samples/seccomp/bpf-helper.h

Source file repositories/reference/linux-study-clean/samples/seccomp/bpf-helper.h

File Facts

System
Linux kernel
Corpus path
samples/seccomp/bpf-helper.h
Extension
.h
Size
7593 bytes
Lines
264
Domain
Support Tooling And Documentation
Bucket
samples
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct bpf_labels {
	int count;
	struct __bpf_label {
		const char *label;
		__u32 location;
	} labels[BPF_LABELS_MAX];
};

int bpf_resolve_jumps(struct bpf_labels *labels,
		      struct sock_filter *filter, size_t count);
__u32 seccomp_bpf_label(struct bpf_labels *labels, const char *label);
void seccomp_bpf_print(struct sock_filter *filter, size_t count);

#define JUMP_JT 0xff
#define JUMP_JF 0xff
#define LABEL_JT 0xfe
#define LABEL_JF 0xfe

#define ALLOW \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)
#define DENY \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
#define JUMP(labels, label) \
	BPF_JUMP(BPF_JMP+BPF_JA, FIND_LABEL((labels), (label)), \
		 JUMP_JT, JUMP_JF)
#define LABEL(labels, label) \
	BPF_JUMP(BPF_JMP+BPF_JA, FIND_LABEL((labels), (label)), \
		 LABEL_JT, LABEL_JF)
#define SYSCALL(nr, jt) \
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (nr), 0, 1), \
	jt

/* Lame, but just an example */
#define FIND_LABEL(labels, label) seccomp_bpf_label((labels), #label)

#define EXPAND(...) __VA_ARGS__

/* Ensure that we load the logically correct offset. */
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)])
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)
#else
#error "Unknown endianness"
#endif

/* Map all width-sensitive operations */
#if __BITS_PER_LONG == 32

#define JEQ(x, jt) JEQ32(x, EXPAND(jt))
#define JNE(x, jt) JNE32(x, EXPAND(jt))
#define JGT(x, jt) JGT32(x, EXPAND(jt))
#define JLT(x, jt) JLT32(x, EXPAND(jt))
#define JGE(x, jt) JGE32(x, EXPAND(jt))
#define JLE(x, jt) JLE32(x, EXPAND(jt))
#define JA(x, jt) JA32(x, EXPAND(jt))
#define ARG(i) ARG_32(i)

#elif __BITS_PER_LONG == 64

/* Ensure that we load the logically correct offset. */
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define ENDIAN(_lo, _hi) _lo, _hi
#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define ENDIAN(_lo, _hi) _hi, _lo
#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)])
#endif

union arg64 {
	struct {
		__u32 ENDIAN(lo32, hi32);
	};
	__u64 u64;
};

#define JEQ(x, jt) \
	JEQ64(((union arg64){.u64 = (x)}).lo32, \
	      ((union arg64){.u64 = (x)}).hi32, \
	      EXPAND(jt))
#define JGT(x, jt) \
	JGT64(((union arg64){.u64 = (x)}).lo32, \
	      ((union arg64){.u64 = (x)}).hi32, \
	      EXPAND(jt))
#define JGE(x, jt) \
	JGE64(((union arg64){.u64 = (x)}).lo32, \
	      ((union arg64){.u64 = (x)}).hi32, \
	      EXPAND(jt))
#define JNE(x, jt) \
	JNE64(((union arg64){.u64 = (x)}).lo32, \

Annotation

Implementation Notes