I've recompiled libselinux with the proposed patch and it looks like
it fixed the bug. Thanks!
2013/12/23 Stephen Smalley <stephen.smalley@xxxxxxxxx>:
> Calling *setfilecon() with a NULL context is a bug in the caller. Not
> opposed to having it return an error, but what do you intend for the
> caller to do in that case? It never should have called it with a NULL
> context in the first place.
The caller here is cp program, from coreutils project, in function
restorecon_private(path="setfiles.8.man", local=true), line 195 of
src/selinux.c [1]. The code runs like this (according to the gdb
backtrace I get):
if (getfscreatecon (&tcon) < 0) /* getfscreatecon sets tcon to
NULL and returns 0 */
return rc;
rc = lsetfilecon (path, tcon); /* call
lsetfilecon("setfiles.8.man", NULL) */
freecon (tcon);
return rc;
If you think this code is doing wrong, there may be a missing check to
test whether tcon is NULL before calling lsetfilecon. Anyway I don't
know what "cp" does if this call to restorecon_private fails, but it
seems to work fine on my system (at least it no longer segfaults).
Nicolas
[1] http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/selinux.c;h=680bc492e5ef2d1a7abd443df7141114b1bc0704;hb=HEAD#l195
[2] http://userspace.selinuxproject.org/trac/browser/libselinux/src/setrans_client.c?rev=aa62cd60f7192123b509c2518e7a2083e34a65a2#L321
---------------- gdb session with "cp" coredump ----------------
Core was generated by `cp -af setfiles.8 setfiles.8.man'.
Program terminated with signal 11, Segmentation fault.
#0 0x00007f31be0b39ba in strlen () from /usr/lib/libc.so.6
(gdb) bt
#0 0x00007f31be0b39ba in strlen () from /usr/lib/libc.so.6
#1 0x00007f31be801be8 in lsetfilecon_raw_internal
(path=path@entry=0x7fffaeb3cea9 "setfiles.8.man", context=0x0) at
lsetfilecon.c:12
#2 0x00007f31be801cab in lsetfilecon (path=path@entry=0x7fffaeb3cea9
"setfiles.8.man", context=<optimized out>) at lsetfilecon.c:38
#3 0x0000000000409a55 in restorecon_private (path=0x7fffaeb3cea9
"setfiles.8.man", local=local@entry=true) at src/selinux.c:195
#4 0x0000000000409f68 in restorecon (path=0x7fffaeb3cea9
"setfiles.8.man", recurse=<optimized out>, local=<optimized out>) at
src/selinux.c:301
#5 0x0000000000405c0b in set_file_security_ctx
(dst_name=0x7fffaeb3cea9 "setfiles.8.man", process_local=<optimized
out>, recurse=<optimized out>, x=<optimized out>) at src/copy.c:835
#6 0x000000000040893b in copy_reg (src_sb=0x7fffaeb3acb0,
new_dst=<synthetic pointer>, omitted_permissions=36,
dst_mode=<optimized out>, x=0x7fffaeb3b0d0,
dst_name=0x7fffaeb3cea9 "setfiles.8.man", src_name=0x7fffaeb3ce9e
"setfiles.8") at src/copy.c:952
#7 copy_internal (src_name=src_name@entry=0x7fffaeb3ce9e
"setfiles.8", dst_name=dst_name@entry=0x7fffaeb3cea9 "setfiles.8.man",
new_dst=<optimized out>, new_dst@entry=false,
device=device@entry=0, ancestors=ancestors@entry=0x0,
x=x@entry=0x7fffaeb3b0d0,
command_line_arg=command_line_arg@entry=true,
first_dir_created_per_command_line_arg=first_dir_created_per_command_line_arg@entry=0x7fffaeb3af6f,
copy_into_self=copy_into_self@entry=0x7fffaeb3afb8,
rename_succeeded=rename_succeeded@entry=0x0) at src/copy.c:2503
#8 0x00000000004094bc in copy (src_name=src_name@entry=0x7fffaeb3ce9e
"setfiles.8", dst_name=dst_name@entry=0x7fffaeb3cea9 "setfiles.8.man",
nonexistent_dst=nonexistent_dst@entry=false,
options=options@entry=0x7fffaeb3b0d0,
copy_into_self=copy_into_self@entry=0x7fffaeb3afb8,
rename_succeeded=rename_succeeded@entry=0x0) at src/copy.c:2809
#9 0x0000000000404fb0 in do_copy (n_files=<optimized out>,
file=0x7fffaeb3b2d8, target_directory=<optimized out>,
target_directory@entry=0x0,
no_target_directory=no_target_directory@entry=false,
x=x@entry=0x7fffaeb3b0d0) at src/cp.c:765
#10 0x0000000000403ba9 in main (argc=4, argv=0x7fffaeb3b2c8) at src/cp.c:1212
(gdb) f 3
#3 0x0000000000409a55 in restorecon_private (path=0x7fffaeb3cea9
"setfiles.8.man", local=local@entry=true) at src/selinux.c:195
195 rc = lsetfilecon (path, tcon);
(gdb) info locals
rc = -1
sb = {st_dev = 139851618037504, st_ino = 139851632465104, st_nlink =
0, st_mode = 2931011792, st_uid = 32767, st_gid = 2931019422, __pad0 =
32767, st_rdev = 140736124407465,
st_size = 140736124399408, st_blksize = 139851630542055, st_blocks =
140733193388033, st_atim = {tv_sec = 0, tv_nsec = 140736124407465},
st_mtim = {tv_sec = 139851618056848, tv_nsec = 420},
st_ctim = {tv_sec = 6434904, tv_nsec = 0}, __unused =
{140736124399824, 140736124407454, 140736124407465}}
scon = 0x0
tcon = 0x0
scontext = 0x0
tcontext = 0x0
contype = <optimized out>
constr = <optimized out>
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