From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756601Ab1HSXPX (ORCPT ); Fri, 19 Aug 2011 19:15:23 -0400 Received: from mga01.intel.com ([192.55.52.88]:4061 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756564Ab1HSXPS (ORCPT ); Fri, 19 Aug 2011 19:15:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.68,253,1312182000"; d="scan'208";a="41891149" From: Andi Kleen To: torvalds@linux-foundation.org Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Andi Kleen Subject: [PATCH] Add a personality to report 2.6.x version numbers Date: Fri, 19 Aug 2011 16:15:10 -0700 Message-Id: <1313795710-30827-1-git-send-email-andi@firstfloor.org> X-Mailer: git-send-email 1.7.4.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andi Kleen Reposting due to popular demand. Several other people are running into the same problem with all kinds of software. Only change is rebase against current master. -Andi -- I ran into a couple of programs which broke with the new Linux 3.0 version. Some of those were binary only. I tried to use LD_PRELOAD to work around it, but it was quite difficult and in one case impossible because of a mix of 32bit and 64bit executables. This patch adds a UNAME26 personality that makes the kernel report a 2.6.40+x version number instead. The x is the x in 3.x. I know this is somewhat ugly, but I didn't find a better workaround, and compatibility to existing programs is important. Some programs also read /proc/sys/kernel/osrelease. This can be worked around in user space with mount --bind (and a mount namespace) To use: wget ftp://ftp.kernel.org/pub/linux/kernel/people/ak/uname26/uname26.c gcc -o uname26 uname26.c ./uname26 program Signed-off-by: Andi Kleen --- include/linux/personality.h | 1 + kernel/sys.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 0 deletions(-) diff --git a/include/linux/personality.h b/include/linux/personality.h index eec3bae..8fc7dd1a 100644 --- a/include/linux/personality.h +++ b/include/linux/personality.h @@ -22,6 +22,7 @@ extern int __set_personality(unsigned int); * These occupy the top three bytes. */ enum { + UNAME26 = 0x0020000, ADDR_NO_RANDOMIZE = 0x0040000, /* disable randomization of VA space */ FDPIC_FUNCPTRS = 0x0080000, /* userspace function ptrs point to descriptors * (signal handling) diff --git a/kernel/sys.c b/kernel/sys.c index a101ba3..bd6d142 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -37,6 +37,8 @@ #include #include #include +#include +#include #include #include @@ -44,6 +46,8 @@ #include #include +/* Move somewhere else to avoid recompiling? */ +#include #include #include @@ -1154,6 +1158,34 @@ DECLARE_RWSEM(uts_sem); #define override_architecture(name) 0 #endif +/* + * Work around broken programs that cannot handle "Linux 3.0". + * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40 + */ +static int override_release(char __user *release, int len) +{ + int ret = 0; + char buf[len]; + + if (current->personality & UNAME26) { + char *rest = UTS_RELEASE; + int ndots = 0; + unsigned v; + + while (*rest) { + if (*rest == '.' && ++ndots >= 3) + break; + if (!isdigit(*rest) && *rest != '.') + break; + rest++; + } + v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40; + snprintf(buf, len, "2.6.%u%s", v, rest); + ret = copy_to_user(release, buf, len); + } + return ret; +} + SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name) { int errno = 0; @@ -1163,6 +1195,8 @@ SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name) errno = -EFAULT; up_read(&uts_sem); + if (!errno && override_release(name->release, sizeof(name->release))) + errno = -EFAULT; if (!errno && override_architecture(name)) errno = -EFAULT; return errno; @@ -1184,6 +1218,8 @@ SYSCALL_DEFINE1(uname, struct old_utsname __user *, name) error = -EFAULT; up_read(&uts_sem); + if (!error && override_release(name->release, sizeof(name->release))) + error = -EFAULT; if (!error && override_architecture(name)) error = -EFAULT; return error; @@ -1218,6 +1254,8 @@ SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name) if (!error && override_architecture(name)) error = -EFAULT; + if (!error && override_release(name->release, sizeof(name->release))) + error = -EFAULT; return error ? -EFAULT : 0; } #endif -- 1.7.4.4