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tests/unix_passfd: sending many and too many SCM_RIGHTS

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o Exercise bounds checking when sending large set of file descriptors,
  that can't fit into single control mbuf.
o Exercise resource limits checks when receiving a large sets.
o Check that socket isn't left in a completely stuck state when we can't
  receive SCM_RIGHTS due to limits.  Current SOCK_STREAM socket would
  free the control, but leave the data in.  This seems to be a legit
  behavior for a stream socket, as we don't want holes in the data.

PR:			239250
Reviewed by:		markj
Differential revision:	https://reviews.freebsd.org/D35315
This commit is contained in:
Gleb Smirnoff 2022-05-25 13:28:40 -07:00
parent e26ef41f79
commit 23402c83f4
1 changed files with 68 additions and 1 deletions
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69
tests/sys/kern/unix_passfd_test.c
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@ -28,10 +28,12 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/un.h>
#include <errno.h>
@ -369,6 +371,70 @@ ATF_TC_BODY(send_and_shutdown, tc)
closesocketpair(fd);
}
/*
* Send maximum possible SCM_RIGHTS message.
* Internally the file descriptors are converted from integers to pointers
* and stored in a single mbuf cluster. Check that we can not send too much
* and that we can successfully send maximum possible amount. Check that we
* can not exploit getrlimit(3).
*/
#define MAXFDS ((MCLBYTES - _ALIGN(sizeof(struct cmsghdr)))/sizeof(void *))
ATF_TC_WITHOUT_HEAD(send_a_lot);
ATF_TC_BODY(send_a_lot, tc)
{
struct msghdr msghdr;
struct iovec iov;
struct rlimit rlim;
int fd[2], nfds;
char *cmsg, ch;
domainsocketpair(fd);
cmsg = malloc(CMSG_SPACE((MAXFDS + 1) * sizeof(int)));
ATF_REQUIRE(cmsg != NULL);
iov.iov_base = &ch;
iov.iov_len = sizeof(ch);
msghdr = (struct msghdr ){
.msg_control = cmsg,
.msg_controllen = CMSG_LEN((MAXFDS + 1) * sizeof(int)),
.msg_iov = &iov,
.msg_iovlen = 1,
};
/* Sending too much fails. */
putfds(cmsg, fd[0], MAXFDS + 1);
ATF_REQUIRE(sendmsg(fd[0], &msghdr, 0) == -1);
ATF_REQUIRE(errno == EMSGSIZE);
/* Sending just the right amount works and everything is received. */
putfds(cmsg, fd[0], MAXFDS);
msghdr.msg_controllen = CMSG_LEN(MAXFDS * sizeof(int));
ATF_REQUIRE(sendmsg(fd[0], &msghdr, 0) == 1);
nfds = getnfds();
ATF_REQUIRE(recvmsg(fd[1], &msghdr, 0) == 1);
ATF_REQUIRE(getnfds() == nfds + MAXFDS);
/* Limit our process open files... */
ATF_REQUIRE(getrlimit(RLIMIT_NOFILE, &rlim) == 0);
nfds = rlim.rlim_cur = getnfds();
ATF_REQUIRE(setrlimit(RLIMIT_NOFILE, &rlim) == 0);
/* ... and try to receive a single descriptor. */
putfds(cmsg, fd[0], 1);
msghdr.msg_controllen = CMSG_LEN(sizeof(int));
ATF_REQUIRE(sendmsg(fd[0], &msghdr, 0) == 1);
ATF_REQUIRE(recvmsg(fd[1], &msghdr, 0) == -1);
/* Such attempt shall fail with EMSGSIZE. */
ATF_REQUIRE(errno == EMSGSIZE);
ATF_REQUIRE(getnfds() == nfds);
/*
* For the SOCK_STREAM the above attempt shall free the control in
* the kernel, so that socket isn't left in a stuck state. Next read
* shall bring us the normal data only.
*/
ATF_REQUIRE(recvmsg(fd[1], &msghdr, 0) == 1);
ATF_REQUIRE(msghdr.msg_controllen == 0);
}
/*
* Send two files. Then receive them. Make sure they are returned in the
* right order, and both get there.
@ -756,6 +822,7 @@ ATF_TP_ADD_TCS(tp)
ATF_TP_ADD_TC(tp, send_and_close);
ATF_TP_ADD_TC(tp, send_and_cancel);
ATF_TP_ADD_TC(tp, send_and_shutdown);
ATF_TP_ADD_TC(tp, send_a_lot);
ATF_TP_ADD_TC(tp, two_files);
ATF_TP_ADD_TC(tp, bundle);
ATF_TP_ADD_TC(tp, bundle_cancel);