iopl() fails intermittently
I am working on a hardware device, where I have to do some GPIO operations.
At the start of my program, I invoke iopl(3). The executable is not root owned, but has capabilities set - cap_sys_rawio+eip. Though this works most of the times
sometimes the process fails with:
iopl: Operation not permitted
Is the capability insufficient ? I cannot run the program as root.
The device is running Ubuntu 14.04.2. dmesg / syslogs are not giving
any hints!
More details:
The start of my main has this:
if (iopl(3) != 0)
perror("iopl");
assert(!"Failed to set privilege!");
Though this works most of the times, sometimes on the hardware platform
(Intel Atom based), this fails with perror printing iopl: Operation not permitted.
ubuntu-14.04 system-calls
asked Nov 15 '18 at 5:16
vyomvyom
6651024
add a comment |
I am working on a hardware device, where I have to do some GPIO operations.
At the start of my program, I invoke iopl(3). The executable is not root owned, but has capabilities set - cap_sys_rawio+eip. Though this works most of the times
sometimes the process fails with:
iopl: Operation not permitted
Is the capability insufficient ? I cannot run the program as root.
The device is running Ubuntu 14.04.2. dmesg / syslogs are not giving
any hints!
More details:
The start of my main has this:
if (iopl(3) != 0)
perror("iopl");
assert(!"Failed to set privilege!");
Though this works most of the times, sometimes on the hardware platform
(Intel Atom based), this fails with perror printing iopl: Operation not permitted.
ubuntu-14.04 system-calls
asked Nov 15 '18 at 5:16
vyomvyom
6651024
Care to provide the code to reproduce the problem? Also, what architecture are you running?
– Ulrich Eckhardt
Nov 26 '18 at 8:30
My program main has:if (iopl(3) != 0) perror("iopl");. I am not able to reproduce the issue at will! :( it happens some times and I am not getting any clue as to whyioplfailed. This is intel Atom (Intel(R) Atom(TM) CPU C2558 @ 2.40GHz) CPU. If you need any more details, please let me know.
– vyom
Nov 27 '18 at 3:55
Add the architecture and the code to your question, including amain()and includes, to make the question more complete. One more think to look at would bestrace. Capture its output and compare the error case to the non-error case. In particular, whether there are symptoms before theiopl()-call. Other than that, I'm at a loss, too.
– Ulrich Eckhardt
Nov 27 '18 at 18:31
@UlrichEckhardt sure, if this happens again, willstraceit
– vyom
Nov 28 '18 at 4:05
add a comment |
I am working on a hardware device, where I have to do some GPIO operations.
At the start of my program, I invoke iopl(3). The executable is not root owned, but has capabilities set - cap_sys_rawio+eip. Though this works most of the times
sometimes the process fails with:
iopl: Operation not permitted
Is the capability insufficient ? I cannot run the program as root.
The device is running Ubuntu 14.04.2. dmesg / syslogs are not giving
any hints!
More details:
The start of my main has this:
if (iopl(3) != 0)
perror("iopl");
assert(!"Failed to set privilege!");
Though this works most of the times, sometimes on the hardware platform
(Intel Atom based), this fails with perror printing iopl: Operation not permitted.
ubuntu-14.04 system-calls
asked Nov 15 '18 at 5:16
vyomvyom
6651024
I am working on a hardware device, where I have to do some GPIO operations.
At the start of my program, I invoke iopl(3). The executable is not root owned, but has capabilities set - cap_sys_rawio+eip. Though this works most of the times
sometimes the process fails with:
iopl: Operation not permitted
Is the capability insufficient ? I cannot run the program as root.
The device is running Ubuntu 14.04.2. dmesg / syslogs are not giving
any hints!
More details:
The start of my main has this:
if (iopl(3) != 0)
perror("iopl");
assert(!"Failed to set privilege!");
Though this works most of the times, sometimes on the hardware platform
(Intel Atom based), this fails with perror printing iopl: Operation not permitted.
ubuntu-14.04 system-calls
ubuntu-14.04 system-calls
asked Nov 15 '18 at 5:16
vyomvyom
6651024
asked Nov 15 '18 at 5:16
vyomvyom
6651024
edited Nov 28 '18 at 9:09
vyom
asked Nov 15 '18 at 5:16
vyomvyom
6651024
asked Nov 15 '18 at 5:16
vyomvyom
6651024
asked Nov 15 '18 at 5:16
vyomvyom
6651024
6651024
Care to provide the code to reproduce the problem? Also, what architecture are you running?
– Ulrich Eckhardt
Nov 26 '18 at 8:30
My program main has:if (iopl(3) != 0) perror("iopl");. I am not able to reproduce the issue at will! :( it happens some times and I am not getting any clue as to whyioplfailed. This is intel Atom (Intel(R) Atom(TM) CPU C2558 @ 2.40GHz) CPU. If you need any more details, please let me know.
– vyom
Nov 27 '18 at 3:55
Add the architecture and the code to your question, including amain()and includes, to make the question more complete. One more think to look at would bestrace. Capture its output and compare the error case to the non-error case. In particular, whether there are symptoms before theiopl()-call. Other than that, I'm at a loss, too.
– Ulrich Eckhardt
Nov 27 '18 at 18:31
@UlrichEckhardt sure, if this happens again, willstraceit
– vyom
Nov 28 '18 at 4:05
add a comment |
Care to provide the code to reproduce the problem? Also, what architecture are you running?
– Ulrich Eckhardt
Nov 26 '18 at 8:30
My program main has:if (iopl(3) != 0) perror("iopl");. I am not able to reproduce the issue at will! :( it happens some times and I am not getting any clue as to whyioplfailed. This is intel Atom (Intel(R) Atom(TM) CPU C2558 @ 2.40GHz) CPU. If you need any more details, please let me know.
– vyom
Nov 27 '18 at 3:55
Add the architecture and the code to your question, including amain()and includes, to make the question more complete. One more think to look at would bestrace. Capture its output and compare the error case to the non-error case. In particular, whether there are symptoms before theiopl()-call. Other than that, I'm at a loss, too.
– Ulrich Eckhardt
Nov 27 '18 at 18:31
@UlrichEckhardt sure, if this happens again, willstraceit
– vyom
Nov 28 '18 at 4:05
Care to provide the code to reproduce the problem? Also, what architecture are you running?
– Ulrich Eckhardt
Nov 26 '18 at 8:30
Care to provide the code to reproduce the problem? Also, what architecture are you running?
– Ulrich Eckhardt
Nov 26 '18 at 8:30
My program main has:
if (iopl(3) != 0) perror("iopl"); . I am not able to reproduce the issue at will! :( it happens some times and I am not getting any clue as to why iopl failed. This is intel Atom (Intel(R) Atom(TM) CPU C2558 @ 2.40GHz) CPU. If you need any more details, please let me know.– vyom
Nov 27 '18 at 3:55
My program main has:
if (iopl(3) != 0) perror("iopl"); . I am not able to reproduce the issue at will! :( it happens some times and I am not getting any clue as to why iopl failed. This is intel Atom (Intel(R) Atom(TM) CPU C2558 @ 2.40GHz) CPU. If you need any more details, please let me know.– vyom
Nov 27 '18 at 3:55
Add the architecture and the code to your question, including a
main() and includes, to make the question more complete. One more think to look at would be strace. Capture its output and compare the error case to the non-error case. In particular, whether there are symptoms before the iopl()-call. Other than that, I'm at a loss, too.– Ulrich Eckhardt
Nov 27 '18 at 18:31
Add the architecture and the code to your question, including a
main() and includes, to make the question more complete. One more think to look at would be strace. Capture its output and compare the error case to the non-error case. In particular, whether there are symptoms before the iopl()-call. Other than that, I'm at a loss, too.– Ulrich Eckhardt
Nov 27 '18 at 18:31
@UlrichEckhardt sure, if this happens again, will
strace it– vyom
Nov 28 '18 at 4:05
@UlrichEckhardt sure, if this happens again, will
strace it– vyom
Nov 28 '18 at 4:05
add a comment |
1 Answer
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Knowing that you cannot run the program as root, I am guessing if you have tried:
chmod u+s /usr/bin/xinit
or if you have root access,
sudo chmod u+s /usr/bin/xinit
If no setuid has been set (considering running without sudo --since you have already root access)
sudo chown root $prefix/Xorg
sudo chmod u+s $prefix/Xorg
answered Nov 26 '18 at 8:17
UnPUnP
8111
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
add a comment |
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1 Answer
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oldest
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1 Answer
1
active
oldest
votes
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oldest
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oldest
votes
Knowing that you cannot run the program as root, I am guessing if you have tried:
chmod u+s /usr/bin/xinit
or if you have root access,
sudo chmod u+s /usr/bin/xinit
If no setuid has been set (considering running without sudo --since you have already root access)
sudo chown root $prefix/Xorg
sudo chmod u+s $prefix/Xorg
answered Nov 26 '18 at 8:17
UnPUnP
8111
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
add a comment |
Knowing that you cannot run the program as root, I am guessing if you have tried:
chmod u+s /usr/bin/xinit
or if you have root access,
sudo chmod u+s /usr/bin/xinit
If no setuid has been set (considering running without sudo --since you have already root access)
sudo chown root $prefix/Xorg
sudo chmod u+s $prefix/Xorg
answered Nov 26 '18 at 8:17
UnPUnP
8111
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
add a comment |
Knowing that you cannot run the program as root, I am guessing if you have tried:
chmod u+s /usr/bin/xinit
or if you have root access,
sudo chmod u+s /usr/bin/xinit
If no setuid has been set (considering running without sudo --since you have already root access)
sudo chown root $prefix/Xorg
sudo chmod u+s $prefix/Xorg
answered Nov 26 '18 at 8:17
UnPUnP
8111
Knowing that you cannot run the program as root, I am guessing if you have tried:
chmod u+s /usr/bin/xinit
or if you have root access,
sudo chmod u+s /usr/bin/xinit
If no setuid has been set (considering running without sudo --since you have already root access)
sudo chown root $prefix/Xorg
sudo chmod u+s $prefix/Xorg
answered Nov 26 '18 at 8:17
UnPUnP
8111
edited Nov 27 '18 at 7:02
answered Nov 26 '18 at 8:17
UnPUnP
8111
answered Nov 26 '18 at 8:17
UnPUnP
8111
answered Nov 26 '18 at 8:17
UnPUnP
8111
8111
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
add a comment |
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Yes, the executable already has capabilities set, so it does not have to run as root
– vyom
Nov 27 '18 at 3:52
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
Is Xorg setuid to root?
– UnP
Nov 27 '18 at 7:01
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
I am not using Xorg at all. This is my own application, for which I am doing setcap and not suid root.
– vyom
Nov 28 '18 at 4:06
add a comment |
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Care to provide the code to reproduce the problem? Also, what architecture are you running?
– Ulrich Eckhardt
Nov 26 '18 at 8:30
My program main has:
if (iopl(3) != 0) perror("iopl");. I am not able to reproduce the issue at will! :( it happens some times and I am not getting any clue as to whyioplfailed. This is intel Atom (Intel(R) Atom(TM) CPU C2558 @ 2.40GHz) CPU. If you need any more details, please let me know.– vyom
Nov 27 '18 at 3:55
Add the architecture and the code to your question, including a
main()and includes, to make the question more complete. One more think to look at would bestrace. Capture its output and compare the error case to the non-error case. In particular, whether there are symptoms before theiopl()-call. Other than that, I'm at a loss, too.– Ulrich Eckhardt
Nov 27 '18 at 18:31
@UlrichEckhardt sure, if this happens again, will
straceit– vyom
Nov 28 '18 at 4:05