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bh=Owmoceg0LHhYZbdMp5jHogqJClJnU6VIhvIygZhSx5E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HKfvSh/JQvHoP2ydk6uJTkzsRsQ/NJ8Alqc0iKgaOH5ltjmm6/WOyFpfpgo6xWZn0 KggObs5mrXy3osHX568HDDzzwbuO7iyEW+yrvTQyZ8pHzrjWGm+t75oI2riyou0JqF IHufAKjOU3+8/7tAzX+vSUiKCE4oppqbkllajCn24cp5LTUT4diU9+qgBSah3s4pAb VJ3u/I2LaZ4DJf8A8O8W+oCUJV6VmNAL7pW75UbyXojUAkBfxdipC40L+IyDNdtZAT 2lRwPxx43Qo4MOMpSE1uSt99WhP1bUuSg18o0ux+b1OzMtMJ8ByJYUMXmFTJfQ7yY8 BrVOoEDTmzpbw== From: SeongJae Park To: Cc: skhan@linuxfoundation.org, keescook@chromium.org, akpm@linux-foundation.org, dmitry.torokhov@gmail.com, dverkamp@chromium.org, hughd@google.com, jeffxu@google.com, jorgelo@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, jannh@google.com, linux-hardening@vger.kernel.org, linux-security-module@vger.kernel.org, kernel test robot Subject: Re: [PATCH v7 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC Date: Fri, 16 Dec 2022 18:39:49 +0000 Message-Id: <20221216183949.169779-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221209160453.3246150-4-jeffxu@google.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 75DB7A0005 X-Stat-Signature: 5dcgqhykz455e8nuk1kb6f4hwnpczr1n X-HE-Tag: 1671215993-589623 X-HE-Meta: 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 c5erWCkt whArST93tKLqETLx7gRLSCazD74tJjRPZqMULcMSsH3c/pkJHYytn+SIhPoSx3i2AaemAQIyD6HTa7AV+H9YQqTvWpUw6Np+zMVV3/SV5TkB1jMY+W/aWIrmep8+f4NPpAzTOfivXTG1o7rJpg95Op1EiHDAVYmMjdufb4iRhKVBDsbKhh11SHS+kPBtZshWP+PZr X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Jeff, > From: Jeff Xu > > The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to > set executable bit at creation time (memfd_create). > > When MFD_NOEXEC_SEAL is set, memfd is created without executable bit > (mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to > be executable (mode: 0777) after creation. > > when MFD_EXEC flag is set, memfd is created with executable bit > (mode:0777), this is the same as the old behavior of memfd_create. > > The new pid namespaced sysctl vm.memfd_noexec has 3 values: > 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like > MFD_EXEC was set. > 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like > MFD_NOEXEC_SEAL was set. > 2: memfd_create() without MFD_NOEXEC_SEAL will be rejected. > > The sysctl allows finer control of memfd_create for old-software > that doesn't set the executable bit, for example, a container with > vm.memfd_noexec=1 means the old-software will create non-executable > memfd by default. Also, the value of memfd_noexec is passed to child > namespace at creation time. For example, if the init namespace has > vm.memfd_noexec=2, all its children namespaces will be created with 2. > > Signed-off-by: Jeff Xu > Co-developed-by: Daniel Verkamp > Signed-off-by: Daniel Verkamp > Reported-by: kernel test robot > --- [...] > diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c > index f4f8cb0435b4..8a98b1af9376 100644 > --- a/kernel/pid_namespace.c > +++ b/kernel/pid_namespace.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include "pid_sysctl.h" > > static DEFINE_MUTEX(pid_caches_mutex); > static struct kmem_cache *pid_ns_cachep; > @@ -110,6 +111,8 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns > ns->ucounts = ucounts; > ns->pid_allocated = PIDNS_ADDING; > > + initialize_memfd_noexec_scope(ns); > + > return ns; > > out_free_idr: > @@ -455,6 +458,8 @@ static __init int pid_namespaces_init(void) > #ifdef CONFIG_CHECKPOINT_RESTORE > register_sysctl_paths(kern_path, pid_ns_ctl_table); > #endif > + > + register_pid_ns_sysctl_table_vm(); > return 0; > } [...] > > diff --git a/kernel/pid_sysctl.h b/kernel/pid_sysctl.h > new file mode 100644 > index 000000000000..90a93161a122 > --- /dev/null > +++ b/kernel/pid_sysctl.h > @@ -0,0 +1,59 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef LINUX_PID_SYSCTL_H > +#define LINUX_PID_SYSCTL_H > + > +#include > + > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE) > +static inline void initialize_memfd_noexec_scope(struct pid_namespace *ns) [...] > +static inline void register_pid_ns_sysctl_table_vm(void) > +{ > + register_sysctl_paths(vm_path, pid_ns_ctl_table_vm); > +} > +#else > +static inline void set_memfd_noexec_scope(struct pid_namespace *ns) {} > +static inline void register_pid_ns_ctl_table_vm(void) {} > +#endif [...] I found this patch makes build fails whne CONFIG_SYSCTL or CONFIG_MEMFD_CREATE are not defined, as initialize_memfd_noexec_scope() and register_pid_ns_sysctl_table_vm() are used from pid_namespace.c without the configs protection. I just posted a patch for that: https://lore.kernel.org/linux-mm/20221216183314.169707-1-sj@kernel.org/ Could you please check? Thanks, SJ