Re: ktrace/kdump give incorrect message on unlinkat() failure due to capabilities
On Mon, Oct 07, 2019 at 09:48:16AM -0700, John Baldwin wrote:
> On 9/25/19 10:33 AM, Sergey Kandaurov wrote:
> >
> > Index: lib/libsysdecode/mktables
> > ===
> > --- lib/libsysdecode/mktables (revision 352685)
> > +++ lib/libsysdecode/mktables (working copy)
> > @@ -157,7 +157,7 @@
> > gen_table "sigcode" "SI_[A-Z]+[[:space:]]+0(x[0-9abcdef]+)?"
> > "sys/signal.h"
> > gen_table "umtxcvwaitflags" "CVWAIT_[A-Z_]+[[:space:]]+0x[0-9]+"
> > "sys/umtx.h"
> > gen_table "umtxrwlockflags" "URWLOCK_PREFER_READER[[:space:]]+0x[0-9]+"
> > "sys/umtx.h"
> > -gen_table "caprights"
> > "CAP_[A-Z_]+[[:space:]]+CAPRIGHT\([0-9],[[:space:]]+0x[0-9]{16}ULL\)"
> > "sys/capsicum.h"
> > +gen_table "caprights"
> > "CAP_[A-Z_]+[[:space:]]+(CAPRIGHT|[()A-Z_|[:space:]]+CAP_LOOKUP)"
> > "sys/capsicum.h"
> > gen_table "sctpprpolicy""SCTP_PR_SCTP_[A-Z_]+[[:space:]]+0x[0-9]+"
> > "netinet/sctp_uio.h" "SCTP_PR_SCTP_ALL"
> > gen_table "cmsgtypesocket" "SCM_[A-Z_]+[[:space:]]+0x[0-9]+"
> > "sys/socket.h"
> > if [ -e "${include_dir}/x86/sysarch.h" ]; then
>
> CAP_SEEK and CAP_MMAP_X might also be subject to this. However, I'm not quite
> understanding the regex, or at least why the modified portion of the regex
> isn't
> something like this:
>
> (CAPRIGHT\(|\(CAP_LOOKUP)
This won't match against CAP_LOOKUP on the right side, as in CAP_FSTATAT,
but since it is built from CAP_FSTAT and CAP_LOOKUP, it should be fine still.
> That is, you currently have [()A-Z_|[:space:]]+ for an expression that I think
> will only ever match a single '(' character.
All this sad magic is for preceding characters before CAP_LOOKUP,
such as in "(CAP_FSTAT | CAP_LOOKUP". But seems it isn't needed.
> A more general form that might work for CAP_SEEK and CAP_MMAP_X might be
> to match on 'CAP_ | 0x
> (CAPRIGHT\(|\([^)]*CAP_[A-Z_]+ \| 0x[0-9]+)
Given the above, it looks fine.
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Re: ktrace/kdump give incorrect message on unlinkat() failure due to capabilities
On 9/25/19 10:33 AM, Sergey Kandaurov wrote:
> On Sat, Sep 21, 2019 at 08:43:58PM -0400, Ryan Stone wrote:
>> I have written a short test program that runs unlinkat(2) in
>> capability mode and fails due to not having the write capabilities:
>>
>> https://people.freebsd.org/~rstone/src/unlink.c
>>
>> If I run the binary under ktrace and look at the kdump output, it
>> gives the following incorrect output:
>>
>> 43775 unlink CALL unlinkat(0x3,0x7fffe995,0)
>> 43775 unlink NAMI "from.QAUlAA0"
>> 43775 unlink CAP operation requires CAP_LOOKUP, descriptor holds
>> CAP_LOOKUP
>> 43775 unlink RET unlinkat -1 errno 93 Capabilities insufficient
>>
>> The message should instead say that the operation requires
>> CAP_UNLINKAT. Looking at sys/capsicum.h, I suspect that the problem
>> is related to the strange definition of CAP_UNLINKAT:
>>
>> #define CAP_UNLINKAT (CAP_LOOKUP | 0x1000ULL)
>
> FYI, with this grep it was able to decode capabilities.
>
> Index: lib/libsysdecode/mktables
> ===
> --- lib/libsysdecode/mktables (revision 352685)
> +++ lib/libsysdecode/mktables (working copy)
> @@ -157,7 +157,7 @@
> gen_table "sigcode" "SI_[A-Z]+[[:space:]]+0(x[0-9abcdef]+)?"
> "sys/signal.h"
> gen_table "umtxcvwaitflags" "CVWAIT_[A-Z_]+[[:space:]]+0x[0-9]+"
> "sys/umtx.h"
> gen_table "umtxrwlockflags" "URWLOCK_PREFER_READER[[:space:]]+0x[0-9]+"
> "sys/umtx.h"
> -gen_table "caprights"
> "CAP_[A-Z_]+[[:space:]]+CAPRIGHT\([0-9],[[:space:]]+0x[0-9]{16}ULL\)"
> "sys/capsicum.h"
> +gen_table "caprights"
> "CAP_[A-Z_]+[[:space:]]+(CAPRIGHT|[()A-Z_|[:space:]]+CAP_LOOKUP)"
> "sys/capsicum.h"
> gen_table "sctpprpolicy""SCTP_PR_SCTP_[A-Z_]+[[:space:]]+0x[0-9]+"
> "netinet/sctp_uio.h" "SCTP_PR_SCTP_ALL"
> gen_table "cmsgtypesocket" "SCM_[A-Z_]+[[:space:]]+0x[0-9]+"
> "sys/socket.h"
> if [ -e "${include_dir}/x86/sysarch.h" ]; then
CAP_SEEK and CAP_MMAP_X might also be subject to this. However, I'm not quite
understanding the regex, or at least why the modified portion of the regex isn't
something like this:
(CAPRIGHT\(|\(CAP_LOOKUP)
That is, you currently have [()A-Z_|[:space:]]+ for an expression that I think
will only ever match a single '(' character.
A more general form that might work for CAP_SEEK and CAP_MMAP_X might be
to match on 'CAP_ | 0xhttps://lists.freebsd.org/mailman/listinfo/freebsd-current
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Re: ktrace/kdump give incorrect message on unlinkat() failure due to capabilities
On Sat, Sep 21, 2019 at 08:43:58PM -0400, Ryan Stone wrote:
> I have written a short test program that runs unlinkat(2) in
> capability mode and fails due to not having the write capabilities:
>
> https://people.freebsd.org/~rstone/src/unlink.c
>
> If I run the binary under ktrace and look at the kdump output, it
> gives the following incorrect output:
>
> 43775 unlink CALL unlinkat(0x3,0x7fffe995,0)
> 43775 unlink NAMI "from.QAUlAA0"
> 43775 unlink CAP operation requires CAP_LOOKUP, descriptor holds
> CAP_LOOKUP
> 43775 unlink RET unlinkat -1 errno 93 Capabilities insufficient
>
> The message should instead say that the operation requires
> CAP_UNLINKAT. Looking at sys/capsicum.h, I suspect that the problem
> is related to the strange definition of CAP_UNLINKAT:
>
> #define CAP_UNLINKAT (CAP_LOOKUP | 0x1000ULL)
FYI, with this grep it was able to decode capabilities.
Index: lib/libsysdecode/mktables
===
--- lib/libsysdecode/mktables (revision 352685)
+++ lib/libsysdecode/mktables (working copy)
@@ -157,7 +157,7 @@
gen_table "sigcode" "SI_[A-Z]+[[:space:]]+0(x[0-9abcdef]+)?"
"sys/signal.h"
gen_table "umtxcvwaitflags" "CVWAIT_[A-Z_]+[[:space:]]+0x[0-9]+"
"sys/umtx.h"
gen_table "umtxrwlockflags" "URWLOCK_PREFER_READER[[:space:]]+0x[0-9]+"
"sys/umtx.h"
-gen_table "caprights"
"CAP_[A-Z_]+[[:space:]]+CAPRIGHT\([0-9],[[:space:]]+0x[0-9]{16}ULL\)"
"sys/capsicum.h"
+gen_table "caprights"
"CAP_[A-Z_]+[[:space:]]+(CAPRIGHT|[()A-Z_|[:space:]]+CAP_LOOKUP)"
"sys/capsicum.h"
gen_table "sctpprpolicy""SCTP_PR_SCTP_[A-Z_]+[[:space:]]+0x[0-9]+"
"netinet/sctp_uio.h" "SCTP_PR_SCTP_ALL"
gen_table "cmsgtypesocket" "SCM_[A-Z_]+[[:space:]]+0x[0-9]+"
"sys/socket.h"
if [ -e "${include_dir}/x86/sysarch.h" ]; then
On unlink.c, it gives:
45494 unlink CALL cap_rights_limit(0x3,0x7fffead0)
45494 unlink STRU cap_rights_t CAP_LOOKUP
45494 unlink RET cap_rights_limit 0
45494 unlink CALL openat(AT_FDCWD,0x200323,0)
45494 unlink NAMI "/tmp"
45494 unlink RET openat 4
45494 unlink CALL cap_rights_limit(0x4,0x7fffead0)
45494 unlink STRU cap_rights_t CAP_LOOKUP,CAP_UNLINKAT
45494 unlink RET cap_rights_limit 0
45494 unlink CALL cap_enter
45494 unlink RET cap_enter 0
45494 unlink CALL unlinkat(0x3,0x7fffeaa5,0)
45494 unlink NAMI "from.YG6jQx2"
45494 unlink CAP operation requires CAP_LOOKUP,CAP_UNLINKAT, descriptor
holds CAP_LOOKUP
> I have observed the same problem with renameat(2) and
> CAP_RENAMEAT_SOURCE and CAP_RENAMEAT_TARGET:
>
> https://people.freebsd.org/~rstone/src/rename.c
49410 rename CAP operation requires CAP_LOOKUP,CAP_RENAMEAT_SOURCE,
descriptor holds CAP_LOOKUP
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ktrace/kdump give incorrect message on unlinkat() failure due to capabilities
I have written a short test program that runs unlinkat(2) in capability mode and fails due to not having the write capabilities: https://people.freebsd.org/~rstone/src/unlink.c If I run the binary under ktrace and look at the kdump output, it gives the following incorrect output: 43775 unlink CALL unlinkat(0x3,0x7fffe995,0) 43775 unlink NAMI "from.QAUlAA0" 43775 unlink CAP operation requires CAP_LOOKUP, descriptor holds CAP_LOOKUP 43775 unlink RET unlinkat -1 errno 93 Capabilities insufficient The message should instead say that the operation requires CAP_UNLINKAT. Looking at sys/capsicum.h, I suspect that the problem is related to the strange definition of CAP_UNLINKAT: #define CAP_UNLINKAT (CAP_LOOKUP | 0x1000ULL) I have observed the same problem with renameat(2) and CAP_RENAMEAT_SOURCE and CAP_RENAMEAT_TARGET: https://people.freebsd.org/~rstone/src/rename.c ___ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
