| Message ID | 20240219234121.make.373-kees@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] bpf: Replace bpf_lpm_trie_key 0-length array with flexible array | expand |
On 2/19/24 17:41, Kees Cook wrote: > Replace deprecated 0-length array in struct bpf_lpm_trie_key with > flexible array. Found with GCC 13: > > ../kernel/bpf/lpm_trie.c:207:51: warning: array subscript i is outside array bounds of 'const __u8[0]' {aka 'const unsigned char[]'} [-Warray-bounds=] > 207 | *(__be16 *)&key->data[i]); > | ^~~~~~~~~~~~~ > ../include/uapi/linux/swab.h:102:54: note: in definition of macro '__swab16' > 102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) > | ^ > ../include/linux/byteorder/generic.h:97:21: note: in expansion of macro '__be16_to_cpu' > 97 | #define be16_to_cpu __be16_to_cpu > | ^~~~~~~~~~~~~ > ../kernel/bpf/lpm_trie.c:206:28: note: in expansion of macro 'be16_to_cpu' > 206 | u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] > ^ > | ^~~~~~~~~~~ > In file included from ../include/linux/bpf.h:7: > ../include/uapi/linux/bpf.h:82:17: note: while referencing 'data' > 82 | __u8 data[0]; /* Arbitrary size */ > | ^~~~ > > And found at run-time under CONFIG_FORTIFY_SOURCE: > > UBSAN: array-index-out-of-bounds in kernel/bpf/lpm_trie.c:218:49 > index 0 is out of range for type '__u8 [*]' > > Changing struct bpf_lpm_trie_key is difficult since has been used by > userspace. For example, in Cilium: > > struct egress_gw_policy_key { > struct bpf_lpm_trie_key lpm_key; > __u32 saddr; > __u32 daddr; > }; > > While direct references to the "data" member haven't been found, there > are static initializers what include the final member. For example, > the "{}" here: > > struct egress_gw_policy_key in_key = { > .lpm_key = { 32 + 24, {} }, > .saddr = CLIENT_IP, > .daddr = EXTERNAL_SVC_IP & 0Xffffff, > }; > > To avoid the build time and run time warnings seen with a 0-sized > trailing array for struct bpf_lpm_trie_key, introduce a new struct > that correctly uses a flexible array for the trailing bytes, > struct bpf_lpm_trie_key_u8. As part of this, include the "header" > portion (which is just the "prefixlen" member), so it can be used > by anything building a bpf_lpr_trie_key that has trailing members that > aren't a u8 flexible array (like the self-test[1]), which is named > struct bpf_lpm_trie_key_hdr. Yep, this `_hdr` tagged struct adds flexibility (no pun intended :p) to flexible structures currently nested in the middle of other structs. We can just use the header members grouped together in the `_hdr` struct, and avoid embedding the flexible-array member. :) > > Adjust the kernel code to use struct bpf_lpm_trie_key_u8 through-out, > and for the selftest to use struct bpf_lpm_trie_key_hdr. Add a comment > to the UAPI header directing folks to the two new options. > > Link: https://lore.kernel.org/all/202206281009.4332AA33@keescook/ [1] > Reported-by: Mark Rutland <mark.rutland@arm.com> > Closes: https://paste.debian.net/hidden/ca500597/ > Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org> Thanks!
On 2/20/24 12:41 AM, Kees Cook wrote: > Replace deprecated 0-length array in struct bpf_lpm_trie_key with > flexible array. Found with GCC 13: > > ../kernel/bpf/lpm_trie.c:207:51: warning: array subscript i is outside array bounds of 'const __u8[0]' {aka 'const unsigned char[]'} [-Warray-bounds=] > 207 | *(__be16 *)&key->data[i]); > | ^~~~~~~~~~~~~ > ../include/uapi/linux/swab.h:102:54: note: in definition of macro '__swab16' > 102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) > | ^ > ../include/linux/byteorder/generic.h:97:21: note: in expansion of macro '__be16_to_cpu' > 97 | #define be16_to_cpu __be16_to_cpu > | ^~~~~~~~~~~~~ > ../kernel/bpf/lpm_trie.c:206:28: note: in expansion of macro 'be16_to_cpu' > 206 | u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] > ^ > | ^~~~~~~~~~~ > In file included from ../include/linux/bpf.h:7: > ../include/uapi/linux/bpf.h:82:17: note: while referencing 'data' > 82 | __u8 data[0]; /* Arbitrary size */ > | ^~~~ > > And found at run-time under CONFIG_FORTIFY_SOURCE: > > UBSAN: array-index-out-of-bounds in kernel/bpf/lpm_trie.c:218:49 > index 0 is out of range for type '__u8 [*]' > > Changing struct bpf_lpm_trie_key is difficult since has been used by > userspace. For example, in Cilium: > > struct egress_gw_policy_key { > struct bpf_lpm_trie_key lpm_key; > __u32 saddr; > __u32 daddr; > }; > > While direct references to the "data" member haven't been found, there > are static initializers what include the final member. For example, > the "{}" here: > > struct egress_gw_policy_key in_key = { > .lpm_key = { 32 + 24, {} }, > .saddr = CLIENT_IP, > .daddr = EXTERNAL_SVC_IP & 0Xffffff, > }; > > To avoid the build time and run time warnings seen with a 0-sized > trailing array for struct bpf_lpm_trie_key, introduce a new struct > that correctly uses a flexible array for the trailing bytes, > struct bpf_lpm_trie_key_u8. As part of this, include the "header" > portion (which is just the "prefixlen" member), so it can be used > by anything building a bpf_lpr_trie_key that has trailing members that > aren't a u8 flexible array (like the self-test[1]), which is named > struct bpf_lpm_trie_key_hdr. > > Adjust the kernel code to use struct bpf_lpm_trie_key_u8 through-out, > and for the selftest to use struct bpf_lpm_trie_key_hdr. Add a comment > to the UAPI header directing folks to the two new options. > > Link: https://lore.kernel.org/all/202206281009.4332AA33@keescook/ [1] > Reported-by: Mark Rutland <mark.rutland@arm.com> > Closes: https://paste.debian.net/hidden/ca500597/ > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > v3- create a new pair of structs -- leave old struct alone > v2- https://lore.kernel.org/lkml/20240216235536.it.234-kees@kernel.org/ > v1- https://lore.kernel.org/lkml/20230204183241.never.481-kees@kernel.org/ > Cc: Daniel Borkmann <daniel@iogearbox.net> > Cc: Alexei Starovoitov <ast@kernel.org> > Cc: Andrii Nakryiko <andrii@kernel.org> > Cc: Martin KaFai Lau <martin.lau@linux.dev> > Cc: Song Liu <song@kernel.org> > Cc: Yonghong Song <yhs@fb.com> > Cc: John Fastabend <john.fastabend@gmail.com> > Cc: KP Singh <kpsingh@kernel.org> > Cc: Stanislav Fomichev <sdf@google.com> > Cc: Hao Luo <haoluo@google.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Mykola Lysenko <mykolal@fb.com> > Cc: Shuah Khan <shuah@kernel.org> > Cc: Haowen Bai <baihaowen@meizu.com> > Cc: bpf@vger.kernel.org > Cc: linux-kselftest@vger.kernel.org > --- > Documentation/bpf/map_lpm_trie.rst | 2 +- > include/uapi/linux/bpf.h | 14 ++++++++++++- > kernel/bpf/lpm_trie.c | 20 +++++++++---------- > samples/bpf/map_perf_test_user.c | 2 +- > samples/bpf/xdp_router_ipv4_user.c | 2 +- > tools/include/uapi/linux/bpf.h | 14 ++++++++++++- > .../selftests/bpf/progs/map_ptr_kern.c | 2 +- > tools/testing/selftests/bpf/test_lpm_map.c | 18 ++++++++--------- > 8 files changed, 49 insertions(+), 25 deletions(-) > > diff --git a/Documentation/bpf/map_lpm_trie.rst b/Documentation/bpf/map_lpm_trie.rst > index 74d64a30f500..f9cd579496c9 100644 > --- a/Documentation/bpf/map_lpm_trie.rst > +++ b/Documentation/bpf/map_lpm_trie.rst > @@ -17,7 +17,7 @@ significant byte. > > LPM tries may be created with a maximum prefix length that is a multiple > of 8, in the range from 8 to 2048. The key used for lookup and update > -operations is a ``struct bpf_lpm_trie_key``, extended by > +operations is a ``struct bpf_lpm_trie_key_u8``, extended by > ``max_prefixlen/8`` bytes. > > - For IPv4 addresses the data length is 4 bytes > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 754e68ca8744..c5a46d12076e 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -77,12 +77,24 @@ struct bpf_insn { > __s32 imm; /* signed immediate constant */ > }; > > -/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ > +/* Deprecated: use struct bpf_lpm_trie_key_u8 (when the "data" member is needed for > + * byte access) or struct bpf_lpm_trie_key_hdr (when using an alternative type for > + * the trailing flexible array member) instead. > + */ > struct bpf_lpm_trie_key { > __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ > __u8 data[0]; /* Arbitrary size */ > }; > > +/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry, with trailing byte array. */ > +struct bpf_lpm_trie_key_u8 { > + __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, > + /* up to 32 for AF_INET, 128 for AF_INET6 */ > + __u32 prefixlen; > + ); > + __u8 data[]; /* Arbitrary size */ > +}; > + > struct bpf_cgroup_storage_key { > __u64 cgroup_inode_id; /* cgroup inode id */ > __u32 attach_type; /* program attach type (enum bpf_attach_type) */ > diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c > index b32be680da6c..050fe1ebf0f7 100644 > --- a/kernel/bpf/lpm_trie.c > +++ b/kernel/bpf/lpm_trie.c > @@ -164,13 +164,13 @@ static inline int extract_bit(const u8 *data, size_t index) > */ > static size_t longest_prefix_match(const struct lpm_trie *trie, > const struct lpm_trie_node *node, > - const struct bpf_lpm_trie_key *key) > + const struct bpf_lpm_trie_key_u8 *key) > { > u32 limit = min(node->prefixlen, key->prefixlen); > u32 prefixlen = 0, i = 0; > > BUILD_BUG_ON(offsetof(struct lpm_trie_node, data) % sizeof(u32)); > - BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key, data) % sizeof(u32)); > + BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key_u8, data) % sizeof(u32)); > > #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(CONFIG_64BIT) > > @@ -229,7 +229,7 @@ static void *trie_lookup_elem(struct bpf_map *map, void *_key) > { > struct lpm_trie *trie = container_of(map, struct lpm_trie, map); > struct lpm_trie_node *node, *found = NULL; > - struct bpf_lpm_trie_key *key = _key; > + struct bpf_lpm_trie_key_u8 *key = _key; > > if (key->prefixlen > trie->max_prefixlen) > return NULL; > @@ -309,7 +309,7 @@ static long trie_update_elem(struct bpf_map *map, > struct lpm_trie *trie = container_of(map, struct lpm_trie, map); > struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; > struct lpm_trie_node __rcu **slot; > - struct bpf_lpm_trie_key *key = _key; > + struct bpf_lpm_trie_key_u8 *key = _key; > unsigned long irq_flags; > unsigned int next_bit; > size_t matchlen = 0; > @@ -437,7 +437,7 @@ static long trie_update_elem(struct bpf_map *map, > static long trie_delete_elem(struct bpf_map *map, void *_key) > { > struct lpm_trie *trie = container_of(map, struct lpm_trie, map); > - struct bpf_lpm_trie_key *key = _key; > + struct bpf_lpm_trie_key_u8 *key = _key; > struct lpm_trie_node __rcu **trim, **trim2; > struct lpm_trie_node *node, *parent; > unsigned long irq_flags; > @@ -536,7 +536,7 @@ static long trie_delete_elem(struct bpf_map *map, void *_key) > sizeof(struct lpm_trie_node)) > #define LPM_VAL_SIZE_MIN 1 > > -#define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key) + (X)) > +#define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key_u8) + (X)) > #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) > #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) > > @@ -565,7 +565,7 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr) > /* copy mandatory map attributes */ > bpf_map_init_from_attr(&trie->map, attr); > trie->data_size = attr->key_size - > - offsetof(struct bpf_lpm_trie_key, data); > + offsetof(struct bpf_lpm_trie_key_u8, data); > trie->max_prefixlen = trie->data_size * 8; > > spin_lock_init(&trie->lock); > @@ -616,7 +616,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) > { > struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; > struct lpm_trie *trie = container_of(map, struct lpm_trie, map); > - struct bpf_lpm_trie_key *key = _key, *next_key = _next_key; > + struct bpf_lpm_trie_key_u8 *key = _key, *next_key = _next_key; > struct lpm_trie_node **node_stack = NULL; > int err = 0, stack_ptr = -1; > unsigned int next_bit; > @@ -703,7 +703,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) > } > do_copy: > next_key->prefixlen = next_node->prefixlen; > - memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data), > + memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key_u8, data), > next_node->data, trie->data_size); > free_stack: > kfree(node_stack); > @@ -715,7 +715,7 @@ static int trie_check_btf(const struct bpf_map *map, > const struct btf_type *key_type, > const struct btf_type *value_type) > { > - /* Keys must have struct bpf_lpm_trie_key embedded. */ > + /* Keys must have struct bpf_lpm_trie_key_u8 embedded. */ > return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? > -EINVAL : 0; > } > diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c > index d2fbcf963cdf..07ff471ed6ae 100644 > --- a/samples/bpf/map_perf_test_user.c > +++ b/samples/bpf/map_perf_test_user.c > @@ -370,7 +370,7 @@ static void run_perf_test(int tasks) > > static void fill_lpm_trie(void) > { > - struct bpf_lpm_trie_key *key; > + struct bpf_lpm_trie_key_u8 *key; > unsigned long value = 0; > unsigned int i; > int r; > diff --git a/samples/bpf/xdp_router_ipv4_user.c b/samples/bpf/xdp_router_ipv4_user.c > index 9d41db09c480..266fdd0b025d 100644 > --- a/samples/bpf/xdp_router_ipv4_user.c > +++ b/samples/bpf/xdp_router_ipv4_user.c > @@ -91,7 +91,7 @@ static int recv_msg(struct sockaddr_nl sock_addr, int sock) > static void read_route(struct nlmsghdr *nh, int nll) > { > char dsts[24], gws[24], ifs[16], dsts_len[24], metrics[24]; > - struct bpf_lpm_trie_key *prefix_key; > + struct bpf_lpm_trie_key_u8 *prefix_key; > struct rtattr *rt_attr; > struct rtmsg *rt_msg; > int rtm_family; > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h > index 7f24d898efbb..c55244bf1a20 100644 > --- a/tools/include/uapi/linux/bpf.h > +++ b/tools/include/uapi/linux/bpf.h > @@ -77,12 +77,24 @@ struct bpf_insn { > __s32 imm; /* signed immediate constant */ > }; > > -/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ > +/* Deprecated: use struct bpf_lpm_trie_key_u8 (when the "data" member is needed for > + * byte access) or struct bpf_lpm_trie_key_hdr (when using an alternative type for > + * the trailing flexible array member) instead. > + */ > struct bpf_lpm_trie_key { > __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ > __u8 data[0]; /* Arbitrary size */ > }; > > +/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry, with trailing byte array. */ > +struct bpf_lpm_trie_key_u8 { > + __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, > + /* up to 32 for AF_INET, 128 for AF_INET6 */ > + __u32 prefixlen; > + ); > + __u8 data[]; /* Arbitrary size */ > +}; > + > struct bpf_cgroup_storage_key { > __u64 cgroup_inode_id; /* cgroup inode id */ > __u32 attach_type; /* program attach type (enum bpf_attach_type) */ This fails the BPF CI : [...] INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/skel_internal.h INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/libbpf_version.h INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/usdt.bpf.h In file included from urandom_read_lib1.c:7: In file included from /tmp/work/bpf/bpf/tools/lib/bpf/libbpf_internal.h:20: In file included from /tmp/work/bpf/bpf/tools/lib/bpf/relo_core.h:7: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: type name requires a specifier or qualifier 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^ /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:58: error: expected identifier 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^ /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:93:18: error: unexpected ';' before ')' 93 | __u32 prefixlen; | ^ /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:95:7: error: flexible array member 'data' not allowed in otherwise empty struct 95 | __u8 data[]; /* Arbitrary size */ | ^ HOSTCC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/fixdep.o 4 errors generated. GEN /tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf-syscall.2 HOSTLD /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/fixdep-in.o LINK /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/fixdep make: *** [Makefile:230: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/liburandom_read.so] Error 1 make: *** Waiting for unfinished jobs.... INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/bpf_helper_defs.h INSTALL libbpf_headers GEN /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.pc MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/ CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/libbpf.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/str_error.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/bpf.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/nlattr.o CC 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/tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/linker.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/gen_loader.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/relo_core.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/usdt.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/zip.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/elf.o MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/features.o MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ MKDIR /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/netlink.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/bpf.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/nlattr.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/bpf_prog_linfo.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/btf.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf_errno.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/str_error.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf_probes.o In file included from /tmp/work/bpf/bpf/tools/include/linux/filter.h:8, from features.c:4: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/hashmap.o In file included from bpf_prog_linfo.c:7: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.h:18, from libbpf_errno.c:14: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from /tmp/work/bpf/bpf/tools/include/linux/filter.h:8, from gen_loader.c:7: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from bpf.c:30: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.c:31: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.h:18, from relo_core.c:64: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from bpf_prog_linfo.c:7: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.h:18, from libbpf_errno.c:14: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from bpf.c:30: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from ringbuf.c:15: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.h:18, from btf_dump.c:22: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from relo_core.h:7, from libbpf_internal.h:20, from strset.c:9: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from bpf.h:26, from usdt.c:18: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from relo_core.h:7, from libbpf_internal.h:20, from nlattr.c:14: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from relo_core.h:7, from libbpf_internal.h:20, from elf.c:11: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.h:18, from linker.c:19: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/btf_dump.o In file included from bpf.h:26, from btf.c:20: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.c:31: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from relo_core.h:7, from libbpf_internal.h:20, from zip.c:16: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from relo_core.h:7, from libbpf_internal.h:20, from nlattr.c:14: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/bpf_prog_linfo.o] Error 1 make[3]: *** Waiting for unfinished jobs.... make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/strset.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/nlattr.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/libbpf_errno.o] Error 1 CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ringbuf.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/strset.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/linker.o CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/gen_loader.o make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:106: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/bpf_prog_linfo.o] Error 1 make[3]: *** Waiting for unfinished jobs.... In file included from bpf.h:26, from btf.c:20: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/elf.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:106: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf_errno.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/zip.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/features.o] Error 1 GEN /tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf-helpers.7 In file included from libbpf.h:18, from btf_dump.c:22: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/usdt.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:106: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/nlattr.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/ringbuf.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/relo_core.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/gen_loader.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/bpf.o] Error 1 In file included from /tmp/work/bpf/bpf/tools/include/linux/filter.h:8, from gen_loader.c:7: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from ringbuf.c:15: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:106: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/bpf.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/btf_dump.o] Error 1 In file included from relo_core.h:7, from libbpf_internal.h:20, from strset.c:9: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ In file included from libbpf.h:18, from linker.c:19: /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: expected specifier-qualifier-list before ‘__struct_group’ 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, | ^~~~~~~~~~~~~~ make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/linker.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/strset.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/btf_dump.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/ringbuf.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/gen_loader.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/btf.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/linker.o] Error 1 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/btf.o] Error 1 GEN /tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf-syscall.2 make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/libbpf.o] Error 1 make[2]: *** [Makefile:157: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/staticobjs/libbpf-in.o] Error 2 make[2]: *** Waiting for unfinished jobs.... make[3]: *** [/tmp/work/bpf/bpf/tools/build/Makefile.build:105: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf.o] Error 1 make[2]: *** [Makefile:148: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf-in.o] Error 2 make[1]: *** [Makefile:140: all] Error 2 make: *** [Makefile:344: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.a] Error 2 GEN /tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf-helpers.7 make: Leaving directory '/tmp/work/bpf/bpf/tools/testing/selftests/bpf' Error: Process completed with exit code 2.
On Tue, Feb 20, 2024 at 11:18:40AM +0100, Daniel Borkmann wrote: > On 2/20/24 12:41 AM, Kees Cook wrote: > > Replace deprecated 0-length array in struct bpf_lpm_trie_key with > > flexible array. Found with GCC 13: > [...] > This fails the BPF CI : > > [...] > INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/skel_internal.h > INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/libbpf_version.h > INSTALL /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/usdt.bpf.h > In file included from urandom_read_lib1.c:7: > In file included from /tmp/work/bpf/bpf/tools/lib/bpf/libbpf_internal.h:20: > In file included from /tmp/work/bpf/bpf/tools/lib/bpf/relo_core.h:7: > /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:2: error: type name requires a specifier or qualifier > 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, > | ^ > /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:91:58: error: expected identifier > 91 | __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, > | ^ > /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:93:18: error: unexpected ';' before ')' > 93 | __u32 prefixlen; > | ^ > /tmp/work/bpf/bpf/tools/include/uapi/linux/bpf.h:95:7: error: flexible array member 'data' not allowed in otherwise empty struct > 95 | __u8 data[]; /* Arbitrary size */ > | ^ Ah-ha, my test build of cilium happened to cover up the lack of stddef.h. Fixed now and sending a v4...
diff --git a/Documentation/bpf/map_lpm_trie.rst b/Documentation/bpf/map_lpm_trie.rst index 74d64a30f500..f9cd579496c9 100644 --- a/Documentation/bpf/map_lpm_trie.rst +++ b/Documentation/bpf/map_lpm_trie.rst @@ -17,7 +17,7 @@ significant byte. LPM tries may be created with a maximum prefix length that is a multiple of 8, in the range from 8 to 2048. The key used for lookup and update -operations is a ``struct bpf_lpm_trie_key``, extended by +operations is a ``struct bpf_lpm_trie_key_u8``, extended by ``max_prefixlen/8`` bytes. - For IPv4 addresses the data length is 4 bytes diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 754e68ca8744..c5a46d12076e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -77,12 +77,24 @@ struct bpf_insn { __s32 imm; /* signed immediate constant */ }; -/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ +/* Deprecated: use struct bpf_lpm_trie_key_u8 (when the "data" member is needed for + * byte access) or struct bpf_lpm_trie_key_hdr (when using an alternative type for + * the trailing flexible array member) instead. + */ struct bpf_lpm_trie_key { __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ __u8 data[0]; /* Arbitrary size */ }; +/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry, with trailing byte array. */ +struct bpf_lpm_trie_key_u8 { + __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, + /* up to 32 for AF_INET, 128 for AF_INET6 */ + __u32 prefixlen; + ); + __u8 data[]; /* Arbitrary size */ +}; + struct bpf_cgroup_storage_key { __u64 cgroup_inode_id; /* cgroup inode id */ __u32 attach_type; /* program attach type (enum bpf_attach_type) */ diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index b32be680da6c..050fe1ebf0f7 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -164,13 +164,13 @@ static inline int extract_bit(const u8 *data, size_t index) */ static size_t longest_prefix_match(const struct lpm_trie *trie, const struct lpm_trie_node *node, - const struct bpf_lpm_trie_key *key) + const struct bpf_lpm_trie_key_u8 *key) { u32 limit = min(node->prefixlen, key->prefixlen); u32 prefixlen = 0, i = 0; BUILD_BUG_ON(offsetof(struct lpm_trie_node, data) % sizeof(u32)); - BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key, data) % sizeof(u32)); + BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key_u8, data) % sizeof(u32)); #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(CONFIG_64BIT) @@ -229,7 +229,7 @@ static void *trie_lookup_elem(struct bpf_map *map, void *_key) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct lpm_trie_node *node, *found = NULL; - struct bpf_lpm_trie_key *key = _key; + struct bpf_lpm_trie_key_u8 *key = _key; if (key->prefixlen > trie->max_prefixlen) return NULL; @@ -309,7 +309,7 @@ static long trie_update_elem(struct bpf_map *map, struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; struct lpm_trie_node __rcu **slot; - struct bpf_lpm_trie_key *key = _key; + struct bpf_lpm_trie_key_u8 *key = _key; unsigned long irq_flags; unsigned int next_bit; size_t matchlen = 0; @@ -437,7 +437,7 @@ static long trie_update_elem(struct bpf_map *map, static long trie_delete_elem(struct bpf_map *map, void *_key) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); - struct bpf_lpm_trie_key *key = _key; + struct bpf_lpm_trie_key_u8 *key = _key; struct lpm_trie_node __rcu **trim, **trim2; struct lpm_trie_node *node, *parent; unsigned long irq_flags; @@ -536,7 +536,7 @@ static long trie_delete_elem(struct bpf_map *map, void *_key) sizeof(struct lpm_trie_node)) #define LPM_VAL_SIZE_MIN 1 -#define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key) + (X)) +#define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key_u8) + (X)) #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) @@ -565,7 +565,7 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr) /* copy mandatory map attributes */ bpf_map_init_from_attr(&trie->map, attr); trie->data_size = attr->key_size - - offsetof(struct bpf_lpm_trie_key, data); + offsetof(struct bpf_lpm_trie_key_u8, data); trie->max_prefixlen = trie->data_size * 8; spin_lock_init(&trie->lock); @@ -616,7 +616,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) { struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; struct lpm_trie *trie = container_of(map, struct lpm_trie, map); - struct bpf_lpm_trie_key *key = _key, *next_key = _next_key; + struct bpf_lpm_trie_key_u8 *key = _key, *next_key = _next_key; struct lpm_trie_node **node_stack = NULL; int err = 0, stack_ptr = -1; unsigned int next_bit; @@ -703,7 +703,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) } do_copy: next_key->prefixlen = next_node->prefixlen; - memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data), + memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key_u8, data), next_node->data, trie->data_size); free_stack: kfree(node_stack); @@ -715,7 +715,7 @@ static int trie_check_btf(const struct bpf_map *map, const struct btf_type *key_type, const struct btf_type *value_type) { - /* Keys must have struct bpf_lpm_trie_key embedded. */ + /* Keys must have struct bpf_lpm_trie_key_u8 embedded. */ return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? -EINVAL : 0; } diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c index d2fbcf963cdf..07ff471ed6ae 100644 --- a/samples/bpf/map_perf_test_user.c +++ b/samples/bpf/map_perf_test_user.c @@ -370,7 +370,7 @@ static void run_perf_test(int tasks) static void fill_lpm_trie(void) { - struct bpf_lpm_trie_key *key; + struct bpf_lpm_trie_key_u8 *key; unsigned long value = 0; unsigned int i; int r; diff --git a/samples/bpf/xdp_router_ipv4_user.c b/samples/bpf/xdp_router_ipv4_user.c index 9d41db09c480..266fdd0b025d 100644 --- a/samples/bpf/xdp_router_ipv4_user.c +++ b/samples/bpf/xdp_router_ipv4_user.c @@ -91,7 +91,7 @@ static int recv_msg(struct sockaddr_nl sock_addr, int sock) static void read_route(struct nlmsghdr *nh, int nll) { char dsts[24], gws[24], ifs[16], dsts_len[24], metrics[24]; - struct bpf_lpm_trie_key *prefix_key; + struct bpf_lpm_trie_key_u8 *prefix_key; struct rtattr *rt_attr; struct rtmsg *rt_msg; int rtm_family; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 7f24d898efbb..c55244bf1a20 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -77,12 +77,24 @@ struct bpf_insn { __s32 imm; /* signed immediate constant */ }; -/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ +/* Deprecated: use struct bpf_lpm_trie_key_u8 (when the "data" member is needed for + * byte access) or struct bpf_lpm_trie_key_hdr (when using an alternative type for + * the trailing flexible array member) instead. + */ struct bpf_lpm_trie_key { __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ __u8 data[0]; /* Arbitrary size */ }; +/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry, with trailing byte array. */ +struct bpf_lpm_trie_key_u8 { + __struct_group(bpf_lpm_trie_key_hdr, hdr, /* no attrs */, + /* up to 32 for AF_INET, 128 for AF_INET6 */ + __u32 prefixlen; + ); + __u8 data[]; /* Arbitrary size */ +}; + struct bpf_cgroup_storage_key { __u64 cgroup_inode_id; /* cgroup inode id */ __u32 attach_type; /* program attach type (enum bpf_attach_type) */ diff --git a/tools/testing/selftests/bpf/progs/map_ptr_kern.c b/tools/testing/selftests/bpf/progs/map_ptr_kern.c index 3325da17ec81..efaf622c28dd 100644 --- a/tools/testing/selftests/bpf/progs/map_ptr_kern.c +++ b/tools/testing/selftests/bpf/progs/map_ptr_kern.c @@ -316,7 +316,7 @@ struct lpm_trie { } __attribute__((preserve_access_index)); struct lpm_key { - struct bpf_lpm_trie_key trie_key; + struct bpf_lpm_trie_key_hdr trie_key; __u32 data; }; diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/test_lpm_map.c index c028d621c744..d98c72dc563e 100644 --- a/tools/testing/selftests/bpf/test_lpm_map.c +++ b/tools/testing/selftests/bpf/test_lpm_map.c @@ -211,7 +211,7 @@ static void test_lpm_map(int keysize) volatile size_t n_matches, n_matches_after_delete; size_t i, j, n_nodes, n_lookups; struct tlpm_node *t, *list = NULL; - struct bpf_lpm_trie_key *key; + struct bpf_lpm_trie_key_u8 *key; uint8_t *data, *value; int r, map; @@ -331,8 +331,8 @@ static void test_lpm_map(int keysize) static void test_lpm_ipaddr(void) { LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_NO_PREALLOC); - struct bpf_lpm_trie_key *key_ipv4; - struct bpf_lpm_trie_key *key_ipv6; + struct bpf_lpm_trie_key_u8 *key_ipv4; + struct bpf_lpm_trie_key_u8 *key_ipv6; size_t key_size_ipv4; size_t key_size_ipv6; int map_fd_ipv4; @@ -423,7 +423,7 @@ static void test_lpm_ipaddr(void) static void test_lpm_delete(void) { LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_NO_PREALLOC); - struct bpf_lpm_trie_key *key; + struct bpf_lpm_trie_key_u8 *key; size_t key_size; int map_fd; __u64 value; @@ -532,7 +532,7 @@ static void test_lpm_delete(void) static void test_lpm_get_next_key(void) { LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_NO_PREALLOC); - struct bpf_lpm_trie_key *key_p, *next_key_p; + struct bpf_lpm_trie_key_u8 *key_p, *next_key_p; size_t key_size; __u32 value = 0; int map_fd; @@ -693,9 +693,9 @@ static void *lpm_test_command(void *arg) { int i, j, ret, iter, key_size; struct lpm_mt_test_info *info = arg; - struct bpf_lpm_trie_key *key_p; + struct bpf_lpm_trie_key_u8 *key_p; - key_size = sizeof(struct bpf_lpm_trie_key) + sizeof(__u32); + key_size = sizeof(*key_p) + sizeof(__u32); key_p = alloca(key_size); for (iter = 0; iter < info->iter; iter++) for (i = 0; i < MAX_TEST_KEYS; i++) { @@ -717,7 +717,7 @@ static void *lpm_test_command(void *arg) ret = bpf_map_lookup_elem(info->map_fd, key_p, &value); assert(ret == 0 || errno == ENOENT); } else { - struct bpf_lpm_trie_key *next_key_p = alloca(key_size); + struct bpf_lpm_trie_key_u8 *next_key_p = alloca(key_size); ret = bpf_map_get_next_key(info->map_fd, key_p, next_key_p); assert(ret == 0 || errno == ENOENT || errno == ENOMEM); } @@ -752,7 +752,7 @@ static void test_lpm_multi_thread(void) /* create a trie */ value_size = sizeof(__u32); - key_size = sizeof(struct bpf_lpm_trie_key) + value_size; + key_size = sizeof(struct bpf_lpm_trie_key_hdr) + value_size; map_fd = bpf_map_create(BPF_MAP_TYPE_LPM_TRIE, NULL, key_size, value_size, 100, &opts); /* create 4 threads to test update, delete, lookup and get_next_key */
Replace deprecated 0-length array in struct bpf_lpm_trie_key with flexible array. Found with GCC 13: ../kernel/bpf/lpm_trie.c:207:51: warning: array subscript i is outside array bounds of 'const __u8[0]' {aka 'const unsigned char[]'} [-Warray-bounds=] 207 | *(__be16 *)&key->data[i]); | ^~~~~~~~~~~~~ ../include/uapi/linux/swab.h:102:54: note: in definition of macro '__swab16' 102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) | ^ ../include/linux/byteorder/generic.h:97:21: note: in expansion of macro '__be16_to_cpu' 97 | #define be16_to_cpu __be16_to_cpu | ^~~~~~~~~~~~~ ../kernel/bpf/lpm_trie.c:206:28: note: in expansion of macro 'be16_to_cpu' 206 | u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] ^ | ^~~~~~~~~~~ In file included from ../include/linux/bpf.h:7: ../include/uapi/linux/bpf.h:82:17: note: while referencing 'data' 82 | __u8 data[0]; /* Arbitrary size */ | ^~~~ And found at run-time under CONFIG_FORTIFY_SOURCE: UBSAN: array-index-out-of-bounds in kernel/bpf/lpm_trie.c:218:49 index 0 is out of range for type '__u8 [*]' Changing struct bpf_lpm_trie_key is difficult since has been used by userspace. For example, in Cilium: struct egress_gw_policy_key { struct bpf_lpm_trie_key lpm_key; __u32 saddr; __u32 daddr; }; While direct references to the "data" member haven't been found, there are static initializers what include the final member. For example, the "{}" here: struct egress_gw_policy_key in_key = { .lpm_key = { 32 + 24, {} }, .saddr = CLIENT_IP, .daddr = EXTERNAL_SVC_IP & 0Xffffff, }; To avoid the build time and run time warnings seen with a 0-sized trailing array for struct bpf_lpm_trie_key, introduce a new struct that correctly uses a flexible array for the trailing bytes, struct bpf_lpm_trie_key_u8. As part of this, include the "header" portion (which is just the "prefixlen" member), so it can be used by anything building a bpf_lpr_trie_key that has trailing members that aren't a u8 flexible array (like the self-test[1]), which is named struct bpf_lpm_trie_key_hdr. Adjust the kernel code to use struct bpf_lpm_trie_key_u8 through-out, and for the selftest to use struct bpf_lpm_trie_key_hdr. Add a comment to the UAPI header directing folks to the two new options. Link: https://lore.kernel.org/all/202206281009.4332AA33@keescook/ [1] Reported-by: Mark Rutland <mark.rutland@arm.com> Closes: https://paste.debian.net/hidden/ca500597/ Signed-off-by: Kees Cook <keescook@chromium.org> --- v3- create a new pair of structs -- leave old struct alone v2- https://lore.kernel.org/lkml/20240216235536.it.234-kees@kernel.org/ v1- https://lore.kernel.org/lkml/20230204183241.never.481-kees@kernel.org/ Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Yonghong Song <yhs@fb.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Stanislav Fomichev <sdf@google.com> Cc: Hao Luo <haoluo@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mykola Lysenko <mykolal@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Haowen Bai <baihaowen@meizu.com> Cc: bpf@vger.kernel.org Cc: linux-kselftest@vger.kernel.org --- Documentation/bpf/map_lpm_trie.rst | 2 +- include/uapi/linux/bpf.h | 14 ++++++++++++- kernel/bpf/lpm_trie.c | 20 +++++++++---------- samples/bpf/map_perf_test_user.c | 2 +- samples/bpf/xdp_router_ipv4_user.c | 2 +- tools/include/uapi/linux/bpf.h | 14 ++++++++++++- .../selftests/bpf/progs/map_ptr_kern.c | 2 +- tools/testing/selftests/bpf/test_lpm_map.c | 18 ++++++++--------- 8 files changed, 49 insertions(+), 25 deletions(-)