diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 124 |
1 files changed, 109 insertions, 15 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 0c92f224c68c..bfe73db1c26c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1174,6 +1174,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, fail_pcpu: while (i > 0) percpu_counter_destroy(&mm->rss_stat[--i]); + destroy_context(mm); fail_nocontext: mm_free_pgd(mm); fail_nopgd: @@ -1625,7 +1626,8 @@ static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) return 0; } -static int copy_files(unsigned long clone_flags, struct task_struct *tsk) +static int copy_files(unsigned long clone_flags, struct task_struct *tsk, + int no_files) { struct files_struct *oldf, *newf; int error = 0; @@ -1637,6 +1639,11 @@ static int copy_files(unsigned long clone_flags, struct task_struct *tsk) if (!oldf) goto out; + if (no_files) { + tsk->files = NULL; + goto out; + } + if (clone_flags & CLONE_FILES) { atomic_inc(&oldf->count); goto out; @@ -1954,6 +1961,91 @@ const struct file_operations pidfd_fops = { #endif }; +/** + * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd + * @pid: the struct pid for which to create a pidfd + * @flags: flags of the new @pidfd + * @pidfd: the pidfd to return + * + * Allocate a new file that stashes @pid and reserve a new pidfd number in the + * caller's file descriptor table. The pidfd is reserved but not installed yet. + + * The helper doesn't perform checks on @pid which makes it useful for pidfds + * created via CLONE_PIDFD where @pid has no task attached when the pidfd and + * pidfd file are prepared. + * + * If this function returns successfully the caller is responsible to either + * call fd_install() passing the returned pidfd and pidfd file as arguments in + * order to install the pidfd into its file descriptor table or they must use + * put_unused_fd() and fput() on the returned pidfd and pidfd file + * respectively. + * + * This function is useful when a pidfd must already be reserved but there + * might still be points of failure afterwards and the caller wants to ensure + * that no pidfd is leaked into its file descriptor table. + * + * Return: On success, a reserved pidfd is returned from the function and a new + * pidfd file is returned in the last argument to the function. On + * error, a negative error code is returned from the function and the + * last argument remains unchanged. + */ +static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret) +{ + int pidfd; + struct file *pidfd_file; + + if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC)) + return -EINVAL; + + pidfd = get_unused_fd_flags(O_RDWR | O_CLOEXEC); + if (pidfd < 0) + return pidfd; + + pidfd_file = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, + flags | O_RDWR | O_CLOEXEC); + if (IS_ERR(pidfd_file)) { + put_unused_fd(pidfd); + return PTR_ERR(pidfd_file); + } + get_pid(pid); /* held by pidfd_file now */ + *ret = pidfd_file; + return pidfd; +} + +/** + * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd + * @pid: the struct pid for which to create a pidfd + * @flags: flags of the new @pidfd + * @pidfd: the pidfd to return + * + * Allocate a new file that stashes @pid and reserve a new pidfd number in the + * caller's file descriptor table. The pidfd is reserved but not installed yet. + * + * The helper verifies that @pid is used as a thread group leader. + * + * If this function returns successfully the caller is responsible to either + * call fd_install() passing the returned pidfd and pidfd file as arguments in + * order to install the pidfd into its file descriptor table or they must use + * put_unused_fd() and fput() on the returned pidfd and pidfd file + * respectively. + * + * This function is useful when a pidfd must already be reserved but there + * might still be points of failure afterwards and the caller wants to ensure + * that no pidfd is leaked into its file descriptor table. + * + * Return: On success, a reserved pidfd is returned from the function and a new + * pidfd file is returned in the last argument to the function. On + * error, a negative error code is returned from the function and the + * last argument remains unchanged. + */ +int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret) +{ + if (!pid || !pid_has_task(pid, PIDTYPE_TGID)) + return -EINVAL; + + return __pidfd_prepare(pid, flags, ret); +} + static void __delayed_free_task(struct rcu_head *rhp) { struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); @@ -2008,7 +2100,7 @@ static void rv_task_fork(struct task_struct *p) * parts of the process environment (as per the clone * flags). The actual kick-off is left to the caller. */ -static __latent_entropy struct task_struct *copy_process( +__latent_entropy struct task_struct *copy_process( struct pid *pid, int trace, int node, @@ -2101,6 +2193,8 @@ static __latent_entropy struct task_struct *copy_process( p->flags &= ~PF_KTHREAD; if (args->kthread) p->flags |= PF_KTHREAD; + if (args->user_worker) + p->flags |= PF_USER_WORKER; if (args->io_thread) { /* * Mark us an IO worker, and block any signal that isn't @@ -2110,6 +2204,9 @@ static __latent_entropy struct task_struct *copy_process( siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)); } + if (args->name) + strscpy_pad(p->comm, args->name, sizeof(p->comm)); + p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL; /* * Clear TID on mm_release()? @@ -2252,7 +2349,7 @@ static __latent_entropy struct task_struct *copy_process( retval = copy_semundo(clone_flags, p); if (retval) goto bad_fork_cleanup_security; - retval = copy_files(clone_flags, p); + retval = copy_files(clone_flags, p, args->no_files); if (retval) goto bad_fork_cleanup_semundo; retval = copy_fs(clone_flags, p); @@ -2277,6 +2374,9 @@ static __latent_entropy struct task_struct *copy_process( if (retval) goto bad_fork_cleanup_io; + if (args->ignore_signals) + ignore_signals(p); + stackleak_task_init(p); if (pid != &init_struct_pid) { @@ -2294,21 +2394,12 @@ static __latent_entropy struct task_struct *copy_process( * if the fd table isn't shared). */ if (clone_flags & CLONE_PIDFD) { - retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC); + /* Note that no task has been attached to @pid yet. */ + retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile); if (retval < 0) goto bad_fork_free_pid; - pidfd = retval; - pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, - O_RDWR | O_CLOEXEC); - if (IS_ERR(pidfile)) { - put_unused_fd(pidfd); - retval = PTR_ERR(pidfile); - goto bad_fork_free_pid; - } - get_pid(pid); /* held by pidfile now */ - retval = put_user(pidfd, args->pidfd); if (retval) goto bad_fork_put_pidfd; @@ -2625,6 +2716,7 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) .fn = fn, .fn_arg = arg, .io_thread = 1, + .user_worker = 1, }; return copy_process(NULL, 0, node, &args); @@ -2728,7 +2820,8 @@ pid_t kernel_clone(struct kernel_clone_args *args) /* * Create a kernel thread. */ -pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) +pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name, + unsigned long flags) { struct kernel_clone_args args = { .flags = ((lower_32_bits(flags) | CLONE_VM | @@ -2736,6 +2829,7 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) .exit_signal = (lower_32_bits(flags) & CSIGNAL), .fn = fn, .fn_arg = arg, + .name = name, .kthread = 1, }; |