[v1,1/2] pid: add pidfd_open()

Message ID	20190516135944.7205-1-christian@brauner.io (mailing list archive)
State	New
Headers	show Return-Path: <linux-kselftest-owner@kernel.org> From: Christian Brauner <christian@brauner.io> To: jannh@google.com, oleg@redhat.com, viro@zeniv.linux.org.uk, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, arnd@arndb.de Cc: akpm@linux-foundation.org, cyphar@cyphar.com, dhowells@redhat.com, ebiederm@xmission.com, elena.reshetova@intel.com, keescook@chromium.org, luto@amacapital.net, luto@kernel.org, tglx@linutronix.de, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, joel@joelfernandes.org, dancol@google.com, serge@hallyn.com, Christian Brauner <christian@brauner.io>, Geert Uytterhoeven <geert@linux-m68k.org> Subject: [PATCH v1 1/2] pid: add pidfd_open() Date: Thu, 16 May 2019 15:59:42 +0200 Message-Id: <20190516135944.7205-1-christian@brauner.io> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk
Series	[v1,1/2] pid: add pidfd_open() \| expand [v1,1/2] pid: add pidfd_open() [v1,2/2] tests: add pidfd_open() tests

diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl index 165f268beafc..ddc3c93ad7a7 100644 --- a/arch/alpha/kernel/syscalls/syscall.tbl +++ b/arch/alpha/kernel/syscalls/syscall.tbl @@ -467,3 +467,4 @@ 535 common io_uring_setup sys_io_uring_setup 536 common io_uring_enter sys_io_uring_enter 537 common io_uring_register sys_io_uring_register +538 common pidfd_open sys_pidfd_open diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl index 0393917eaa57..fc41fb34a636 100644 --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -441,3 +441,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h index 23f1a44acada..350e2049b4a9 100644 --- a/arch/arm64/include/asm/unistd32.h +++ b/arch/arm64/include/asm/unistd32.h @@ -874,6 +874,8 @@ __SYSCALL(__NR_io_uring_setup, sys_io_uring_setup) __SYSCALL(__NR_io_uring_enter, sys_io_uring_enter) #define __NR_io_uring_register 427 __SYSCALL(__NR_io_uring_register, sys_io_uring_register) +#define __NR_pidfd_open 428 +__SYSCALL(__NR_pidfd_open, sys_pidfd_open) /* * Please add new compat syscalls above this comment and update diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl index 56e3d0b685e1..7115f6dd347a 100644 --- a/arch/ia64/kernel/syscalls/syscall.tbl +++ b/arch/ia64/kernel/syscalls/syscall.tbl @@ -348,3 +348,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl index df4ec3ec71d1..44bf12b16ffe 100644 --- a/arch/m68k/kernel/syscalls/syscall.tbl +++ b/arch/m68k/kernel/syscalls/syscall.tbl @@ -427,3 +427,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl index 4964947732af..0d32e5152dc0 100644 --- a/arch/microblaze/kernel/syscalls/syscall.tbl +++ b/arch/microblaze/kernel/syscalls/syscall.tbl @@ -433,3 +433,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl index 9392dfe33f97..726e107b3c9f 100644 --- a/arch/mips/kernel/syscalls/syscall_n32.tbl +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl @@ -366,3 +366,4 @@ 425 n32 io_uring_setup sys_io_uring_setup 426 n32 io_uring_enter sys_io_uring_enter 427 n32 io_uring_register sys_io_uring_register +428 n32 pidfd_open sys_pidfd_open diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl index fe8ca623add8..83b46b568d51 100644 --- a/arch/parisc/kernel/syscalls/syscall.tbl +++ b/arch/parisc/kernel/syscalls/syscall.tbl @@ -424,3 +424,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl index 00f5a63c8d9a..5294d04d7fa5 100644 --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl @@ -509,3 +509,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl index 061418f787c3..dcdb838adf49 100644 --- a/arch/s390/kernel/syscalls/syscall.tbl +++ b/arch/s390/kernel/syscalls/syscall.tbl @@ -430,3 +430,4 @@ 425 common io_uring_setup sys_io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open sys_pidfd_open diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl index 480b057556ee..8e66edfbc521 100644 --- a/arch/sh/kernel/syscalls/syscall.tbl +++ b/arch/sh/kernel/syscalls/syscall.tbl @@ -430,3 +430,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl index a1dd24307b00..d6f3bc686939 100644 --- a/arch/sparc/kernel/syscalls/syscall.tbl +++ b/arch/sparc/kernel/syscalls/syscall.tbl @@ -473,3 +473,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 4cd5f982b1e5..1af6b469160a 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -438,3 +438,4 @@ 425 i386 io_uring_setup sys_io_uring_setup __ia32_sys_io_uring_setup 426 i386 io_uring_enter sys_io_uring_enter __ia32_sys_io_uring_enter 427 i386 io_uring_register sys_io_uring_register __ia32_sys_io_uring_register +428 i386 pidfd_open sys_pidfd_open __ia32_sys_pidfd_open diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index 64ca0d06259a..c18e6ebe3387 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -355,6 +355,7 @@ 425 common io_uring_setup __x64_sys_io_uring_setup 426 common io_uring_enter __x64_sys_io_uring_enter 427 common io_uring_register __x64_sys_io_uring_register +428 common pidfd_open __x64_sys_pidfd_open # # 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 30084eaf8422..21ee795f3003 100644 --- a/arch/xtensa/kernel/syscalls/syscall.tbl +++ b/arch/xtensa/kernel/syscalls/syscall.tbl @@ -398,3 +398,4 @@ 425 common io_uring_setup sys_io_uring_setup 426 common io_uring_enter sys_io_uring_enter 427 common io_uring_register sys_io_uring_register +428 common pidfd_open sys_pidfd_open diff --git a/include/linux/pid.h b/include/linux/pid.h index 3c8ef5a199ca..c938a92eab99 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -67,6 +67,7 @@ struct pid extern struct pid init_struct_pid; extern const struct file_operations pidfd_fops; +extern int pidfd_create(struct pid *pid); static inline struct pid *get_pid(struct pid *pid) { diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index e2870fe1be5b..989055e0b501 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -929,6 +929,7 @@ asmlinkage long sys_clock_adjtime32(clockid_t which_clock, struct old_timex32 __user *tx); asmlinkage long sys_syncfs(int fd); asmlinkage long sys_setns(int fd, int nstype); +asmlinkage long sys_pidfd_open(pid_t pid, unsigned int flags); asmlinkage long sys_sendmmsg(int fd, struct mmsghdr __user *msg, unsigned int vlen, unsigned flags); asmlinkage long sys_process_vm_readv(pid_t pid, diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index dee7292e1df6..94a257a93d20 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -832,9 +832,11 @@ __SYSCALL(__NR_io_uring_setup, sys_io_uring_setup) __SYSCALL(__NR_io_uring_enter, sys_io_uring_enter) #define __NR_io_uring_register 427 __SYSCALL(__NR_io_uring_register, sys_io_uring_register) +#define __NR_pidfd_open 428 +__SYSCALL(__NR_pidfd_open, sys_pidfd_open) #undef __NR_syscalls -#define __NR_syscalls 428 +#define __NR_syscalls 429 /* * 32 bit systems traditionally used different diff --git a/kernel/fork.c b/kernel/fork.c index 737db1828437..980cc1d2b8d4 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1714,7 +1714,7 @@ const struct file_operations pidfd_fops = { * Return: On success, a cloexec pidfd is returned. * On error, a negative errno number will be returned. */ -static int pidfd_create(struct pid *pid) +int pidfd_create(struct pid *pid) { int fd; diff --git a/kernel/pid.c b/kernel/pid.c index 20881598bdfa..4afca3d6dcb8 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -38,6 +38,7 @@ #include <linux/syscalls.h> #include <linux/proc_ns.h> #include <linux/proc_fs.h> +#include <linux/sched/signal.h> #include <linux/sched/task.h> #include <linux/idr.h> @@ -451,6 +452,55 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns) return idr_get_next(&ns->idr, &nr); } +/** + * pidfd_open() - Open new pid file descriptor. + * + * @pid: pid for which to retrieve a pidfd + * @flags: flags to pass + * + * This creates a new pid file descriptor with the O_CLOEXEC flag set for + * the process identified by @pid. Currently, the process identified by + * @pid must be a thread-group leader. This restriction currently exists + * for all aspects of pidfds including pidfd creation (CLONE_PIDFD cannot + * be used with CLONE_THREAD) and pidfd polling (only supports thread group + * leaders). + * + * Return: On success, a cloexec pidfd is returned. + * On error, a negative errno number will be returned. + */ +SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags) +{ + int fd, ret; + struct pid *p; + struct task_struct *tsk; + + if (flags) + return -EINVAL; + + if (pid <= 0) + return -EINVAL; + + p = find_get_pid(pid); + if (!p) + return -ESRCH; + + ret = 0; + rcu_read_lock(); + /* + * If this returns non-NULL the pid was used as a thread-group + * leader. Note, we race with exec here: If it changes the + * thread-group leader we might return the old leader. + */ + tsk = pid_task(p, PIDTYPE_TGID); + if (!tsk) + ret = -ESRCH; + rcu_read_unlock(); + + fd = ret ?: pidfd_create(p); + put_pid(p); + return fd; +} + void __init pid_idr_init(void) { /* Verify no one has done anything silly: */

[v1,1/2] pid: add pidfd_open()

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