| Message ID | 073173502d762faf87bde0ca23e609c84848dd7e.1661192455.git.dxu@dxuuu.xyz (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | Support direct writes to nf_conn:mark | expand |
On Mon, 22 Aug 2022 at 20:26, Daniel Xu <dxu@dxuuu.xyz> wrote: > > Support direct writes to nf_conn:mark from TC and XDP prog types. This > is useful when applications want to store per-connection metadata. This > is also particularly useful for applications that run both bpf and > iptables/nftables because the latter can trivially access this metadata. > > One example use case would be if a bpf prog is responsible for advanced > packet classification and iptables/nftables is later used for routing > due to pre-existing/legacy code. > > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> > --- > include/net/netfilter/nf_conntrack_bpf.h | 22 ++++++ > net/core/filter.c | 34 +++++++++ > net/netfilter/nf_conntrack_bpf.c | 91 +++++++++++++++++++++++- > net/netfilter/nf_conntrack_core.c | 1 + > 4 files changed, 147 insertions(+), 1 deletion(-) > > diff --git a/include/net/netfilter/nf_conntrack_bpf.h b/include/net/netfilter/nf_conntrack_bpf.h > index a473b56842c5..6fc03066846b 100644 > --- a/include/net/netfilter/nf_conntrack_bpf.h > +++ b/include/net/netfilter/nf_conntrack_bpf.h > @@ -3,6 +3,7 @@ > #ifndef _NF_CONNTRACK_BPF_H > #define _NF_CONNTRACK_BPF_H > > +#include <linux/bpf.h> > #include <linux/btf.h> > #include <linux/kconfig.h> > > @@ -10,6 +11,13 @@ > (IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) > > extern int register_nf_conntrack_bpf(void); > +extern void cleanup_nf_conntrack_bpf(void); > +extern int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag); > > #else > > @@ -18,6 +26,20 @@ static inline int register_nf_conntrack_bpf(void) > return 0; > } > > +static inline void cleanup_nf_conntrack_bpf(void) > +{ > +} > + > +static inline int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag) > +{ > + return -EACCES; > +} > + > #endif > > #endif /* _NF_CONNTRACK_BPF_H */ > diff --git a/net/core/filter.c b/net/core/filter.c > index 1acfaffeaf32..25bdbf6dc76b 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -18,6 +18,7 @@ > */ > > #include <linux/atomic.h> > +#include <linux/bpf_verifier.h> > #include <linux/module.h> > #include <linux/types.h> > #include <linux/mm.h> > @@ -55,6 +56,7 @@ > #include <net/sock_reuseport.h> > #include <net/busy_poll.h> > #include <net/tcp.h> > +#include <net/netfilter/nf_conntrack_bpf.h> > #include <net/xfrm.h> > #include <net/udp.h> > #include <linux/bpf_trace.h> > @@ -8628,6 +8630,21 @@ static bool tc_cls_act_is_valid_access(int off, int size, > return bpf_skb_is_valid_access(off, size, type, prog, info); > } > > +static int tc_cls_act_btf_struct_access(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag) > +{ > + if (atype == BPF_READ) > + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, > + flag); > + > + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, > + next_btf_id, flag); > +} > + > static bool __is_valid_xdp_access(int off, int size) > { > if (off < 0 || off >= sizeof(struct xdp_md)) > @@ -8687,6 +8704,21 @@ void bpf_warn_invalid_xdp_action(struct net_device *dev, struct bpf_prog *prog, > } > EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action); > > +static int xdp_btf_struct_access(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag) > +{ > + if (atype == BPF_READ) > + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, > + flag); > + > + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, > + next_btf_id, flag); > +} > + > static bool sock_addr_is_valid_access(int off, int size, > enum bpf_access_type type, > const struct bpf_prog *prog, > @@ -10581,6 +10613,7 @@ const struct bpf_verifier_ops tc_cls_act_verifier_ops = { > .convert_ctx_access = tc_cls_act_convert_ctx_access, > .gen_prologue = tc_cls_act_prologue, > .gen_ld_abs = bpf_gen_ld_abs, > + .btf_struct_access = tc_cls_act_btf_struct_access, > }; > > const struct bpf_prog_ops tc_cls_act_prog_ops = { > @@ -10592,6 +10625,7 @@ const struct bpf_verifier_ops xdp_verifier_ops = { > .is_valid_access = xdp_is_valid_access, > .convert_ctx_access = xdp_convert_ctx_access, > .gen_prologue = bpf_noop_prologue, > + .btf_struct_access = xdp_btf_struct_access, > }; > > const struct bpf_prog_ops xdp_prog_ops = { > diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c > index 1cd87b28c9b0..da54355927d4 100644 > --- a/net/netfilter/nf_conntrack_bpf.c > +++ b/net/netfilter/nf_conntrack_bpf.c > @@ -6,8 +6,10 @@ > * are exposed through to BPF programs is explicitly unstable. > */ > > +#include <linux/bpf_verifier.h> > #include <linux/bpf.h> > #include <linux/btf.h> > +#include <linux/mutex.h> > #include <linux/types.h> > #include <linux/btf_ids.h> > #include <linux/net_namespace.h> > @@ -184,6 +186,79 @@ static struct nf_conn *__bpf_nf_ct_lookup(struct net *net, > return ct; > } > > +BTF_ID_LIST(btf_nf_conn_ids) > +BTF_ID(struct, nf_conn) > +BTF_ID(struct, nf_conn___init) > + > +static DEFINE_MUTEX(btf_access_lock); > +static int (*nfct_bsa)(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag); > + > +/* Check writes into `struct nf_conn` */ > +static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag) > +{ > + const struct btf_type *ncit; > + const struct btf_type *nct; > + size_t end; > + > + ncit = btf_type_by_id(btf, btf_nf_conn_ids[1]); > + nct = btf_type_by_id(btf, btf_nf_conn_ids[0]); > + > + if (t != nct && t != ncit) { > + bpf_log(log, "only read is supported\n"); > + return -EACCES; > + } > + > + /* `struct nf_conn` and `struct nf_conn___init` have the same layout > + * so we are safe to simply merge offset checks here > + */ > + switch (off) { > +#if defined(CONFIG_NF_CONNTRACK_MARK) > + case offsetof(struct nf_conn, mark): > + end = offsetofend(struct nf_conn, mark); > + break; > +#endif > + default: > + bpf_log(log, "no write support to nf_conn at off %d\n", off); > + return -EACCES; > + } > + > + if (off + size > end) { > + bpf_log(log, > + "write access at off %d with size %d beyond the member of nf_conn ended at %zu\n", > + off, size, end); > + return -EACCES; > + } > + > + return 0; > +} > + > +int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > + const struct btf *btf, > + const struct btf_type *t, int off, > + int size, enum bpf_access_type atype, > + u32 *next_btf_id, > + enum bpf_type_flag *flag) > +{ > + int ret = -EACCES; > + > + mutex_lock(&btf_access_lock); > + if (nfct_bsa) > + ret = nfct_bsa(log, btf, t, off, size, atype, next_btf_id, flag); > + mutex_unlock(&btf_access_lock); > + > + return ret; > +} Did you test this for CONFIG_NF_CONNTRACK=m? For me it isn't building :P. It won't work like this. When nf_conntrack is a module, the vmlinux.o of the kernel isn't linked to the object file nf_conntrack_bpf.o. Hence it would be an undefined reference error. You don't see it in BPF CI as we set CONFIG_NF_CONNTRACK=y (to simplify testing). So you need to have code that locks and checks the cb pointer when calling it outside the module, which means the global lock variable and global cb pointer also need to be in the kernel. The module then takes the same lock and sets cb pointer when loading. During unload, it takes the same lock and sets it back to NULL. You can have global variables in vmlinux that you reference from modules. The compiler will emit a relocation for the module object file which will be handled by the kernel during module load. So please test it once with nf_conntrack built as a module before sending the next revision. The only thing you need to do before running ./test_progs -t bpf_nf is loading the module nf_conntrack.ko (and its dependencies, nf_defrag_ipv{4,6}.ko).
On Tue, Aug 23, 2022 at 02:16:42AM +0200, Kumar Kartikeya Dwivedi wrote: > On Mon, 22 Aug 2022 at 20:26, Daniel Xu <dxu@dxuuu.xyz> wrote: > > > > Support direct writes to nf_conn:mark from TC and XDP prog types. This > > is useful when applications want to store per-connection metadata. This > > is also particularly useful for applications that run both bpf and > > iptables/nftables because the latter can trivially access this metadata. > > > > One example use case would be if a bpf prog is responsible for advanced > > packet classification and iptables/nftables is later used for routing > > due to pre-existing/legacy code. > > > > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> > > --- > > include/net/netfilter/nf_conntrack_bpf.h | 22 ++++++ > > net/core/filter.c | 34 +++++++++ > > net/netfilter/nf_conntrack_bpf.c | 91 +++++++++++++++++++++++- > > net/netfilter/nf_conntrack_core.c | 1 + > > 4 files changed, 147 insertions(+), 1 deletion(-) > > > > diff --git a/include/net/netfilter/nf_conntrack_bpf.h b/include/net/netfilter/nf_conntrack_bpf.h > > index a473b56842c5..6fc03066846b 100644 > > --- a/include/net/netfilter/nf_conntrack_bpf.h > > +++ b/include/net/netfilter/nf_conntrack_bpf.h > > @@ -3,6 +3,7 @@ > > #ifndef _NF_CONNTRACK_BPF_H > > #define _NF_CONNTRACK_BPF_H > > > > +#include <linux/bpf.h> > > #include <linux/btf.h> > > #include <linux/kconfig.h> > > > > @@ -10,6 +11,13 @@ > > (IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) > > > > extern int register_nf_conntrack_bpf(void); > > +extern void cleanup_nf_conntrack_bpf(void); > > +extern int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag); > > > > #else > > > > @@ -18,6 +26,20 @@ static inline int register_nf_conntrack_bpf(void) > > return 0; > > } > > > > +static inline void cleanup_nf_conntrack_bpf(void) > > +{ > > +} > > + > > +static inline int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag) > > +{ > > + return -EACCES; > > +} > > + > > #endif > > > > #endif /* _NF_CONNTRACK_BPF_H */ > > diff --git a/net/core/filter.c b/net/core/filter.c > > index 1acfaffeaf32..25bdbf6dc76b 100644 > > --- a/net/core/filter.c > > +++ b/net/core/filter.c > > @@ -18,6 +18,7 @@ > > */ > > > > #include <linux/atomic.h> > > +#include <linux/bpf_verifier.h> > > #include <linux/module.h> > > #include <linux/types.h> > > #include <linux/mm.h> > > @@ -55,6 +56,7 @@ > > #include <net/sock_reuseport.h> > > #include <net/busy_poll.h> > > #include <net/tcp.h> > > +#include <net/netfilter/nf_conntrack_bpf.h> > > #include <net/xfrm.h> > > #include <net/udp.h> > > #include <linux/bpf_trace.h> > > @@ -8628,6 +8630,21 @@ static bool tc_cls_act_is_valid_access(int off, int size, > > return bpf_skb_is_valid_access(off, size, type, prog, info); > > } > > > > +static int tc_cls_act_btf_struct_access(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag) > > +{ > > + if (atype == BPF_READ) > > + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, > > + flag); > > + > > + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, > > + next_btf_id, flag); > > +} > > + > > static bool __is_valid_xdp_access(int off, int size) > > { > > if (off < 0 || off >= sizeof(struct xdp_md)) > > @@ -8687,6 +8704,21 @@ void bpf_warn_invalid_xdp_action(struct net_device *dev, struct bpf_prog *prog, > > } > > EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action); > > > > +static int xdp_btf_struct_access(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag) > > +{ > > + if (atype == BPF_READ) > > + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, > > + flag); > > + > > + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, > > + next_btf_id, flag); > > +} > > + > > static bool sock_addr_is_valid_access(int off, int size, > > enum bpf_access_type type, > > const struct bpf_prog *prog, > > @@ -10581,6 +10613,7 @@ const struct bpf_verifier_ops tc_cls_act_verifier_ops = { > > .convert_ctx_access = tc_cls_act_convert_ctx_access, > > .gen_prologue = tc_cls_act_prologue, > > .gen_ld_abs = bpf_gen_ld_abs, > > + .btf_struct_access = tc_cls_act_btf_struct_access, > > }; > > > > const struct bpf_prog_ops tc_cls_act_prog_ops = { > > @@ -10592,6 +10625,7 @@ const struct bpf_verifier_ops xdp_verifier_ops = { > > .is_valid_access = xdp_is_valid_access, > > .convert_ctx_access = xdp_convert_ctx_access, > > .gen_prologue = bpf_noop_prologue, > > + .btf_struct_access = xdp_btf_struct_access, > > }; > > > > const struct bpf_prog_ops xdp_prog_ops = { > > diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c > > index 1cd87b28c9b0..da54355927d4 100644 > > --- a/net/netfilter/nf_conntrack_bpf.c > > +++ b/net/netfilter/nf_conntrack_bpf.c > > @@ -6,8 +6,10 @@ > > * are exposed through to BPF programs is explicitly unstable. > > */ > > > > +#include <linux/bpf_verifier.h> > > #include <linux/bpf.h> > > #include <linux/btf.h> > > +#include <linux/mutex.h> > > #include <linux/types.h> > > #include <linux/btf_ids.h> > > #include <linux/net_namespace.h> > > @@ -184,6 +186,79 @@ static struct nf_conn *__bpf_nf_ct_lookup(struct net *net, > > return ct; > > } > > > > +BTF_ID_LIST(btf_nf_conn_ids) > > +BTF_ID(struct, nf_conn) > > +BTF_ID(struct, nf_conn___init) > > + > > +static DEFINE_MUTEX(btf_access_lock); > > +static int (*nfct_bsa)(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag); > > + > > +/* Check writes into `struct nf_conn` */ > > +static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag) > > +{ > > + const struct btf_type *ncit; > > + const struct btf_type *nct; > > + size_t end; > > + > > + ncit = btf_type_by_id(btf, btf_nf_conn_ids[1]); > > + nct = btf_type_by_id(btf, btf_nf_conn_ids[0]); > > + > > + if (t != nct && t != ncit) { > > + bpf_log(log, "only read is supported\n"); > > + return -EACCES; > > + } > > + > > + /* `struct nf_conn` and `struct nf_conn___init` have the same layout > > + * so we are safe to simply merge offset checks here > > + */ > > + switch (off) { > > +#if defined(CONFIG_NF_CONNTRACK_MARK) > > + case offsetof(struct nf_conn, mark): > > + end = offsetofend(struct nf_conn, mark); > > + break; > > +#endif > > + default: > > + bpf_log(log, "no write support to nf_conn at off %d\n", off); > > + return -EACCES; > > + } > > + > > + if (off + size > end) { > > + bpf_log(log, > > + "write access at off %d with size %d beyond the member of nf_conn ended at %zu\n", > > + off, size, end); > > + return -EACCES; > > + } > > + > > + return 0; > > +} > > + > > +int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > + const struct btf *btf, > > + const struct btf_type *t, int off, > > + int size, enum bpf_access_type atype, > > + u32 *next_btf_id, > > + enum bpf_type_flag *flag) > > +{ > > + int ret = -EACCES; > > + > > + mutex_lock(&btf_access_lock); > > + if (nfct_bsa) > > + ret = nfct_bsa(log, btf, t, off, size, atype, next_btf_id, flag); > > + mutex_unlock(&btf_access_lock); > > + > > + return ret; > > +} > > Did you test this for CONFIG_NF_CONNTRACK=m? For me it isn't building :P. > > It won't work like this. When nf_conntrack is a module, the vmlinux.o > of the kernel isn't linked to the object file nf_conntrack_bpf.o. > Hence it would be an undefined reference error. You don't see it in > BPF CI as we set CONFIG_NF_CONNTRACK=y (to simplify testing). Sorry about that. Will make sure to test that config setting. > So you need to have code that locks and checks the cb pointer when > calling it outside the module, which means the global lock variable > and global cb pointer also need to be in the kernel. The module then > takes the same lock and sets cb pointer when loading. During unload, > it takes the same lock and sets it back to NULL. > > You can have global variables in vmlinux that you reference from > modules. The compiler will emit a relocation for the module object > file which will be handled by the kernel during module load. Sure, I'll take a look. I was trying to keep conntrack symbols out of the core object files as much as possible but looks like that won't be possible. However, I think to keep the globals symbols in vmlinux we'll need to EXPORT_SYMBOL_GPL() some symbols. Hopefully that is OK. There's also some other issues I'm uncovering with duplicate BTF IDs for nf_conn. Might have to do a lookup by name instead of the BTF_ID_LIST(). > So please test it once with nf_conntrack built as a module before > sending the next revision. The only thing you need to do before > running ./test_progs -t bpf_nf is loading the module nf_conntrack.ko > (and its dependencies, nf_defrag_ipv{4,6}.ko). Will do. Thanks again for the reviews, Daniel
On Tue, 23 Aug 2022 at 04:19, Daniel Xu <dxu@dxuuu.xyz> wrote: > > On Tue, Aug 23, 2022 at 02:16:42AM +0200, Kumar Kartikeya Dwivedi wrote: > > On Mon, 22 Aug 2022 at 20:26, Daniel Xu <dxu@dxuuu.xyz> wrote: > > > > > > Support direct writes to nf_conn:mark from TC and XDP prog types. This > > > is useful when applications want to store per-connection metadata. This > > > is also particularly useful for applications that run both bpf and > > > iptables/nftables because the latter can trivially access this metadata. > > > > > > One example use case would be if a bpf prog is responsible for advanced > > > packet classification and iptables/nftables is later used for routing > > > due to pre-existing/legacy code. > > > > > > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> > > > --- > > > include/net/netfilter/nf_conntrack_bpf.h | 22 ++++++ > > > net/core/filter.c | 34 +++++++++ > > > net/netfilter/nf_conntrack_bpf.c | 91 +++++++++++++++++++++++- > > > net/netfilter/nf_conntrack_core.c | 1 + > > > 4 files changed, 147 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/net/netfilter/nf_conntrack_bpf.h b/include/net/netfilter/nf_conntrack_bpf.h > > > index a473b56842c5..6fc03066846b 100644 > > > --- a/include/net/netfilter/nf_conntrack_bpf.h > > > +++ b/include/net/netfilter/nf_conntrack_bpf.h > > > @@ -3,6 +3,7 @@ > > > #ifndef _NF_CONNTRACK_BPF_H > > > #define _NF_CONNTRACK_BPF_H > > > > > > +#include <linux/bpf.h> > > > #include <linux/btf.h> > > > #include <linux/kconfig.h> > > > > > > @@ -10,6 +11,13 @@ > > > (IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) > > > > > > extern int register_nf_conntrack_bpf(void); > > > +extern void cleanup_nf_conntrack_bpf(void); > > > +extern int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag); > > > > > > #else > > > > > > @@ -18,6 +26,20 @@ static inline int register_nf_conntrack_bpf(void) > > > return 0; > > > } > > > > > > +static inline void cleanup_nf_conntrack_bpf(void) > > > +{ > > > +} > > > + > > > +static inline int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag) > > > +{ > > > + return -EACCES; > > > +} > > > + > > > #endif > > > > > > #endif /* _NF_CONNTRACK_BPF_H */ > > > diff --git a/net/core/filter.c b/net/core/filter.c > > > index 1acfaffeaf32..25bdbf6dc76b 100644 > > > --- a/net/core/filter.c > > > +++ b/net/core/filter.c > > > @@ -18,6 +18,7 @@ > > > */ > > > > > > #include <linux/atomic.h> > > > +#include <linux/bpf_verifier.h> > > > #include <linux/module.h> > > > #include <linux/types.h> > > > #include <linux/mm.h> > > > @@ -55,6 +56,7 @@ > > > #include <net/sock_reuseport.h> > > > #include <net/busy_poll.h> > > > #include <net/tcp.h> > > > +#include <net/netfilter/nf_conntrack_bpf.h> > > > #include <net/xfrm.h> > > > #include <net/udp.h> > > > #include <linux/bpf_trace.h> > > > @@ -8628,6 +8630,21 @@ static bool tc_cls_act_is_valid_access(int off, int size, > > > return bpf_skb_is_valid_access(off, size, type, prog, info); > > > } > > > > > > +static int tc_cls_act_btf_struct_access(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag) > > > +{ > > > + if (atype == BPF_READ) > > > + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, > > > + flag); > > > + > > > + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, > > > + next_btf_id, flag); > > > +} > > > + > > > static bool __is_valid_xdp_access(int off, int size) > > > { > > > if (off < 0 || off >= sizeof(struct xdp_md)) > > > @@ -8687,6 +8704,21 @@ void bpf_warn_invalid_xdp_action(struct net_device *dev, struct bpf_prog *prog, > > > } > > > EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action); > > > > > > +static int xdp_btf_struct_access(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag) > > > +{ > > > + if (atype == BPF_READ) > > > + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, > > > + flag); > > > + > > > + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, > > > + next_btf_id, flag); > > > +} > > > + > > > static bool sock_addr_is_valid_access(int off, int size, > > > enum bpf_access_type type, > > > const struct bpf_prog *prog, > > > @@ -10581,6 +10613,7 @@ const struct bpf_verifier_ops tc_cls_act_verifier_ops = { > > > .convert_ctx_access = tc_cls_act_convert_ctx_access, > > > .gen_prologue = tc_cls_act_prologue, > > > .gen_ld_abs = bpf_gen_ld_abs, > > > + .btf_struct_access = tc_cls_act_btf_struct_access, > > > }; > > > > > > const struct bpf_prog_ops tc_cls_act_prog_ops = { > > > @@ -10592,6 +10625,7 @@ const struct bpf_verifier_ops xdp_verifier_ops = { > > > .is_valid_access = xdp_is_valid_access, > > > .convert_ctx_access = xdp_convert_ctx_access, > > > .gen_prologue = bpf_noop_prologue, > > > + .btf_struct_access = xdp_btf_struct_access, > > > }; > > > > > > const struct bpf_prog_ops xdp_prog_ops = { > > > diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c > > > index 1cd87b28c9b0..da54355927d4 100644 > > > --- a/net/netfilter/nf_conntrack_bpf.c > > > +++ b/net/netfilter/nf_conntrack_bpf.c > > > @@ -6,8 +6,10 @@ > > > * are exposed through to BPF programs is explicitly unstable. > > > */ > > > > > > +#include <linux/bpf_verifier.h> > > > #include <linux/bpf.h> > > > #include <linux/btf.h> > > > +#include <linux/mutex.h> > > > #include <linux/types.h> > > > #include <linux/btf_ids.h> > > > #include <linux/net_namespace.h> > > > @@ -184,6 +186,79 @@ static struct nf_conn *__bpf_nf_ct_lookup(struct net *net, > > > return ct; > > > } > > > > > > +BTF_ID_LIST(btf_nf_conn_ids) > > > +BTF_ID(struct, nf_conn) > > > +BTF_ID(struct, nf_conn___init) > > > + > > > +static DEFINE_MUTEX(btf_access_lock); > > > +static int (*nfct_bsa)(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag); > > > + > > > +/* Check writes into `struct nf_conn` */ > > > +static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag) > > > +{ > > > + const struct btf_type *ncit; > > > + const struct btf_type *nct; > > > + size_t end; > > > + > > > + ncit = btf_type_by_id(btf, btf_nf_conn_ids[1]); > > > + nct = btf_type_by_id(btf, btf_nf_conn_ids[0]); > > > + > > > + if (t != nct && t != ncit) { > > > + bpf_log(log, "only read is supported\n"); > > > + return -EACCES; > > > + } > > > + > > > + /* `struct nf_conn` and `struct nf_conn___init` have the same layout > > > + * so we are safe to simply merge offset checks here > > > + */ > > > + switch (off) { > > > +#if defined(CONFIG_NF_CONNTRACK_MARK) > > > + case offsetof(struct nf_conn, mark): > > > + end = offsetofend(struct nf_conn, mark); > > > + break; > > > +#endif > > > + default: > > > + bpf_log(log, "no write support to nf_conn at off %d\n", off); > > > + return -EACCES; > > > + } > > > + > > > + if (off + size > end) { > > > + bpf_log(log, > > > + "write access at off %d with size %d beyond the member of nf_conn ended at %zu\n", > > > + off, size, end); > > > + return -EACCES; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > +int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > > > + const struct btf *btf, > > > + const struct btf_type *t, int off, > > > + int size, enum bpf_access_type atype, > > > + u32 *next_btf_id, > > > + enum bpf_type_flag *flag) > > > +{ > > > + int ret = -EACCES; > > > + > > > + mutex_lock(&btf_access_lock); > > > + if (nfct_bsa) > > > + ret = nfct_bsa(log, btf, t, off, size, atype, next_btf_id, flag); > > > + mutex_unlock(&btf_access_lock); > > > + > > > + return ret; > > > +} > > > > Did you test this for CONFIG_NF_CONNTRACK=m? For me it isn't building :P. > > > > It won't work like this. When nf_conntrack is a module, the vmlinux.o > > of the kernel isn't linked to the object file nf_conntrack_bpf.o. > > Hence it would be an undefined reference error. You don't see it in > > BPF CI as we set CONFIG_NF_CONNTRACK=y (to simplify testing). > > Sorry about that. Will make sure to test that config setting. > No worries. We should probably think about being able to test it automatically in CI, but not sure how that would be possible... > > So you need to have code that locks and checks the cb pointer when > > calling it outside the module, which means the global lock variable > > and global cb pointer also need to be in the kernel. The module then > > takes the same lock and sets cb pointer when loading. During unload, > > it takes the same lock and sets it back to NULL. > > > > You can have global variables in vmlinux that you reference from > > modules. The compiler will emit a relocation for the module object > > file which will be handled by the kernel during module load. > > Sure, I'll take a look. I was trying to keep conntrack symbols out of > the core object files as much as possible but looks like that won't be > possible. Yeah, for now hardcoding is ok I figure, later when we have more modules doing this we can generalize it. > > However, I think to keep the globals symbols in vmlinux we'll need to > EXPORT_SYMBOL_GPL() some symbols. Hopefully that is OK. > Yes, that should be ok. > There's also some other issues I'm uncovering with duplicate BTF IDs for > nf_conn. Might have to do a lookup by name instead of the BTF_ID_LIST(). > I think I also hit this problem back when I was working on these patches, is it similar to this? https://lore.kernel.org/bpf/20211028014428.rsuq6rkfvqzq23tg@apollo.localdomain I think this might be a bug in the BTF generation, since there should only be one BTF ID for a type, either in vmlinux or the module BTF. Maybe Andrii would be able to confirm. > > So please test it once with nf_conntrack built as a module before > > sending the next revision. The only thing you need to do before > > running ./test_progs -t bpf_nf is loading the module nf_conntrack.ko > > (and its dependencies, nf_defrag_ipv{4,6}.ko). > > Will do. > > Thanks again for the reviews, > Daniel
Hi Daniel,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/Daniel-Xu/bpf-Remove-duplicate-PTR_TO_BTF_ID-RO-check/20220823-032643
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: x86_64-rhel-8.3-kselftests (https://download.01.org/0day-ci/archive/20220823/202208232110.vsR1bsL0-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/496ec6d75c8e8758f93c6b987eee83713c911a05
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Daniel-Xu/bpf-Remove-duplicate-PTR_TO_BTF_ID-RO-check/20220823-032643
git checkout 496ec6d75c8e8758f93c6b987eee83713c911a05
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
ld: net/core/filter.o: in function `tc_cls_act_btf_struct_access':
net/core/filter.c:8644: undefined reference to `nf_conntrack_btf_struct_access'
ld: net/core/filter.o: in function `xdp_btf_struct_access':
>> include/net/net_namespace.h:369: undefined reference to `nf_conntrack_btf_struct_access'
pahole: .tmp_vmlinux.btf: Invalid argument
.btf.vmlinux.bin.o: file not recognized: file format not recognized
vim +369 include/net/net_namespace.h
8f424b5f32d78b Eric Dumazet 2008-11-12 365
0c5c9fb5510633 Eric W. Biederman 2015-03-11 366 static inline struct net *read_pnet(const possible_net_t *pnet)
8f424b5f32d78b Eric Dumazet 2008-11-12 367 {
0c5c9fb5510633 Eric W. Biederman 2015-03-11 368 #ifdef CONFIG_NET_NS
0c5c9fb5510633 Eric W. Biederman 2015-03-11 @369 return pnet->net;
8f424b5f32d78b Eric Dumazet 2008-11-12 370 #else
0c5c9fb5510633 Eric W. Biederman 2015-03-11 371 return &init_net;
8f424b5f32d78b Eric Dumazet 2008-11-12 372 #endif
0c5c9fb5510633 Eric W. Biederman 2015-03-11 373 }
5d1e4468a7705d Denis V. Lunev 2008-04-16 374
Hi Daniel,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/Daniel-Xu/bpf-Remove-duplicate-PTR_TO_BTF_ID-RO-check/20220823-032643
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: x86_64-rhel-8.3-kselftests (https://download.01.org/0day-ci/archive/20220902/202209022000.s58TmR9h-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/496ec6d75c8e8758f93c6b987eee83713c911a05
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Daniel-Xu/bpf-Remove-duplicate-PTR_TO_BTF_ID-RO-check/20220823-032643
git checkout 496ec6d75c8e8758f93c6b987eee83713c911a05
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
ld: net/core/filter.o: in function `tc_cls_act_btf_struct_access':
>> net/core/filter.c:8644: undefined reference to `nf_conntrack_btf_struct_access'
ld: net/core/filter.o: in function `xdp_btf_struct_access':
include/net/net_namespace.h:369: undefined reference to `nf_conntrack_btf_struct_access'
pahole: .tmp_vmlinux.btf: No such file or directory
.btf.vmlinux.bin.o: file not recognized: file format not recognized
vim +8644 net/core/filter.c
8632
8633 static int tc_cls_act_btf_struct_access(struct bpf_verifier_log *log,
8634 const struct btf *btf,
8635 const struct btf_type *t, int off,
8636 int size, enum bpf_access_type atype,
8637 u32 *next_btf_id,
8638 enum bpf_type_flag *flag)
8639 {
8640 if (atype == BPF_READ)
8641 return btf_struct_access(log, btf, t, off, size, atype, next_btf_id,
8642 flag);
8643
> 8644 return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype,
8645 next_btf_id, flag);
8646 }
8647
Hi Kumar, On Tue, Aug 23, 2022 at 04:29:17AM +0200, Kumar Kartikeya Dwivedi wrote: > On Tue, 23 Aug 2022 at 04:19, Daniel Xu <dxu@dxuuu.xyz> wrote: [...] > > There's also some other issues I'm uncovering with duplicate BTF IDs for > > nf_conn. Might have to do a lookup by name instead of the BTF_ID_LIST(). > > > > I think I also hit this problem back when I was working on these > patches, is it similar to this? > https://lore.kernel.org/bpf/20211028014428.rsuq6rkfvqzq23tg@apollo.localdomain Yes, identical I think. > > I think this might be a bug in the BTF generation, since there should > only be one BTF ID for a type, either in vmlinux or the module BTF. > Maybe Andrii would be able to confirm. Had to put out some fires last week. I chased this down a bit today and best I can tell was the `nf_conn` definitions in BTF were all slightly different. For example, here were the 3 definitions in nf_conntrack.ko alone: [88439] STRUCT 'nf_conn' size=296 vlen=11 'ct_general' type_id=67058 bits_offset=0 'lock' type_id=373 bits_offset=64 'timeout' type_id=160 bits_offset=576 'tuplehash' type_id=67235 bits_offset=640 'status' type_id=1 bits_offset=1536 'ct_net' type_id=4298 bits_offset=1600 '__nfct_init_offset' type_id=4213 bits_offset=1664 'master' type_id=88438 bits_offset=1664 'mark' type_id=67192 bits_offset=1728 'ext' type_id=67236 bits_offset=1792 'proto' type_id=67234 bits_offset=1856 [90882] STRUCT 'nf_conn' size=296 vlen=11 'ct_general' type_id=67058 bits_offset=0 'lock' type_id=373 bits_offset=64 'timeout' type_id=160 bits_offset=576 'tuplehash' type_id=67235 bits_offset=640 'status' type_id=1 bits_offset=1536 'ct_net' type_id=90574 bits_offset=1600 '__nfct_init_offset' type_id=4213 bits_offset=1664 'master' type_id=90881 bits_offset=1664 'mark' type_id=67192 bits_offset=1728 'ext' type_id=67236 bits_offset=1792 'proto' type_id=67234 bits_offset=1856 [92469] STRUCT 'nf_conn' size=296 vlen=11 'ct_general' type_id=67058 bits_offset=0 'lock' type_id=373 bits_offset=64 'timeout' type_id=160 bits_offset=576 'tuplehash' type_id=67235 bits_offset=640 'status' type_id=1 bits_offset=1536 'ct_net' type_id=92160 bits_offset=1600 '__nfct_init_offset' type_id=4213 bits_offset=1664 'master' type_id=92468 bits_offset=1664 'mark' type_id=67192 bits_offset=1728 'ext' type_id=67236 bits_offset=1792 'proto' type_id=67234 bits_offset=1856 Note how `master` and `ct_net` all have different BTF IDs. Best I can tell is that there's some kind of subtle difference in BTF types and it's confusing the dedup algorithm. I went and upgraded to latest pahole (built from today's source tree) to chase the issue down further but the problem went away. Figured I'd write this up in case someone stumbles onto this in the future. [...] Thanks, Daniel
diff --git a/include/net/netfilter/nf_conntrack_bpf.h b/include/net/netfilter/nf_conntrack_bpf.h index a473b56842c5..6fc03066846b 100644 --- a/include/net/netfilter/nf_conntrack_bpf.h +++ b/include/net/netfilter/nf_conntrack_bpf.h @@ -3,6 +3,7 @@ #ifndef _NF_CONNTRACK_BPF_H #define _NF_CONNTRACK_BPF_H +#include <linux/bpf.h> #include <linux/btf.h> #include <linux/kconfig.h> @@ -10,6 +11,13 @@ (IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) extern int register_nf_conntrack_bpf(void); +extern void cleanup_nf_conntrack_bpf(void); +extern int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag); #else @@ -18,6 +26,20 @@ static inline int register_nf_conntrack_bpf(void) return 0; } +static inline void cleanup_nf_conntrack_bpf(void) +{ +} + +static inline int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + return -EACCES; +} + #endif #endif /* _NF_CONNTRACK_BPF_H */ diff --git a/net/core/filter.c b/net/core/filter.c index 1acfaffeaf32..25bdbf6dc76b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -18,6 +18,7 @@ */ #include <linux/atomic.h> +#include <linux/bpf_verifier.h> #include <linux/module.h> #include <linux/types.h> #include <linux/mm.h> @@ -55,6 +56,7 @@ #include <net/sock_reuseport.h> #include <net/busy_poll.h> #include <net/tcp.h> +#include <net/netfilter/nf_conntrack_bpf.h> #include <net/xfrm.h> #include <net/udp.h> #include <linux/bpf_trace.h> @@ -8628,6 +8630,21 @@ static bool tc_cls_act_is_valid_access(int off, int size, return bpf_skb_is_valid_access(off, size, type, prog, info); } +static int tc_cls_act_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + if (atype == BPF_READ) + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, + flag); + + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, + next_btf_id, flag); +} + static bool __is_valid_xdp_access(int off, int size) { if (off < 0 || off >= sizeof(struct xdp_md)) @@ -8687,6 +8704,21 @@ void bpf_warn_invalid_xdp_action(struct net_device *dev, struct bpf_prog *prog, } EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action); +static int xdp_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + if (atype == BPF_READ) + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, + flag); + + return nf_conntrack_btf_struct_access(log, btf, t, off, size, atype, + next_btf_id, flag); +} + static bool sock_addr_is_valid_access(int off, int size, enum bpf_access_type type, const struct bpf_prog *prog, @@ -10581,6 +10613,7 @@ const struct bpf_verifier_ops tc_cls_act_verifier_ops = { .convert_ctx_access = tc_cls_act_convert_ctx_access, .gen_prologue = tc_cls_act_prologue, .gen_ld_abs = bpf_gen_ld_abs, + .btf_struct_access = tc_cls_act_btf_struct_access, }; const struct bpf_prog_ops tc_cls_act_prog_ops = { @@ -10592,6 +10625,7 @@ const struct bpf_verifier_ops xdp_verifier_ops = { .is_valid_access = xdp_is_valid_access, .convert_ctx_access = xdp_convert_ctx_access, .gen_prologue = bpf_noop_prologue, + .btf_struct_access = xdp_btf_struct_access, }; const struct bpf_prog_ops xdp_prog_ops = { diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c index 1cd87b28c9b0..da54355927d4 100644 --- a/net/netfilter/nf_conntrack_bpf.c +++ b/net/netfilter/nf_conntrack_bpf.c @@ -6,8 +6,10 @@ * are exposed through to BPF programs is explicitly unstable. */ +#include <linux/bpf_verifier.h> #include <linux/bpf.h> #include <linux/btf.h> +#include <linux/mutex.h> #include <linux/types.h> #include <linux/btf_ids.h> #include <linux/net_namespace.h> @@ -184,6 +186,79 @@ static struct nf_conn *__bpf_nf_ct_lookup(struct net *net, return ct; } +BTF_ID_LIST(btf_nf_conn_ids) +BTF_ID(struct, nf_conn) +BTF_ID(struct, nf_conn___init) + +static DEFINE_MUTEX(btf_access_lock); +static int (*nfct_bsa)(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag); + +/* Check writes into `struct nf_conn` */ +static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + const struct btf_type *ncit; + const struct btf_type *nct; + size_t end; + + ncit = btf_type_by_id(btf, btf_nf_conn_ids[1]); + nct = btf_type_by_id(btf, btf_nf_conn_ids[0]); + + if (t != nct && t != ncit) { + bpf_log(log, "only read is supported\n"); + return -EACCES; + } + + /* `struct nf_conn` and `struct nf_conn___init` have the same layout + * so we are safe to simply merge offset checks here + */ + switch (off) { +#if defined(CONFIG_NF_CONNTRACK_MARK) + case offsetof(struct nf_conn, mark): + end = offsetofend(struct nf_conn, mark); + break; +#endif + default: + bpf_log(log, "no write support to nf_conn at off %d\n", off); + return -EACCES; + } + + if (off + size > end) { + bpf_log(log, + "write access at off %d with size %d beyond the member of nf_conn ended at %zu\n", + off, size, end); + return -EACCES; + } + + return 0; +} + +int nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + int ret = -EACCES; + + mutex_lock(&btf_access_lock); + if (nfct_bsa) + ret = nfct_bsa(log, btf, t, off, size, atype, next_btf_id, flag); + mutex_unlock(&btf_access_lock); + + return ret; +} + __diag_push(); __diag_ignore_all("-Wmissing-prototypes", "Global functions as their definitions will be in nf_conntrack BTF"); @@ -449,5 +524,19 @@ int register_nf_conntrack_bpf(void) int ret; ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &nf_conntrack_kfunc_set); - return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_kfunc_set); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_kfunc_set); + if (!ret) { + mutex_lock(&btf_access_lock); + nfct_bsa = _nf_conntrack_btf_struct_access; + mutex_unlock(&btf_access_lock); + } + + return ret; +} + +void cleanup_nf_conntrack_bpf(void) +{ + mutex_lock(&btf_access_lock); + nfct_bsa = NULL; + mutex_unlock(&btf_access_lock); } diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index da65c6e8eeeb..0195f60fc43b 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -2512,6 +2512,7 @@ static int kill_all(struct nf_conn *i, void *data) void nf_conntrack_cleanup_start(void) { + cleanup_nf_conntrack_bpf(); conntrack_gc_work.exiting = true; }
Support direct writes to nf_conn:mark from TC and XDP prog types. This is useful when applications want to store per-connection metadata. This is also particularly useful for applications that run both bpf and iptables/nftables because the latter can trivially access this metadata. One example use case would be if a bpf prog is responsible for advanced packet classification and iptables/nftables is later used for routing due to pre-existing/legacy code. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> --- include/net/netfilter/nf_conntrack_bpf.h | 22 ++++++ net/core/filter.c | 34 +++++++++ net/netfilter/nf_conntrack_bpf.c | 91 +++++++++++++++++++++++- net/netfilter/nf_conntrack_core.c | 1 + 4 files changed, 147 insertions(+), 1 deletion(-)