d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

MFC r285275 (only the part that fixes PR 199568):

Browse Source 
Obtain proper capsicum rights for dump files so rotation of such files works when requested.  This is equivalent to cherry picking the following upstream commits:

commit c6d472bf63488b0c2ab7ab9f4b32c68dd2c8ea2b
commit f08eb851eedf9775e6485ab75c0d8cf8d1306be6
commit d83a284abc80d3d09f6bddd087760bb1b01d9cc7

PR: 		199568
Approved by:	re
This commit is contained in:
pkelsey 2015-07-18 01:29:27 +00:00
parent 752b1ca18b
commit 8515ac5674
1 changed files with 77 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
contrib/tcpdump/tcpdump.c
View File

@ -684,6 +684,76 @@ get_next_file(FILE *VFile, char *ptr)
return ret;
}
#ifdef __FreeBSD__
/*
* Ensure that, on a dump file's descriptor, we have all the rights
* necessary to make the standard I/O library work with an fdopen()ed
* FILE * from that descriptor.
*
* A long time ago, in a galaxy far far away, AT&T decided that, instead
* of providing separate APIs for getting and setting the FD_ flags on a
* descriptor, getting and setting the O_ flags on a descriptor, and
* locking files, they'd throw them all into a kitchen-sink fcntl() call
* along the lines of ioctl(), the fact that ioctl() operations are
* largely specific to particular character devices but fcntl() operations
* are either generic to all descriptors or generic to all descriptors for
* regular files nonwithstanding.
*
* The Capsicum people decided that fine-grained control of descriptor
* operations was required, so that you need to grant permission for
* reading, writing, seeking, and fcntl-ing. The latter, courtesy of
* AT&T's decision, means that "fcntl-ing" isn't a thing, but a motley
* collection of things, so there are *individual* fcntls for which
* permission needs to be granted.
*
* The FreeBSD standard I/O people implemented some optimizations that
* requires that the standard I/O routines be able to determine whether
* the descriptor for the FILE * is open append-only or not; as that
* descriptor could have come from an open() rather than an fopen(),
* that requires that it be able to do an F_GETFL fcntl() to read
* the O_ flags.
*
* Tcpdump uses ftell() to determine how much data has been written
* to a file in order to, when used with -C, determine when it's time
* to rotate capture files. ftell() therefore needs to do an lseek()
* to find out the file offset and must, thanks to the aforementioned
* optimization, also know whether the descriptor is open append-only
* or not.
*
* The net result of all the above is that we need to grant CAP_SEEK,
* CAP_WRITE, and CAP_FCNTL with the CAP_FCNTL_GETFL subcapability.
*
* Perhaps this is the universe's way of saying that either
*
* 1) there needs to be an fopenat() call and a pcap_dump_openat() call
* using it, so that Capsicum-capable tcpdump wouldn't need to do
* an fdopen()
*
* or
*
* 2) there needs to be a cap_fdopen() call in the FreeBSD standard
* I/O library that knows what rights are needed by the standard
* I/O library, based on the open mode, and assigns them, perhaps
* with an additional argument indicating, for example, whether
* seeking should be allowed, so that tcpdump doesn't need to know
* what the standard I/O library happens to require this week.
*/
static void
set_dumper_capsicum_rights(pcap_dumper_t *p)
{
int fd = fileno(pcap_dump_file(p));
cap_rights_t rights;
cap_rights_init(&rights, CAP_SEEK, CAP_WRITE, CAP_FCNTL);
if (cap_rights_limit(fd, &rights) < 0 && errno != ENOSYS) {
error("unable to limit dump descriptor");
}
if (cap_fcntls_limit(fd, CAP_FCNTL_GETFL) < 0 && errno != ENOSYS) {
error("unable to limit dump descriptor fcntls");
}
}
#endif
int
main(int argc, char **argv)
{
@ -1524,11 +1594,7 @@ main(int argc, char **argv)
if (p == NULL)
error("%s", pcap_geterr(pd));
#ifdef __FreeBSD__
cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
if (cap_rights_limit(fileno(pcap_dump_file(p)), &rights) < 0 &&
errno != ENOSYS) {
error("unable to limit dump descriptor");
}
set_dumper_capsicum_rights(p);
#endif
if (Cflag != 0 || Gflag != 0) {
#ifdef __FreeBSD__
@ -1545,6 +1611,10 @@ main(int argc, char **argv)
errno != ENOSYS) {
error("unable to limit directory rights");
}
if (cap_fcntls_limit(fileno(pcap_dump_file(p)), CAP_FCNTL_GETFL) < 0 &&
errno != ENOSYS) {
error("unable to limit dump descriptor fcntls");
}
#else /* !__FreeBSD__ */
dumpinfo.WFileName = WFileName;
#endif
@ -1839,9 +1909,6 @@ static void
dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
struct dump_info *dump_info;
#ifdef __FreeBSD__
cap_rights_t rights;
#endif
++packets_captured;
@ -1945,11 +2012,7 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
if (dump_info->p == NULL)
error("%s", pcap_geterr(pd));
#ifdef __FreeBSD__
cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
if (cap_rights_limit(fileno(pcap_dump_file(dump_info->p)),
&rights) < 0 && errno != ENOSYS) {
error("unable to limit dump descriptor");
}
set_dumper_capsicum_rights(dump_info->p);
#endif
}
}
@ -2006,11 +2069,7 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
if (dump_info->p == NULL)
error("%s", pcap_geterr(pd));
#ifdef __FreeBSD__
cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
if (cap_rights_limit(fileno(pcap_dump_file(dump_info->p)),
&rights) < 0 && errno != ENOSYS) {
error("unable to limit dump descriptor");
}
set_dumper_capsicum_rights(dump_info->p);
#endif
}