[ammarfaizi2-block:google/android/kernel/common/deprecated/android-4.9-p-release 3994/9999] security/commoncap.c:75:5: warning: no previous declaration for '__cap_capable'

From: kernel test robot
Date: Wed Mar 02 2022 - 18:55:21 EST


Hi John,

FYI, the error/warning still remains.

tree: https://github.com/ammarfaizi2/linux-block google/android/kernel/common/deprecated/android-4.9-p-release
head: 74f5cdd2ad41ea660f18bcaf7ce3d8d3e8e88428
commit: 0268f76e4b39897c7b9ecf5fae695dbbc7bb7426 [3994/9999] ANDROID: commoncap: Begin to warn users of implicit PARANOID_NETWORK capability grants
config: i386-randconfig-r034-20211122 (https://download.01.org/0day-ci/archive/20220303/202203030705.8QZOBwpb-lkp@xxxxxxxxx/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build):
# https://github.com/ammarfaizi2/linux-block/commit/0268f76e4b39897c7b9ecf5fae695dbbc7bb7426
git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
git fetch --no-tags ammarfaizi2-block google/android/kernel/common/deprecated/android-4.9-p-release
git checkout 0268f76e4b39897c7b9ecf5fae695dbbc7bb7426
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=i386 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 >>):

In file included from include/linux/audit.h:26:0,
from security/commoncap.c:11:
include/linux/sched.h:1260:1: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
const struct sched_group_energy * const(*sched_domain_energy_f)(int cpu);
^~~~~
>> 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:15:0,
from security/commoncap.c:10:
security/commoncap.c: In function 'cap_prctl_drop':
include/uapi/linux/capability.h:355:27: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
^
security/commoncap.c:903:7: note: in expansion of macro 'cap_valid'
if (!cap_valid(cap))
^~~~~~~~~
security/commoncap.c: In function 'cap_task_prctl':
include/uapi/linux/capability.h:355:27: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
^
security/commoncap.c:933:8: note: in expansion of macro 'cap_valid'
if (!cap_valid(arg2))
^~~~~~~~~
include/uapi/linux/capability.h:355:27: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
^
security/commoncap.c:1017:10: 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 /* Have we tried all of the parent namespaces? */
90 if (ns == &init_user_ns)
91 return -EPERM;
92
93 /*
94 * The owner of the user namespace in the parent of the
95 * user namespace has all caps.
96 */
97 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
98 return 0;
99
100 /*
101 * If you have a capability in a parent user ns, then you have
102 * it over all children user namespaces as well.
103 */
104 ns = ns->parent;
105 }
106
107 /* We never get here */
108 }
109

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