0335695dfa
The current_user_ns() macro currently returns &init_user_ns when user
namespaces are disabled, and that causes several warnings when building
with gcc-6.0 in code that compares the result of the macro to
&init_user_ns itself:
fs/xfs/xfs_ioctl.c: In function 'xfs_ioctl_setattr_check_projid':
fs/xfs/xfs_ioctl.c:1249:22: error: self-comparison always evaluates to true [-Werror=tautological-compare]
if (current_user_ns() == &init_user_ns)
This is a legitimate warning in principle, but here it isn't really
helpful, so I'm reprasing the definition in a way that shuts up the
warning. Apparently gcc only warns when comparing identical literals,
but it can figure out that the result of an inline function can be
identical to a constant expression in order to optimize a condition yet
not warn about the fact that the condition is known at compile time.
This is exactly what we want here, and it looks reasonable because we
generally prefer inline functions over macros anyway.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
244 lines
7.1 KiB
C
244 lines
7.1 KiB
C
/*
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* This is <linux/capability.h>
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*
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* Andrew G. Morgan <morgan@kernel.org>
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* Alexander Kjeldaas <astor@guardian.no>
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* with help from Aleph1, Roland Buresund and Andrew Main.
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*
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* See here for the libcap library ("POSIX draft" compliance):
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*
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* ftp://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/
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*/
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#ifndef _LINUX_CAPABILITY_H
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#define _LINUX_CAPABILITY_H
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#include <uapi/linux/capability.h>
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#define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
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#define _KERNEL_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_3
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extern int file_caps_enabled;
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typedef struct kernel_cap_struct {
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__u32 cap[_KERNEL_CAPABILITY_U32S];
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} kernel_cap_t;
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/* exact same as vfs_cap_data but in cpu endian and always filled completely */
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struct cpu_vfs_cap_data {
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__u32 magic_etc;
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kernel_cap_t permitted;
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kernel_cap_t inheritable;
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};
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#define _USER_CAP_HEADER_SIZE (sizeof(struct __user_cap_header_struct))
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#define _KERNEL_CAP_T_SIZE (sizeof(kernel_cap_t))
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struct file;
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struct inode;
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struct dentry;
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struct user_namespace;
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extern const kernel_cap_t __cap_empty_set;
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extern const kernel_cap_t __cap_init_eff_set;
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/*
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* Internal kernel functions only
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*/
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#define CAP_FOR_EACH_U32(__capi) \
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for (__capi = 0; __capi < _KERNEL_CAPABILITY_U32S; ++__capi)
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/*
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* CAP_FS_MASK and CAP_NFSD_MASKS:
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*
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* The fs mask is all the privileges that fsuid==0 historically meant.
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* At one time in the past, that included CAP_MKNOD and CAP_LINUX_IMMUTABLE.
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*
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* It has never meant setting security.* and trusted.* xattrs.
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*
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* We could also define fsmask as follows:
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* 1. CAP_FS_MASK is the privilege to bypass all fs-related DAC permissions
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* 2. The security.* and trusted.* xattrs are fs-related MAC permissions
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*/
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# define CAP_FS_MASK_B0 (CAP_TO_MASK(CAP_CHOWN) \
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| CAP_TO_MASK(CAP_MKNOD) \
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| CAP_TO_MASK(CAP_DAC_OVERRIDE) \
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| CAP_TO_MASK(CAP_DAC_READ_SEARCH) \
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| CAP_TO_MASK(CAP_FOWNER) \
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| CAP_TO_MASK(CAP_FSETID))
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# define CAP_FS_MASK_B1 (CAP_TO_MASK(CAP_MAC_OVERRIDE))
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#if _KERNEL_CAPABILITY_U32S != 2
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# error Fix up hand-coded capability macro initializers
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#else /* HAND-CODED capability initializers */
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#define CAP_LAST_U32 ((_KERNEL_CAPABILITY_U32S) - 1)
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#define CAP_LAST_U32_VALID_MASK (CAP_TO_MASK(CAP_LAST_CAP + 1) -1)
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# define CAP_EMPTY_SET ((kernel_cap_t){{ 0, 0 }})
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# define CAP_FULL_SET ((kernel_cap_t){{ ~0, CAP_LAST_U32_VALID_MASK }})
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# define CAP_FS_SET ((kernel_cap_t){{ CAP_FS_MASK_B0 \
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| CAP_TO_MASK(CAP_LINUX_IMMUTABLE), \
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CAP_FS_MASK_B1 } })
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# define CAP_NFSD_SET ((kernel_cap_t){{ CAP_FS_MASK_B0 \
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| CAP_TO_MASK(CAP_SYS_RESOURCE), \
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CAP_FS_MASK_B1 } })
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#endif /* _KERNEL_CAPABILITY_U32S != 2 */
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# define cap_clear(c) do { (c) = __cap_empty_set; } while (0)
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#define cap_raise(c, flag) ((c).cap[CAP_TO_INDEX(flag)] |= CAP_TO_MASK(flag))
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#define cap_lower(c, flag) ((c).cap[CAP_TO_INDEX(flag)] &= ~CAP_TO_MASK(flag))
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#define cap_raised(c, flag) ((c).cap[CAP_TO_INDEX(flag)] & CAP_TO_MASK(flag))
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#define CAP_BOP_ALL(c, a, b, OP) \
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do { \
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unsigned __capi; \
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CAP_FOR_EACH_U32(__capi) { \
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c.cap[__capi] = a.cap[__capi] OP b.cap[__capi]; \
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} \
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} while (0)
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#define CAP_UOP_ALL(c, a, OP) \
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do { \
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unsigned __capi; \
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CAP_FOR_EACH_U32(__capi) { \
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c.cap[__capi] = OP a.cap[__capi]; \
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} \
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} while (0)
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static inline kernel_cap_t cap_combine(const kernel_cap_t a,
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const kernel_cap_t b)
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{
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kernel_cap_t dest;
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CAP_BOP_ALL(dest, a, b, |);
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return dest;
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}
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static inline kernel_cap_t cap_intersect(const kernel_cap_t a,
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const kernel_cap_t b)
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{
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kernel_cap_t dest;
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CAP_BOP_ALL(dest, a, b, &);
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return dest;
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}
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static inline kernel_cap_t cap_drop(const kernel_cap_t a,
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const kernel_cap_t drop)
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{
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kernel_cap_t dest;
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CAP_BOP_ALL(dest, a, drop, &~);
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return dest;
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}
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static inline kernel_cap_t cap_invert(const kernel_cap_t c)
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{
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kernel_cap_t dest;
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CAP_UOP_ALL(dest, c, ~);
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return dest;
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}
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static inline bool cap_isclear(const kernel_cap_t a)
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{
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unsigned __capi;
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CAP_FOR_EACH_U32(__capi) {
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if (a.cap[__capi] != 0)
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return false;
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}
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return true;
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}
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/*
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* Check if "a" is a subset of "set".
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* return true if ALL of the capabilities in "a" are also in "set"
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* cap_issubset(0101, 1111) will return true
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* return false if ANY of the capabilities in "a" are not in "set"
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* cap_issubset(1111, 0101) will return false
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*/
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static inline bool cap_issubset(const kernel_cap_t a, const kernel_cap_t set)
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{
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kernel_cap_t dest;
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dest = cap_drop(a, set);
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return cap_isclear(dest);
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}
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/* Used to decide between falling back on the old suser() or fsuser(). */
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static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
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{
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const kernel_cap_t __cap_fs_set = CAP_FS_SET;
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return cap_drop(a, __cap_fs_set);
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}
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static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
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const kernel_cap_t permitted)
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{
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const kernel_cap_t __cap_fs_set = CAP_FS_SET;
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return cap_combine(a,
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cap_intersect(permitted, __cap_fs_set));
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}
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static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
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{
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const kernel_cap_t __cap_fs_set = CAP_NFSD_SET;
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return cap_drop(a, __cap_fs_set);
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}
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static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
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const kernel_cap_t permitted)
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{
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const kernel_cap_t __cap_nfsd_set = CAP_NFSD_SET;
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return cap_combine(a,
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cap_intersect(permitted, __cap_nfsd_set));
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}
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#ifdef CONFIG_MULTIUSER
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extern bool has_capability(struct task_struct *t, int cap);
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extern bool has_ns_capability(struct task_struct *t,
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struct user_namespace *ns, int cap);
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extern bool has_capability_noaudit(struct task_struct *t, int cap);
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extern bool has_ns_capability_noaudit(struct task_struct *t,
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struct user_namespace *ns, int cap);
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extern bool capable(int cap);
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extern bool ns_capable(struct user_namespace *ns, int cap);
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#else
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static inline bool has_capability(struct task_struct *t, int cap)
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{
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return true;
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}
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static inline bool has_ns_capability(struct task_struct *t,
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struct user_namespace *ns, int cap)
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{
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return true;
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}
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static inline bool has_capability_noaudit(struct task_struct *t, int cap)
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{
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return true;
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}
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static inline bool has_ns_capability_noaudit(struct task_struct *t,
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struct user_namespace *ns, int cap)
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{
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return true;
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}
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static inline bool capable(int cap)
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{
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return true;
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}
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static inline bool ns_capable(struct user_namespace *ns, int cap)
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{
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return true;
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}
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#endif /* CONFIG_MULTIUSER */
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extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
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extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
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/* audit system wants to get cap info from files as well */
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extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
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#endif /* !_LINUX_CAPABILITY_H */
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