[ammarfaizi2-block:google/android/kernel/common/deprecated/android-4.14-p-release 137/6167] security/commoncap.c:75:5: warning: no previous declaration for '__cap_capable'

[kernel test robot]

Hi John,

FYI, the error/warning still remains.

tree:   https://github.com/ammarfaizi2/linux-block google/android/kernel/common/deprecated/android-4.14-p-release
head:   0ca5d5ac9152d01b3494fb2efb5390319eb9904a
commit: 2b02b4ab89b9cba5aec936046d8538962c5142fc [137/6167] ANDROID: net: paranoid: commoncap: Begin to warn users of implicit PARANOID_NETWORK capability grants
config: arm-zeus_defconfig (https://download.01.org/0day-ci/archive/20220303/202203030333.1rYTj1jB-lkp@xxxxxxxxx/config)
compiler: arm-linux-gnueabi-gcc (GCC) 7.5.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/ammarfaizi2/linux-block/commit/2b02b4ab89b9cba5aec936046d8538962c5142fc
        git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
        git fetch --no-tags ammarfaizi2-block google/android/kernel/common/deprecated/android-4.14-p-release
        git checkout 2b02b4ab89b9cba5aec936046d8538962c5142fc
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-7.5.0 make.cross O=build_dir ARCH=arm SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> security/commoncap.c:75:5: warning: no previous declaration for '__cap_capable' [-Wmissing-declarations]
    int __cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
        ^~~~~~~~~~~~~
   In file included from include/linux/capability.h:16:0,
                    from security/commoncap.c:10:
   security/commoncap.c: In function 'cap_prctl_drop':
   include/uapi/linux/capability.h:372:27: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
    #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
                              ^
   security/commoncap.c:1112:7: note: in expansion of macro 'cap_valid'
     if (!cap_valid(cap))
          ^~~~~~~~~
   security/commoncap.c: In function 'cap_task_prctl':
   include/uapi/linux/capability.h:372:27: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
    #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
                              ^
   security/commoncap.c:1142:8: note: in expansion of macro 'cap_valid'
      if (!cap_valid(arg2))
           ^~~~~~~~~
   include/uapi/linux/capability.h:372:27: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
    #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
                              ^
   security/commoncap.c:1226:10: note: in expansion of macro 'cap_valid'
      if (((!cap_valid(arg3)) | arg4 | arg5))
             ^~~~~~~~~


vim +/__cap_capable +75 security/commoncap.c

    59	
    60	/**
    61	 * __cap_capable - Determine whether a task has a particular effective capability
    62	 * @cred: The credentials to use
    63	 * @ns:  The user namespace in which we need the capability
    64	 * @cap: The capability to check for
    65	 * @audit: Whether to write an audit message or not
    66	 *
    67	 * Determine whether the nominated task has the specified capability amongst
    68	 * its effective set, returning 0 if it does, -ve if it does not.
    69	 *
    70	 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
    71	 * and has_capability() functions.  That is, it has the reverse semantics:
    72	 * cap_has_capability() returns 0 when a task has a capability, but the
    73	 * kernel's capable() and has_capability() returns 1 for this case.
    74	 */
  > 75	int __cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
    76			int cap, int audit)
    77	{
    78		struct user_namespace *ns = targ_ns;
    79	
    80		/* See if cred has the capability in the target user namespace
    81		 * by examining the target user namespace and all of the target
    82		 * user namespace's parents.
    83		 */
    84		for (;;) {
    85			/* Do we have the necessary capabilities? */
    86			if (ns == cred->user_ns)
    87				return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
    88	
    89			/*
    90			 * If we're already at a lower level than we're looking for,
    91			 * we're done searching.
    92			 */
    93			if (ns->level <= cred->user_ns->level)
    94				return -EPERM;
    95	
    96			/* 
    97			 * The owner of the user namespace in the parent of the
    98			 * user namespace has all caps.
    99			 */
   100			if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
   101				return 0;
   102	
   103			/*
   104			 * If you have a capability in a parent user ns, then you have
   105			 * it over all children user namespaces as well.
   106			 */
   107			ns = ns->parent;
   108		}
   109	
   110		/* We never get here */
   111	}
   112	

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