| Message ID | 20190701163103.237550-2-sdf@google.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: allow wide (u64) aligned stores for some fields of bpf_sock_addr | expand |
On Mon, Jul 1, 2019 at 9:51 AM Stanislav Fomichev <sdf@google.com> wrote: > > Since commit cd17d7770578 ("bpf/tools: sync bpf.h") clang decided > that it can do a single u64 store into user_ip6[2] instead of two > separate u32 ones: > > # 17: (18) r2 = 0x100000000000000 > # ; ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); > # 19: (7b) *(u64 *)(r1 +16) = r2 > # invalid bpf_context access off=16 size=8 > > From the compiler point of view it does look like a correct thing > to do, so let's support it on the kernel side. > > Credit to Andrii Nakryiko for a proper implementation of > bpf_ctx_wide_store_ok. > > Cc: Andrii Nakryiko <andriin@fb.com> > Cc: Yonghong Song <yhs@fb.com> > Fixes: cd17d7770578 ("bpf/tools: sync bpf.h") > Reported-by: kernel test robot <rong.a.chen@intel.com> > Acked-by: Yonghong Song <yhs@fb.com> > Acked-by: Andrii Nakryiko <andriin@fb.com> > Signed-off-by: Stanislav Fomichev <sdf@google.com> > --- > include/linux/filter.h | 6 ++++++ > include/uapi/linux/bpf.h | 4 ++-- > net/core/filter.c | 22 ++++++++++++++-------- > 3 files changed, 22 insertions(+), 10 deletions(-) > > diff --git a/include/linux/filter.h b/include/linux/filter.h > index 340f7d648974..3901007e36f1 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -746,6 +746,12 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default) > return size <= size_default && (size & (size - 1)) == 0; > } > > +#define bpf_ctx_wide_store_ok(off, size, type, field) \ > + (size == sizeof(__u64) && \ > + off >= offsetof(type, field) && \ > + off + sizeof(__u64) <= offsetofend(type, field) && \ > + off % sizeof(__u64) == 0) > + > #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0])) > > static inline void bpf_prog_lock_ro(struct bpf_prog *fp) > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index a396b516a2b2..586867fe6102 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -3237,7 +3237,7 @@ struct bpf_sock_addr { > __u32 user_ip4; /* Allows 1,2,4-byte read and 4-byte write. > * Stored in network byte order. > */ > - __u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write. > + __u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4,8-byte write. typo: an -> and > * Stored in network byte order. > */ > __u32 user_port; /* Allows 4-byte read and write. > @@ -3249,7 +3249,7 @@ struct bpf_sock_addr { > __u32 msg_src_ip4; /* Allows 1,2,4-byte read an 4-byte write. same > * Stored in network byte order. > */ > - __u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write. > + __u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4,8-byte write. the power of copy/paste! :) > * Stored in network byte order. > */ > __bpf_md_ptr(struct bpf_sock *, sk); > diff --git a/net/core/filter.c b/net/core/filter.c > index dc8534be12fc..5d33f2146dab 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -6849,6 +6849,16 @@ static bool sock_addr_is_valid_access(int off, int size, > if (!bpf_ctx_narrow_access_ok(off, size, size_default)) > return false; > } else { > + if (bpf_ctx_wide_store_ok(off, size, > + struct bpf_sock_addr, > + user_ip6)) > + return true; > + > + if (bpf_ctx_wide_store_ok(off, size, > + struct bpf_sock_addr, > + msg_src_ip6)) > + return true; > + > if (size != size_default) > return false; > } > @@ -7689,9 +7699,6 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > /* SOCK_ADDR_STORE_NESTED_FIELD_OFF() has semantic similar to > * SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF() but for store operation. > * > - * It doesn't support SIZE argument though since narrow stores are not > - * supported for now. > - * > * In addition it uses Temporary Field TF (member of struct S) as the 3rd > * "register" since two registers available in convert_ctx_access are not > * enough: we can't override neither SRC, since it contains value to store, nor > @@ -7699,7 +7706,7 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > * instructions. But we need a temporary place to save pointer to nested > * structure whose field we want to store to. > */ > -#define SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, OFF, TF) \ > +#define SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, SIZE, OFF, TF) \ > do { \ > int tmp_reg = BPF_REG_9; \ > if (si->src_reg == tmp_reg || si->dst_reg == tmp_reg) \ > @@ -7710,8 +7717,7 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > offsetof(S, TF)); \ > *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(S, F), tmp_reg, \ > si->dst_reg, offsetof(S, F)); \ > - *insn++ = BPF_STX_MEM( \ > - BPF_FIELD_SIZEOF(NS, NF), tmp_reg, si->src_reg, \ > + *insn++ = BPF_STX_MEM(SIZE, tmp_reg, si->src_reg, \ > bpf_target_off(NS, NF, FIELD_SIZEOF(NS, NF), \ > target_size) \ > + OFF); \ > @@ -7723,8 +7729,8 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > TF) \ > do { \ > if (type == BPF_WRITE) { \ > - SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, OFF, \ > - TF); \ > + SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, SIZE, \ > + OFF, TF); \ > } else { \ > SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF( \ > S, NS, F, NF, SIZE, OFF); \ > -- > 2.22.0.410.gd8fdbe21b5-goog >
On 07/01, Andrii Nakryiko wrote: > On Mon, Jul 1, 2019 at 9:51 AM Stanislav Fomichev <sdf@google.com> wrote: > > > > Since commit cd17d7770578 ("bpf/tools: sync bpf.h") clang decided > > that it can do a single u64 store into user_ip6[2] instead of two > > separate u32 ones: > > > > # 17: (18) r2 = 0x100000000000000 > > # ; ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); > > # 19: (7b) *(u64 *)(r1 +16) = r2 > > # invalid bpf_context access off=16 size=8 > > > > From the compiler point of view it does look like a correct thing > > to do, so let's support it on the kernel side. > > > > Credit to Andrii Nakryiko for a proper implementation of > > bpf_ctx_wide_store_ok. > > > > Cc: Andrii Nakryiko <andriin@fb.com> > > Cc: Yonghong Song <yhs@fb.com> > > Fixes: cd17d7770578 ("bpf/tools: sync bpf.h") > > Reported-by: kernel test robot <rong.a.chen@intel.com> > > Acked-by: Yonghong Song <yhs@fb.com> > > Acked-by: Andrii Nakryiko <andriin@fb.com> > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > --- > > include/linux/filter.h | 6 ++++++ > > include/uapi/linux/bpf.h | 4 ++-- > > net/core/filter.c | 22 ++++++++++++++-------- > > 3 files changed, 22 insertions(+), 10 deletions(-) > > > > diff --git a/include/linux/filter.h b/include/linux/filter.h > > index 340f7d648974..3901007e36f1 100644 > > --- a/include/linux/filter.h > > +++ b/include/linux/filter.h > > @@ -746,6 +746,12 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default) > > return size <= size_default && (size & (size - 1)) == 0; > > } > > > > +#define bpf_ctx_wide_store_ok(off, size, type, field) \ > > + (size == sizeof(__u64) && \ > > + off >= offsetof(type, field) && \ > > + off + sizeof(__u64) <= offsetofend(type, field) && \ > > + off % sizeof(__u64) == 0) > > + > > #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0])) > > > > static inline void bpf_prog_lock_ro(struct bpf_prog *fp) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index a396b516a2b2..586867fe6102 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -3237,7 +3237,7 @@ struct bpf_sock_addr { > > __u32 user_ip4; /* Allows 1,2,4-byte read and 4-byte write. > > * Stored in network byte order. > > */ > > - __u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write. > > + __u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4,8-byte write. > > typo: an -> and Oh, I was thinking that it was an article :-/ Will send a v3 with a fix, thanks! > > * Stored in network byte order. > > */ > > __u32 user_port; /* Allows 4-byte read and write. > > @@ -3249,7 +3249,7 @@ struct bpf_sock_addr { > > __u32 msg_src_ip4; /* Allows 1,2,4-byte read an 4-byte write. > > same > > > * Stored in network byte order. > > */ > > - __u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write. > > + __u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4,8-byte write. > > the power of copy/paste! :) > > > * Stored in network byte order. > > */ > > __bpf_md_ptr(struct bpf_sock *, sk); > > diff --git a/net/core/filter.c b/net/core/filter.c > > index dc8534be12fc..5d33f2146dab 100644 > > --- a/net/core/filter.c > > +++ b/net/core/filter.c > > @@ -6849,6 +6849,16 @@ static bool sock_addr_is_valid_access(int off, int size, > > if (!bpf_ctx_narrow_access_ok(off, size, size_default)) > > return false; > > } else { > > + if (bpf_ctx_wide_store_ok(off, size, > > + struct bpf_sock_addr, > > + user_ip6)) > > + return true; > > + > > + if (bpf_ctx_wide_store_ok(off, size, > > + struct bpf_sock_addr, > > + msg_src_ip6)) > > + return true; > > + > > if (size != size_default) > > return false; > > } > > @@ -7689,9 +7699,6 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > > /* SOCK_ADDR_STORE_NESTED_FIELD_OFF() has semantic similar to > > * SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF() but for store operation. > > * > > - * It doesn't support SIZE argument though since narrow stores are not > > - * supported for now. > > - * > > * In addition it uses Temporary Field TF (member of struct S) as the 3rd > > * "register" since two registers available in convert_ctx_access are not > > * enough: we can't override neither SRC, since it contains value to store, nor > > @@ -7699,7 +7706,7 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > > * instructions. But we need a temporary place to save pointer to nested > > * structure whose field we want to store to. > > */ > > -#define SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, OFF, TF) \ > > +#define SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, SIZE, OFF, TF) \ > > do { \ > > int tmp_reg = BPF_REG_9; \ > > if (si->src_reg == tmp_reg || si->dst_reg == tmp_reg) \ > > @@ -7710,8 +7717,7 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > > offsetof(S, TF)); \ > > *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(S, F), tmp_reg, \ > > si->dst_reg, offsetof(S, F)); \ > > - *insn++ = BPF_STX_MEM( \ > > - BPF_FIELD_SIZEOF(NS, NF), tmp_reg, si->src_reg, \ > > + *insn++ = BPF_STX_MEM(SIZE, tmp_reg, si->src_reg, \ > > bpf_target_off(NS, NF, FIELD_SIZEOF(NS, NF), \ > > target_size) \ > > + OFF); \ > > @@ -7723,8 +7729,8 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, > > TF) \ > > do { \ > > if (type == BPF_WRITE) { \ > > - SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, OFF, \ > > - TF); \ > > + SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, SIZE, \ > > + OFF, TF); \ > > } else { \ > > SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF( \ > > S, NS, F, NF, SIZE, OFF); \ > > -- > > 2.22.0.410.gd8fdbe21b5-goog > >
diff --git a/include/linux/filter.h b/include/linux/filter.h index 340f7d648974..3901007e36f1 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -746,6 +746,12 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default) return size <= size_default && (size & (size - 1)) == 0; } +#define bpf_ctx_wide_store_ok(off, size, type, field) \ + (size == sizeof(__u64) && \ + off >= offsetof(type, field) && \ + off + sizeof(__u64) <= offsetofend(type, field) && \ + off % sizeof(__u64) == 0) + #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0])) static inline void bpf_prog_lock_ro(struct bpf_prog *fp) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index a396b516a2b2..586867fe6102 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3237,7 +3237,7 @@ struct bpf_sock_addr { __u32 user_ip4; /* Allows 1,2,4-byte read and 4-byte write. * Stored in network byte order. */ - __u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write. + __u32 user_ip6[4]; /* Allows 1,2,4-byte read an 4,8-byte write. * Stored in network byte order. */ __u32 user_port; /* Allows 4-byte read and write. @@ -3249,7 +3249,7 @@ struct bpf_sock_addr { __u32 msg_src_ip4; /* Allows 1,2,4-byte read an 4-byte write. * Stored in network byte order. */ - __u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4-byte write. + __u32 msg_src_ip6[4]; /* Allows 1,2,4-byte read an 4,8-byte write. * Stored in network byte order. */ __bpf_md_ptr(struct bpf_sock *, sk); diff --git a/net/core/filter.c b/net/core/filter.c index dc8534be12fc..5d33f2146dab 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6849,6 +6849,16 @@ static bool sock_addr_is_valid_access(int off, int size, if (!bpf_ctx_narrow_access_ok(off, size, size_default)) return false; } else { + if (bpf_ctx_wide_store_ok(off, size, + struct bpf_sock_addr, + user_ip6)) + return true; + + if (bpf_ctx_wide_store_ok(off, size, + struct bpf_sock_addr, + msg_src_ip6)) + return true; + if (size != size_default) return false; } @@ -7689,9 +7699,6 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, /* SOCK_ADDR_STORE_NESTED_FIELD_OFF() has semantic similar to * SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF() but for store operation. * - * It doesn't support SIZE argument though since narrow stores are not - * supported for now. - * * In addition it uses Temporary Field TF (member of struct S) as the 3rd * "register" since two registers available in convert_ctx_access are not * enough: we can't override neither SRC, since it contains value to store, nor @@ -7699,7 +7706,7 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, * instructions. But we need a temporary place to save pointer to nested * structure whose field we want to store to. */ -#define SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, OFF, TF) \ +#define SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, SIZE, OFF, TF) \ do { \ int tmp_reg = BPF_REG_9; \ if (si->src_reg == tmp_reg || si->dst_reg == tmp_reg) \ @@ -7710,8 +7717,7 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, offsetof(S, TF)); \ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(S, F), tmp_reg, \ si->dst_reg, offsetof(S, F)); \ - *insn++ = BPF_STX_MEM( \ - BPF_FIELD_SIZEOF(NS, NF), tmp_reg, si->src_reg, \ + *insn++ = BPF_STX_MEM(SIZE, tmp_reg, si->src_reg, \ bpf_target_off(NS, NF, FIELD_SIZEOF(NS, NF), \ target_size) \ + OFF); \ @@ -7723,8 +7729,8 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, TF) \ do { \ if (type == BPF_WRITE) { \ - SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, OFF, \ - TF); \ + SOCK_ADDR_STORE_NESTED_FIELD_OFF(S, NS, F, NF, SIZE, \ + OFF, TF); \ } else { \ SOCK_ADDR_LOAD_NESTED_FIELD_SIZE_OFF( \ S, NS, F, NF, SIZE, OFF); \
Since commit cd17d7770578 ("bpf/tools: sync bpf.h") clang decided that it can do a single u64 store into user_ip6[2] instead of two separate u32 ones: # 17: (18) r2 = 0x100000000000000 # ; ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); # 19: (7b) *(u64 *)(r1 +16) = r2 # invalid bpf_context access off=16 size=8 From the compiler point of view it does look like a correct thing to do, so let's support it on the kernel side. Credit to Andrii Nakryiko for a proper implementation of bpf_ctx_wide_store_ok. Cc: Andrii Nakryiko <andriin@fb.com> Cc: Yonghong Song <yhs@fb.com> Fixes: cd17d7770578 ("bpf/tools: sync bpf.h") Reported-by: kernel test robot <rong.a.chen@intel.com> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> --- include/linux/filter.h | 6 ++++++ include/uapi/linux/bpf.h | 4 ++-- net/core/filter.c | 22 ++++++++++++++-------- 3 files changed, 22 insertions(+), 10 deletions(-)