fedora 9 help with unknown symbols in kernel -- cap_capget cap_capset_set

[Skunk Worx]

stan wrote:
> Skunk Worx wrote:
>> stan wrote:
>>> Skunk Worx wrote:
>>>> Hello,
>>>>
>>>> I asked over on 'users' a few days ago and no help yet. I hope you 
>>>> don't mind my repeating the question here.
>>>>
>>>> We're a small company using some altera-based boards and our own 
>>>> driver to control them.
>>>>
>>>> Fedora 7 was working well, but we are getting some unknown symbols 
>>>> while evaluating an upgrade to F9.
>>>>
>>>> Any help, comments, suggestions are greatly appreciated.
>>>>
>>>> ---
>>>> John
>>>>
>>>> code and issues :
>>>>
>>>>   struct sched_param param = {70};
>>>>   kernel_cap_t effective, inheritable, permitted, all;
>>>>
>>>>   cap_set_full(all); // be sure we have enough permissions to call
>>>>                      // sched_setscheduler.
>>>>                      // probably only need CAP_SYS_NICE, but let's be
>>>>                      // "(un)safe"
>>>>
>>>>
>>>>   // save old permissions
>>>>   cap_capget(current,&effective, &inheritable, &permitted);
>>>>
>>>>   // setup permissions to do this
>>>>   cap_capset_set(current,&all, &all, &all);
>>>>
>>>>   // setup realtime priority
>>>>   ret=sched_setscheduler(current,SCHED_RR,&param);
>>>>
>>>>   // restore permissions
>>>>   cap_capset_set(current,&effective, &inheritable, &permitted);
>>>>
>>>>
>>>> used to be able to do this in f7 / 2.6.23 kernel, now we get:
>>>>
>>>> WARNING: "cap_capset_set" [/usr/CSM/src/ONI/oni_driver/oni.ko] 
>>>> undefined!
>>>> WARNING: "cap_capget" [/usr/CSM/src/ONI/oni_driver/oni.ko] undefined!
>>>>
>>>> when building and of course:
>>>>
>>>> oni: Unknown symbol cap_capget
>>>> oni: Unknown symbol cap_capset_set
>>>>
>>>> when insmod'ing under f9 / 2.6.25
>>>>
>>> Now if you are writing drivers you are sophisticated users.  I would 
>>> think you have already tried these, but just in case.
>>>
>>
>> We write our own driver, there is no "oni.ko" in Fedora...we add it.
>>
> I misunderstood.  I thought you were linking a kernel module and it 
> wasn't finding symbols.
> 
> [snip]
>> We've searched for the POSIX cap_* functions, and from what we can 
>> tell they should be exported, but for some reason no longer appear to 
>> be. I am not sure if this is the right language to explain the 
>> problem, but we can't seem to get to the symbols any more.
>>
>>
> I think you are saying that they are no longer in a header file. 

I'm looking at the source code for the two kernels now.

2.6.23:
-------
extern int cap_capget (struct task_struct *target, kernel_cap_t 
*effective, kernel_cap_t *inheritable, kernel_cap_t *permitted);
./linux-2.6.23/include/linux/security.h

and

int cap_capget (struct task_struct *target, kernel_cap_t *effective,
EXPORT_SYMBOL(cap_capget);
./linux-2.6.23/security/commoncap.c


2.6.25:
-------
extern int cap_capget (struct task_struct *target, kernel_cap_t 
*effective, kernel_cap_t *inheritable, kernel_cap_t *permitted);	
./linux-2.6.25/include/linux/security.h

and

int cap_capget (struct task_struct *target, kernel_cap_t *effective,
./linux-2.6.25/security/commoncap.c

...so someone took out a group of EXPORT_SYMBOLS :

EXPORT_SYMBOL(cap_capable);
EXPORT_SYMBOL(cap_settime);
EXPORT_SYMBOL(cap_ptrace);
EXPORT_SYMBOL(cap_capget);
EXPORT_SYMBOL(cap_capset_check);
EXPORT_SYMBOL(cap_capset_set);
EXPORT_SYMBOL(cap_bprm_set_security);
EXPORT_SYMBOL(cap_bprm_apply_creds);
EXPORT_SYMBOL(cap_bprm_secureexec);
EXPORT_SYMBOL(cap_inode_setxattr);
EXPORT_SYMBOL(cap_inode_removexattr);
EXPORT_SYMBOL(cap_task_post_setuid);
EXPORT_SYMBOL(cap_task_reparent_to_init);
EXPORT_SYMBOL(cap_syslog);
EXPORT_SYMBOL(cap_vm_enough_memory);

This seems relevant :

http://lists.openwall.net/linux-kernel/2007/08/14/418

...esp. the statement : "- remove a bunch of no longer used exports"

Sounds like people can't use the POSIX capability API to set things like 
CAP_SYS_NICE in their drivers any more, or maybe there is a new way to 
do such things.

At least one of our ring nodes (sometimes more) need to adjust the 
scheduler to keep up with the incoming data.

---
John