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Hallyn" To: Jinjie Ruan Cc: kees@kernel.org, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, paul@paul-moore.com, jmorris@namei.org, shuah@kernel.org, oleg@redhat.com, brauner@kernel.org, alexjlzheng@tencent.com, jannh@google.com, jaime.saguillo@gmail.com, elver@google.com, blbllhy@gmail.com, bvanassche@acm.org, pjw@kernel.org, broonie@kernel.org, debug@rivosinc.com, tglx@kernel.org, aleksey.oladko@virtuozzo.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, morgan@kernel.org Subject: Re: [RFC PATCH v2 0/3] security: Add PR_CAPBSET_DROP_MASK Message-ID: References: <20260929130200.1638343-1-ruanjinjie@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260929130200.1638343-1-ruanjinjie@huawei.com> X-Rspamd-Queue-Id: 13E1D20009 X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: s643hkxq7s4e1fpthco5nb9jw68ydewg X-HE-Tag: 1791900550-43831 X-HE-Meta: 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 p8o/5f+/ YG/8QmMrTYO8p/JXUW/sC1elUq3z6UpOhf8K9Wqk7+TUJjKusm3J43YY1onI/nSwV83tIlWrOEuMJRjDRhGHf0INk0ezDZ//chTy45PH/Ke1DXk9CDhzqLeuQXvSKPjO0RPzvzlcxxMvwIeg+ymNUKU3sd4Z8MeB203dokf+ZRdm/wcAkpr+FCUvNLTKCo1hla7CP99m7mUn7oO5S11KShA12siMlQcdFcjhRVKDdg0tXsuiLRCNLfYKiWolCKk3x+u/O+GQ2yogGsKNQXBZ0fIW8cZ+qlERpWrjjDguFDqbwYWy8paSc+0HW3fcYvfhfZ3RbP6YsnfJJDh9WZVs5gJT9zxrIf6upwSntk4hFytTd7iCr0zEXJwhwKwc3LuypiZJEVmhZvJ9+p6DC3DiuTbwc8FNfdqfevp+Q678IzgKv0YmyLq0n4YX73w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 29, 2026 at 09:01:57PM +0800, Jinjie Ruan wrote: > PR_CAPBSET_DROP only affects the calling thread, so dropping capabilities > for a whole process means one call per capability per thread. For a > long-lived, multi-threaded process such as gVisor's sentry this is > stop-the-world signal delivery and costs milliseconds per sandbox on a > many-core host. > > This series adds PR_CAPBSET_DROP_MASK, which removes a 64-bit mask of > capabilities from the whole thread group in a single call. The drop is > recorded per thread group and folded into the bounding set wherever it > gates gaining a capability, so already-running, concurrently-created and > later-created threads -- as well as children forked by a sibling -- all > observe it. > > Trimming 41 capabilities in an arm64 KVM guest goes from ~8.5-23.6ms with > the per-thread loop to ~11-14us, independent of the thread count. > > Changes in RFC v2: > - Solve concurrently clone and concurrently drop mask problem. > - Solove sashiko problems in [1]. > - Link to RFC v1: https://lore.kernel.org/all/20260922095816.1191799-1-ruanjinjie@huawei.com/ > [1] https://sashiko.dev/#/patchset/20260922095816.1191799-1-ruanjinjie%40huawei.com Sorry, somehow I didn't notice this version until today. I will take a close look later this week. Thanks. > Jinjie Ruan (3): > capability: Move mk_kernel_cap() to header > security: Add PR_CAPBSET_DROP_MASK for process-wide bounding-set drops > selftests: prctl: add process-wide bounding-set drop tests > > fs/proc/array.c | 3 +- > include/linux/capability.h | 10 + > include/linux/sched/signal.h | 8 + > include/uapi/linux/prctl.h | 1 + > kernel/capability.c | 5 - > kernel/fork.c | 1 + > security/commoncap.c | 91 ++- > tools/testing/selftests/prctl/Makefile | 12 +- > .../selftests/prctl/cap-bset-drop-test.c | 641 ++++++++++++++++++ > 9 files changed, 759 insertions(+), 13 deletions(-) > create mode 100644 tools/testing/selftests/prctl/cap-bset-drop-test.c > > -- > 2.34.1