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nl: improve how we surface errors
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Closes #3057.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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Christian Brauner committed Mar 20, 2020
1 parent a5f5cb4 commit 19bfd55
Showing 1 changed file with 63 additions and 80 deletions.
143 changes: 63 additions & 80 deletions src/lxc/nl.c
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Expand Up @@ -19,16 +19,19 @@

lxc_log_define(nl, lxc);

extern size_t nlmsg_len(const struct nlmsg *nlmsg)
size_t nlmsg_len(const struct nlmsg *nlmsg)
{
return nlmsg->nlmsghdr->nlmsg_len - NLMSG_HDRLEN;
}

extern void *nlmsg_data(struct nlmsg *nlmsg)
void *nlmsg_data(struct nlmsg *nlmsg)
{
char *data = ((char *)nlmsg) + NLMSG_HDRLEN;
char *data;

data = ((char *)nlmsg) + NLMSG_HDRLEN;
if (!nlmsg_len(nlmsg))
return NULL;
return ret_set_errno(NULL, EINVAL);

return data;
}

Expand All @@ -40,49 +43,50 @@ static int nla_put(struct nlmsg *nlmsg, int attr,
size_t tlen = NLMSG_ALIGN(nlmsg->nlmsghdr->nlmsg_len) + RTA_ALIGN(rtalen);

if (tlen > nlmsg->cap)
return -ENOMEM;
return ret_errno(ENOMEM);

rta = NLMSG_TAIL(nlmsg->nlmsghdr);
rta->rta_type = attr;
rta->rta_len = rtalen;
if (data && len)
memcpy(RTA_DATA(rta), data, len);
nlmsg->nlmsghdr->nlmsg_len = tlen;

return 0;
}

extern int nla_put_buffer(struct nlmsg *nlmsg, int attr,
const void *data, size_t size)
int nla_put_buffer(struct nlmsg *nlmsg, int attr, const void *data, size_t size)
{
return nla_put(nlmsg, attr, data, size);
}

extern int nla_put_string(struct nlmsg *nlmsg, int attr, const char *string)
int nla_put_string(struct nlmsg *nlmsg, int attr, const char *string)
{
return nla_put(nlmsg, attr, string, strlen(string) + 1);
}

extern int nla_put_u32(struct nlmsg *nlmsg, int attr, int value)
int nla_put_u32(struct nlmsg *nlmsg, int attr, int value)
{
return nla_put(nlmsg, attr, &value, sizeof(value));
}

extern int nla_put_u16(struct nlmsg *nlmsg, int attr, unsigned short value)
int nla_put_u16(struct nlmsg *nlmsg, int attr, unsigned short value)
{
return nla_put(nlmsg, attr, &value, 2);
}

extern int nla_put_attr(struct nlmsg *nlmsg, int attr)
int nla_put_attr(struct nlmsg *nlmsg, int attr)
{
return nla_put(nlmsg, attr, NULL, 0);
}

struct rtattr *nla_begin_nested(struct nlmsg *nlmsg, int attr)
{
struct rtattr *rtattr = NLMSG_TAIL(nlmsg->nlmsghdr);
struct rtattr *rtattr;

rtattr = NLMSG_TAIL(nlmsg->nlmsghdr);
if (nla_put_attr(nlmsg, attr))
return NULL;
return ret_set_errno(NULL, ENOMEM);

return rtattr;
}
Expand All @@ -92,37 +96,34 @@ void nla_end_nested(struct nlmsg *nlmsg, struct rtattr *attr)
attr->rta_len = (void *)NLMSG_TAIL(nlmsg->nlmsghdr) - (void *)attr;
}

extern struct nlmsg *nlmsg_alloc(size_t size)
struct nlmsg *nlmsg_alloc(size_t size)
{
struct nlmsg *nlmsg;
__do_free struct nlmsg *nlmsg = NULL;
size_t len = NLMSG_HDRLEN + NLMSG_ALIGN(size);

nlmsg = (struct nlmsg *)malloc(sizeof(struct nlmsg));
nlmsg = malloc(sizeof(struct nlmsg));
if (!nlmsg)
return NULL;
return ret_set_errno(NULL, ENOMEM);

nlmsg->nlmsghdr = (struct nlmsghdr *)malloc(len);
nlmsg->nlmsghdr = malloc(len);
if (!nlmsg->nlmsghdr)
goto errout;
return ret_set_errno(NULL, ENOMEM);

memset(nlmsg->nlmsghdr, 0, len);
nlmsg->cap = len;
nlmsg->nlmsghdr->nlmsg_len = NLMSG_HDRLEN;

return nlmsg;
errout:
free(nlmsg);
return NULL;
return move_ptr(nlmsg);
}

extern void *nlmsg_reserve(struct nlmsg *nlmsg, size_t len)
void *nlmsg_reserve(struct nlmsg *nlmsg, size_t len)
{
void *buf;
size_t nlmsg_len = nlmsg->nlmsghdr->nlmsg_len;
size_t tlen = NLMSG_ALIGN(len);

if (nlmsg_len + tlen > nlmsg->cap)
return NULL;
return ret_set_errno(NULL, ENOMEM);

buf = ((char *)(nlmsg->nlmsghdr)) + nlmsg_len;
nlmsg->nlmsghdr->nlmsg_len += tlen;
Expand All @@ -133,29 +134,28 @@ extern void *nlmsg_reserve(struct nlmsg *nlmsg, size_t len)
return buf;
}

extern struct nlmsg *nlmsg_alloc_reserve(size_t size)
struct nlmsg *nlmsg_alloc_reserve(size_t size)
{
struct nlmsg *nlmsg;

nlmsg = nlmsg_alloc(size);
if (!nlmsg)
return NULL;
return ret_set_errno(NULL, ENOMEM);

/* Just set message length to cap directly. */
nlmsg->nlmsghdr->nlmsg_len = nlmsg->cap;
return nlmsg;
}

extern void nlmsg_free(struct nlmsg *nlmsg)
void nlmsg_free(struct nlmsg *nlmsg)
{
if (!nlmsg)
return;

free(nlmsg->nlmsghdr);
free(nlmsg);
if (nlmsg) {
free(nlmsg->nlmsghdr);
free(nlmsg);
}
}

extern int __netlink_recv(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
int __netlink_recv(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
{
int ret;
struct sockaddr_nl nladdr;
Expand All @@ -182,26 +182,24 @@ extern int __netlink_recv(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
if (errno == EINTR)
goto again;

return -1;
return ret_errno(errno);
}

if (!ret)
return 0;

if (msg.msg_flags & MSG_TRUNC && (ret == nlmsghdr->nlmsg_len)) {
errno = EMSGSIZE;
ret = -1;
}
if (msg.msg_flags & MSG_TRUNC && (ret == nlmsghdr->nlmsg_len))
return ret_errno(EMSGSIZE);

return ret;
}

extern int netlink_rcv(struct nl_handler *handler, struct nlmsg *answer)
int netlink_rcv(struct nl_handler *handler, struct nlmsg *answer)
{
return __netlink_recv(handler, answer->nlmsghdr);
}

extern int __netlink_send(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
int __netlink_send(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
{
int ret;
struct sockaddr_nl nladdr;
Expand All @@ -223,7 +221,7 @@ extern int __netlink_send(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)

ret = sendmsg(handler->fd, &msg, MSG_NOSIGNAL);
if (ret < 0)
return -1;
return ret_errno(errno);

return ret;
}
Expand All @@ -241,21 +239,19 @@ extern int __netlink_transaction(struct nl_handler *handler,

ret = __netlink_send(handler, request);
if (ret < 0)
return -1;
return ret;

ret = __netlink_recv(handler, answer);
if (ret < 0)
return -1;
return ret;

ret = 0;
if (answer->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(answer);
errno = -err->error;
if (err->error < 0)
ret = -1;
return ret_errno(-err->error);
}

return ret;
return 0;
}

extern int netlink_transaction(struct nl_handler *handler,
Expand All @@ -267,56 +263,44 @@ extern int netlink_transaction(struct nl_handler *handler,

extern int netlink_open(struct nl_handler *handler, int protocol)
{
__do_close int fd = -EBADF;
socklen_t socklen;
int sndbuf = 32768;
int rcvbuf = 32768;
int err;

memset(handler, 0, sizeof(*handler));
handler->fd = -EBADF;

handler->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, protocol);
if (handler->fd < 0)
return -errno;
fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, protocol);
if (fd < 0)
return ret_errno(errno);

if (setsockopt(handler->fd, SOL_SOCKET, SO_SNDBUF,
&sndbuf, sizeof(sndbuf)) < 0)
goto err_with_errno;
if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf)) < 0)
return ret_errno(errno);

if (setsockopt(handler->fd, SOL_SOCKET, SO_RCVBUF,
&rcvbuf,sizeof(rcvbuf)) < 0)
goto err_with_errno;
if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf,sizeof(rcvbuf)) < 0)
return ret_errno(errno);

memset(&handler->local, 0, sizeof(handler->local));
handler->local.nl_family = AF_NETLINK;
handler->local.nl_groups = 0;

if (bind(handler->fd, (struct sockaddr*)&handler->local,
sizeof(handler->local)) < 0)
goto err_with_errno;
if (bind(fd, (struct sockaddr*)&handler->local, sizeof(handler->local)) < 0)
return ret_errno(errno);

socklen = sizeof(handler->local);
if (getsockname(handler->fd, (struct sockaddr*)&handler->local,
&socklen) < 0)
goto err_with_errno;
if (getsockname(fd, (struct sockaddr*)&handler->local, &socklen) < 0)
return ret_errno(errno);

if (socklen != sizeof(handler->local)) {
err = -EINVAL;
goto errclose;
}
if (socklen != sizeof(handler->local))
return ret_errno(EINVAL);

if (handler->local.nl_family != AF_NETLINK) {
err = -EINVAL;
goto errclose;
}
if (handler->local.nl_family != AF_NETLINK)
return ret_errno(EINVAL);

handler->seq = time(NULL);

handler->fd = move_fd(fd);
return 0;
err_with_errno:
err = -errno;
errclose:
close(handler->fd);
return err;
}

extern void netlink_close(struct nl_handler *handler)
Expand All @@ -330,9 +314,8 @@ int addattr(struct nlmsghdr *n, size_t maxlen, int type, const void *data,
int len = RTA_LENGTH(alen);
struct rtattr *rta;

errno = EMSGSIZE;
if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen)
return -1;
return ret_errno(EMSGSIZE);

rta = NLMSG_TAIL(n);
rta->rta_type = type;
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