno(NOTIFY_BAD) == -EPERM) Forthcoming patches convert several cpu notifiers to return encapsulate errno value with notifier_from_errno(). Signed-off-by:
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Akinobu Mita authored
No functional change. These are just wrappers of raw_cpu_notifier_call_chain. Signed-off-by:
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Wu Fengguang authored
Extend KCORE_TEXT to cover the pages between _text and _stext, to allow examining some important page table pages. `readelf -a` output on x86_64 before and after patch: Type Offset VirtAddr PhysAddr before LOAD 0x00007fff8100c000 0xffffffff81009000 0x0000000000000000 after LOAD 0x00007fff81003000 0xffffffff81000000 0x0000000000000000 The newly covered pages are: 0xffffffff81000000 <startup_64> etc. 0xffffffff81001000 <init_level4_pgt> 0xffffffff81002000 <level3_ident_pgt> 0xffffffff81003000 <level3_kernel_pgt> 0xffffffff81004000 <level2_fixmap_pgt> 0xffffffff81005000 <level1_fixmap_pgt> 0xffffffff81006000 <level2_ident_pgt> 0xffffffff81007000 <level2_kernel_pgt> 0xffffffff81008000 <level2_spare_pgt> Before patch, /proc/kcore shows outdated contents for the above page table pages, for example: (gdb) p level3_ident_pgt $1 = {<text variable, no debug info>} 0xffffffff81002000 <level3_ident_pgt> (gdb) p/x *((pud_t *)&level3_ident_pgt)@512 $2 = {{pud = 0x1006063}, {pud = 0x0} <repeats 511 times>} while the real content is: root@hp /home/wfg# hexdump -s 0x1002000 -n 4096 /dev/mem 1002000 6063 0100 0000 0000 8067 0000 0000 0000 1002010 0000 0000 0000 0000 0000 0000 0000 0000 * 1003000 That is, on a x86_64 box with 2GB memory, we can see first-1GB / full-2GB identity mapping before/after patch: (gdb) p/x *((pud_t *)&level3_ident_pgt)@512 before $1 = {{pud = 0x1006063}, {pud = 0x0} <repeats 511 times>} after $1 = {{pud = 0x1006063}, {pud = 0x8067}, {pud = 0x0} <repeats 510 times>} Obviously the content before patch is wrong. Signed-off-by:Wu Fengguang <fengguang.wu@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
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Amerigo Wang authored
A quick test shows these comments are obsolete, so just remove them. Signed-off-by:
WANG Cong <amwang@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
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Dan Carpenter authored
I removed 3 unused assignments. The first two get reset on the first statement of their functions. For "err" in root.c we don't return an error and we don't use the variable again. Signed-off-by:
Dan Carpenter <error27@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by:
Serge Hallyn <serue@us.ibm.com> Reviewed-by:
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by:
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Oleg Nesterov authored
No functional changes, just s/atomic_t count/int nr_threads/. With the recent changes this counter has a single user, get_nr_threads() And, none of its callers need the really accurate number of threads, not to mention each caller obviously races with fork/exit. It is only used to report this value to the user-space, except first_tid() uses it to avoid the unnecessary while_each_thread() loop in the unlikely case. It is a bit sad we need a word in struct signal_struct for this, perhaps we can change get_nr_threads() to approximate the number of threads using signal->live and kill ->nr_threads later. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by:
Roland McGrath <roland@redhat.com> Signed-off-by:
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Oleg Nesterov authored
No functional changes. keyctl_session_to_parent() is the only user of signal->count which needs the correct value. Change it to use thread_group_empty() instead, this must be strictly equivalent under tasklist, and imho looks better. Signed-off-by:
David Howells <dhowells@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Acked-by:
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Oleg Nesterov authored
Trivial, use get_nr_threads() helper to read signal->count which we are going to change. Like other callers, proc_sched_show_task() doesn't need the exactly precise nr_threads. David said: : Note that get_nr_threads() isn't completely equivalent (it can return 0 : where proc_sched_show_task() will display a 1). But I don't think this : should be a problem. Signed-off-by:
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Oleg Nesterov authored
Now that task->signal can't go away get_nr_threads() doesn't need ->siglock to read signal->count. Also, make it inline, move into sched.h, and convert 2 other proc users of signal->count to use this (now trivial) helper. Henceforth get_nr_threads() is the only valid user of signal->count, we are ready to turn it into "int nr_threads" or, perhaps, kill it. Signed-off-by:
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Oleg Nesterov authored
check_unshare_flags(CLONE_SIGHAND) adds CLONE_THREAD to *flags_ptr if the task is multithreaded to ensure unshare_thread() will fail. Not only this is a bit strange way to return the error, this is absolutely meaningless. If signal->count > 1 then sighand->count must be also > 1, and unshare_sighand() will fail anyway. In fact, all CLONE_THREAD/SIGHAND/VM checks inside sys_unshare() do not look right. Fortunately this code doesn't really work anyway. Signed-off-by:
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Oleg Nesterov authored
Move taskstats_tgid_free() from __exit_signal() to free_signal_struct(). This way signal->stats never points to nowhere and we can read ->stats lockless. Signed-off-by:
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Oleg Nesterov authored
Kill the empty thread_group_cputime_free() helper. It was needed to free the per-cpu data which we no longer have. Signed-off-by:
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Oleg Nesterov authored
Cleanup: - Add the boolean, group_dead = thread_group_leader(), for clarity. - Do not test/set sig == NULL to detect the all-dead case, use this boolean. - Pass this boolen to __unhash_process() and use it instead of another thread_group_leader() call which needs ->group_leader. This can be considered as microoptimization, but hopefully this also allows us do do other cleanups later. Signed-off-by:
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Oleg Nesterov authored
Now that task->signal can't go away we can revert the horrible hack added by ad474cac ("fix for account_group_exec_runtime(), make sure ->signal can't be freed under rq->lock"). And we can do more cleanups sched_stats.h/posix-cpu-timers.c later. Signed-off-by:
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Oleg Nesterov authored
When the last thread exits signal->tty is freed, but the pointer is not cleared and points to nowhere. This is OK. Nobody should use signal->tty lockless, and it is no longer possible to take ->siglock. However this looks wrong even if correct, and the nice OOPS is better than subtle and hard to find bugs. Change __exit_signal() to clear signal->tty under ->siglock. Note: __exit_signal() needs more cleanups. It should not check "sig != NULL" to detect the all-dead case and we have the same issues with signal->stats. Signed-off-by:
Peter Zijlstra <peterz@infradead.org> Acked-by:
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Oleg Nesterov authored
We have a lot of problems with accessing task_struct->signal, it can "disappear" at any moment. Even current can't use its ->signal safely after exit_notify(). ->siglock helps, but it is not convenient, not always possible, and sometimes it makes sense to use task->signal even after this task has already dead. This patch adds the reference counter, sigcnt, into signal_struct. This reference is owned by task_struct and it is dropped in __put_task_struct(). Perhaps it makes sense to export get/put_signal_struct() later, but currently I don't see the immediate reason. Rename __cleanup_signal() to free_signal_struct() and unexport it. With the previous changes it does nothing except kmem_cache_free(). Change __exit_signal() to not clear/free ->signal, it will be freed when the last reference to any thread in the thread group goes away. Note: - when the last thead exits signal->tty can point to nowhere, see the next patch. - with or without this patch signal_struct->count should go away, or at least it should be "int nr_threads" for fs/proc. This will be addressed later. Signed-off-by:
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Oleg Nesterov authored
tty_kref_put() has two callsites in copy_process() paths, 1. if copy_process() suceeds it is called before we copy signal->tty from parent 2. otherwise it is called from __cleanup_signal() under bad_fork_cleanup_signal: label In both cases tty_kref_put() is not right and unneeded because we don't have the balancing tty_kref_get(). Fortunately, this is harmless because this can only happen without CLONE_THREAD, and in this case signal->tty must be NULL. Remove tty_kref_put() from copy_process() and __cleanup_signal(), and change another caller of __cleanup_signal(), __exit_signal(), to call tty_kref_put() by hand. I hope this change makes sense by itself, but it is also needed to make ->signal refcountable. Signed-off-by:
Alan Cox <alan@linux.intel.com> Acked-by:
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Oleg Nesterov authored
Preparation to make task->signal immutable, no functional changes. It doesn't matter which pointer we check under tasklist to ensure the task was not released, ->signal or ->sighand. But we are going to make ->signal refcountable, change the code to use ->sighand. Note: this code doesn't need this check and tasklist_lock at all, it should be converted to use lock_task_sighand(). And, the code under SIGNAL_STOP_STOPPED check looks wrong. Signed-off-by:
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Oleg Nesterov authored
Preparation to make task->signal immutable, no functional changes. posix-cpu-timers.c checks task->signal != NULL to ensure this task is alive and didn't pass __exit_signal(). This is correct but we are going to change the lifetime rules for ->signal and never reset this pointer. Change the code to check ->sighand instead, it doesn't matter which pointer we check under tasklist, they both are cleared simultaneously. As Roland pointed out, some of these changes are not strictly needed and probably it makes sense to revert them later, when ->signal will be pinned to task_struct. But this patch tries to ensure the subsequent changes in fork/exit can't make any visible impact on posix cpu timers. Signed-off-by:
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Oleg Nesterov authored
Change __exit_signal() to check thread_group_leader() instead of atomic_dec_and_test(&sig->count). This must be equivalent, the group leader must be released only after all other threads have exited and passed __exit_signal(). Henceforth sig->count is not actually used, except in fs/proc for get_nr_threads/etc. Signed-off-by:
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Oleg Nesterov authored
de_thread() and __exit_signal() use signal_struct->count/notify_count for synchronization. We can simplify the code and use ->notify_count only. Instead of comparing these two counters, we can change de_thread() to set ->notify_count = nr_of_sub_threads, then change __exit_signal() to dec-and-test this counter and notify group_exit_task. Note that __exit_signal() checks "notify_count > 0" just for symmetry with exit_notify(), we could just check it is != 0. Signed-off-by:
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Oleg Nesterov authored
Change zap_other_threads() to return the number of other sub-threads found on ->thread_group list. Other changes are cosmetic: - change the code to use while_each_thread() helper - remove the obsolete comment about SIGKILL/SIGSTOP Signed-off-by:
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Oleg Nesterov authored
signal_struct->count in its current form must die. - it has no reasons to be atomic_t - it looks like a reference counter, but it is not - otoh, we really need to make task->signal refcountable, just look at the extremely ugly task_rq_unlock_wait() called from __exit_signals(). - we should change the lifetime rules for task->signal, it should be pinned to task_struct. We have a lot of code which can be simplified after that. - it is not needed! while the code is correct, any usage of this counter is artificial, except fs/proc uses it correctly to show the number of threads. This series removes the usage of sig->count from exit pathes. This patch: Now that Veaceslav changed copy_signal() to use zalloc(), exit_notify() can just check notify_count < 0 to ensure the execing sub-threads needs the notification from us. No need to do other checks, notify_count != 0 must always mean ->group_exit_task != NULL is waiting for us. Signed-off-by:
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Oleg Nesterov authored
- move the cprm.mm_flags checks up, before we take mmap_sem - move down_write(mmap_sem) and ->core_state check from do_coredump() to coredump_wait() This simplifies the code and makes the locking symmetrical. Signed-off-by:
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Oleg Nesterov authored
Given that do_coredump() calls put_cred() on exit path, it is a bit ugly to do put_cred() + "goto fail" twice, just add the new "fail_creds" label. Signed-off-by:
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Oleg Nesterov authored
- kill "int dump_count", argv_split(argcp) accepts argcp == NULL. - move "int dump_count" under " if (ispipe)" branch, fail_dropcount can check ispipe. - move "char **helper_argv" as well, change the code to do argv_free() right after call_usermodehelper_fns(). - If call_usermodehelper_fns() fails goto close_fail label instead of closing the file by hand. Signed-off-by:
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Oleg Nesterov authored
do_coredump() does a lot of file checks after it opens the file or calls usermode helper. But all of these checks are only needed in !ispipe case. Move this code into the "else" branch and kill the ugly repetitive ispipe checks. Signed-off-by:
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Oleg Nesterov authored
UMH_WAIT_EXEC should report the error if kernel_thread() fails, like UMH_WAIT_PROC does. Signed-off-by:
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Oleg Nesterov authored
__call_usermodehelper(UMH_NO_WAIT) has 2 problems: - if kernel_thread() fails, call_usermodehelper_freeinfo() is not called. - for unknown reason UMH_NO_WAIT has UMH_WAIT_PROC logic, we spawn yet another thread which waits until the user mode application exits. Change the UMH_NO_WAIT code to use ____call_usermodehelper() instead of wait_for_helper(), and do call_usermodehelper_freeinfo() unconditionally. We can rely on CLONE_VFORK, do_fork(CLONE_VFORK) until the child exits or execs. With or without this patch UMH_NO_WAIT does not report the error if kernel_thread() fails, this is correct since the caller doesn't wait for result. Signed-off-by:
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Oleg Nesterov authored
1. wait_for_helper() calls allow_signal(SIGCHLD) to ensure the child can't autoreap itself. However, this means that a spurious SIGCHILD from user-space can set TIF_SIGPENDING and: - kernel_thread() or sys_wait4() can fail due to signal_pending() - worse, wait4() can fail before ____call_usermodehelper() execs or exits. In this case the caller may kfree(subprocess_info) while the child still uses this memory. Change the code to use SIG_DFL instead of magic "(void __user *)2" set by allow_signal(). This means that SIGCHLD won't be delivered, yet the child won't autoreap itsefl. The problem is minor, only root can send a signal to this kthread. 2. If sys_wait4(&ret) fails it doesn't populate "ret", in this case wait_for_helper() reports a random value from uninitialized var. With this patch sys_wait4() should never fail, but still it makes sense to initialize ret = -ECHILD so that the caller can notice the problem. Signed-off-by:
Neil Horman <nhorman@tuxdriver.com> Signed-off-by:
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Oleg Nesterov authored
____call_usermodehelper() correctly calls flush_signal_handlers() to set SIG_DFL, but sigemptyset(->blocked) and recalc_sigpending() are not needed. This kthread was forked by workqueue thread, all signals must be unblocked and ignored, no pending signal is possible. Signed-off-by:
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Oleg Nesterov authored
Now that nobody ever changes subprocess_info->cred we can kill this member and related code. ____call_usermodehelper() always runs in the context of freshly forked kernel thread, it has the proper ->cred copied from its parent kthread, keventd. Signed-off-by:
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Oleg Nesterov authored
call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change subprocess_info->cred in advance. Now that we have info->init() we can change this code to set tgcred->session_keyring in context of execing kernel thread. Note: since currently call_usermodehelper_keys() is never called with UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup() are not really needed, we could rely on install_session_keyring_to_cred() which does key_get() on success. Signed-off-by:
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Neil Horman authored
The first patch in this series introduced an init function to the call_usermodehelper api so that processes could be customized by caller. This patch takes advantage of that fact, by customizing the helper in do_coredump to create the pipe and set its core limit to one (for our recusrsion check). This lets us clean up the previous uglyness in the usermodehelper internals and factor call_usermodehelper out entirely. While I'm at it, we can also modify the helper setup to look for a core limit value of 1 rather than zero for our recursion check Signed-off-by:
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Neil Horman authored
About 6 months ago, I made a set of changes to how the core-dump-to-a-pipe feature in the kernel works. We had reports of several races, including some reports of apps bypassing our recursion check so that a process that was forked as part of a core_pattern setup could infinitely crash and refork until the system crashed. We fixed those by improving our recursion checks. The new check basically refuses to fork a process if its core limit is zero, which works well. Unfortunately, I've been getting grief from maintainer of user space programs that are inserted as the forked process of core_pattern. They contend that in order for their programs (such as abrt and apport) to work, all the running processes in a system must have their core limits set to a non-zero value, to which I say 'yes'. I did this by design, and think thats the right way to do things. But I've been asked to ease this burden on user space enough times that I thought I would take a look at it. The first suggestion was to make the recursion check fail on a non-zero 'special' number, like one. That way the core collector process could set its core size ulimit to 1, and enable the kernel's recursion detection. This isn't a bad idea on the surface, but I don't like it since its opt-in, in that if a program like abrt or apport has a bug and fails to set such a core limit, we're left with a recursively crashing system again. So I've come up with this. What I've done is modify the call_usermodehelper api such that an extra parameter is added, a function pointer which will be called by the user helper task, after it forks, but before it exec's the required process. This will give the caller the opportunity to get a call back in the processes context, allowing it to do whatever it needs to to the process in the kernel prior to exec-ing the user space code. In the case of do_coredump, this callback is ues to set the core ulimit of the helper process to 1. This elimnates the opt-in problem that I had above, as it allows the ulimit for core sizes to be set to the value of 1, which is what the recursion check looks for in do_coredump. This patch: Create new function call_usermodehelper_fns() and allow it to assign both an init and cleanup function, as we'll as arbitrary data. The init function is called from the context of the forked process and allows for customization of the helper process prior to calling exec. Its return code gates the continuation of the process, or causes its exit. Also add an arbitrary data pointer to the subprocess_info struct allowing for data to be passed from the caller to the new process, and the subsequent cleanup process Also, use this patch to cleanup the cleanup function. It currently takes an argp and envp pointer for freeing, which is ugly. Lets instead just make the subprocess_info structure public, and pass that to the cleanup and init routines Signed-off-by:
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Oleg Nesterov authored
Andrew Tridgell reports that aio_read(SIGEV_SIGNAL) can fail if the notification from the helper thread races with setresuid(), see http://samba.org/~tridge/junkcode/aio_uid.c This happens because check_kill_permission() doesn't permit sending a signal to the task with the different cred->xids. But there is not any security reason to check ->cred's when the task sends a signal (private or group-wide) to its sub-thread. Whatever we do, any thread can bypass all security checks and send SIGKILL to all threads, or it can block a signal SIG and do kill(gettid(), SIG) to deliver this signal to another sub-thread. Not to mention that CLONE_THREAD implies CLONE_VM. Change check_kill_permission() to avoid the credentials check when the sender and the target are from the same thread group. Also, move "cred = current_cred()" down to avoid calling get_current() twice. Note: David Howells pointed out we could relax this even more, the CLONE_SIGHAND (without CLONE_THREAD) case probably does not need these checks too. Roland said: : The glibc (libpthread) that does set*id across threads has : been in use for a while (2.3.4?), probably in distro's using kernels as old : or older than any active -stable streams. In the race in question, this : kernel bug is breaking valid POSIX application expectations. Reported-by:
Andrew Tridgell <tridge@samba.org> Signed-off-by:
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Oleg Nesterov authored
Now that Mike Frysinger unified the FDPIC ptrace code, we can fix the unsafe usage of child->mm in ptrace_request(PTRACE_GETFDPIC). We have the reference to task_struct, and ptrace_check_attach() verified the tracee is stopped. But nothing can protect from SIGKILL after that, we must not assume child->mm != NULL. Signed-off-by:
Mike Frysinger <vapier.adi@gmail.com> Acked-by:
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