From 51d6ca373f459fa6c91743e14ae69854d844aa38 Mon Sep 17 00:00:00 2001 From: Thomas Weißschuh Date: Tue, 4 Feb 2025 13:05:38 +0100 Subject: vdso: Add generic random data storage MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Extend the generic vDSO data storage with a page for the random state data. The random state data is stored in a dedicated page, as the existing storage page is only meant for time-related, time-namespace-aware data. This simplifies to access logic to not need to handle time namespaces anymore and also frees up more space in the time-related page. In case further generic vDSO data store is required it can be added to the random state page. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-6-13a4669dfc8c@linutronix.de --- lib/vdso/datastore.c | 14 ++++++++++++++ lib/vdso/getrandom.c | 8 ++++++-- 2 files changed, 20 insertions(+), 2 deletions(-) (limited to 'lib/vdso') diff --git a/lib/vdso/datastore.c b/lib/vdso/datastore.c index d3181768424c..9260b00dc852 100644 --- a/lib/vdso/datastore.c +++ b/lib/vdso/datastore.c @@ -17,6 +17,15 @@ struct vdso_time_data *vdso_k_time_data = vdso_time_data_store.data; static_assert(sizeof(vdso_time_data_store) == PAGE_SIZE); #endif /* CONFIG_HAVE_GENERIC_VDSO */ +#ifdef CONFIG_VDSO_GETRANDOM +static union { + struct vdso_rng_data data; + u8 page[PAGE_SIZE]; +} vdso_rng_data_store __page_aligned_data; +struct vdso_rng_data *vdso_k_rng_data = &vdso_rng_data_store.data; +static_assert(sizeof(vdso_rng_data_store) == PAGE_SIZE); +#endif /* CONFIG_VDSO_GETRANDOM */ + static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) { @@ -53,6 +62,11 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, return VM_FAULT_SIGBUS; pfn = __phys_to_pfn(__pa_symbol(vdso_k_time_data)); break; + case VDSO_RNG_PAGE_OFFSET: + if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM)) + return VM_FAULT_SIGBUS; + pfn = __phys_to_pfn(__pa_symbol(vdso_k_rng_data)); + break; default: return VM_FAULT_SIGBUS; } diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c index 938ca539aaa6..440f8a6203a6 100644 --- a/lib/vdso/getrandom.c +++ b/lib/vdso/getrandom.c @@ -12,6 +12,9 @@ #include #include +/* Bring in default accessors */ +#include + #undef PAGE_SIZE #undef PAGE_MASK #define PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) @@ -152,7 +155,7 @@ retry_generation: /* * Prevent the syscall from being reordered wrt current_generation. Pairs with the - * smp_store_release(&_vdso_rng_data.generation) in random.c. + * smp_store_release(&vdso_k_rng_data->generation) in random.c. */ smp_rmb(); @@ -256,5 +259,6 @@ fallback_syscall: static __always_inline ssize_t __cvdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len) { - return __cvdso_getrandom_data(__arch_get_vdso_rng_data(), buffer, len, flags, opaque_state, opaque_len); + return __cvdso_getrandom_data(__arch_get_vdso_u_rng_data(), buffer, len, flags, + opaque_state, opaque_len); } -- cgit v1.2.3