Re: [PATCH][LSM] setfsuid/setgsuid bug fix 4/4

From: Chris Wright (chrisat_private)
Date: Fri Jun 13 2003 - 00:22:24 PDT

  • Next message: Chris Wright: "Re: [PATCH][LSM] Early init for security modules 1/4"

    Patch from Jakub Jelínek <jakubat_private>
    
    [LSM] make sure setfsuid/setfsgid return values are right. Before
    include/linux/security.h was added, setfsuid/setfsgid always returned
    old_fsuid, no matter if the fsuid was actually changed or not.  With
    the default security ops it seems to do the same, because both
    security_task_setuid and security_task_post_setuid return 0, but
    these are hooks which seem to return 0 on success, -errno on failure,
    so if some non-default security hook is installed and ever returns
    -errno in setfsuid/setfsgid, -errno will be returned from the syscall
    instead of the expected old_fsuid. This makes it hard to distinguish
    uids 0xfffff001 .. 0xffffffff from errors of security hooks.
    
    --- linus-2.5/kernel/sys.c.setfsuid	Thu Jun 12 22:53:14 2003
    +++ linus-2.5/kernel/sys.c	Thu Jun 12 22:53:14 2003
    @@ -831,13 +831,11 @@
     asmlinkage long sys_setfsuid(uid_t uid)
     {
     	int old_fsuid;
    -	int retval;
    -
    -	retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS);
    -	if (retval)
    -		return retval;
     
     	old_fsuid = current->fsuid;
    +	if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS))
    +		return old_fsuid;
    +
     	if (uid == current->uid || uid == current->euid ||
     	    uid == current->suid || uid == current->fsuid || 
     	    capable(CAP_SETUID))
    @@ -850,9 +848,7 @@
     		current->fsuid = uid;
     	}
     
    -	retval = security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS);
    -	if (retval)
    -		return retval;
    +	security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS);
     
     	return old_fsuid;
     }
    @@ -863,13 +859,11 @@
     asmlinkage long sys_setfsgid(gid_t gid)
     {
     	int old_fsgid;
    -	int retval;
    -
    -	retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS);
    -	if (retval)
    -		return retval;
     
     	old_fsgid = current->fsgid;
    +	if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS))
    +		return old_fsgid;
    +
     	if (gid == current->gid || gid == current->egid ||
     	    gid == current->sgid || gid == current->fsgid || 
     	    capable(CAP_SETGID))
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