From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967353AbdEXJF4 (ORCPT ); Wed, 24 May 2017 05:05:56 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:37495 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161625AbdEXJAz (ORCPT ); Wed, 24 May 2017 05:00:55 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Linus Torvalds Cc: Linux Containers , Date: Wed, 24 May 2017 03:54:20 -0500 Message-ID: <878tlmeitf.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1dDSA1-0001GJ-J8;;;mid=<878tlmeitf.fsf@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=97.121.81.159;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+ZQTuNAYxZSYZYPaePNzF/5QVCkKkSr74= X-SA-Exim-Connect-IP: 97.121.81.159 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 TVD_RCVD_IP Message was received from an IP address * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa05 1397; Body=1 Fuz1=1 Fuz2=1] * 1.0 XMSubMetaSx_00 1+ Sexy Words * 1.2 XMSubMetaSxObfu_03 Obfuscated Sexy Noun-People * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa05 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **;Linus Torvalds X-Spam-Relay-Country: X-Spam-Timing: total 324 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 2.4 (0.8%), b_tie_ro: 1.66 (0.5%), parse: 0.86 (0.3%), extract_message_metadata: 3.9 (1.2%), get_uri_detail_list: 2.2 (0.7%), tests_pri_-1000: 3.5 (1.1%), tests_pri_-950: 1.09 (0.3%), tests_pri_-900: 0.90 (0.3%), tests_pri_-400: 22 (6.8%), check_bayes: 21 (6.5%), b_tokenize: 8 (2.5%), b_tok_get_all: 7 (2.1%), b_comp_prob: 1.99 (0.6%), b_tok_touch_all: 2.9 (0.9%), b_finish: 0.58 (0.2%), tests_pri_0: 277 (85.4%), check_dkim_signature: 0.53 (0.2%), check_dkim_adsp: 3.5 (1.1%), tests_pri_500: 5 (1.6%), rewrite_mail: 0.00 (0.0%) Subject: [GIT PULL] ptrace fix for v4.12-rc3 X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, Please pull the for-linus branch from the git tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-linus HEAD: c70d9d809fdeecedb96972457ee45c49a232d97f ptrace: Properly initialize ptracer_cred on fork This fixes a brown paper bag bug. When I fixed the ptrace interaction with user namespaces I added a new field ptracer_cred in struct_task and I failed to properly initialize it on fork. This dangling pointer wound up breaking runing setuid applications run from the enlightenment window manager. As this is the worst sort of bug. A regression breaking user space for no good reason let's get this fixed. Eric Eric W. Biederman (1): ptrace: Properly initialize ptracer_cred on fork include/linux/ptrace.h | 7 +++++-- kernel/ptrace.c | 20 +++++++++++++------- 2 files changed, 18 insertions(+), 9 deletions(-) diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 422bc2e4cb6a..ef3eb8bbfee4 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -54,7 +54,8 @@ extern int ptrace_request(struct task_struct *child, long request, unsigned long addr, unsigned long data); extern void ptrace_notify(int exit_code); extern void __ptrace_link(struct task_struct *child, - struct task_struct *new_parent); + struct task_struct *new_parent, + const struct cred *ptracer_cred); extern void __ptrace_unlink(struct task_struct *child); extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead); #define PTRACE_MODE_READ 0x01 @@ -206,7 +207,7 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) if (unlikely(ptrace) && current->ptrace) { child->ptrace = current->ptrace; - __ptrace_link(child, current->parent); + __ptrace_link(child, current->parent, current->ptracer_cred); if (child->ptrace & PT_SEIZED) task_set_jobctl_pending(child, JOBCTL_TRAP_STOP); @@ -215,6 +216,8 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) set_tsk_thread_flag(child, TIF_SIGPENDING); } + else + child->ptracer_cred = NULL; } /** diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 266ddcc1d8bb..60f356d91060 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -60,19 +60,25 @@ int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, } +void __ptrace_link(struct task_struct *child, struct task_struct *new_parent, + const struct cred *ptracer_cred) +{ + BUG_ON(!list_empty(&child->ptrace_entry)); + list_add(&child->ptrace_entry, &new_parent->ptraced); + child->parent = new_parent; + child->ptracer_cred = get_cred(ptracer_cred); +} + /* * ptrace a task: make the debugger its new parent and * move it to the ptrace list. * * Must be called with the tasklist lock write-held. */ -void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) +static void ptrace_link(struct task_struct *child, struct task_struct *new_parent) { - BUG_ON(!list_empty(&child->ptrace_entry)); - list_add(&child->ptrace_entry, &new_parent->ptraced); - child->parent = new_parent; rcu_read_lock(); - child->ptracer_cred = get_cred(__task_cred(new_parent)); + __ptrace_link(child, new_parent, __task_cred(new_parent)); rcu_read_unlock(); } @@ -386,7 +392,7 @@ static int ptrace_attach(struct task_struct *task, long request, flags |= PT_SEIZED; task->ptrace = flags; - __ptrace_link(task, current); + ptrace_link(task, current); /* SEIZE doesn't trap tracee on attach */ if (!seize) @@ -459,7 +465,7 @@ static int ptrace_traceme(void) */ if (!ret && !(current->real_parent->flags & PF_EXITING)) { current->ptrace = PT_PTRACED; - __ptrace_link(current, current->real_parent); + ptrace_link(current, current->real_parent); } } write_unlock_irq(&tasklist_lock); -- 2.10.1