[PATCH v3 13/16] netlink: introduce nla_decoder_t to parse netlink attribute data
Dmitry V. Levin
ldv at altlinux.org
Tue Jun 20 00:06:45 UTC 2017
On Mon, Jun 19, 2017 at 09:15:37AM +0800, JingPiao Chen wrote:
> * nlattr.h (nla_decoder_t): New typedef.
> (DECL_NLA): New macro.
> (decode_nlattr): Add decoders, size and opaque_data argument.
> * nlattr.c: (decode_nlattr_with_data): Likewise.
> (decode_nla_*): New functions.
> * netlink_sock_diag.c (decode_inet_diag_req_compat)
> (decode_inet_diag_req_v2, decode_inet_diag_msg)
> (decode_netlink_diag_msg, (decode_packet_diag_msg)
> (decode_smc_diag_msg, decode_unix_diag_msg): Add decoders,
> size and opaque_data arguments. All callers updated.
>
> Co-authored-by: Fabien Siron <fabien.siron at epita.fr>
> ---
> netlink_sock_diag.c | 21 ++++++++++++------
> nlattr.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++----
> nlattr.h | 27 +++++++++++++++++++++--
> 3 files changed, 98 insertions(+), 13 deletions(-)
>
> diff --git a/netlink_sock_diag.c b/netlink_sock_diag.c
> index f46c441..57c2439 100644
> --- a/netlink_sock_diag.c
> +++ b/netlink_sock_diag.c
> @@ -149,7 +149,8 @@ decode_unix_diag_msg(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - unix_diag_attrs, "UNIX_DIAG_???");
> + unix_diag_attrs, "UNIX_DIAG_???",
> + NULL, 0, NULL);
> }
> }
>
> @@ -238,7 +239,8 @@ decode_netlink_diag_msg(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - netlink_diag_attrs, "NETLINK_DIAG_???");
> + netlink_diag_attrs, "NETLINK_DIAG_???",
> + NULL, 0, NULL);
> }
> }
>
> @@ -309,7 +311,8 @@ decode_packet_diag_msg(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - packet_diag_attrs, "PACKET_DIAG_???");
> + packet_diag_attrs, "PACKET_DIAG_???",
> + NULL, 0, NULL);
> }
> }
>
> @@ -373,7 +376,8 @@ decode_inet_diag_req_compat(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - inet_diag_req_attrs, "INET_DIAG_REQ_???");
> + inet_diag_req_attrs, "INET_DIAG_REQ_???",
> + NULL, 0, NULL);
> }
> }
>
> @@ -417,7 +421,8 @@ decode_inet_diag_req_v2(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - inet_diag_req_attrs, "INET_DIAG_REQ_???");
> + inet_diag_req_attrs, "INET_DIAG_REQ_???",
> + NULL, 0, NULL);
> }
> }
>
> @@ -483,7 +488,8 @@ decode_inet_diag_msg(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - inet_diag_attrs, "INET_DIAG_???");
> + inet_diag_attrs, "INET_DIAG_???",
> + NULL, 0, NULL);
> }
> }
>
> @@ -563,7 +569,8 @@ decode_smc_diag_msg(struct tcb *const tcp,
> if (decode_nla && len > offset) {
> tprints(", ");
> decode_nlattr(tcp, addr + offset, len - offset,
> - smc_diag_attrs, "SMC_DIAG_???");
> + smc_diag_attrs, "SMC_DIAG_???",
> + NULL, 0, NULL);
> }
> }
> #endif
> diff --git a/nlattr.c b/nlattr.c
> index eaf7e39..daa8261 100644
> --- a/nlattr.c
> +++ b/nlattr.c
> @@ -28,6 +28,7 @@
> */
>
> #include "defs.h"
> +#include "nlattr.h"
>
> #include <linux/netlink.h>
>
> @@ -66,7 +67,10 @@ decode_nlattr_with_data(struct tcb *tcp,
> kernel_ulong_t addr,
> kernel_ulong_t len,
> const struct xlat *const table,
> - const char *const dflt)
> + const char *const dflt,
> + const nla_decoder_t *decoders,
> + unsigned int size,
> + void *const opaque_data)
> {
> unsigned int nla_len = nla->nla_len > len ? len : nla->nla_len;
>
> @@ -77,7 +81,13 @@ decode_nlattr_with_data(struct tcb *tcp,
>
> if (nla_len > NLA_HDRLEN) {
> tprints(", ");
> - printstrn(tcp, addr + NLA_HDRLEN, nla_len - NLA_HDRLEN);
> + if (!decoders
> + || nla->nla_type >= size
> + || !decoders[nla->nla_type]
> + || !decoders[nla->nla_type](tcp, addr + NLA_HDRLEN,
> + nla_len - NLA_HDRLEN,
> + opaque_data))
> + printstrn(tcp, addr + NLA_HDRLEN, len - NLA_HDRLEN);
> tprints("}");
> }
> }
> @@ -87,7 +97,10 @@ decode_nlattr(struct tcb *const tcp,
> kernel_ulong_t addr,
> kernel_ulong_t len,
> const struct xlat *const table,
> - const char *const dflt)
> + const char *const dflt,
> + const nla_decoder_t *decoders,
> + unsigned int size,
> + void *const opaque_data)
> {
> struct nlattr nla;
> bool print_array = false;
> @@ -115,7 +128,8 @@ decode_nlattr(struct tcb *const tcp,
> print_array = true;
> }
>
> - decode_nlattr_with_data(tcp, &nla, addr, len, table, dflt);
> + decode_nlattr_with_data(tcp, &nla, addr, len, table, dflt,
> + decoders, size, opaque_data);
>
> if (!next_addr)
> break;
> @@ -129,3 +143,44 @@ decode_nlattr(struct tcb *const tcp,
> tprints("]");
> }
> }
> +
> +bool
> +decode_nla_str(struct tcb *tcp, kernel_ulong_t addr,
> + kernel_ulong_t len, void *const opaque_data)
> +{
> + printstr(tcp, addr);
I'm afraid this is not correct, "len" should be taken into account, too.
Maybe printstr_ex(tcp, addr, len, QUOTE_0_TERMINATED) or something like this.
> +
> + return true;
> +}
> +
> +bool
> +decode_nla_strn(struct tcb *tcp, kernel_ulong_t addr,
> + kernel_ulong_t len, void *const opaque_data)
> +{
> + printstrn(tcp, addr, len);
> +
> + return true;
> +}
> +
> +#define DECODE_NLA_INTEGER(name, type, fmt) \
> +bool \
> +decode_nla_ ## name(struct tcb *tcp, kernel_ulong_t addr, \
> + kernel_ulong_t len, void *const opaque_data) \
> +{ \
> + type num; \
> + \
> + if (len < sizeof(num)) \
> + return false; \
> + else if (!umove_or_printaddr(tcp, addr, &num)) \
No need for "else" after "return".
> + tprintf(fmt, num); \
> + return true; \
> +}
> +
> +DECODE_NLA_INTEGER(u8, uint8_t, "%" PRIu8)
> +DECODE_NLA_INTEGER(u16, uint16_t, "%" PRIu16)
> +DECODE_NLA_INTEGER(u32, uint32_t, "%" PRIu32)
> +DECODE_NLA_INTEGER(u64, uint64_t, "%" PRIu64)
> +DECODE_NLA_INTEGER(s8, int8_t, "%" PRId8)
> +DECODE_NLA_INTEGER(s16, int16_t, "%" PRId16)
> +DECODE_NLA_INTEGER(s32, int32_t, "%" PRId32)
> +DECODE_NLA_INTEGER(s64, int64_t, "%" PRId64)
> diff --git a/nlattr.h b/nlattr.h
> index 6b94fc1..8501c4d 100644
> --- a/nlattr.h
> +++ b/nlattr.h
> @@ -27,6 +27,29 @@
> * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> */
>
> +typedef bool (*nla_decoder_t)(struct tcb *, kernel_ulong_t addr,
> + kernel_ulong_t len, void *opaque_data);
> extern void
> -decode_nlattr(struct tcb *, kernel_ulong_t addr, kernel_ulong_t len,
> - const struct xlat *, const char *);
> +decode_nlattr(struct tcb *,
> + kernel_ulong_t addr,
> + kernel_ulong_t len,
> + const struct xlat *,
> + const char *,
> + const nla_decoder_t *,
> + unsigned int size,
> + void *);
> +
> +#define DECL_NLA(name) \
> +extern bool \
> +decode_nla_ ## name(struct tcb *, kernel_ulong_t addr, \
> + kernel_ulong_t len, void *)
> +DECL_NLA(u8);
> +DECL_NLA(u16);
> +DECL_NLA(u32);
> +DECL_NLA(u64);
> +DECL_NLA(s8);
> +DECL_NLA(s16);
> +DECL_NLA(s32);
> +DECL_NLA(s64);
> +DECL_NLA(str);
> +DECL_NLA(strn);
--
ldv
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