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ptrace: Set PF_SUPERPRIV when checking capability 

Commit 69f594a389 ("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 6b3ad6649a ("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 98f368e9e2 ("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: 6b3ad6649a ("ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()")
Fixes: 69f594a389 ("ptrace: do not audit capability check when outputing /proc/pid/stat")
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Jann Horn <jannh@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201030123849.770769-2-mic@digikod.net
This commit is contained in:
Mickaël Salaün 2020-10-30 13:38:48 +01:00 committed by Kees Cook
parent 09162bc32c
commit cf23705244
1 changed files with 5 additions and 11 deletions
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16
kernel/ptrace.c
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@ -264,17 +264,11 @@ 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. */
@ -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);