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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id a9sm119023pfo.69.2021.06.15.14.50.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jun 2021 14:50:40 -0700 (PDT) Date: Tue, 15 Jun 2021 14:50:39 -0700 From: Kees Cook To: Linus Torvalds Cc: youling 257 , Christian Brauner , Andrea Righi , Linux Kernel Mailing List , stable , regressions@lists.linux.dev, LSM List , Paul Moore , Stephen Smalley , SElinux list Subject: Re: [PATCH] proc: Track /proc/$pid/attr/ opener mm_struct Message-ID: <202106151449.816D7DA682@keescook> References: <20210608171221.276899-1-keescook@chromium.org> <20210614100234.12077-1-youling257@gmail.com> <202106140826.7912F27CD@keescook> <202106140941.7CE5AE64@keescook> <202106141503.B3144DFE@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Jun 15, 2021 at 11:19:04AM -0700, Linus Torvalds wrote: > On Mon, Jun 14, 2021 at 6:55 PM youling 257 wrote: > > > > if try to find problem on userspace, i used linux 5.13rc6 on old > > android 7 cm14.1, not aosp android 11. > > http://git.osdn.net/view?p=android-x86/system-core.git;a=blob;f=init/service.cpp;h=a5334f447fc2fc34453d2f6a37523bedccadc690;hb=refs/heads/cm-14.1-x86#l457 > > > > 457 if (!seclabel_.empty()) { > > 458 if (setexeccon(seclabel_.c_str()) < 0) { > > 459 ERROR("cannot setexeccon('%s'): %s\n", > > 460 seclabel_.c_str(), strerror(errno)); > > 461 _exit(127); > > 462 } > > 463 } > > I have no idea where the cm14.1 libraries are. Does anybody know where > the matching source code for setexeccon() would be? > > For me - obviously not on cm14.1 - all "setexeccon()" does is > > n = openat(AT_FDCWD, "/proc/thread-self/attr/exec", O_RDWR|O_CLOEXEC) > write(n, string, len) > close(n) > > and if that fails, it would seem to indicate that proc_mem_open() > failed. Which would be mm_access() failing. But I don't see how that > can be the case, because mm_access() explicitly allows "mm == > current->mm" (which the above clearly should be). Yeah, that was what I saw too. > youling, can you double-check with the current -git tree? But as far > as I can tell, my minimal patch is exactly the same as Kees' patch > (just smaller and simpler). FWIW, for that patch: Acked-by: Kees Cook Cc: stable@vger.kernel.org > > Kees, do you see anything? No, I haven't been able to reproduce the failure. :( -- Kees Cook