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authorStanislav Fomichev <sdf@google.com>2019-06-27 23:38:47 +0300
committerAlexei Starovoitov <ast@kernel.org>2019-06-28 01:25:16 +0300
commit0d01da6afc5402f60325c5da31b22f7d56689b49 (patch)
treeafb8dd2975f8aa50d3577cb42310eb298d6491ac /include/linux/bpf-cgroup.h
parent3b1c667e47e4066cfe61610825ad50bc6b4a57e1 (diff)
downloadlinux-0d01da6afc5402f60325c5da31b22f7d56689b49.tar.xz
bpf: implement getsockopt and setsockopt hooks
Implement new BPF_PROG_TYPE_CGROUP_SOCKOPT program type and BPF_CGROUP_{G,S}ETSOCKOPT cgroup hooks. BPF_CGROUP_SETSOCKOPT can modify user setsockopt arguments before passing them down to the kernel or bypass kernel completely. BPF_CGROUP_GETSOCKOPT can can inspect/modify getsockopt arguments that kernel returns. Both hooks reuse existing PTR_TO_PACKET{,_END} infrastructure. The buffer memory is pre-allocated (because I don't think there is a precedent for working with __user memory from bpf). This might be slow to do for each {s,g}etsockopt call, that's why I've added __cgroup_bpf_prog_array_is_empty that exits early if there is nothing attached to a cgroup. Note, however, that there is a race between __cgroup_bpf_prog_array_is_empty and BPF_PROG_RUN_ARRAY where cgroup program layout might have changed; this should not be a problem because in general there is a race between multiple calls to {s,g}etsocktop and user adding/removing bpf progs from a cgroup. The return code of the BPF program is handled as follows: * 0: EPERM * 1: success, continue with next BPF program in the cgroup chain v9: * allow overwriting setsockopt arguments (Alexei Starovoitov): * use set_fs (same as kernel_setsockopt) * buffer is always kzalloc'd (no small on-stack buffer) v8: * use s32 for optlen (Andrii Nakryiko) v7: * return only 0 or 1 (Alexei Starovoitov) * always run all progs (Alexei Starovoitov) * use optval=0 as kernel bypass in setsockopt (Alexei Starovoitov) (decided to use optval=-1 instead, optval=0 might be a valid input) * call getsockopt hook after kernel handlers (Alexei Starovoitov) v6: * rework cgroup chaining; stop as soon as bpf program returns 0 or 2; see patch with the documentation for the details * drop Andrii's and Martin's Acked-by (not sure they are comfortable with the new state of things) v5: * skip copy_to_user() and put_user() when ret == 0 (Martin Lau) v4: * don't export bpf_sk_fullsock helper (Martin Lau) * size != sizeof(__u64) for uapi pointers (Martin Lau) * offsetof instead of bpf_ctx_range when checking ctx access (Martin Lau) v3: * typos in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY comments (Andrii Nakryiko) * reverse christmas tree in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY (Andrii Nakryiko) * use __bpf_md_ptr instead of __u32 for optval{,_end} (Martin Lau) * use BPF_FIELD_SIZEOF() for consistency (Martin Lau) * new CG_SOCKOPT_ACCESS macro to wrap repeated parts v2: * moved bpf_sockopt_kern fields around to remove a hole (Martin Lau) * aligned bpf_sockopt_kern->buf to 8 bytes (Martin Lau) * bpf_prog_array_is_empty instead of bpf_prog_array_length (Martin Lau) * added [0,2] return code check to verifier (Martin Lau) * dropped unused buf[64] from the stack (Martin Lau) * use PTR_TO_SOCKET for bpf_sockopt->sk (Martin Lau) * dropped bpf_target_off from ctx rewrites (Martin Lau) * use return code for kernel bypass (Martin Lau & Andrii Nakryiko) Cc: Andrii Nakryiko <andriin@fb.com> Cc: Martin Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/bpf-cgroup.h')
-rw-r--r--include/linux/bpf-cgroup.h45
1 files changed, 45 insertions, 0 deletions
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index bd79ae32909a..169fd25f6bc2 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -124,6 +124,14 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
loff_t *ppos, void **new_buf,
enum bpf_attach_type type);
+int __cgroup_bpf_run_filter_setsockopt(struct sock *sock, int *level,
+ int *optname, char __user *optval,
+ int *optlen, char **kernel_optval);
+int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
+ int optname, char __user *optval,
+ int __user *optlen, int max_optlen,
+ int retval);
+
static inline enum bpf_cgroup_storage_type cgroup_storage_type(
struct bpf_map *map)
{
@@ -286,6 +294,38 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
__ret; \
})
+#define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen, \
+ kernel_optval) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled) \
+ __ret = __cgroup_bpf_run_filter_setsockopt(sock, level, \
+ optname, optval, \
+ optlen, \
+ kernel_optval); \
+ __ret; \
+})
+
+#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled) \
+ get_user(__ret, optlen); \
+ __ret; \
+})
+
+#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, optlen, \
+ max_optlen, retval) \
+({ \
+ int __ret = retval; \
+ if (cgroup_bpf_enabled) \
+ __ret = __cgroup_bpf_run_filter_getsockopt(sock, level, \
+ optname, optval, \
+ optlen, max_optlen, \
+ retval); \
+ __ret; \
+})
+
int cgroup_bpf_prog_attach(const union bpf_attr *attr,
enum bpf_prog_type ptype, struct bpf_prog *prog);
int cgroup_bpf_prog_detach(const union bpf_attr *attr,
@@ -357,6 +397,11 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
#define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
#define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
#define BPF_CGROUP_RUN_PROG_SYSCTL(head,table,write,buf,count,pos,nbuf) ({ 0; })
+#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, \
+ optlen, max_optlen, retval) ({ retval; })
+#define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen, \
+ kernel_optval) ({ 0; })
#define for_each_cgroup_storage_type(stype) for (; false; )