[PATCH 1/1] file capabilities: introduce cap_setfcap

From: Serge E . Hallyn
Date: Wed Jun 27 2007 - 13:09:20 EST


Setting file capabilities previously required the
cap_sys_admin capability, since they are stored as
extended attributes in the security.* namespace.

Introduce CAP_SETFCAP (to mirror CAP_SETPCAP), and
require it for setting file capabilities instead of
CAP_SYS_ADMIN.

Quoting Andrew Morgan,

"CAP_SYS_ADMIN is way too overloaded and this
functionality is special."

Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
include/linux/capability.h | 4 +++-
security/commoncap.c | 12 ++++++++++--
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/include/linux/capability.h b/include/linux/capability.h
index 89125df..cdfaa10 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -324,7 +324,9 @@ typedef __u32 kernel_cap_t;

#define CAP_AUDIT_CONTROL 30

-#define CAP_NUMCAPS 31
+#define CAP_SETFCAP 31
+
+#define CAP_NUMCAPS 32

#ifdef __KERNEL__
/*
diff --git a/security/commoncap.c b/security/commoncap.c
index 4e9ff02..24de4fa 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -290,7 +290,11 @@ int cap_bprm_secureexec (struct linux_binprm *bprm)
int cap_inode_setxattr(struct dentry *dentry, char *name, void *value,
size_t size, int flags)
{
- if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ if (!strcmp(name, XATTR_NAME_CAPS)) {
+ if (!capable(CAP_SETFCAP))
+ return -EPERM;
+ return 0;
+ } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
sizeof(XATTR_SECURITY_PREFIX) - 1) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -299,7 +303,11 @@ int cap_inode_setxattr(struct dentry *dentry, char *name, void *value,

int cap_inode_removexattr(struct dentry *dentry, char *name)
{
- if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ if (!strcmp(name, XATTR_NAME_CAPS)) {
+ if (!capable(CAP_SETFCAP))
+ return -EPERM;
+ return 0;
+ } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
sizeof(XATTR_SECURITY_PREFIX) - 1) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
--
1.5.1.1.GIT

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