Re: [Bugme-new] [Bug 10748] New: dhclient fails to run; capabilities error

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Mon, 19 May 2008 06:25:00 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

http://bugzilla.kernel.org/show_bug.cgi?id=10748

           Summary: dhclient fails to run; capabilities error
           Product: Networking
           Version: 2.5
     KernelVersion: 2.6.26-rc2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: IPV4
        AssignedTo: shemminger@linux-foundation.org
        ReportedBy: shahamit@gmail.com


Latest working kernel version: 2.6.25
Earliest failing kernel version: 2.6.26-rc1
Distribution: Kubuntu Hardy
Hardware Environment: AMD
Software Environment:
Problem Description: On a default Kubuntu Hardy install, I fetched the git tree
from Linus; compiled and installed the kernel. This persists even with
2.6.26-rc2+ (commit f26a3988917913b3d11b2bd741601a2c64ab9204)

If this isn't known, I'll bisect and report the bad commit

Steps to reproduce: 'sudo dhclient eth2' returns

drop_privileges: could not keep capabilities: Invalid argument

eth2 is an e1000e card.

whoa, weird.  Could you please run `sudo strace -f dhclient eth2' and send us
the last page or so of output?

Quoting Andrew Morton (akpm@linux-foundation.org):

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Mon, 19 May 2008 06:25:00 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

quoted

http://bugzilla.kernel.org/show_bug.cgi?id=10748

           Summary: dhclient fails to run; capabilities error
           Product: Networking
           Version: 2.5
     KernelVersion: 2.6.26-rc2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: IPV4
        AssignedTo: shemminger@linux-foundation.org
        ReportedBy: shahamit@gmail.com


Latest working kernel version: 2.6.25
Earliest failing kernel version: 2.6.26-rc1
Distribution: Kubuntu Hardy
Hardware Environment: AMD
Software Environment:
Problem Description: On a default Kubuntu Hardy install, I fetched the git tree
from Linus; compiled and installed the kernel. This persists even with
2.6.26-rc2+ (commit f26a3988917913b3d11b2bd741601a2c64ab9204)

If this isn't known, I'll bisect and report the bad commit

Steps to reproduce: 'sudo dhclient eth2' returns

drop_privileges: could not keep capabilities: Invalid argument

eth2 is an e1000e card.

whoa, weird.  Could you please run `sudo strace -f dhclient eth2' and send us
the last page or so of output?

Also, please send your .config, or at least the result of
grep SECURITY .config

thanks,
-serge

On Tue, 2008-05-20 at 08:49 -0500, Serge E. Hallyn wrote:

Quoting Andrew Morton (akpm@linux-foundation.org):

quoted

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Mon, 19 May 2008 06:25:00 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

quoted

http://bugzilla.kernel.org/show_bug.cgi?id=10748

           Summary: dhclient fails to run; capabilities error
           Product: Networking
           Version: 2.5
     KernelVersion: 2.6.26-rc2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: IPV4
        AssignedTo: shemminger@linux-foundation.org
        ReportedBy: shahamit@gmail.com


Latest working kernel version: 2.6.25
Earliest failing kernel version: 2.6.26-rc1
Distribution: Kubuntu Hardy
Hardware Environment: AMD
Software Environment:
Problem Description: On a default Kubuntu Hardy install, I fetched the git tree
from Linus; compiled and installed the kernel. This persists even with
2.6.26-rc2+ (commit f26a3988917913b3d11b2bd741601a2c64ab9204)

If this isn't known, I'll bisect and report the bad commit

Steps to reproduce: 'sudo dhclient eth2' returns

drop_privileges: could not keep capabilities: Invalid argument

eth2 is an e1000e card.

whoa, weird.  Could you please run `sudo strace -f dhclient eth2' and send us
the last page or so of output?

Also, please send your .config, or at least the result of
grep SECURITY .config

His .config was attached to the bugzilla.
CONFIG_SECURITY=y
CONFIG_SECURITY_NETWORK=y
# CONFIG_SECURITY_NETWORK_XFRM is not set
# CONFIG_SECURITY_CAPABILITIES is not set
CONFIG_SECURITY_DEFAULT_MMAP_MIN_ADDR=0
# CONFIG_SECURITY_SELINUX is not set

Which means that he is using the dummy security module.
And it appears that a prior commit moved KEEPCAPS handling from
core prctl() to cap_task_prctl(), but didn't replicate it in
the dummy_task_prctl().

The dummy module really needs to die.

-- 
Stephen Smalley
National Security Agency

On Mon, May 19, 2008 at 11:58 PM, Andrew Morton
[off-list ref] wrote:

whoa, weird.  Could you please run `sudo strace -f dhclient eth2' and send us
the last page or so of output?

Sorry, I should've done that earlier.

9311  open("/var/lib/dhcp3/dhclient.leases", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 4
9311  chown("/var/lib/dhcp3/dhclient.leases", 100, 4294967295) = 0
9311  fstat(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
9311  mmap(NULL, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc511e8f000
9311  write(4, "lease {\n  interface \"eth0\";\n  fi"..., 531) = 531
9311  open("/var/run/dhclient.pid", O_WRONLY|O_CREAT|O_TRUNC, 0644) = 5
9311  fcntl(5, F_GETFL)                 = 0x8001 (flags O_WRONLY|O_LARGEFILE)
9311  fstat(5, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
9311  mmap(NULL, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc511e8e000
9311  lseek(5, 0, SEEK_CUR)             = 0
9311  open("/etc/passwd", O_RDONLY|0x80000 /* O_??? */) = 6
9311  lseek(6, 0, SEEK_CUR)             = 0
9311  fstat(6, {st_mode=S_IFREG|0644, st_size=1558, ...}) = 0
9311  mmap(NULL, 1558, PROT_READ, MAP_SHARED, 6, 0) = 0x7fc511e8d000
9311  lseek(6, 1558, SEEK_SET)          = 1558
9311  munmap(0x7fc511e8d000, 1558)      = 0
9311  close(6)                          = 0
9311  socket(PF_FILE, SOCK_STREAM, 0)   = 6
9311  fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK) = 0
9311  connect(6, {sa_family=AF_FILE, path="/var/run/nscd/socket"},
110) = -1 ENOENT (No such file or directory)
9311  close(6)                          = 0
9311  socket(PF_FILE, SOCK_STREAM, 0)   = 6
9311  fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK) = 0
9311  connect(6, {sa_family=AF_FILE, path="/var/run/nscd/socket"},
110) = -1 ENOENT (No such file or directory)
9311  close(6)                          = 0
9311  open("/etc/group", O_RDONLY|0x80000 /* O_??? */) = 6
9311  lseek(6, 0, SEEK_CUR)             = 0
9311  fstat(6, {st_mode=S_IFREG|0644, st_size=923, ...}) = 0
9311  mmap(NULL, 923, PROT_READ, MAP_SHARED, 6, 0) = 0x7fc511e8d000
9311  lseek(6, 923, SEEK_SET)           = 923
9311  munmap(0x7fc511e8d000, 923)       = 0
9311  close(6)                          = 0
9311  prctl(0x8, 0x1, 0, 0, 0)          = -1 EINVAL (Invalid argument)
9311  dup(2)                            = 6
9311  fcntl(6, F_GETFL)                 = 0x8002 (flags O_RDWR|O_LARGEFILE)
9311  fstat(6, {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 2), ...}) = 0
9311  mmap(NULL, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc511e8d000
9311  lseek(6, 0, SEEK_CUR)             = -1 ESPIPE (Illegal seek)
9311  write(6, "drop_privileges: could not keep "..., 63) = 63
9311  close(6)                          = 0
9311  munmap(0x7fc511e8d000, 4096)      = 0
9311  exit_group(-1)                    = ?

-- 
Amit Shah
http://www.amitshah.net/

On Tue, 2008-05-20 at 09:38 -0400, Stephen Smalley wrote:

On Tue, 2008-05-20 at 08:49 -0500, Serge E. Hallyn wrote:

quoted

Quoting Andrew Morton (akpm@linux-foundation.org):

quoted

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Mon, 19 May 2008 06:25:00 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

quoted

http://bugzilla.kernel.org/show_bug.cgi?id=10748

           Summary: dhclient fails to run; capabilities error
           Product: Networking
           Version: 2.5
     KernelVersion: 2.6.26-rc2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: IPV4
        AssignedTo: shemminger@linux-foundation.org
        ReportedBy: shahamit@gmail.com


Latest working kernel version: 2.6.25
Earliest failing kernel version: 2.6.26-rc1
Distribution: Kubuntu Hardy
Hardware Environment: AMD
Software Environment:
Problem Description: On a default Kubuntu Hardy install, I fetched the git tree
from Linus; compiled and installed the kernel. This persists even with
2.6.26-rc2+ (commit f26a3988917913b3d11b2bd741601a2c64ab9204)

If this isn't known, I'll bisect and report the bad commit

Steps to reproduce: 'sudo dhclient eth2' returns

drop_privileges: could not keep capabilities: Invalid argument

eth2 is an e1000e card.

whoa, weird.  Could you please run `sudo strace -f dhclient eth2' and send us
the last page or so of output?

Also, please send your .config, or at least the result of
grep SECURITY .config

His .config was attached to the bugzilla.
CONFIG_SECURITY=y
CONFIG_SECURITY_NETWORK=y
# CONFIG_SECURITY_NETWORK_XFRM is not set
# CONFIG_SECURITY_CAPABILITIES is not set
CONFIG_SECURITY_DEFAULT_MMAP_MIN_ADDR=0
# CONFIG_SECURITY_SELINUX is not set

Which means that he is using the dummy security module.
And it appears that a prior commit moved KEEPCAPS handling from
core prctl() to cap_task_prctl(), but didn't replicate it in
the dummy_task_prctl().

The dummy module really needs to die.

Question for the bug reporter:  did you really mean to build a kernel
without capabilities support?  Surprise!  They don't really work when
disabled.

-- 
Stephen Smalley
National Security Agency

On Tue, May 20, 2008 at 7:28 PM, Stephen Smalley [off-list ref] wrote:

On Tue, 2008-05-20 at 09:38 -0400, Stephen Smalley wrote:

quoted

Which means that he is using the dummy security module.
And it appears that a prior commit moved KEEPCAPS handling from
core prctl() to cap_task_prctl(), but didn't replicate it in
the dummy_task_prctl().

The dummy module really needs to die.

Question for the bug reporter:  did you really mean to build a kernel
without capabilities support?  Surprise!  They don't really work when
disabled.

No; I was just trying out some random configs. This config worked till
.25 properly though.

-- 
Amit Shah
http://www.amitshah.net/

On Tue, 2008-05-20 at 19:37 +0530, Amit Shah wrote:

On Tue, May 20, 2008 at 7:28 PM, Stephen Smalley [off-list ref] wrote:

quoted

On Tue, 2008-05-20 at 09:38 -0400, Stephen Smalley wrote:

quoted

Which means that he is using the dummy security module.
And it appears that a prior commit moved KEEPCAPS handling from
core prctl() to cap_task_prctl(), but didn't replicate it in
the dummy_task_prctl().

The dummy module really needs to die.

Question for the bug reporter:  did you really mean to build a kernel
without capabilities support?  Surprise!  They don't really work when
disabled.

No; I was just trying out some random configs. This config worked till
.25 properly though.

The dummy module is generally in the untenable position of having to lie
to userspace or break the existing capability-related system call
interface.  It should just go away, and make capability the default
module (w/ stubs for the rest of the LSM hooks as with dummy).  Then
CONFIG_SECURITY=n will yield the same result as CONFIG_SECURITY=y w/o
any further options.

-- 
Stephen Smalley
National Security Agency

On Tue, 2008-05-20 at 10:45 -0400, Stephen Smalley wrote:

On Tue, 2008-05-20 at 19:37 +0530, Amit Shah wrote:

quoted

On Tue, May 20, 2008 at 7:28 PM, Stephen Smalley [off-list ref] wrote:

quoted

On Tue, 2008-05-20 at 09:38 -0400, Stephen Smalley wrote:

quoted

Which means that he is using the dummy security module.
And it appears that a prior commit moved KEEPCAPS handling from
core prctl() to cap_task_prctl(), but didn't replicate it in
the dummy_task_prctl().

The dummy module really needs to die.

Question for the bug reporter:  did you really mean to build a kernel
without capabilities support?  Surprise!  They don't really work when
disabled.

No; I was just trying out some random configs. This config worked till
.25 properly though.

The dummy module is generally in the untenable position of having to lie
to userspace or break the existing capability-related system call
interface.  It should just go away, and make capability the default
module (w/ stubs for the rest of the LSM hooks as with dummy).  Then
CONFIG_SECURITY=n will yield the same result as CONFIG_SECURITY=y w/o
any further options.

(cc Chris Wright and linux-security-module list)

s/same result/same user-visible behavior/ 

-- 
Stephen Smalley
National Security Agency