From 7f645462ca01d01abb94d75e6768c8b3ed3a188b Mon Sep 17 00:00:00 2001 From: Wei Yongjun Date: Thu, 30 Apr 2020 08:18:51 +0000 Subject: bpf: Fix error return code in map_lookup_and_delete_elem() Fix to return negative error code -EFAULT from the copy_to_user() error handling case instead of 0, as done elsewhere in this function. Fixes: bd513cd08f10 ("bpf: add MAP_LOOKUP_AND_DELETE_ELEM syscall") Signed-off-by: Wei Yongjun Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20200430081851.166996-1-weiyongjun1@huawei.com --- kernel/bpf/syscall.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7626b8024471..2843bbba9ca1 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1485,8 +1485,10 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr) if (err) goto free_value; - if (copy_to_user(uvalue, value, value_size) != 0) + if (copy_to_user(uvalue, value, value_size) != 0) { + err = -EFAULT; goto free_value; + } err = 0; -- cgit v1.2.3-71-gd317 From 333291ce5055f2039afc907badaf5b66bc1adfdc Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 12 May 2020 16:59:25 -0700 Subject: bpf: Fix bug in mmap() implementation for BPF array map mmap() subsystem allows user-space application to memory-map region with initial page offset. This wasn't taken into account in initial implementation of BPF array memory-mapping. This would result in wrong pages, not taking into account requested page shift, being memory-mmaped into user-space. This patch fixes this gap and adds a test for such scenario. Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200512235925.3817805-1-andriin@fb.com --- kernel/bpf/arraymap.c | 7 ++++++- tools/testing/selftests/bpf/prog_tests/mmap.c | 8 ++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 95d77770353c..1d6120fd5ba6 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -486,7 +486,12 @@ static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma) if (!(map->map_flags & BPF_F_MMAPABLE)) return -EINVAL; - return remap_vmalloc_range(vma, array_map_vmalloc_addr(array), pgoff); + if (vma->vm_pgoff * PAGE_SIZE + (vma->vm_end - vma->vm_start) > + PAGE_ALIGN((u64)array->map.max_entries * array->elem_size)) + return -EINVAL; + + return remap_vmalloc_range(vma, array_map_vmalloc_addr(array), + vma->vm_pgoff + pgoff); } const struct bpf_map_ops array_map_ops = { diff --git a/tools/testing/selftests/bpf/prog_tests/mmap.c b/tools/testing/selftests/bpf/prog_tests/mmap.c index 56d80adcf4bd..6b9dce431d41 100644 --- a/tools/testing/selftests/bpf/prog_tests/mmap.c +++ b/tools/testing/selftests/bpf/prog_tests/mmap.c @@ -217,6 +217,14 @@ void test_mmap(void) munmap(tmp2, 4 * page_size); + /* map all 4 pages, but with pg_off=1 page, should fail */ + tmp1 = mmap(NULL, 4 * page_size, PROT_READ, MAP_SHARED | MAP_FIXED, + data_map_fd, page_size /* initial page shift */); + if (CHECK(tmp1 != MAP_FAILED, "adv_mmap7", "unexpected success")) { + munmap(tmp1, 4 * page_size); + goto cleanup; + } + tmp1 = mmap(NULL, map_sz, PROT_READ, MAP_SHARED, data_map_fd, 0); if (CHECK(tmp1 == MAP_FAILED, "last_mmap", "failed %d\n", errno)) goto cleanup; -- cgit v1.2.3-71-gd317 From e92888c72fbdc6f9d07b3b0604c012e81d7c0da7 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Wed, 13 May 2020 22:32:05 -0700 Subject: bpf: Enforce returning 0 for fentry/fexit progs Currently, tracing/fentry and tracing/fexit prog return values are not enforced. In trampoline codes, the fentry/fexit prog return values are ignored. Let us enforce it to be 0 to avoid confusion and allows potential future extension. This patch also explicitly added return value checking for tracing/raw_tp, tracing/fmod_ret, and freplace programs such that these program return values can be anything. The purpose are two folds: 1. to make it explicit about return value expectations for these programs in verifier. 2. for tracing prog_type, if a future attach type is added, the default is -ENOTSUPP which will enforce to specify return value ranges explicitly. Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline") Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200514053206.1298415-1-yhs@fb.com --- kernel/bpf/verifier.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fa1d8245b925..a44ba6672688 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7059,6 +7059,23 @@ static int check_return_code(struct bpf_verifier_env *env) return 0; range = tnum_const(0); break; + case BPF_PROG_TYPE_TRACING: + switch (env->prog->expected_attach_type) { + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + range = tnum_const(0); + break; + case BPF_TRACE_RAW_TP: + case BPF_MODIFY_RETURN: + return 0; + default: + return -ENOTSUPP; + } + break; + case BPF_PROG_TYPE_EXT: + /* freplace program can return anything as its return value + * depends on the to-be-replaced kernel func or bpf program. + */ default: return 0; } -- cgit v1.2.3-71-gd317 From 47cc0ed574abcbbde0cf143ddb21a0baed1aa2df Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 15 May 2020 12:11:17 +0200 Subject: bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range Given bpf_probe_read{,str}() BPF helpers are now only available under CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, we need to add the drop-in replacements of bpf_probe_read_{kernel,user}_str() to do_refine_retval_range() as well to avoid hitting the same issue as in 849fa50662fbc ("bpf/verifier: refine retval R0 state for bpf_get_stack helper"). Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200515101118.6508-3-daniel@iogearbox.net --- kernel/bpf/verifier.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a44ba6672688..8d7ee40e2748 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4340,7 +4340,9 @@ static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type, if (ret_type != RET_INTEGER || (func_id != BPF_FUNC_get_stack && - func_id != BPF_FUNC_probe_read_str)) + func_id != BPF_FUNC_probe_read_str && + func_id != BPF_FUNC_probe_read_kernel_str && + func_id != BPF_FUNC_probe_read_user_str)) return; ret_reg->smax_value = meta->msize_max_value; -- cgit v1.2.3-71-gd317 From dfeb376dd4cb2c5004aeb625e2475f58a5ff2ea7 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 18 May 2020 22:38:24 -0700 Subject: bpf: Prevent mmap()'ing read-only maps as writable As discussed in [0], it's dangerous to allow mapping BPF map, that's meant to be frozen and is read-only on BPF program side, because that allows user-space to actually store a writable view to the page even after it is frozen. This is exacerbated by BPF verifier making a strong assumption that contents of such frozen map will remain unchanged. To prevent this, disallow mapping BPF_F_RDONLY_PROG mmap()'able BPF maps as writable, ever. [0] https://lore.kernel.org/bpf/CAEf4BzYGWYhXdp6BJ7_=9OQPJxQpgug080MMjdSB72i9R+5c6g@mail.gmail.com/ Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") Suggested-by: Jann Horn Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Reviewed-by: Jann Horn Link: https://lore.kernel.org/bpf/20200519053824.1089415-1-andriin@fb.com --- kernel/bpf/syscall.c | 17 ++++++++++++++--- tools/testing/selftests/bpf/prog_tests/mmap.c | 13 ++++++++++++- tools/testing/selftests/bpf/progs/test_mmap.c | 8 ++++++++ 3 files changed, 34 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 2843bbba9ca1..4e6dee19a668 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -623,9 +623,20 @@ static int bpf_map_mmap(struct file *filp, struct vm_area_struct *vma) mutex_lock(&map->freeze_mutex); - if ((vma->vm_flags & VM_WRITE) && map->frozen) { - err = -EPERM; - goto out; + if (vma->vm_flags & VM_WRITE) { + if (map->frozen) { + err = -EPERM; + goto out; + } + /* map is meant to be read-only, so do not allow mapping as + * writable, because it's possible to leak a writable page + * reference and allows user-space to still modify it after + * freezing, while verifier will assume contents do not change + */ + if (map->map_flags & BPF_F_RDONLY_PROG) { + err = -EACCES; + goto out; + } } /* set default open/close callbacks */ diff --git a/tools/testing/selftests/bpf/prog_tests/mmap.c b/tools/testing/selftests/bpf/prog_tests/mmap.c index 6b9dce431d41..43d0b5578f46 100644 --- a/tools/testing/selftests/bpf/prog_tests/mmap.c +++ b/tools/testing/selftests/bpf/prog_tests/mmap.c @@ -19,7 +19,7 @@ void test_mmap(void) const size_t map_sz = roundup_page(sizeof(struct map_data)); const int zero = 0, one = 1, two = 2, far = 1500; const long page_size = sysconf(_SC_PAGE_SIZE); - int err, duration = 0, i, data_map_fd, data_map_id, tmp_fd; + int err, duration = 0, i, data_map_fd, data_map_id, tmp_fd, rdmap_fd; struct bpf_map *data_map, *bss_map; void *bss_mmaped = NULL, *map_mmaped = NULL, *tmp1, *tmp2; struct test_mmap__bss *bss_data; @@ -37,6 +37,17 @@ void test_mmap(void) data_map = skel->maps.data_map; data_map_fd = bpf_map__fd(data_map); + rdmap_fd = bpf_map__fd(skel->maps.rdonly_map); + tmp1 = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, rdmap_fd, 0); + if (CHECK(tmp1 != MAP_FAILED, "rdonly_write_mmap", "unexpected success\n")) { + munmap(tmp1, 4096); + goto cleanup; + } + /* now double-check if it's mmap()'able at all */ + tmp1 = mmap(NULL, 4096, PROT_READ, MAP_SHARED, rdmap_fd, 0); + if (CHECK(tmp1 == MAP_FAILED, "rdonly_read_mmap", "failed: %d\n", errno)) + goto cleanup; + /* get map's ID */ memset(&map_info, 0, map_info_sz); err = bpf_obj_get_info_by_fd(data_map_fd, &map_info, &map_info_sz); diff --git a/tools/testing/selftests/bpf/progs/test_mmap.c b/tools/testing/selftests/bpf/progs/test_mmap.c index 6239596cd14e..4eb42cff5fe9 100644 --- a/tools/testing/selftests/bpf/progs/test_mmap.c +++ b/tools/testing/selftests/bpf/progs/test_mmap.c @@ -7,6 +7,14 @@ char _license[] SEC("license") = "GPL"; +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 4096); + __uint(map_flags, BPF_F_MMAPABLE | BPF_F_RDONLY_PROG); + __type(key, __u32); + __type(value, char); +} rdonly_map SEC(".maps"); + struct { __uint(type, BPF_MAP_TYPE_ARRAY); __uint(max_entries, 512 * 4); /* at least 4 pages of data */ -- cgit v1.2.3-71-gd317