From 7f192e3cd316ba58c88dfa26796cf77789dd9872 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Sat, 25 May 2019 11:36:41 +0200 Subject: [PATCH 1/3] fork: add clone3 This adds the clone3 system call. As mentioned several times already (cf. [7], [8]) here's the promised patchset for clone3(). We recently merged the CLONE_PIDFD patchset (cf. [1]). It took the last free flag from clone(). Independent of the CLONE_PIDFD patchset a time namespace has been discussed at Linux Plumber Conference last year and has been sent out and reviewed (cf. [5]). It is expected that it will go upstream in the not too distant future. However, it relies on the addition of the CLONE_NEWTIME flag to clone(). The only other good candidate - CLONE_DETACHED - is currently not recyclable as we have identified at least two large or widely used codebases that currently pass this flag (cf. [2], [3], and [4]). Given that CLONE_PIDFD grabbed the last clone() flag the time namespace is effectively blocked. clone3() has the advantage that it will unblock this patchset again. In general, clone3() is extensible and allows for the implementation of new features. The idea is to keep clone3() very simple and close to the original clone(), specifically, to keep on supporting old clone()-based workloads. We know there have been various creative proposals how a new process creation syscall or even api is supposed to look like. Some people even going so far as to argue that the traditional fork()+exec() split should be abandoned in favor of an in-kernel version of spawn(). Independent of whether or not we personally think spawn() is a good idea this patchset has and does not want to have anything to do with this. One stance we take is that there's no real good alternative to clone()+exec() and we need and want to support this model going forward; independent of spawn(). The following requirements guided clone3(): - bump the number of available flags - move arguments that are currently passed as separate arguments in clone() into a dedicated struct clone_args - choose a struct layout that is easy to handle on 32 and on 64 bit - choose a struct layout that is extensible - give new flags that currently need to abuse another flag's dedicated return argument in clone() their own dedicated return argument (e.g. CLONE_PIDFD) - use a separate kernel internal struct kernel_clone_args that is properly typed according to current kernel conventions in fork.c and is different from the uapi struct clone_args - port _do_fork() to use kernel_clone_args so that all process creation syscalls such as fork(), vfork(), clone(), and clone3() behave identical (Arnd suggested, that we can probably also port do_fork() itself in a separate patchset.) - ease of transition for userspace from clone() to clone3() This very much means that we do *not* remove functionality that userspace currently relies on as the latter is a good way of creating a syscall that won't be adopted. - do not try to be clever or complex: keep clone3() as dumb as possible In accordance with Linus suggestions (cf. [11]), clone3() has the following signature: /* uapi */ struct clone_args { __aligned_u64 flags; __aligned_u64 pidfd; __aligned_u64 child_tid; __aligned_u64 parent_tid; __aligned_u64 exit_signal; __aligned_u64 stack; __aligned_u64 stack_size; __aligned_u64 tls; }; /* kernel internal */ struct kernel_clone_args { u64 flags; int __user *pidfd; int __user *child_tid; int __user *parent_tid; int exit_signal; unsigned long stack; unsigned long stack_size; unsigned long tls; }; long sys_clone3(struct clone_args __user *uargs, size_t size) clone3() cleanly supports all of the supported flags from clone() and thus all legacy workloads. The advantage of sticking close to the old clone() is the low cost for userspace to switch to this new api. Quite a lot of userspace apis (e.g. pthreads) are based on the clone() syscall. With the new clone3() syscall supporting all of the old workloads and opening up the ability to add new features should make switching to it for userspace more appealing. In essence, glibc can just write a simple wrapper to switch from clone() to clone3(). There has been some interest in this patchset already. We have received a patch from the CRIU corner for clone3() that would set the PID/TID of a restored process without /proc/sys/kernel/ns_last_pid to eliminate a race. /* User visible differences to legacy clone() */ - CLONE_DETACHED will cause EINVAL with clone3() - CSIGNAL is deprecated It is superseeded by a dedicated "exit_signal" argument in struct clone_args freeing up space for additional flags. This is based on a suggestion from Andrei and Linus (cf. [9] and [10]) /* References */ [1]: b3e5838252665ee4cfa76b82bdf1198dca81e5be [2]: https://dxr.mozilla.org/mozilla-central/source/security/sandbox/linux/SandboxFilter.cpp#343 [3]: https://git.musl-libc.org/cgit/musl/tree/src/thread/pthread_create.c#n233 [4]: https://sources.debian.org/src/blcr/0.8.5-2.3/cr_module/cr_dump_self.c/?hl=740#L740 [5]: https://lore.kernel.org/lkml/20190425161416.26600-1-dima@arista.com/ [6]: https://lore.kernel.org/lkml/20190425161416.26600-2-dima@arista.com/ [7]: https://lore.kernel.org/lkml/CAHrFyr5HxpGXA2YrKza-oB-GGwJCqwPfyhD-Y5wbktWZdt0sGQ@mail.gmail.com/ [8]: https://lore.kernel.org/lkml/20190524102756.qjsjxukuq2f4t6bo@brauner.io/ [9]: https://lore.kernel.org/lkml/20190529222414.GA6492@gmail.com/ [10]: https://lore.kernel.org/lkml/CAHk-=whQP-Ykxi=zSYaV9iXsHsENa+2fdj-zYKwyeyed63Lsfw@mail.gmail.com/ [11]: https://lore.kernel.org/lkml/CAHk-=wieuV4hGwznPsX-8E0G2FKhx3NjZ9X3dTKh5zKd+iqOBw@mail.gmail.com/ Suggested-by: Linus Torvalds Signed-off-by: Christian Brauner Acked-by: Arnd Bergmann Acked-by: Serge Hallyn Cc: Kees Cook Cc: Pavel Emelyanov Cc: Jann Horn Cc: David Howells Cc: Andrew Morton Cc: Oleg Nesterov Cc: Adrian Reber Cc: Linus Torvalds Cc: Andrei Vagin Cc: Al Viro Cc: Florian Weimer Cc: linux-api@vger.kernel.org --- arch/x86/ia32/sys_ia32.c | 12 ++- include/linux/sched/task.h | 17 +++- include/linux/syscalls.h | 4 + include/uapi/linux/sched.h | 16 +++ kernel/fork.c | 201 ++++++++++++++++++++++++++++--------- 5 files changed, 199 insertions(+), 51 deletions(-) diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c index a43212036257..64a6c952091e 100644 --- a/arch/x86/ia32/sys_ia32.c +++ b/arch/x86/ia32/sys_ia32.c @@ -237,6 +237,14 @@ COMPAT_SYSCALL_DEFINE5(x86_clone, unsigned long, clone_flags, unsigned long, newsp, int __user *, parent_tidptr, unsigned long, tls_val, int __user *, child_tidptr) { - return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, - tls_val); + struct kernel_clone_args args = { + .flags = (clone_flags & ~CSIGNAL), + .child_tid = child_tidptr, + .parent_tid = parent_tidptr, + .exit_signal = (clone_flags & CSIGNAL), + .stack = newsp, + .tls = tls_val, + }; + + return _do_fork(&args); } diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index f1227f2c38a4..109a0df5af39 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -8,11 +8,26 @@ */ #include +#include struct task_struct; struct rusage; union thread_union; +/* All the bits taken by the old clone syscall. */ +#define CLONE_LEGACY_FLAGS 0xffffffffULL + +struct kernel_clone_args { + u64 flags; + int __user *pidfd; + int __user *child_tid; + int __user *parent_tid; + int exit_signal; + unsigned long stack; + unsigned long stack_size; + unsigned long tls; +}; + /* * This serializes "schedule()" and also protects * the run-queue from deletions/modifications (but @@ -73,7 +88,7 @@ extern void do_group_exit(int); extern void exit_files(struct task_struct *); extern void exit_itimers(struct signal_struct *); -extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long); +extern long _do_fork(struct kernel_clone_args *kargs); extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *); struct task_struct *fork_idle(int); struct mm_struct *copy_init_mm(void); diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index e2870fe1be5b..60a81f374ca3 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -70,6 +70,7 @@ struct sigaltstack; struct rseq; union bpf_attr; struct io_uring_params; +struct clone_args; #include #include @@ -852,6 +853,9 @@ asmlinkage long sys_clone(unsigned long, unsigned long, int __user *, int __user *, unsigned long); #endif #endif + +asmlinkage long sys_clone3(struct clone_args __user *uargs, size_t size); + asmlinkage long sys_execve(const char __user *filename, const char __user *const __user *argv, const char __user *const __user *envp); diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h index ed4ee170bee2..f5331dbdcaa2 100644 --- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -2,6 +2,8 @@ #ifndef _UAPI_LINUX_SCHED_H #define _UAPI_LINUX_SCHED_H +#include + /* * cloning flags: */ @@ -31,6 +33,20 @@ #define CLONE_NEWNET 0x40000000 /* New network namespace */ #define CLONE_IO 0x80000000 /* Clone io context */ +/* + * Arguments for the clone3 syscall + */ +struct clone_args { + __aligned_u64 flags; + __aligned_u64 pidfd; + __aligned_u64 child_tid; + __aligned_u64 parent_tid; + __aligned_u64 exit_signal; + __aligned_u64 stack; + __aligned_u64 stack_size; + __aligned_u64 tls; +}; + /* * Scheduling policies */ diff --git a/kernel/fork.c b/kernel/fork.c index b4cba953040a..08ff131f26b4 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1760,19 +1760,15 @@ static __always_inline void delayed_free_task(struct task_struct *tsk) * flags). The actual kick-off is left to the caller. */ static __latent_entropy struct task_struct *copy_process( - unsigned long clone_flags, - unsigned long stack_start, - unsigned long stack_size, - int __user *parent_tidptr, - int __user *child_tidptr, struct pid *pid, int trace, - unsigned long tls, - int node) + int node, + struct kernel_clone_args *args) { int pidfd = -1, retval; struct task_struct *p; struct multiprocess_signals delayed; + u64 clone_flags = args->flags; /* * Don't allow sharing the root directory with processes in a different @@ -1821,27 +1817,12 @@ static __latent_entropy struct task_struct *copy_process( } if (clone_flags & CLONE_PIDFD) { - int reserved; - /* - * - CLONE_PARENT_SETTID is useless for pidfds and also - * parent_tidptr is used to return pidfds. * - CLONE_DETACHED is blocked so that we can potentially * reuse it later for CLONE_PIDFD. * - CLONE_THREAD is blocked until someone really needs it. */ - if (clone_flags & - (CLONE_DETACHED | CLONE_PARENT_SETTID | CLONE_THREAD)) - return ERR_PTR(-EINVAL); - - /* - * Verify that parent_tidptr is sane so we can potentially - * reuse it later. - */ - if (get_user(reserved, parent_tidptr)) - return ERR_PTR(-EFAULT); - - if (reserved != 0) + if (clone_flags & (CLONE_DETACHED | CLONE_THREAD)) return ERR_PTR(-EINVAL); } @@ -1874,11 +1855,11 @@ static __latent_entropy struct task_struct *copy_process( * p->set_child_tid which is (ab)used as a kthread's data pointer for * kernel threads (PF_KTHREAD). */ - p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; + p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL; /* * Clear TID on mm_release()? */ - p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; + p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL; ftrace_graph_init_task(p); @@ -2037,7 +2018,8 @@ static __latent_entropy struct task_struct *copy_process( retval = copy_io(clone_flags, p); if (retval) goto bad_fork_cleanup_namespaces; - retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls); + retval = copy_thread_tls(clone_flags, args->stack, args->stack_size, p, + args->tls); if (retval) goto bad_fork_cleanup_io; @@ -2062,7 +2044,7 @@ static __latent_entropy struct task_struct *copy_process( goto bad_fork_free_pid; pidfd = retval; - retval = put_user(pidfd, parent_tidptr); + retval = put_user(pidfd, args->pidfd); if (retval) goto bad_fork_put_pidfd; } @@ -2105,7 +2087,7 @@ static __latent_entropy struct task_struct *copy_process( if (clone_flags & CLONE_PARENT) p->exit_signal = current->group_leader->exit_signal; else - p->exit_signal = (clone_flags & CSIGNAL); + p->exit_signal = args->exit_signal; p->group_leader = p; p->tgid = p->pid; } @@ -2313,8 +2295,11 @@ static inline void init_idle_pids(struct task_struct *idle) struct task_struct *fork_idle(int cpu) { struct task_struct *task; - task = copy_process(CLONE_VM, 0, 0, NULL, NULL, &init_struct_pid, 0, 0, - cpu_to_node(cpu)); + struct kernel_clone_args args = { + .flags = CLONE_VM, + }; + + task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args); if (!IS_ERR(task)) { init_idle_pids(task); init_idle(task, cpu); @@ -2334,13 +2319,9 @@ struct mm_struct *copy_init_mm(void) * It copies the process, and if successful kick-starts * it and waits for it to finish using the VM if required. */ -long _do_fork(unsigned long clone_flags, - unsigned long stack_start, - unsigned long stack_size, - int __user *parent_tidptr, - int __user *child_tidptr, - unsigned long tls) +long _do_fork(struct kernel_clone_args *args) { + u64 clone_flags = args->flags; struct completion vfork; struct pid *pid; struct task_struct *p; @@ -2356,7 +2337,7 @@ long _do_fork(unsigned long clone_flags, if (!(clone_flags & CLONE_UNTRACED)) { if (clone_flags & CLONE_VFORK) trace = PTRACE_EVENT_VFORK; - else if ((clone_flags & CSIGNAL) != SIGCHLD) + else if (args->exit_signal != SIGCHLD) trace = PTRACE_EVENT_CLONE; else trace = PTRACE_EVENT_FORK; @@ -2365,8 +2346,7 @@ long _do_fork(unsigned long clone_flags, trace = 0; } - p = copy_process(clone_flags, stack_start, stack_size, parent_tidptr, - child_tidptr, NULL, trace, tls, NUMA_NO_NODE); + p = copy_process(NULL, trace, NUMA_NO_NODE, args); add_latent_entropy(); if (IS_ERR(p)) @@ -2382,7 +2362,7 @@ long _do_fork(unsigned long clone_flags, nr = pid_vnr(pid); if (clone_flags & CLONE_PARENT_SETTID) - put_user(nr, parent_tidptr); + put_user(nr, args->parent_tid); if (clone_flags & CLONE_VFORK) { p->vfork_done = &vfork; @@ -2414,8 +2394,16 @@ long do_fork(unsigned long clone_flags, int __user *parent_tidptr, int __user *child_tidptr) { - return _do_fork(clone_flags, stack_start, stack_size, - parent_tidptr, child_tidptr, 0); + struct kernel_clone_args args = { + .flags = (clone_flags & ~CSIGNAL), + .child_tid = child_tidptr, + .parent_tid = parent_tidptr, + .exit_signal = (clone_flags & CSIGNAL), + .stack = stack_start, + .stack_size = stack_size, + }; + + return _do_fork(&args); } #endif @@ -2424,15 +2412,25 @@ long do_fork(unsigned long clone_flags, */ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) { - return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, - (unsigned long)arg, NULL, NULL, 0); + struct kernel_clone_args args = { + .flags = ((flags | CLONE_VM | CLONE_UNTRACED) & ~CSIGNAL), + .exit_signal = (flags & CSIGNAL), + .stack = (unsigned long)fn, + .stack_size = (unsigned long)arg, + }; + + return _do_fork(&args); } #ifdef __ARCH_WANT_SYS_FORK SYSCALL_DEFINE0(fork) { #ifdef CONFIG_MMU - return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0); + struct kernel_clone_args args = { + .exit_signal = SIGCHLD, + }; + + return _do_fork(&args); #else /* can not support in nommu mode */ return -EINVAL; @@ -2443,8 +2441,12 @@ SYSCALL_DEFINE0(fork) #ifdef __ARCH_WANT_SYS_VFORK SYSCALL_DEFINE0(vfork) { - return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, - 0, NULL, NULL, 0); + struct kernel_clone_args args = { + .flags = CLONE_VFORK | CLONE_VM, + .exit_signal = SIGCHLD, + }; + + return _do_fork(&args); } #endif @@ -2472,7 +2474,110 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, unsigned long, tls) #endif { - return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls); + struct kernel_clone_args args = { + .flags = (clone_flags & ~CSIGNAL), + .pidfd = parent_tidptr, + .child_tid = child_tidptr, + .parent_tid = parent_tidptr, + .exit_signal = (clone_flags & CSIGNAL), + .stack = newsp, + .tls = tls, + }; + + /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */ + if ((clone_flags & CLONE_PIDFD) && (clone_flags & CLONE_PARENT_SETTID)) + return -EINVAL; + + return _do_fork(&args); +} + +noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, + struct clone_args __user *uargs, + size_t size) +{ + struct clone_args args; + + if (unlikely(size > PAGE_SIZE)) + return -E2BIG; + + if (unlikely(size < sizeof(struct clone_args))) + return -EINVAL; + + if (unlikely(!access_ok(uargs, size))) + return -EFAULT; + + if (size > sizeof(struct clone_args)) { + unsigned char __user *addr; + unsigned char __user *end; + unsigned char val; + + addr = (void __user *)uargs + sizeof(struct clone_args); + end = (void __user *)uargs + size; + + for (; addr < end; addr++) { + if (get_user(val, addr)) + return -EFAULT; + if (val) + return -E2BIG; + } + + size = sizeof(struct clone_args); + } + + if (copy_from_user(&args, uargs, size)) + return -EFAULT; + + *kargs = (struct kernel_clone_args){ + .flags = args.flags, + .pidfd = u64_to_user_ptr(args.pidfd), + .child_tid = u64_to_user_ptr(args.child_tid), + .parent_tid = u64_to_user_ptr(args.parent_tid), + .exit_signal = args.exit_signal, + .stack = args.stack, + .stack_size = args.stack_size, + .tls = args.tls, + }; + + return 0; +} + +static bool clone3_args_valid(const struct kernel_clone_args *kargs) +{ + /* + * All lower bits of the flag word are taken. + * Verify that no other unknown flags are passed along. + */ + if (kargs->flags & ~CLONE_LEGACY_FLAGS) + return false; + + /* + * - make the CLONE_DETACHED bit reuseable for clone3 + * - make the CSIGNAL bits reuseable for clone3 + */ + if (kargs->flags & (CLONE_DETACHED | CSIGNAL)) + return false; + + if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) && + kargs->exit_signal) + return false; + + return true; +} + +SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size) +{ + int err; + + struct kernel_clone_args kargs; + + err = copy_clone_args_from_user(&kargs, uargs, size); + if (err) + return err; + + if (!clone3_args_valid(&kargs)) + return -EINVAL; + + return _do_fork(&kargs); } #endif From 8f3220a806545442f6f26195bc491520f5276e7c Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Sat, 25 May 2019 11:37:43 +0200 Subject: [PATCH 2/3] arch: wire-up clone3() syscall Wire up the clone3() call on all arches that don't require hand-rolled assembly. Some of the arches look like they need special assembly massaging and it is probably smarter if the appropriate arch maintainers would do the actual wiring. Arches that are wired-up are: - x86{_32,64} - arm{64} - xtensa Signed-off-by: Christian Brauner Acked-by: Arnd Bergmann Cc: Kees Cook Cc: David Howells Cc: Andrew Morton Cc: Oleg Nesterov Cc: Adrian Reber Cc: Linus Torvalds Cc: Al Viro Cc: Florian Weimer Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org --- arch/arm/tools/syscall.tbl | 1 + arch/arm64/include/asm/unistd.h | 2 +- arch/arm64/include/asm/unistd32.h | 2 ++ arch/microblaze/kernel/syscalls/syscall.tbl | 1 + arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + arch/xtensa/kernel/syscalls/syscall.tbl | 1 + include/uapi/asm-generic/unistd.h | 4 +++- 8 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl index aaf479a9e92d..e99a82bdb93a 100644 --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -447,3 +447,4 @@ 431 common fsconfig sys_fsconfig 432 common fsmount sys_fsmount 433 common fspick sys_fspick +436 common clone3 sys_clone3 diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h index 70e6882853c0..24480c2d95da 100644 --- a/arch/arm64/include/asm/unistd.h +++ b/arch/arm64/include/asm/unistd.h @@ -44,7 +44,7 @@ #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5) #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800) -#define __NR_compat_syscalls 434 +#define __NR_compat_syscalls 437 #endif #define __ARCH_WANT_SYS_CLONE diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h index c39e90600bb3..b144ea675d70 100644 --- a/arch/arm64/include/asm/unistd32.h +++ b/arch/arm64/include/asm/unistd32.h @@ -886,6 +886,8 @@ __SYSCALL(__NR_fsconfig, sys_fsconfig) __SYSCALL(__NR_fsmount, sys_fsmount) #define __NR_fspick 433 __SYSCALL(__NR_fspick, sys_fspick) +#define __NR_clone3 436 +__SYSCALL(__NR_clone3, sys_clone3) /* * Please add new compat syscalls above this comment and update diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl index 26339e417695..3110440bcc31 100644 --- a/arch/microblaze/kernel/syscalls/syscall.tbl +++ b/arch/microblaze/kernel/syscalls/syscall.tbl @@ -439,3 +439,4 @@ 431 common fsconfig sys_fsconfig 432 common fsmount sys_fsmount 433 common fspick sys_fspick +436 common clone3 sys_clone3 diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index ad968b7bac72..80e26211feff 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -438,3 +438,4 @@ 431 i386 fsconfig sys_fsconfig __ia32_sys_fsconfig 432 i386 fsmount sys_fsmount __ia32_sys_fsmount 433 i386 fspick sys_fspick __ia32_sys_fspick +436 i386 clone3 sys_clone3 __ia32_sys_clone3 diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index b4e6f9e6204a..7968f0b5b5e8 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -355,6 +355,7 @@ 431 common fsconfig __x64_sys_fsconfig 432 common fsmount __x64_sys_fsmount 433 common fspick __x64_sys_fspick +436 common clone3 __x64_sys_clone3/ptregs # # x32-specific system call numbers start at 512 to avoid cache impact diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl index 5fa0ee1c8e00..b2767c8c2b4e 100644 --- a/arch/xtensa/kernel/syscalls/syscall.tbl +++ b/arch/xtensa/kernel/syscalls/syscall.tbl @@ -404,3 +404,4 @@ 431 common fsconfig sys_fsconfig 432 common fsmount sys_fsmount 433 common fspick sys_fspick +436 common clone3 sys_clone3 diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index a87904daf103..45bc87687c47 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -844,9 +844,11 @@ __SYSCALL(__NR_fsconfig, sys_fsconfig) __SYSCALL(__NR_fsmount, sys_fsmount) #define __NR_fspick 433 __SYSCALL(__NR_fspick, sys_fspick) +#define __NR_clone3 436 +__SYSCALL(__NR_clone3, sys_clone3) #undef __NR_syscalls -#define __NR_syscalls 434 +#define __NR_syscalls 437 /* * 32 bit systems traditionally used different From d68dbb0c9ac8b1ff52eb09aa58ce6358400fa939 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 21 Jun 2019 01:26:35 +0200 Subject: [PATCH 3/3] arch: handle arches who do not yet define clone3 This cleanly handles arches who do not yet define clone3. clone3() was initially placed under __ARCH_WANT_SYS_CLONE under the assumption that this would cleanly handle all architectures. It does not. Architectures such as nios2 or h8300 simply take the asm-generic syscall definitions and generate their syscall table from it. Since they don't define __ARCH_WANT_SYS_CLONE the build would fail complaining about sys_clone3 missing. The reason this doesn't happen for legacy clone is that nios2 and h8300 provide assembly stubs for sys_clone. This seems to be done for architectural reasons. The build failures for nios2 and h8300 were caught int -next luckily. The solution is to define __ARCH_WANT_SYS_CLONE3 that architectures can add. Additionally, we need a cond_syscall(clone3) for architectures such as nios2 or h8300 that generate their syscall table in the way I explained above. Fixes: 8f3220a80654 ("arch: wire-up clone3() syscall") Signed-off-by: Christian Brauner Cc: Arnd Bergmann Cc: Kees Cook Cc: David Howells Cc: Andrew Morton Cc: Oleg Nesterov Cc: Adrian Reber Cc: Linus Torvalds Cc: Al Viro Cc: Florian Weimer Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org --- arch/arm/include/asm/unistd.h | 1 + arch/arm64/include/asm/unistd.h | 1 + arch/x86/include/asm/unistd.h | 1 + arch/xtensa/include/asm/unistd.h | 1 + kernel/fork.c | 2 ++ kernel/sys_ni.c | 2 ++ 6 files changed, 8 insertions(+) diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h index 7a39e77984ef..aa35aa5d68dc 100644 --- a/arch/arm/include/asm/unistd.h +++ b/arch/arm/include/asm/unistd.h @@ -40,6 +40,7 @@ #define __ARCH_WANT_SYS_FORK #define __ARCH_WANT_SYS_VFORK #define __ARCH_WANT_SYS_CLONE +#define __ARCH_WANT_SYS_CLONE3 /* * Unimplemented (or alternatively implemented) syscalls diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h index 24480c2d95da..e4e0523102e2 100644 --- a/arch/arm64/include/asm/unistd.h +++ b/arch/arm64/include/asm/unistd.h @@ -48,6 +48,7 @@ #endif #define __ARCH_WANT_SYS_CLONE +#define __ARCH_WANT_SYS_CLONE3 #ifndef __COMPAT_SYSCALL_NR #include diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h index 146859efd83c..097589753fec 100644 --- a/arch/x86/include/asm/unistd.h +++ b/arch/x86/include/asm/unistd.h @@ -54,5 +54,6 @@ # define __ARCH_WANT_SYS_FORK # define __ARCH_WANT_SYS_VFORK # define __ARCH_WANT_SYS_CLONE +# define __ARCH_WANT_SYS_CLONE3 #endif /* _ASM_X86_UNISTD_H */ diff --git a/arch/xtensa/include/asm/unistd.h b/arch/xtensa/include/asm/unistd.h index 30af4dc3ce7b..b52236245e51 100644 --- a/arch/xtensa/include/asm/unistd.h +++ b/arch/xtensa/include/asm/unistd.h @@ -3,6 +3,7 @@ #define _XTENSA_UNISTD_H #define __ARCH_WANT_SYS_CLONE +#define __ARCH_WANT_SYS_CLONE3 #include #define __ARCH_WANT_NEW_STAT diff --git a/kernel/fork.c b/kernel/fork.c index 08ff131f26b4..98abea995629 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2490,7 +2490,9 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, return _do_fork(&args); } +#endif +#ifdef __ARCH_WANT_SYS_CLONE3 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, struct clone_args __user *uargs, size_t size) diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 4d9ae5ea6caf..34b76895b81e 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -137,6 +137,8 @@ COND_SYSCALL(capset); /* kernel/exit.c */ /* kernel/fork.c */ +/* __ARCH_WANT_SYS_CLONE3 */ +COND_SYSCALL(clone3); /* kernel/futex.c */ COND_SYSCALL(futex);