kernel/include/linux/bpf.h, branch linux-6.16.y

bpf: Fix oob access in cgroup local storage

2025-08-15T14:39:14Z

[ Upstream commit abad3d0bad72a52137e0c350c59542d75ae4f513 ] Lonial reported that an out-of-bounds access in cgroup local storage can be crafted via tail calls. Given two programs each utilizing a cgroup local storage with a different value size, and one program doing a tail call into the other. The verifier will validate each of the indivial programs just fine. However, in the runtime context the bpf_cg_run_ctx holds an bpf_prog_array_item which contains the BPF program as well as any cgroup local storage flavor the program uses. Helpers such as bpf_get_local_storage() pick this up from the runtime context: ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx); storage = ctx->prog_item->cgroup_storage[stype]; if (stype == BPF_CGROUP_STORAGE_SHARED) ptr = &READ_ONCE(storage->buf)->data[0]; else ptr = this_cpu_ptr(storage->percpu_buf); For the second program which was called from the originally attached one, this means bpf_get_local_storage() will pick up the former program's map, not its own. With mismatching sizes, this can result in an unintended out-of-bounds access. To fix this issue, we need to extend bpf_map_owner with an array of storage_cookie[] to match on i) the exact maps from the original program if the second program was using bpf_get_local_storage(), or ii) allow the tail call combination if the second program was not using any of the cgroup local storage maps. Fixes: 7d9c3427894f ("bpf: Make cgroup storages shared between programs on the same cgroup") Reported-by: Lonial Con Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-4-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

bpf: Move cgroup iterator helpers to bpf.h

2025-08-15T14:39:14Z

[ Upstream commit 9621e60f59eae87eb9ffe88d90f24f391a1ef0f0 ] Move them into bpf.h given we also need them in core code. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-3-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Stable-dep-of: abad3d0bad72 ("bpf: Fix oob access in cgroup local storage") Signed-off-by: Sasha Levin

bpf: Move bpf map owner out of common struct

2025-08-15T14:39:14Z

[ Upstream commit fd1c98f0ef5cbcec842209776505d9e70d8fcd53 ] Given this is only relevant for BPF tail call maps, it is adding up space and penalizing other map types. We also need to extend this with further objects to track / compare to. Therefore, lets move this out into a separate structure and dynamically allocate it only for BPF tail call maps. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-2-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Stable-dep-of: abad3d0bad72 ("bpf: Fix oob access in cgroup local storage") Signed-off-by: Sasha Levin

bpf: Add cookie object to bpf maps

2025-08-15T14:39:14Z

[ Upstream commit 12df58ad294253ac1d8df0c9bb9cf726397a671d ] Add a cookie to BPF maps to uniquely identify BPF maps for the timespan when the node is up. This is different to comparing a pointer or BPF map id which could get rolled over and reused. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Stable-dep-of: abad3d0bad72 ("bpf: Fix oob access in cgroup local storage") Signed-off-by: Sasha Levin

bpf: WARN_ONCE on verifier bugs

2025-05-19T15:17:08Z

Throughout the verifier's logic, there are multiple checks for inconsistent states that should never happen and would indicate a verifier bug. These bugs are typically logged in the verifier logs and sometimes preceded by a WARN_ONCE. This patch reworks these checks to consistently emit a verifier log AND a warning when CONFIG_DEBUG_KERNEL is enabled. The consistent use of WARN_ONCE should help fuzzers (ex. syzkaller) expose any situation where they are actually able to reach one of those buggy verifier states. Acked-by: Andrii Nakryiko Signed-off-by: Paul Chaignon Link: https://lore.kernel.org/r/aCs1nYvNNMq8dAWP@mail.gmail.com Signed-off-by: Alexei Starovoitov

helpers: make few bpf helpers public

2025-05-13T01:29:03Z

Make bpf_dynptr_slice_rdwr, bpf_dynptr_check_off_len and __bpf_dynptr_write available outside of the helpers.c by adding their prototypes into linux/include/bpf.h. bpf_dynptr_check_off_len() implementation is moved to header and made inline explicitly, as small function should typically be inlined. These functions are going to be used from bpf_trace.c in the next patch of this series. Acked-by: Andrii Nakryiko Signed-off-by: Mykyta Yatsenko Link: https://lore.kernel.org/r/20250512205348.191079-2-mykyta.yatsenko5@gmail.com Signed-off-by: Alexei Starovoitov

Merge tag 'bpf_try_alloc_pages' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2025-03-30T20:45:28Z

Pull bpf try_alloc_pages() support from Alexei Starovoitov: "The pull includes work from Sebastian, Vlastimil and myself with a lot of help from Michal and Shakeel. This is a first step towards making kmalloc reentrant to get rid of slab wrappers: bpf_mem_alloc, kretprobe's objpool, etc. These patches make page allocator safe from any context. Vlastimil kicked off this effort at LSFMM 2024: https://lwn.net/Articles/974138/ and we continued at LSFMM 2025: https://lore.kernel.org/all/CAADnVQKfkGxudNUkcPJgwe3nTZ=xohnRshx9kLZBTmR_E1DFEg@mail.gmail.com/ Why: SLAB wrappers bind memory to a particular subsystem making it unavailable to the rest of the kernel. Some BPF maps in production consume Gbytes of preallocated memory. Top 5 in Meta: 1.5G, 1.2G, 1.1G, 300M, 200M. Once we have kmalloc that works in any context BPF map preallocation won't be necessary. How: Synchronous kmalloc/page alloc stack has multiple stages going from fast to slow: cmpxchg16 -> slab_alloc -> new_slab -> alloc_pages -> rmqueue_pcplist -> __rmqueue, where rmqueue_pcplist was already relying on trylock. This set changes rmqueue_bulk/rmqueue_buddy to attempt a trylock and return ENOMEM if alloc_flags & ALLOC_TRYLOCK. It then wraps this functionality into try_alloc_pages() helper. We make sure that the logic is sane in PREEMPT_RT. End result: try_alloc_pages()/free_pages_nolock() are safe to call from any context. try_kmalloc() for any context with similar trylock approach will follow. It will use try_alloc_pages() when slab needs a new page. Though such try_kmalloc/page_alloc() is an opportunistic allocator, this design ensures that the probability of successful allocation of small objects (up to one page in size) is high. Even before we have try_kmalloc(), we already use try_alloc_pages() in BPF arena implementation and it's going to be used more extensively in BPF" * tag 'bpf_try_alloc_pages' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: mm: Fix the flipped condition in gfpflags_allow_spinning() bpf: Use try_alloc_pages() to allocate pages for bpf needs. mm, bpf: Use memcg in try_alloc_pages(). memcg: Use trylock to access memcg stock_lock. mm, bpf: Introduce free_pages_nolock() mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation locking/local_lock: Introduce localtry_lock_t

Merge tag 'bpf_res_spin_lock' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2025-03-30T20:06:27Z

Pull bpf relisient spinlock support from Alexei Starovoitov: "This patch set introduces Resilient Queued Spin Lock (or rqspinlock with res_spin_lock() and res_spin_unlock() APIs). This is a qspinlock variant which recovers the kernel from a stalled state when the lock acquisition path cannot make forward progress. This can occur when a lock acquisition attempt enters a deadlock situation (e.g. AA, or ABBA), or more generally, when the owner of the lock (which we’re trying to acquire) isn’t making forward progress. Deadlock detection is the main mechanism used to provide instant recovery, with the timeout mechanism acting as a final line of defense. Detection is triggered immediately when beginning the waiting loop of a lock slow path. Additionally, BPF programs attached to different parts of the kernel can introduce new control flow into the kernel, which increases the likelihood of deadlocks in code not written to handle reentrancy. There have been multiple syzbot reports surfacing deadlocks in internal kernel code due to the diverse ways in which BPF programs can be attached to different parts of the kernel. By switching the BPF subsystem’s lock usage to rqspinlock, all of these issues are mitigated at runtime. This spin lock implementation allows BPF maps to become safer and remove mechanisms that have fallen short in assuring safety when nesting programs in arbitrary ways in the same context or across different contexts. We run benchmarks that stress locking scalability and perform comparison against the baseline (qspinlock). For the rqspinlock case, we replace the default qspinlock with it in the kernel, such that all spin locks in the kernel use the rqspinlock slow path. As such, benchmarks that stress kernel spin locks end up exercising rqspinlock. More details in the cover letter in commit 6ffb9017e932 ("Merge branch 'resilient-queued-spin-lock'")" * tag 'bpf_res_spin_lock' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (24 commits) selftests/bpf: Add tests for rqspinlock bpf: Maintain FIFO property for rqspinlock unlock bpf: Implement verifier support for rqspinlock bpf: Introduce rqspinlock kfuncs bpf: Convert lpm_trie.c to rqspinlock bpf: Convert percpu_freelist.c to rqspinlock bpf: Convert hashtab.c to rqspinlock rqspinlock: Add locktorture support rqspinlock: Add entry to Makefile, MAINTAINERS rqspinlock: Add macros for rqspinlock usage rqspinlock: Add basic support for CONFIG_PARAVIRT rqspinlock: Add a test-and-set fallback rqspinlock: Add deadlock detection and recovery rqspinlock: Protect waiters in trylock fallback from stalls rqspinlock: Protect waiters in queue from stalls rqspinlock: Protect pending bit owners from stalls rqspinlock: Hardcode cond_acquire loops for arm64 rqspinlock: Add support for timeouts rqspinlock: Drop PV and virtualization support rqspinlock: Add rqspinlock.h header ...

bpf: Add struct_ops context information to struct bpf_prog_aux

2025-03-20T23:54:41Z

This patch adds struct_ops context information to struct bpf_prog_aux. This context information will be used in the kfunc filter. Currently the added context information includes struct_ops member offset and a pointer to struct bpf_struct_ops. Signed-off-by: Juntong Deng Signed-off-by: Amery Hung Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Link: https://patch.msgid.link/20250319215358.2287371-2-ameryhung@gmail.com

bpf: Implement verifier support for rqspinlock

2025-03-19T15:03:06Z

Introduce verifier-side support for rqspinlock kfuncs. The first step is allowing bpf_res_spin_lock type to be defined in map values and allocated objects, so BTF-side is updated with a new BPF_RES_SPIN_LOCK field to recognize and validate. Any object cannot have both bpf_spin_lock and bpf_res_spin_lock, only one of them (and at most one of them per-object, like before) must be present. The bpf_res_spin_lock can also be used to protect objects that require lock protection for their kfuncs, like BPF rbtree and linked list. The verifier plumbing to simulate success and failure cases when calling the kfuncs is done by pushing a new verifier state to the verifier state stack which will verify the failure case upon calling the kfunc. The path where success is indicated creates all lock reference state and IRQ state (if necessary for irqsave variants). In the case of failure, the state clears the registers r0-r5, sets the return value, and skips kfunc processing, proceeding to the next instruction. When marking the return value for success case, the value is marked as 0, and for the failure case as [-MAX_ERRNO, -1]. Then, in the program, whenever user checks the return value as 'if (ret)' or 'if (ret < 0)' the verifier never traverses such branches for success cases, and would be aware that the lock is not held in such cases. We push the kfunc state in check_kfunc_call whenever rqspinlock kfuncs are invoked. We introduce a kfunc_class state to avoid mixing lock irqrestore kfuncs with IRQ state created by bpf_local_irq_save. With all this infrastructure, these kfuncs become usable in programs while satisfying all safety properties required by the kernel. Acked-by: Eduard Zingerman Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250316040541.108729-24-memxor@gmail.com Signed-off-by: Alexei Starovoitov