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| author | Edward Cree <ecree.xilinx@gmail.com> | 2022-10-18 17:37:27 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-10-19 23:00:04 +0300 |
| commit | 51c352bdbcd23d7ce46b06c1e64c82754dc44044 (patch) | |
| tree | 9bd79cfe375349b5afa3be84fe04a27ae0c8e791 /include/linux/netlink.h | |
| parent | a526a3cc9c8d426713f8bebc18ebbe39a8495d82 (diff) | |
| download | linux-51c352bdbcd23d7ce46b06c1e64c82754dc44044.tar.xz | |
netlink: add support for formatted extack messages
Include an 80-byte buffer in struct netlink_ext_ack that can be used
for scnprintf()ed messages. This does mean that the resulting string
can't be enumerated, translated etc. in the way NL_SET_ERR_MSG() was
designed to allow.
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/linux/netlink.h')
| -rw-r--r-- | include/linux/netlink.h | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h index d51e041d2242..d81bde5a5844 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -64,6 +64,7 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) /* this can be increased when necessary - don't expose to userland */ #define NETLINK_MAX_COOKIE_LEN 20 +#define NETLINK_MAX_FMTMSG_LEN 80 /** * struct netlink_ext_ack - netlink extended ACK report struct @@ -75,6 +76,8 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) * @miss_nest: nest missing an attribute (%NULL if missing top level attr) * @cookie: cookie data to return to userspace (for success) * @cookie_len: actual cookie data length + * @_msg_buf: output buffer for formatted message strings - don't access + * directly, use %NL_SET_ERR_MSG_FMT */ struct netlink_ext_ack { const char *_msg; @@ -84,13 +87,13 @@ struct netlink_ext_ack { u16 miss_type; u8 cookie[NETLINK_MAX_COOKIE_LEN]; u8 cookie_len; + char _msg_buf[NETLINK_MAX_FMTMSG_LEN]; }; /* Always use this macro, this allows later putting the * message into a separate section or such for things * like translation or listing all possible messages. - * Currently string formatting is not supported (due - * to the lack of an output buffer.) + * If string formatting is needed use NL_SET_ERR_MSG_FMT. */ #define NL_SET_ERR_MSG(extack, msg) do { \ static const char __msg[] = msg; \ @@ -102,9 +105,31 @@ struct netlink_ext_ack { __extack->_msg = __msg; \ } while (0) +/* We splice fmt with %s at each end even in the snprintf so that both calls + * can use the same string constant, avoiding its duplication in .ro + */ +#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \ + struct netlink_ext_ack *__extack = (extack); \ + \ + if (!__extack) \ + break; \ + if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \ + "%s" fmt "%s", "", ##args, "") >= \ + NETLINK_MAX_FMTMSG_LEN) \ + net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \ + ##args, "\n"); \ + \ + do_trace_netlink_extack(__extack->_msg_buf); \ + \ + __extack->_msg = __extack->_msg_buf; \ +} while (0) + #define NL_SET_ERR_MSG_MOD(extack, msg) \ NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) +#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \ + NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args) + #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \ if ((extack)) { \ (extack)->bad_attr = (attr); \ |