On Fri, Jun 16, 2017 at 01:35:07PM +0800, JingPiao Chen wrote: > * defs.h (decode_nlattr): New prototype. > * linux/unix_diag.h (UNIX_DIAG_*): New enum. > * netlink.c (fetch_nlattr, print_nlattr, > decode_nlattr_with_data, decode_nlattr): New functions.
Looks like there is no necessity to place these new nlattr related
functions into netlink.c, what do you think about creating a new source
file for this purpose, e.g. nlattr.c?
> * netlink_sock_diag.c: Include "xlat/unix_diag_attrs.h".
> (decode_unix_diag_msg): Use decode_nlattr.
> * xlat/unix_diag_attrs.in: New file.
>
> co-authored-by: Fabien Siron <fabien.si...@epita.fr>
> ---
> defs.h | 3 ++
> linux/unix_diag.h | 11 +++++--
> netlink.c | 76
> +++++++++++++++++++++++++++++++++++++++++++++++++
> netlink_sock_diag.c | 4 +++
> xlat/unix_diag_attrs.in | 7 +++++
> 5 files changed, 99 insertions(+), 2 deletions(-)
> create mode 100644 xlat/unix_diag_attrs.in
>
> diff --git a/defs.h b/defs.h
> index 487e51b..7e3912d 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -632,6 +632,9 @@ tprint_iov_upto(struct tcb *, kernel_ulong_t len,
> kernel_ulong_t addr,
>
> extern void
> decode_netlink(struct tcb *, int fd, kernel_ulong_t addr, kernel_ulong_t
> len);
> +extern void
> +decode_nlattr(struct tcb *tcp, kernel_ulong_t addr, kernel_ulong_t len,
> + int, const struct xlat *, const char *);
>
> extern void tprint_open_modes(unsigned int);
> extern const char *sprint_open_modes(unsigned int);
> diff --git a/linux/unix_diag.h b/linux/unix_diag.h
> index a6b62ba..3c9d99f 100644
> --- a/linux/unix_diag.h
> +++ b/linux/unix_diag.h
> @@ -27,7 +27,14 @@ struct unix_diag_msg {
> uint32_t udiag_cookie[2];
> };
>
> -#define UNIX_DIAG_NAME 0
> -#define UNIX_DIAG_PEER 2
> +enum {
> + UNIX_DIAG_NAME,
> + UNIX_DIAG_VFS,
> + UNIX_DIAG_PEER,
> + UNIX_DIAG_ICONS,
> + UNIX_DIAG_RQLEN,
> + UNIX_DIAG_MEMINFO,
> + UNIX_DIAG_SHUTDOWN,
> +};
>
> #endif /* !STRACE_LINUX_UNIX_DIAG_H */
> diff --git a/netlink.c b/netlink.c
> index 4bef949..52f3806 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -49,6 +49,82 @@
> #undef NLMSG_HDRLEN
> #define NLMSG_HDRLEN NLMSG_ALIGN(sizeof(struct nlmsghdr))
>
> +static bool
> +fetch_nlattr(struct tcb *tcp, struct nlattr *nlattr,
You can add some const qualifiers here, like in fetch_nlmsghdr that was
used as a template for this new function.
> + const kernel_ulong_t addr, const kernel_ulong_t len)
> +{
> + if (len < sizeof(struct nlattr)) {
> + printstrn(tcp, addr, len);
> + return false;
> + }
> +
> + if (umove_or_printaddr(tcp, addr, nlattr))
> + return false;
> +
> + return true;
> +}
> +
> +static void
> +print_nlattr(const struct nlattr *const nla,
> + const struct xlat *table, const char *dflt)
> +{
> + tprintf("{nla_len=%u, nla_type=", nla->nla_len);
> + if (nla->nla_type & NLA_F_NESTED)
> + tprints("NLA_F_NESTED|");
> + if (nla->nla_type & NLA_F_NET_BYTEORDER)
> + tprints("NLA_F_NET_BYTEORDER|");
> + printxval(table, nla->nla_type & NLA_TYPE_MASK, dflt);
> + tprints("}");
> +}
> +
> +static void
> +decode_nlattr_with_data(struct tcb *tcp, kernel_ulong_t addr,
> + kernel_ulong_t len, const struct xlat *table,
> + const char *dflt)
> +{
> + struct nlattr nlattr;
> +
> + while (fetch_nlattr(tcp, &nlattr, addr, len)) {
> + unsigned long nlattr_len = NLA_ALIGN(nlattr.nla_len);
> + kernel_ulong_t next_addr = 0;
> + kernel_ulong_t next_len = 0;
This new function is made after decode_netlink, which is fine,
but it misses the abbrev(tcp) logic which is present in decode_netlink.
Could you reintroduce it here, too, please?
> +
> + if (nlattr.nla_len >= sizeof(struct nlattr)) {
> + next_len = (len >= nlattr_len) ? len - nlattr_len : 0;
> +
> + if (next_len && addr + nlattr_len > addr)
> + next_addr = addr + nlattr_len;
> + }
> +
> + tprints("{");
> + print_nlattr(&nlattr, table, dflt);
> + if (nlattr.nla_len > NLA_HDRLEN) {
> + tprints(", ");
> + printstrn(tcp, addr + NLA_HDRLEN,
> + nlattr.nla_len - NLA_HDRLEN);
> + }
> + tprints("}");
> +
> + if (!next_addr)
> + break;
> +
> + tprints(", ");
> + addr = next_addr;
> + len = next_len;
> + }
> +}
> +
> +void
> +decode_nlattr(struct tcb *tcp, kernel_ulong_t addr, kernel_ulong_t len,
> + int hdrlen, const struct xlat *table, const char *dflt)
> +{
> + if (len > NLMSG_ALIGN(hdrlen)) {
> + tprints(", ");
> + decode_nlattr_with_data(tcp, addr + NLMSG_ALIGN(hdrlen),
> + len - NLMSG_ALIGN(hdrlen), table, dflt);
> + }
I'm not sure we need this proxy function, the caller is capable of performing
the check and invoking the decoder with the right address and length.
> +}
> +
> /*
> * Fetch a struct nlmsghdr from the given address.
> */
> diff --git a/netlink_sock_diag.c b/netlink_sock_diag.c
> index 8dbfd07..6d79ba4 100644
> --- a/netlink_sock_diag.c
> +++ b/netlink_sock_diag.c
> @@ -55,6 +55,7 @@
> # include "xlat/smc_states.h"
> #endif
>
> +#include "xlat/unix_diag_attrs.h"
> #include "xlat/unix_diag_show.h"
>
> static void
> @@ -109,32 +110,35 @@ static void
> decode_unix_diag_msg(struct tcb *const tcp,
> const struct nlmsghdr *const nlmsghdr,
> const uint8_t family,
> const kernel_ulong_t addr,
> const kernel_ulong_t len)
> {
> struct unix_diag_msg msg = { .udiag_family = family };
> const size_t offset = sizeof(msg.udiag_family);
>
> tprints("{udiag_family=");
> printxval(addrfams, msg.udiag_family, "AF_???");
>
> tprints(", ");
> if (len >= sizeof(msg)) {
> if (!umoven_or_printaddr(tcp, addr + offset,
> sizeof(msg) - offset,
> (void *) &msg + offset)) {
> tprints("udiag_type=");
> printxval(socktypes, msg.udiag_type, "SOCK_???");
> tprintf(", udiag_state=");
> printxval(tcp_states, msg.udiag_state, "TCP_???");
> tprintf(", udiag_ino=%" PRIu32
> ", udiag_cookie=[%" PRIu32 ", %" PRIu32 "]",
> msg.udiag_ino,
> msg.udiag_cookie[0], msg.udiag_cookie[1]);
The invocation of nlattr decoder should be placed here:
offset = NLMSG_ALIGN(sizeof(msg));
if (len > offset) {
tprints(", ");
decode_nlattr(tcp, addr + offset, len - offset,
unix_diag_attrs, "UNIX_DIAG_???");
}
> }
> } else
> tprints("...");
> tprints("}");
> +
> + decode_nlattr(tcp, addr, len, sizeof(msg), unix_diag_attrs,
> + "UNIX_DIAG_???");
> }
>
> static void
> diff --git a/xlat/unix_diag_attrs.in b/xlat/unix_diag_attrs.in
> new file mode 100644
> index 0000000..0fb2f23
> --- /dev/null
> +++ b/xlat/unix_diag_attrs.in
> @@ -0,0 +1,7 @@
> +UNIX_DIAG_NAME 0
> +UNIX_DIAG_VFS 1
> +UNIX_DIAG_PEER 2
> +UNIX_DIAG_ICONS 3
> +UNIX_DIAG_RQLEN 4
> +UNIX_DIAG_MEMINFO 5
> +UNIX_DIAG_SHUTDOWN 6
As these constants are guaranteed to be defined by local linux/unix_diag.h
file, there is no need to provide fallback definitions, just the opposite,
these xlat entries should be unconditional:
--- /dev/null
+++ b/xlat/unix_diag_attrs.in
@@ -0,0 +1,8 @@
+#unconditional
+UNIX_DIAG_NAME
+UNIX_DIAG_VFS
+UNIX_DIAG_PEER
+UNIX_DIAG_ICONS
+UNIX_DIAG_RQLEN
+UNIX_DIAG_MEMINFO
+UNIX_DIAG_SHUTDOWN
--
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