Fix bpf_probe_read_user_str() overcopying #340
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do_strncpy_from_user() may copy some extra bytes after the NUL terminator into the destination buffer. This usually does not matter for normal string operations. However, when BPF programs key BPF maps with strings, this matters a lot. A BPF program may read strings from user memory by calling the bpf_probe_read_user_str() helper which eventually calls do_strncpy_from_user(). The program can then key a map with the resulting string. BPF map keys are fixed-width and string-agnostic, meaning that map keys are treated as a set of bytes. The issue is when do_strncpy_from_user() overcopies bytes after the NUL terminator, it can result in seemingly identical strings occupying multiple slots in a BPF map. This behavior is subtle and totally unexpected by the user. This commit has strncpy start copying a byte at a time if a NUL is spotted. Fixes: 6ae08ae ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers") Signed-off-by: Daniel Xu <[email protected]>
…ter NUL Previously, bpf_probe_read_user_str() could potentially overcopy the trailing bytes after the NUL due to how do_strncpy_from_user() does the copy in long-sized strides. The issue has been fixed in the previous commit. This commit adds a selftest that ensures we don't regress bpf_probe_read_user_str() again. Acked-by: Song Liu <[email protected]> Acked-by: Andrii Nakryiko <[email protected]> Signed-off-by: Daniel Xu <[email protected]>
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Master branch: 9602182 |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=382319 expired. Closing PR. |
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Add a test case which replaces an active ingress qdisc while keeping the miniq in-tact during the transition period to the new clsact qdisc. # ./vmtest.sh -- ./test_progs -t tc_link [...] ./test_progs -t tc_link [ 3.412871] bpf_testmod: loading out-of-tree module taints kernel. [ 3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #332 tc_links_after:OK #333 tc_links_append:OK #334 tc_links_basic:OK #335 tc_links_before:OK #336 tc_links_chain_classic:OK #337 tc_links_chain_mixed:OK #338 tc_links_dev_chain0:OK #339 tc_links_dev_cleanup:OK #340 tc_links_dev_mixed:OK #341 tc_links_ingress:OK #342 tc_links_invalid:OK #343 tc_links_prepend:OK #344 tc_links_replace:OK #345 tc_links_revision:OK Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <[email protected]> Cc: Martin KaFai Lau <[email protected]>
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Add a test case which replaces an active ingress qdisc while keeping the miniq in-tact during the transition period to the new clsact qdisc. # ./vmtest.sh -- ./test_progs -t tc_link [...] ./test_progs -t tc_link [ 3.412871] bpf_testmod: loading out-of-tree module taints kernel. [ 3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #332 tc_links_after:OK #333 tc_links_append:OK #334 tc_links_basic:OK #335 tc_links_before:OK #336 tc_links_chain_classic:OK #337 tc_links_chain_mixed:OK #338 tc_links_dev_chain0:OK #339 tc_links_dev_cleanup:OK #340 tc_links_dev_mixed:OK #341 tc_links_ingress:OK #342 tc_links_invalid:OK #343 tc_links_prepend:OK #344 tc_links_replace:OK #345 tc_links_revision:OK Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <[email protected]> Cc: Martin KaFai Lau <[email protected]>
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Add a test case which replaces an active ingress qdisc while keeping the miniq in-tact during the transition period to the new clsact qdisc. # ./vmtest.sh -- ./test_progs -t tc_link [...] ./test_progs -t tc_link [ 3.412871] bpf_testmod: loading out-of-tree module taints kernel. [ 3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #332 tc_links_after:OK #333 tc_links_append:OK #334 tc_links_basic:OK #335 tc_links_before:OK #336 tc_links_chain_classic:OK #337 tc_links_chain_mixed:OK #338 tc_links_dev_chain0:OK #339 tc_links_dev_cleanup:OK #340 tc_links_dev_mixed:OK #341 tc_links_ingress:OK #342 tc_links_invalid:OK #343 tc_links_prepend:OK #344 tc_links_replace:OK #345 tc_links_revision:OK Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <[email protected]> Cc: Martin KaFai Lau <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Martin KaFai Lau <[email protected]>
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While working on the lazy MMU mode enablement for s390 I hit pretty curious issues in the kasan code. The first is related to a custom kasan-based sanitizer aimed at catching invalid accesses to PTEs and is inspired by [1] conversation. The kasan complains on valid PTE accesses, while the shadow memory is reported as unpoisoned: [ 102.783993] ================================================================== [ 102.784008] BUG: KASAN: out-of-bounds in set_pte_range+0x36c/0x390 [ 102.784016] Read of size 8 at addr 0000780084cf9608 by task vmalloc_test/0/5542 [ 102.784019] [ 102.784040] CPU: 1 UID: 0 PID: 5542 Comm: vmalloc_test/0 Kdump: loaded Tainted: G OE 6.16.0-gcc-ipte-kasan-11657-gb2d930c4950e kernel-patches#340 PREEMPT [ 102.784047] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [ 102.784049] Hardware name: IBM 8561 T01 703 (LPAR) [ 102.784052] Call Trace: [ 102.784054] [<00007fffe0147ac0>] dump_stack_lvl+0xe8/0x140 [ 102.784059] [<00007fffe0112484>] print_address_description.constprop.0+0x34/0x2d0 [ 102.784066] [<00007fffe011282c>] print_report+0x10c/0x1f8 [ 102.784071] [<00007fffe090785a>] kasan_report+0xfa/0x220 [ 102.784078] [<00007fffe01d3dec>] set_pte_range+0x36c/0x390 [ 102.784083] [<00007fffe01d41c2>] leave_ipte_batch+0x3b2/0xb10 [ 102.784088] [<00007fffe07d3650>] apply_to_pte_range+0x2f0/0x4e0 [ 102.784094] [<00007fffe07e62e4>] apply_to_pmd_range+0x194/0x3e0 [ 102.784099] [<00007fffe07e820e>] __apply_to_page_range+0x2fe/0x7a0 [ 102.784104] [<00007fffe07e86d8>] apply_to_page_range+0x28/0x40 [ 102.784109] [<00007fffe090a3ec>] __kasan_populate_vmalloc+0xec/0x310 [ 102.784114] [<00007fffe090aa36>] kasan_populate_vmalloc+0x96/0x130 [ 102.784118] [<00007fffe0833a04>] alloc_vmap_area+0x3d4/0xf30 [ 102.784123] [<00007fffe083a8ba>] __get_vm_area_node+0x1aa/0x4c0 [ 102.784127] [<00007fffe083c4f6>] __vmalloc_node_range_noprof+0x126/0x4e0 [ 102.784131] [<00007fffe083c980>] __vmalloc_node_noprof+0xd0/0x110 [ 102.784135] [<00007fffe083ca32>] vmalloc_noprof+0x32/0x40 [ 102.784139] [<00007fff608aa336>] fix_size_alloc_test+0x66/0x150 [test_vmalloc] [ 102.784147] [<00007fff608aa710>] test_func+0x2f0/0x430 [test_vmalloc] [ 102.784153] [<00007fffe02841f8>] kthread+0x3f8/0x7a0 [ 102.784159] [<00007fffe014d8b4>] __ret_from_fork+0xd4/0x7d0 [ 102.784164] [<00007fffe299c00a>] ret_from_fork+0xa/0x30 [ 102.784173] no locks held by vmalloc_test/0/5542. [ 102.784176] [ 102.784178] The buggy address belongs to the physical page: [ 102.784186] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x84cf9 [ 102.784198] flags: 0x3ffff00000000000(node=0|zone=1|lastcpupid=0x1ffff) [ 102.784212] page_type: f2(table) [ 102.784225] raw: 3ffff00000000000 0000000000000000 0000000000000122 0000000000000000 [ 102.784234] raw: 0000000000000000 0000000000000000 f200000000000001 0000000000000000 [ 102.784248] page dumped because: kasan: bad access detected [ 102.784250] [ 102.784252] Memory state around the buggy address: [ 102.784260] 0000780084cf9500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 102.784274] 0000780084cf9580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 102.784277] >0000780084cf9600: fd 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 102.784290] ^ [ 102.784293] 0000780084cf9680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 102.784303] 0000780084cf9700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 102.784306] ================================================================== The second issue hits when the custom sanitizer above is not implemented, but the kasan itself is still active: [ 1554.438028] Unable to handle kernel pointer dereference in virtual kernel address space [ 1554.438065] Failing address: 001c0ff0066f0000 TEID: 001c0ff0066f0403 [ 1554.438076] Fault in home space mode while using kernel ASCE. [ 1554.438103] AS:00000000059d400b R2:0000000ffec5c00b R3:00000000c6c9c007 S:0000000314470001 P:00000000d0ab413d [ 1554.438158] Oops: 0011 ilc:2 [kernel-patches#1]SMP [ 1554.438175] Modules linked in: test_vmalloc(E+) nft_fib_inet(E) nft_fib_ipv4(E) nft_fib_ipv6(E) nft_fib(E) nft_reject_inet(E) nf_reject_ipv4(E) nf_reject_ipv6(E) nft_reject(E) nft_ct(E) nft_chain_nat(E) nf_nat(E) nf_conntrack(E) nf_defrag_ipv6(E) nf_defrag_ipv4(E) nf_tables(E) sunrpc(E) pkey_pckmo(E) uvdevice(E) s390_trng(E) rng_core(E) eadm_sch(E) vfio_ccw(E) mdev(E) vfio_iommu_type1(E) vfio(E) sch_fq_codel(E) drm(E) loop(E) i2c_core(E) drm_panel_orientation_quirks(E) nfnetlink(E) ctcm(E) fsm(E) zfcp(E) scsi_transport_fc(E) diag288_wdt(E) watchdog(E) ghash_s390(E) prng(E) aes_s390(E) des_s390(E) libdes(E) sha3_512_s390(E) sha3_256_s390(E) sha512_s390(E) sha1_s390(E) sha_common(E) pkey(E) autofs4(E) [ 1554.438319] Unloaded tainted modules: pkey_uv(E):1 hmac_s390(E):2 [ 1554.438354] CPU: 1 UID: 0 PID: 1715 Comm: vmalloc_test/0 Kdump: loaded Tainted: G E 6.16.0-gcc-ipte-kasan-11657-gb2d930c4950e kernel-patches#350 PREEMPT [ 1554.438368] Tainted: [E]=UNSIGNED_MODULE [ 1554.438374] Hardware name: IBM 8561 T01 703 (LPAR) [ 1554.438381] Krnl PSW : 0704e00180000000 00007fffe1d3d6ae (memset+0x5e/0x98) [ 1554.438396] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 [ 1554.438409] Krnl GPRS: 0000000000000001 001c0ff0066f0000 001c0ff0066f0000 00000000000000f8 [ 1554.438418] 00000000000009fe 0000000000000009 0000000000000000 0000000000000002 [ 1554.438426] 0000000000005000 000078031ae655c8 00000feffdcf9f59 0000780258672a20 [ 1554.438433] 0000780243153500 00007f8033780000 00007fffe083a510 00007f7fee7cfa00 [ 1554.438452] Krnl Code: 00007fffe1d3d6a0: eb540008000c srlg %r5,%r4,8 00007fffe1d3d6a6: b9020055 ltgr %r5,%r5 #00007fffe1d3d6aa: a784000b brc 8,00007fffe1d3d6c0 >00007fffe1d3d6ae: 42301000 stc %r3,0(%r1) 00007fffe1d3d6b2: d2fe10011000 mvc 1(255,%r1),0(%r1) 00007fffe1d3d6b8: 41101100 la %r1,256(%r1) 00007fffe1d3d6bc: a757fff9 brctg %r5,00007fffe1d3d6ae 00007fffe1d3d6c0: 42301000 stc %r3,0(%r1) [ 1554.438539] Call Trace: [ 1554.438545] [<00007fffe1d3d6ae>] memset+0x5e/0x98 [ 1554.438552] ([<00007fffe083a510>] remove_vm_area+0x220/0x400) [ 1554.438562] [<00007fffe083a9d6>] vfree.part.0+0x26/0x810 [ 1554.438569] [<00007fff6073bd50>] fix_align_alloc_test+0x50/0x90 [test_vmalloc] [ 1554.438583] [<00007fff6073c73a>] test_func+0x46a/0x6c0 [test_vmalloc] [ 1554.438593] [<00007fffe0283ac8>] kthread+0x3f8/0x7a0 [ 1554.438603] [<00007fffe014d8b4>] __ret_from_fork+0xd4/0x7d0 [ 1554.438613] [<00007fffe299ac0a>] ret_from_fork+0xa/0x30 [ 1554.438622] INFO: lockdep is turned off. [ 1554.438627] Last Breaking-Event-Address: [ 1554.438632] [<00007fffe1d3d65c>] memset+0xc/0x98 [ 1554.438644] Kernel panic - not syncing: Fatal exception: panic_on_oops This series fixes the above issues and is a pre-requisite for the s390 lazy MMU mode implementation. test_vmalloc was used to stress-test the fixes. This patch (of 2): When vmalloc shadow memory is established the modification of the corresponding page tables is not protected by any locks. Instead, the locking is done per-PTE. This scheme however has defects. kasan_populate_vmalloc_pte() - while ptep_get() read is atomic the sequence pte_none(ptep_get()) is not. Doing that outside of the lock might lead to a concurrent PTE update and what could be seen as a shadow memory corruption as result. kasan_depopulate_vmalloc_pte() - by the time a page whose address was extracted from ptep_get() read and cached in a local variable outside of the lock is attempted to get free, could actually be freed already. To avoid these put ptep_get() itself and the code that manipulates the result of the read under lock. In addition, move freeing of the page out of the atomic context. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/adb258634194593db294c0d1fb35646e894d6ead.1755528662.git.agordeev@linux.ibm.com Link: https://lore.kernel.org/linux-mm/[email protected]/ [1] Fixes: 3c5c3cf ("kasan: support backing vmalloc space with real shadow memory") Signed-off-by: Alexander Gordeev <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Daniel Axtens <[email protected]> Cc: Marc Rutland <[email protected]> Cc: Ryan Roberts <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
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Pull request for series with
subject: Fix bpf_probe_read_user_str() overcopying
version: 5
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=382319