linux-kernel - [PATCH v2] capability: Remove unused has

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Message-ID: <20241219172859.188117-1-linux@treblig.org>
Date: Thu, 19 Dec 2024 17:28:59 +0000
From: linux@...blig.org
To: serge@...lyn.com,
	paul@...l-moore.com,
	linux-security-module@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	"Dr. David Alan Gilbert" <linux@...blig.org>
Subject: [PATCH v2] capability: Remove unused has_capability

From: "Dr. David Alan Gilbert" <linux@...blig.org>

The vanilla has_capability() function has been unused since 2018's
commit dcb569cf6ac9 ("Smack: ptrace capability use fixes")

Remove it.

Fixup a comment in security/commoncap.c that referenced it.

Signed-off-by: Dr. David Alan Gilbert <linux@...blig.org>
---
 include/linux/capability.h |  5 -----
 kernel/capability.c        | 16 ----------------
 security/commoncap.c       |  9 +++++----
 3 files changed, 5 insertions(+), 25 deletions(-)

diff --git a/include/linux/capability.h b/include/linux/capability.h
index 0c356a517991..1fb08922552c 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -139,7 +139,6 @@ static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
 }
 
 #ifdef CONFIG_MULTIUSER
-extern bool has_capability(struct task_struct *t, int cap);
 extern bool has_ns_capability(struct task_struct *t,
 			      struct user_namespace *ns, int cap);
 extern bool has_capability_noaudit(struct task_struct *t, int cap);
@@ -150,10 +149,6 @@ extern bool ns_capable(struct user_namespace *ns, int cap);
 extern bool ns_capable_noaudit(struct user_namespace *ns, int cap);
 extern bool ns_capable_setid(struct user_namespace *ns, int cap);
 #else
-static inline bool has_capability(struct task_struct *t, int cap)
-{
-	return true;
-}
 static inline bool has_ns_capability(struct task_struct *t,
 			      struct user_namespace *ns, int cap)
 {
diff --git a/kernel/capability.c b/kernel/capability.c
index dac4df77e376..67094b628ea9 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -289,22 +289,6 @@ bool has_ns_capability(struct task_struct *t,
 	return (ret == 0);
 }
 
-/**
- * has_capability - Does a task have a capability in init_user_ns
- * @t: The task in question
- * @cap: The capability to be tested for
- *
- * Return true if the specified task has the given superior capability
- * currently in effect to the initial user namespace, false if not.
- *
- * Note that this does not set PF_SUPERPRIV on the task.
- */
-bool has_capability(struct task_struct *t, int cap)
-{
-	return has_ns_capability(t, &init_user_ns, cap);
-}
-EXPORT_SYMBOL(has_capability);
-
 /**
  * has_ns_capability_noaudit - Does a task have a capability (unaudited)
  * in a specific user ns.
diff --git a/security/commoncap.c b/security/commoncap.c
index cefad323a0b1..7019d0e47e62 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -59,10 +59,11 @@ static void warn_setuid_and_fcaps_mixed(const char *fname)
  * Determine whether the nominated task has the specified capability amongst
  * its effective set, returning 0 if it does, -ve if it does not.
  *
- * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
- * and has_capability() functions.  That is, it has the reverse semantics:
- * cap_has_capability() returns 0 when a task has a capability, but the
- * kernel's capable() and has_capability() returns 1 for this case.
+ * NOTE WELL: cap_capable() has reverse semantics to the capable() call
+ * and friends. That is cap_capable() returns an int 0 when a task has
+ * a capability, while the kernel's capable(), has_ns_capability(),
+ * has_ns_capability_noaudit(), and has_capability_noaudit() return a
+ * bool true (1) for this case.
  */
 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
 		int cap, unsigned int opts)
-- 
2.47.1