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2020-08-11selftests/bpf: Fix segmentation fault in test_progsJianlin Lv1-6/+13
test_progs reports the segmentation fault as below: $ sudo ./test_progs -t mmap --verbose test_mmap:PASS:skel_open_and_load 0 nsec [...] test_mmap:PASS:adv_mmap1 0 nsec test_mmap:PASS:adv_mmap2 0 nsec test_mmap:PASS:adv_mmap3 0 nsec test_mmap:PASS:adv_mmap4 0 nsec Segmentation fault This issue was triggered because mmap() and munmap() used inconsistent length parameters; mmap() creates a new mapping of 3 * page_size, but the length parameter set in the subsequent re-map and munmap() functions is 4 * page_size; this leads to the destruction of the process space. To fix this issue, first create 4 pages of anonymous mapping, then do all the mmap() with MAP_FIXED. Another issue is that when unmap the second page fails, the length parameter to delete tmp1 mappings should be 4 * page_size. Signed-off-by: Jianlin Lv <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Acked-by: Andrii Nakryiko <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2020-05-20bpf: Prevent mmap()'ing read-only maps as writableAndrii Nakryiko1-1/+12
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 <[email protected]> Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Reviewed-by: Jann Horn <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2020-05-14bpf: Fix bug in mmap() implementation for BPF array mapAndrii Nakryiko1-0/+8
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 <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Acked-by: Yonghong Song <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2020-04-14selftests/bpf: Validate frozen map contents stays frozenAndrii Nakryiko1-2/+60
Test that frozen and mmap()'ed BPF map can't be mprotect()'ed as writable or executable memory. Also validate that "downgrading" from writable to read-only doesn't screw up internal writable count accounting for the purposes of map freezing. Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2019-12-17bpftool, selftests/bpf: Embed object file inside skeletonAndrii Nakryiko1-3/+1
Embed contents of BPF object file used for BPF skeleton generation inside skeleton itself. This allows to keep BPF object file and its skeleton in sync at all times, and simpifies skeleton instantiation. Also switch existing selftests to not require BPF_EMBED_OBJ anymore. Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Acked-by: Yonghong Song <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2019-12-15selftests/bpf: Convert few more selftest to skeletonsAndrii Nakryiko1-35/+23
Convert few more selftests to use generated BPF skeletons as a demonstration on how to use it. Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Acked-by: Martin KaFai Lau <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2019-11-18selftests/bpf: Add BPF_TYPE_MAP_ARRAY mmap() testsAndrii Nakryiko1-0/+220
Add selftests validating mmap()-ing BPF array maps: both single-element and multi-element ones. Check that plain bpf_map_update_elem() and bpf_map_lookup_elem() work correctly with memory-mapped array. Also convert CO-RE relocation tests to use memory-mapped views of global data. Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Acked-by: Song Liu <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
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