From ba75444ae218bc590a9d3a49aa538ad089a0161a Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 16 Jul 2020 03:37:10 -0700 Subject: [PATCH] nptl: Zero-extend arguments to SETXID syscalls [BZ #26248] nptl has /* Opcodes and data types for communication with the signal handler to change user/group IDs. */ struct xid_command { int syscall_no; long int id[3]; volatile int cntr; volatile int error; }; /* This must be last, otherwise the current thread might not have permissions to send SIGSETXID syscall to the other threads. */ result = INTERNAL_SYSCALL_NCS (cmdp->syscall_no, 3, cmdp->id[0], cmdp->id[1], cmdp->id[2]); But the second argument of setgroups syscal is a pointer: int setgroups(size_t size, const gid_t *list); But on x32, pointers passed to syscall must have pointer type so that they will be zero-extended. The kernel XID arguments are unsigned and do not require sign extension. Change xid_command to struct xid_command { int syscall_no; unsigned long int id[3]; volatile int cntr; volatile int error; }; so that all arguments are zero-extended. A testcase is added for x32 and setgroups returned with EFAULT when running as root without the fix. --- nptl/descr.h | 8 +- sysdeps/unix/sysv/linux/x86_64/x32/Makefile | 4 + .../sysv/linux/x86_64/x32/tst-setgroups.c | 79 +++++++++++++++++++ 3 files changed, 90 insertions(+), 1 deletion(-) create mode 100644 sysdeps/unix/sysv/linux/x86_64/x32/tst-setgroups.c diff --git a/nptl/descr.h b/nptl/descr.h index 6a509b6725..a0fc3fda0f 100644 --- a/nptl/descr.h +++ b/nptl/descr.h @@ -95,7 +95,13 @@ struct pthread_unwind_buf struct xid_command { int syscall_no; - long int id[3]; + /* Enforce zero-extension for the pointer argument in + + int setgroups(size_t size, const gid_t *list); + + The kernel XID arguments are unsigned and do not require sign + extension. */ + unsigned long int id[3]; volatile int cntr; volatile int error; /* -1: no call yet, 0: success seen, >0: error seen. */ }; diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/Makefile b/sysdeps/unix/sysv/linux/x86_64/x32/Makefile index 16b768d8ba..1a6c984f96 100644 --- a/sysdeps/unix/sysv/linux/x86_64/x32/Makefile +++ b/sysdeps/unix/sysv/linux/x86_64/x32/Makefile @@ -5,6 +5,10 @@ ifeq ($(subdir),misc) sysdep_routines += arch_prctl endif +ifeq ($(subdir),nptl) +xtests += tst-setgroups +endif + ifeq ($(subdir),conform) # For bugs 16437 and 21279. conformtest-xfail-conds += x86_64-x32-linux diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/tst-setgroups.c b/sysdeps/unix/sysv/linux/x86_64/x32/tst-setgroups.c new file mode 100644 index 0000000000..1ebd0b4cff --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86_64/x32/tst-setgroups.c @@ -0,0 +1,79 @@ +/* Test setgroups as root and in the presence of threads (Bug 26248) + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* The purpose of this test is to test the setgroups API as root and in + the presence of threads. Once we create a thread the setgroups + implementation must ensure that all threads are set to the same + group and this operation should not fail. Lastly we test setgroups + with a zero sized group and a bad address and verify we get EPERM. */ + +static void * +start_routine (void *args) +{ + return NULL; +} + +static int +do_test (void) +{ + int size; + /* NB: Stack address is at 0xfffXXXXX. */ + gid_t list[NGROUPS_MAX]; + int status = EXIT_SUCCESS; + + pthread_t thread = xpthread_create (NULL, start_routine, NULL); + + size = getgroups (sizeof (list) / sizeof (list[0]), list); + if (size < 0) + { + status = EXIT_FAILURE; + error (0, errno, "getgroups failed"); + } + if (setgroups (size, list) < 0) + { + if (errno == EPERM) + status = EXIT_UNSUPPORTED; + else + { + status = EXIT_FAILURE; + error (0, errno, "setgroups failed"); + } + } + + if (status == EXIT_SUCCESS && setgroups (0, list) < 0) + { + status = EXIT_FAILURE; + error (0, errno, "setgroups failed"); + } + + xpthread_join (thread); + + return status; +} + +#include -- 2.26.2