Created attachment 1130226 [details]
strace output

Description of problem:
When I try to add a socket printer in Fedora with SELinux MLS policy I get:

/usr/sbin/lpadmin -p test -E -v socket://localhost:9100 -m drv:///sample.drv/generic.ppd
lpadmin: Internal Server Error

with strace I see (see attached strace output for the whole log)
[ snip ]
poll([{fd=4, events=POLLIN}], 1, 1000)  = 1 ([{fd=4, revents=POLLIN|POLLHUP}])
poll([{fd=4, events=POLLIN}], 1, 60000) = 1 ([{fd=4, revents=POLLIN|POLLHUP}])
recvfrom(4, "HTTP/1.1 100 Continue\r\n\r\nHTTP/1."..., 2048, 0, NULL, NULL) = 711
access("/usr/share/locale/en_US/cups_en_US.po", F_OK) = -1 ENOENT (No such file or directory)
access("/usr/share/locale/en/cups_en.po", F_OK) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/C/cups_C.po", O_RDONLY) = -1 ENOENT (No such file or directory)
close(4)                                = 0
socket(PF_LOCAL, SOCK_STREAM, 0)        = 4
setsockopt(4, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
setsockopt(4, SOL_SOCKET, SO_REUSEPORT, [1], 4) = 0
setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = -1 EOPNOTSUPP (Operation not supported)
fcntl(4, F_SETFD, FD_CLOEXEC)           = 0
fcntl(4, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
connect(4, {sa_family=AF_LOCAL, sun_path="/var/run/cups/cups.sock"}, 26) = 0
fcntl(4, F_SETFL, O_RDWR)               = 0
close(4)                                = 0
socket(PF_LOCAL, SOCK_STREAM, 0)        = 4
setsockopt(4, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
setsockopt(4, SOL_SOCKET, SO_REUSEPORT, [1], 4) = 0
setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = -1 EOPNOTSUPP (Operation not supported)
fcntl(4, F_SETFD, FD_CLOEXEC)           = 0
fcntl(4, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
connect(4, {sa_family=AF_LOCAL, sun_path="/var/run/cups/cups.sock"}, 26) = 0
fcntl(4, F_SETFL, O_RDWR)               = 0
sendto(4, "POST /admin/ HTTP/1.1\r\nContent-L"..., 188, 0, NULL, 0) = 188
sendto(4, "\1\1@\3\0\0\0\2\1G\0\22attributes-charset\0\5"..., 207, 0, NULL, 0) = 207
poll([{fd=4, events=POLLIN}], 1, 1000)  = 1 ([{fd=4, revents=POLLIN|POLLHUP}])
poll([{fd=4, events=POLLIN}], 1, 60000) = 1 ([{fd=4, revents=POLLIN|POLLHUP}])
recvfrom(4, "HTTP/1.1 100 Continue\r\n\r\nHTTP/1."..., 2048, 0, NULL, NULL) = 711
write(2, "lpadmin: Internal Server Error\n", 31lpadmin: Internal Server Error
) = 31
exit_group(1)                           = ?
+++ exited with 1 +++

Version-Release number of selected component (if applicable):
cups-2.1.3-1.fc23

How reproducible:
100%

Steps to Reproduce:
1. Install Fedora 23 with MLS selinux policy enabled
2. Start cupsd
3. /usr/sbin/lpadmin -p test -E -v socket://localhost:9100 -m drv:///sample.drv/generic.ppd

Actual results:
lpadmin: Internal Server Error

Expected results:
lpadmin works as expected