diff options
Diffstat (limited to 'kernel/seccomp.c')
| -rw-r--r-- | kernel/seccomp.c | 64 |
1 files changed, 46 insertions, 18 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 676d4af62103..8ad7a293255a 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -196,6 +196,10 @@ struct seccomp_filter { */ static void populate_seccomp_data(struct seccomp_data *sd) { + /* + * Instead of using current_pt_reg(), we're already doing the work + * to safely fetch "current", so just use "task" everywhere below. + */ struct task_struct *task = current; struct pt_regs *regs = task_pt_regs(task); unsigned long args[6]; @@ -910,7 +914,7 @@ out: if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) return 0; - syscall_set_return_value(current, task_pt_regs(current), + syscall_set_return_value(current, current_pt_regs(), err, ret); return -1; } @@ -943,13 +947,13 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, /* Set low-order bits as an errno, capped at MAX_ERRNO. */ if (data > MAX_ERRNO) data = MAX_ERRNO; - syscall_set_return_value(current, task_pt_regs(current), + syscall_set_return_value(current, current_pt_regs(), -data, 0); goto skip; case SECCOMP_RET_TRAP: /* Show the handler the original registers. */ - syscall_rollback(current, task_pt_regs(current)); + syscall_rollback(current, current_pt_regs()); /* Let the filter pass back 16 bits of data. */ seccomp_send_sigsys(this_syscall, data); goto skip; @@ -962,7 +966,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, /* ENOSYS these calls if there is no tracer attached. */ if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { syscall_set_return_value(current, - task_pt_regs(current), + current_pt_regs(), -ENOSYS, 0); goto skip; } @@ -982,7 +986,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, if (fatal_signal_pending(current)) goto skip; /* Check if the tracer forced the syscall to be skipped. */ - this_syscall = syscall_get_nr(current, task_pt_regs(current)); + this_syscall = syscall_get_nr(current, current_pt_regs()); if (this_syscall < 0) goto skip; @@ -1020,20 +1024,20 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, default: seccomp_log(this_syscall, SIGSYS, action, true); /* Dump core only if this is the last remaining thread. */ - if (action == SECCOMP_RET_KILL_PROCESS || + if (action != SECCOMP_RET_KILL_THREAD || get_nr_threads(current) == 1) { kernel_siginfo_t info; /* Show the original registers in the dump. */ - syscall_rollback(current, task_pt_regs(current)); + syscall_rollback(current, current_pt_regs()); /* Trigger a manual coredump since do_exit skips it. */ seccomp_init_siginfo(&info, this_syscall, data); do_coredump(&info); } - if (action == SECCOMP_RET_KILL_PROCESS) - do_group_exit(SIGSYS); - else + if (action == SECCOMP_RET_KILL_THREAD) do_exit(SIGSYS); + else + do_group_exit(SIGSYS); } unreachable(); @@ -1060,7 +1064,7 @@ int __secure_computing(const struct seccomp_data *sd) return 0; this_syscall = sd ? sd->nr : - syscall_get_nr(current, task_pt_regs(current)); + syscall_get_nr(current, current_pt_regs()); switch (mode) { case SECCOMP_MODE_STRICT: @@ -1472,13 +1476,7 @@ static const struct file_operations seccomp_notify_ops = { static struct file *init_listener(struct seccomp_filter *filter) { - struct file *ret = ERR_PTR(-EBUSY); - struct seccomp_filter *cur; - - for (cur = current->seccomp.filter; cur; cur = cur->prev) { - if (cur->notif) - goto out; - } + struct file *ret; ret = ERR_PTR(-ENOMEM); filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL); @@ -1504,6 +1502,31 @@ out: return ret; } +/* + * Does @new_child have a listener while an ancestor also has a listener? + * If so, we'll want to reject this filter. + * This only has to be tested for the current process, even in the TSYNC case, + * because TSYNC installs @child with the same parent on all threads. + * Note that @new_child is not hooked up to its parent at this point yet, so + * we use current->seccomp.filter. + */ +static bool has_duplicate_listener(struct seccomp_filter *new_child) +{ + struct seccomp_filter *cur; + + /* must be protected against concurrent TSYNC */ + lockdep_assert_held(¤t->sighand->siglock); + + if (!new_child->notif) + return false; + for (cur = current->seccomp.filter; cur; cur = cur->prev) { + if (cur->notif) + return true; + } + + return false; +} + /** * seccomp_set_mode_filter: internal function for setting seccomp filter * @flags: flags to change filter behavior @@ -1575,6 +1598,11 @@ static long seccomp_set_mode_filter(unsigned int flags, if (!seccomp_may_assign_mode(seccomp_mode)) goto out; + if (has_duplicate_listener(prepared)) { + ret = -EBUSY; + goto out; + } + ret = seccomp_attach_filter(flags, prepared); if (ret) goto out; |