net: introduce SO_BPF_EXTENSIONS

For user space packet capturing libraries such as libpcap, there's currently only one way to check which BPF extensions are supported by the kernel, that is, commit aa1113d ("net: filter: return -EINVAL if BPF_S_ANC* operation is not supported"). For querying all extensions at once this might be rather inconvenient. Therefore, this patch introduces a new option which can be used as an argument for getsockopt(), and allows one to obtain information about which BPF extensions are supported by the current kernel. As David Miller suggests, we do not need to define any bits right now and status quo can just return 0 in order to state that this versions supports SKF_AD_PROTOCOL up to SKF_AD_PAY_OFFSET. Later additions to BPF extensions need to add their bits to the bpf_tell_extensions() function, as documented in the comment. Signed-off-by: Michal Sekletar <[email protected]> Cc: David Miller <[email protected]> Reviewed-by: Daniel Borkmann <[email protected]> Signed-off-by: David S. Miller <[email protected]>
jackyding2679 · Jan 19, 2014 · ea02f94 · ea02f94
1 parent 4180442
commit ea02f94
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Showing 16 changed files with 43 additions and 0 deletions.
diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
@@ -85,4 +85,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _UAPI_ASM_SOCKET_H */
diff --git a/arch/avr32/include/uapi/asm/socket.h b/arch/avr32/include/uapi/asm/socket.h
@@ -78,4 +78,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _UAPI__ASM_AVR32_SOCKET_H */
diff --git a/arch/cris/include/uapi/asm/socket.h b/arch/cris/include/uapi/asm/socket.h
@@ -80,6 +80,8 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _ASM_SOCKET_H */
 
 
diff --git a/arch/frv/include/uapi/asm/socket.h b/arch/frv/include/uapi/asm/socket.h
@@ -78,5 +78,7 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _ASM_SOCKET_H */
 
diff --git a/arch/ia64/include/uapi/asm/socket.h b/arch/ia64/include/uapi/asm/socket.h
@@ -87,4 +87,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _ASM_IA64_SOCKET_H */
diff --git a/arch/m32r/include/uapi/asm/socket.h b/arch/m32r/include/uapi/asm/socket.h
@@ -78,4 +78,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _ASM_M32R_SOCKET_H */
diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
@@ -96,4 +96,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _UAPI_ASM_SOCKET_H */
diff --git a/arch/mn10300/include/uapi/asm/socket.h b/arch/mn10300/include/uapi/asm/socket.h
@@ -78,4 +78,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
@@ -77,4 +77,6 @@
 
 #define SO_MAX_PACING_RATE	0x4028
 
+#define SO_BPF_EXTENSIONS	0x4029
+
 #endif /* _UAPI_ASM_SOCKET_H */
diff --git a/arch/powerpc/include/uapi/asm/socket.h b/arch/powerpc/include/uapi/asm/socket.h
@@ -85,4 +85,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif	/* _ASM_POWERPC_SOCKET_H */
diff --git a/arch/s390/include/uapi/asm/socket.h b/arch/s390/include/uapi/asm/socket.h
@@ -84,4 +84,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
@@ -74,6 +74,8 @@
 
 #define SO_MAX_PACING_RATE	0x0031
 
+#define SO_BPF_EXTENSIONS	0x0032
+
 /* Security levels - as per NRL IPv6 - don't actually do anything */
 #define SO_SECURITY_AUTHENTICATION		0x5001
 #define SO_SECURITY_ENCRYPTION_TRANSPORT	0x5002

diff --git a/arch/xtensa/include/uapi/asm/socket.h b/arch/xtensa/include/uapi/asm/socket.h
@@ -89,4 +89,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif	/* _XTENSA_SOCKET_H */
diff --git a/include/linux/filter.h b/include/linux/filter.h
@@ -83,6 +83,17 @@ static inline void bpf_jit_free(struct sk_filter *fp)
 #define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns)
 #endif
 
+static inline int bpf_tell_extensions(void)
+{
+	/* When adding new BPF extension it is necessary to enumerate
+	 * it here, so userspace software which wants to know what is
+	 * supported can do so by inspecting return value of this
+	 * function
+	 */
+
+	return 0;
+}
+
 enum {
 	BPF_S_RET_K = 1,
 	BPF_S_RET_A,

diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
@@ -80,4 +80,6 @@
 
 #define SO_MAX_PACING_RATE	47
 
+#define SO_BPF_EXTENSIONS	48
+
 #endif /* __ASM_GENERIC_SOCKET_H */
diff --git a/net/core/sock.c b/net/core/sock.c
@@ -1167,6 +1167,10 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 		v.val = sock_flag(sk, SOCK_FILTER_LOCKED);
 		break;
 
+	case SO_BPF_EXTENSIONS:
+		v.val = bpf_tell_extensions();
+		break;
+
 	case SO_SELECT_ERR_QUEUE:
 		v.val = sock_flag(sk, SOCK_SELECT_ERR_QUEUE);
 		break;
Original file line number	Diff line number	Diff line change
Expand Up		@@ -85,4 +85,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _UAPI_ASM_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -78,4 +78,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _UAPI__ASM_AVR32_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -80,6 +80,8 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _ASM_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -78,5 +78,7 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _ASM_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -87,4 +87,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _ASM_IA64_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -96,4 +96,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _UAPI_ASM_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -77,4 +77,6 @@

		#define SO_MAX_PACING_RATE 0x4028

		#define SO_BPF_EXTENSIONS 0x4029

		#endif /* _UAPI_ASM_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -84,4 +84,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _ASM_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -89,4 +89,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* _XTENSA_SOCKET_H */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -80,4 +80,6 @@

		#define SO_MAX_PACING_RATE 47

		#define SO_BPF_EXTENSIONS 48

		#endif /* __ASM_GENERIC_SOCKET_H */