From: "Mickaël Salaün" <mic@digikod.net>
To: Christian Brauner <christian.brauner@ubuntu.com>,
Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
Oleg Nesterov <oleg@redhat.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
"Eric Paris" <eparis@redhat.com>,
"James Morris" <jmorris@namei.org>,
"Serge E . Hallyn" <serge@hallyn.com>,
"Tyler Hicks" <tyhicks@linux.microsoft.com>,
"Will Drewry" <wad@chromium.org>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
"Mickaël Salaün" <mic@linux.microsoft.com>
Subject: [PATCH v1 1/2] ptrace: Set PF_SUPERPRIV when checking capability
Date: Fri, 30 Oct 2020 13:38:48 +0100 [thread overview]
Message-ID: <20201030123849.770769-2-mic@digikod.net> (raw)
In-Reply-To: <20201030123849.770769-1-mic@digikod.net>
From: Mickaël Salaün <mic@linux.microsoft.com>
Commit 69f594a38967 ("ptrace: do not audit capability check when outputing
/proc/pid/stat") replaced the use of ns_capable() with
has_ns_capability{,_noaudit}() which doesn't set PF_SUPERPRIV.
Commit 6b3ad6649a4c ("ptrace: reintroduce usage of subjective credentials in
ptrace_has_cap()") replaced has_ns_capability{,_noaudit}() with
security_capable(), which doesn't set PF_SUPERPRIV neither.
Since commit 98f368e9e263 ("kernel: Add noaudit variant of ns_capable()"), a
new ns_capable_noaudit() helper is available. Let's use it!
As a result, the signature of ptrace_has_cap() is restored to its original one.
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: stable@vger.kernel.org
Fixes: 6b3ad6649a4c ("ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()")
Fixes: 69f594a38967 ("ptrace: do not audit capability check when outputing /proc/pid/stat")
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
---
kernel/ptrace.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 43d6179508d6..aa3c2fd6e41b 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -264,23 +264,17 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
return ret;
}
-static bool ptrace_has_cap(const struct cred *cred, struct user_namespace *ns,
- unsigned int mode)
+static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
{
- int ret;
-
if (mode & PTRACE_MODE_NOAUDIT)
- ret = security_capable(cred, ns, CAP_SYS_PTRACE, CAP_OPT_NOAUDIT);
- else
- ret = security_capable(cred, ns, CAP_SYS_PTRACE, CAP_OPT_NONE);
-
- return ret == 0;
+ return ns_capable_noaudit(ns, CAP_SYS_PTRACE);
+ return ns_capable(ns, CAP_SYS_PTRACE);
}
/* Returns 0 on success, -errno on denial. */
static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
{
- const struct cred *cred = current_cred(), *tcred;
+ const struct cred *const cred = current_cred(), *tcred;
struct mm_struct *mm;
kuid_t caller_uid;
kgid_t caller_gid;
@@ -326,7 +320,7 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
gid_eq(caller_gid, tcred->sgid) &&
gid_eq(caller_gid, tcred->gid))
goto ok;
- if (ptrace_has_cap(cred, tcred->user_ns, mode))
+ if (ptrace_has_cap(tcred->user_ns, mode))
goto ok;
rcu_read_unlock();
return -EPERM;
@@ -345,7 +339,7 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
mm = task->mm;
if (mm &&
((get_dumpable(mm) != SUID_DUMP_USER) &&
- !ptrace_has_cap(cred, mm->user_ns, mode)))
+ !ptrace_has_cap(mm->user_ns, mode)))
return -EPERM;
return security_ptrace_access_check(task, mode);
--
2.28.0
next prev parent reply other threads:[~2020-10-30 12:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-30 12:38 [PATCH v1 0/2] Fix misuse of security_capable() Mickaël Salaün
2020-10-30 12:38 ` Mickaël Salaün [this message]
2020-10-30 15:47 ` [PATCH v1 1/2] ptrace: Set PF_SUPERPRIV when checking capability Jann Horn
2020-10-30 16:06 ` Mickaël Salaün
2020-10-30 18:00 ` Jann Horn
2020-10-30 12:38 ` [PATCH v1 2/2] seccomp: " Mickaël Salaün
2020-10-30 15:34 ` Jann Horn
2020-11-17 21:08 ` [PATCH v1 0/2] Fix misuse of security_capable() Kees Cook
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