From 974802eaa1afdc87e00821df7020a2b3c6fee623 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 12 Jun 2009 12:46:55 +0200 Subject: perf_counter: Add forward/backward attribute ABI compatibility Provide for means of extending the perf_counter_attr in a 'natural' way. We allow growing the structure by appending fields at the end by specifying the full structure size inside it. When a new kernel sees a smaller (old) structure, it will 0 pad the tail. When an old kernel sees a larger (new) structure, it will verify the tail consists of 0s, otherwise fail. If we fail due to a size-mismatch, we return -E2BIG and write the kernel's native attribe size back into the provided structure. Furthermore, add some attribute verification, so that we'll fail counter creation when unknown bits are present (PERF_SAMPLE, PERF_FORMAT, or in the __reserved fields). (This ABI detail is introduced while keeping the existing syscall ABI.) Signed-off-by: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 86 insertions(+), 3 deletions(-) (limited to 'kernel/perf_counter.c') diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 663bbe01505..29b685f551a 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -3584,6 +3584,9 @@ perf_counter_alloc(struct perf_counter_attr *attr, case PERF_TYPE_TRACEPOINT: pmu = tp_perf_counter_init(counter); break; + + default: + break; } done: err = 0; @@ -3610,6 +3613,85 @@ done: return counter; } +static int perf_copy_attr(struct perf_counter_attr __user *uattr, + struct perf_counter_attr *attr) +{ + int ret; + u32 size; + + if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0)) + return -EFAULT; + + /* + * zero the full structure, so that a short copy will be nice. + */ + memset(attr, 0, sizeof(*attr)); + + ret = get_user(size, &uattr->size); + if (ret) + return ret; + + if (size > PAGE_SIZE) /* silly large */ + goto err_size; + + if (!size) /* abi compat */ + size = PERF_ATTR_SIZE_VER0; + + if (size < PERF_ATTR_SIZE_VER0) + goto err_size; + + /* + * If we're handed a bigger struct than we know of, + * ensure all the unknown bits are 0. + */ + if (size > sizeof(*attr)) { + unsigned long val; + unsigned long __user *addr; + unsigned long __user *end; + + addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr), + sizeof(unsigned long)); + end = PTR_ALIGN((void __user *)uattr + size, + sizeof(unsigned long)); + + for (; addr < end; addr += sizeof(unsigned long)) { + ret = get_user(val, addr); + if (ret) + return ret; + if (val) + goto err_size; + } + } + + ret = copy_from_user(attr, uattr, size); + if (ret) + return -EFAULT; + + /* + * If the type exists, the corresponding creation will verify + * the attr->config. + */ + if (attr->type >= PERF_TYPE_MAX) + return -EINVAL; + + if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3) + return -EINVAL; + + if (attr->sample_type & ~(PERF_SAMPLE_MAX-1)) + return -EINVAL; + + if (attr->read_format & ~(PERF_FORMAT_MAX-1)) + return -EINVAL; + +out: + return ret; + +err_size: + put_user(sizeof(*attr), &uattr->size); + ret = -E2BIG; + goto out; +} + /** * sys_perf_counter_open - open a performance counter, associate it to a task/cpu * @@ -3619,7 +3701,7 @@ done: * @group_fd: group leader counter fd */ SYSCALL_DEFINE5(perf_counter_open, - const struct perf_counter_attr __user *, attr_uptr, + struct perf_counter_attr __user *, attr_uptr, pid_t, pid, int, cpu, int, group_fd, unsigned long, flags) { struct perf_counter *counter, *group_leader; @@ -3635,8 +3717,9 @@ SYSCALL_DEFINE5(perf_counter_open, if (flags) return -EINVAL; - if (copy_from_user(&attr, attr_uptr, sizeof(attr)) != 0) - return -EFAULT; + ret = perf_copy_attr(attr_uptr, &attr); + if (ret) + return ret; if (!attr.exclude_kernel) { if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) -- cgit v1.2.3