| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <201109072340.31460.vda.linux@googlemail.com>
Date: Wed, 7 Sep 2011 23:40:31 +0200
From: Denys Vlasenko <vda.linux@...glemail.com>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
Denys Vlasenko <vda.linux@...glemail.com>, dvlasenk@...hat.com
Subject: [PATCH v2] Make PTRACE_SEIZE set ptrace options specified in 'data' parameter
Make PTRACE_SEIZE set ptrace options specified in 'data' parameter
This can be used to close a few corner cases in strace where we get
unwanted racy behavior after attach, but before we have a chance
to set options (the notorious post-execve SIGTRAP comes to mind),
and removes the need to track "did we set opts for this task" state
in strace internals.
While we are at it:
Make it possible to extend SEIZE in the future with more functionality
by passing non-zero 'addr' parameter.
To that end, error out if 'addr' is non-zero.
PTRACE_ATTACH did not (and still does not) have such check,
and users (strace) do pass garbage there... let's avoid repeating
this mistake with SEIZE.
Set all task->ptrace bits in one operation - before this change,
we were adding PT_SEIZED and PT_PTRACE_CAP with task->ptrace |= BIT.
This was probably ok (not a bug), but let's be on a safer side.
Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 0316200..43aa09c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -212,6 +212,7 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
}
static int ptrace_attach(struct task_struct *task, long request,
+ unsigned long addr,
unsigned long flags)
{
bool seize = (request == PTRACE_SEIZE);
@@ -219,19 +220,27 @@ static int ptrace_attach(struct task_struct *task, long request,
/*
* SEIZE will enable new ptrace behaviors which will be implemented
- * gradually. SEIZE_DEVEL is used to prevent applications
+ * gradually. SEIZE_DEVEL bit is used to prevent applications
* expecting full SEIZE behaviors trapping on kernel commits which
* are still in the process of implementing them.
*
* Only test programs for new ptrace behaviors being implemented
* should set SEIZE_DEVEL. If unset, SEIZE will fail with -EIO.
*
- * Once SEIZE behaviors are completely implemented, this flag and
- * the following test will be removed.
+ * Once SEIZE behaviors are completely implemented, this flag
+ * will be removed.
*/
retval = -EIO;
- if (seize && !(flags & PTRACE_SEIZE_DEVEL))
- goto out;
+ if (seize) {
+ if (addr != 0)
+ goto out;
+ if ((flags & ~(long)PTRACE_O_MASK) != PTRACE_SEIZE_DEVEL)
+ goto out;
+ flags &= ~PTRACE_SEIZE_DEVEL;
+ flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
+ } else {
+ flags = PT_PTRACED;
+ }
audit_ptrace(task);
@@ -263,11 +272,9 @@ static int ptrace_attach(struct task_struct *task, long request,
if (task->ptrace)
goto unlock_tasklist;
- task->ptrace = PT_PTRACED;
- if (seize)
- task->ptrace |= PT_SEIZED;
if (task_ns_capable(task, CAP_SYS_PTRACE))
- task->ptrace |= PT_PTRACE_CAP;
+ flags |= PT_PTRACE_CAP;
+ task->ptrace = flags;
__ptrace_link(task, current);
@@ -865,7 +872,7 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
}
if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
- ret = ptrace_attach(child, request, data);
+ ret = ptrace_attach(child, request, addr, data);
/*
* Some architectures need to do book-keeping after
* a ptrace attach.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists