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This is similar to `bpf_copy_from_user_str` but accepts a `struct task_struct*` argument. Signed-off-by: Jordan Rome Acked-by: Andrii Nakryiko --- kernel/bpf/helpers.c | 51 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) -- 2.43.5 diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index f27ce162427a..c26fabf97afd 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3082,6 +3082,56 @@ __bpf_kfunc void bpf_local_irq_restore(unsigned long *flags__irq_flag) local_irq_restore(*flags__irq_flag); } +/** + * bpf_copy_from_user_task_str() - Copy a string from an task's address space + * @dst: Destination address, in kernel space. This buffer must be + * at least @dst__sz bytes long. + * @dst__sz: Maximum number of bytes to copy, includes the trailing NUL. + * @unsafe_ptr__ign: Source address in the task's address space. + * @tsk: The task whose address space will be used + * @flags: The only supported flag is BPF_F_PAD_ZEROS + * + * Copies a NULL-terminated string from a task's address space to *dst* buffer. + * If user string is too long this will still ensure zero termination in the + * dst buffer unless buffer size is 0. + * + * If BPF_F_PAD_ZEROS flag is set, memset the tail of @dst to 0 on success and + * memset all of @dst on failure. + * + * Return: The number of copied bytes on success, including the NULL-terminator. + * A negative error code on failure. + */ +__bpf_kfunc int bpf_copy_from_user_task_str(void *dst, + u32 dst__sz, + const void __user *unsafe_ptr__ign, + struct task_struct *tsk, + u64 flags) +{ + int ret = 0; + + if (unlikely(flags & ~BPF_F_PAD_ZEROS)) + return -EINVAL; + + if (unlikely(!dst__sz)) + return 0; + + ret = copy_remote_vm_str(tsk, (unsigned long)unsafe_ptr__ign, dst, dst__sz, 0); + + if (ret <= 0) { + if (flags & BPF_F_PAD_ZEROS) + memset(dst, 0, dst__sz); + return ret ?: -EINVAL; + } + + if (ret < dst__sz) { + if (flags & BPF_F_PAD_ZEROS) + memset(dst + ret, 0, dst__sz - ret); + return ret + 1; + } + + return ret; +} + __bpf_kfunc_end_defs(); BTF_KFUNCS_START(generic_btf_ids) @@ -3174,6 +3224,7 @@ BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW) BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_copy_from_user_task_str, KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_get_kmem_cache) BTF_ID_FLAGS(func, bpf_iter_kmem_cache_new, KF_ITER_NEW | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_iter_kmem_cache_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE)