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-rw-r--r--fs/xattr.c6
-rw-r--r--include/linux/capability.h2
-rw-r--r--include/linux/security.h2
-rw-r--r--include/uapi/linux/capability.h22
-rw-r--r--security/commoncap.c270
5 files changed, 280 insertions, 22 deletions
diff --git a/fs/xattr.c b/fs/xattr.c
index 464c94bf65f9..7b03df6b8be2 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -441,6 +441,12 @@ setxattr(struct dentry *d, const char __user *name, const void __user *value,
if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
(strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
posix_acl_fix_xattr_from_user(kvalue, size);
+ else if (strcmp(kname, XATTR_NAME_CAPS) == 0) {
+ error = cap_convert_nscap(d, &kvalue, size);
+ if (error < 0)
+ goto out;
+ size = error;
+ }
}
error = vfs_setxattr(d, kname, kvalue, size, flags);
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 6ffb67e10c06..b52e278e4744 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -248,4 +248,6 @@ extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns);
/* audit system wants to get cap info from files as well */
extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
+extern int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size);
+
#endif /* !_LINUX_CAPABILITY_H */
diff --git a/include/linux/security.h b/include/linux/security.h
index b6ea1dc9cc9d..6fff8c924718 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -91,6 +91,8 @@ extern int cap_inode_setxattr(struct dentry *dentry, const char *name,
extern int cap_inode_removexattr(struct dentry *dentry, const char *name);
extern int cap_inode_need_killpriv(struct dentry *dentry);
extern int cap_inode_killpriv(struct dentry *dentry);
+extern int cap_inode_getsecurity(struct inode *inode, const char *name,
+ void **buffer, bool alloc);
extern int cap_mmap_addr(unsigned long addr);
extern int cap_mmap_file(struct file *file, unsigned long reqprot,
unsigned long prot, unsigned long flags);
diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 6fe14d001f68..230e05d35191 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -60,9 +60,13 @@ typedef struct __user_cap_data_struct {
#define VFS_CAP_U32_2 2
#define XATTR_CAPS_SZ_2 (sizeof(__le32)*(1 + 2*VFS_CAP_U32_2))
-#define XATTR_CAPS_SZ XATTR_CAPS_SZ_2
-#define VFS_CAP_U32 VFS_CAP_U32_2
-#define VFS_CAP_REVISION VFS_CAP_REVISION_2
+#define VFS_CAP_REVISION_3 0x03000000
+#define VFS_CAP_U32_3 2
+#define XATTR_CAPS_SZ_3 (sizeof(__le32)*(2 + 2*VFS_CAP_U32_3))
+
+#define XATTR_CAPS_SZ XATTR_CAPS_SZ_3
+#define VFS_CAP_U32 VFS_CAP_U32_3
+#define VFS_CAP_REVISION VFS_CAP_REVISION_3
struct vfs_cap_data {
__le32 magic_etc; /* Little endian */
@@ -72,6 +76,18 @@ struct vfs_cap_data {
} data[VFS_CAP_U32];
};
+/*
+ * same as vfs_cap_data but with a rootid at the end
+ */
+struct vfs_ns_cap_data {
+ __le32 magic_etc;
+ struct {
+ __le32 permitted; /* Little endian */
+ __le32 inheritable; /* Little endian */
+ } data[VFS_CAP_U32];
+ __le32 rootid;
+};
+
#ifndef __KERNEL__
/*
diff --git a/security/commoncap.c b/security/commoncap.c
index d59320282294..c37d27dd1e2c 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -335,6 +335,209 @@ int cap_inode_killpriv(struct dentry *dentry)
return error;
}
+static bool rootid_owns_currentns(kuid_t kroot)
+{
+ struct user_namespace *ns;
+
+ if (!uid_valid(kroot))
+ return false;
+
+ for (ns = current_user_ns(); ; ns = ns->parent) {
+ if (from_kuid(ns, kroot) == 0)
+ return true;
+ if (ns == &init_user_ns)
+ break;
+ }
+
+ return false;
+}
+
+static __u32 sansflags(__u32 m)
+{
+ return m & ~VFS_CAP_FLAGS_EFFECTIVE;
+}
+
+static bool is_v2header(size_t size, __le32 magic)
+{
+ __u32 m = le32_to_cpu(magic);
+ if (size != XATTR_CAPS_SZ_2)
+ return false;
+ return sansflags(m) == VFS_CAP_REVISION_2;
+}
+
+static bool is_v3header(size_t size, __le32 magic)
+{
+ __u32 m = le32_to_cpu(magic);
+
+ if (size != XATTR_CAPS_SZ_3)
+ return false;
+ return sansflags(m) == VFS_CAP_REVISION_3;
+}
+
+/*
+ * getsecurity: We are called for security.* before any attempt to read the
+ * xattr from the inode itself.
+ *
+ * This gives us a chance to read the on-disk value and convert it. If we
+ * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler.
+ *
+ * Note we are not called by vfs_getxattr_alloc(), but that is only called
+ * by the integrity subsystem, which really wants the unconverted values -
+ * so that's good.
+ */
+int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
+ bool alloc)
+{
+ int size, ret;
+ kuid_t kroot;
+ uid_t root, mappedroot;
+ char *tmpbuf = NULL;
+ struct vfs_cap_data *cap;
+ struct vfs_ns_cap_data *nscap;
+ struct dentry *dentry;
+ struct user_namespace *fs_ns;
+
+ if (strcmp(name, "capability") != 0)
+ return -EOPNOTSUPP;
+
+ dentry = d_find_alias(inode);
+ if (!dentry)
+ return -EINVAL;
+
+ size = sizeof(struct vfs_ns_cap_data);
+ ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS,
+ &tmpbuf, size, GFP_NOFS);
+ dput(dentry);
+
+ if (ret < 0)
+ return ret;
+
+ fs_ns = inode->i_sb->s_user_ns;
+ cap = (struct vfs_cap_data *) tmpbuf;
+ if (is_v2header((size_t) ret, cap->magic_etc)) {
+ /* If this is sizeof(vfs_cap_data) then we're ok with the
+ * on-disk value, so return that. */
+ if (alloc)
+ *buffer = tmpbuf;
+ else
+ kfree(tmpbuf);
+ return ret;
+ } else if (!is_v3header((size_t) ret, cap->magic_etc)) {
+ kfree(tmpbuf);
+ return -EINVAL;
+ }
+
+ nscap = (struct vfs_ns_cap_data *) tmpbuf;
+ root = le32_to_cpu(nscap->rootid);
+ kroot = make_kuid(fs_ns, root);
+
+ /* If the root kuid maps to a valid uid in current ns, then return
+ * this as a nscap. */
+ mappedroot = from_kuid(current_user_ns(), kroot);
+ if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
+ if (alloc) {
+ *buffer = tmpbuf;
+ nscap->rootid = cpu_to_le32(mappedroot);
+ } else
+ kfree(tmpbuf);
+ return size;
+ }
+
+ if (!rootid_owns_currentns(kroot)) {
+ kfree(tmpbuf);
+ return -EOPNOTSUPP;
+ }
+
+ /* This comes from a parent namespace. Return as a v2 capability */
+ size = sizeof(struct vfs_cap_data);
+ if (alloc) {
+ *buffer = kmalloc(size, GFP_ATOMIC);
+ if (*buffer) {
+ struct vfs_cap_data *cap = *buffer;
+ __le32 nsmagic, magic;
+ magic = VFS_CAP_REVISION_2;
+ nsmagic = le32_to_cpu(nscap->magic_etc);
+ if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
+ magic |= VFS_CAP_FLAGS_EFFECTIVE;
+ memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
+ cap->magic_etc = cpu_to_le32(magic);
+ }
+ }
+ kfree(tmpbuf);
+ return size;
+}
+
+static kuid_t rootid_from_xattr(const void *value, size_t size,
+ struct user_namespace *task_ns)
+{
+ const struct vfs_ns_cap_data *nscap = value;
+ uid_t rootid = 0;
+
+ if (size == XATTR_CAPS_SZ_3)
+ rootid = le32_to_cpu(nscap->rootid);
+
+ return make_kuid(task_ns, rootid);
+}
+
+static bool validheader(size_t size, __le32 magic)
+{
+ return is_v2header(size, magic) || is_v3header(size, magic);
+}
+
+/*
+ * User requested a write of security.capability. If needed, update the
+ * xattr to change from v2 to v3, or to fixup the v3 rootid.
+ *
+ * If all is ok, we return the new size, on error return < 0.
+ */
+int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size)
+{
+ struct vfs_ns_cap_data *nscap;
+ uid_t nsrootid;
+ const struct vfs_cap_data *cap = *ivalue;
+ __u32 magic, nsmagic;
+ struct inode *inode = d_backing_inode(dentry);
+ struct user_namespace *task_ns = current_user_ns(),
+ *fs_ns = inode->i_sb->s_user_ns;
+ kuid_t rootid;
+ size_t newsize;
+
+ if (!*ivalue)
+ return -EINVAL;
+ if (!validheader(size, cap->magic_etc))
+ return -EINVAL;
+ if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
+ return -EPERM;
+ if (size == XATTR_CAPS_SZ_2)
+ if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
+ /* user is privileged, just write the v2 */
+ return size;
+
+ rootid = rootid_from_xattr(*ivalue, size, task_ns);
+ if (!uid_valid(rootid))
+ return -EINVAL;
+
+ nsrootid = from_kuid(fs_ns, rootid);
+ if (nsrootid == -1)
+ return -EINVAL;
+
+ newsize = sizeof(struct vfs_ns_cap_data);
+ nscap = kmalloc(newsize, GFP_ATOMIC);
+ if (!nscap)
+ return -ENOMEM;
+ nscap->rootid = cpu_to_le32(nsrootid);
+ nsmagic = VFS_CAP_REVISION_3;
+ magic = le32_to_cpu(cap->magic_etc);
+ if (magic & VFS_CAP_FLAGS_EFFECTIVE)
+ nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
+ nscap->magic_etc = cpu_to_le32(nsmagic);
+ memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
+
+ kvfree(*ivalue);
+ *ivalue = nscap;
+ return newsize;
+}
+
/*
* Calculate the new process capability sets from the capability sets attached
* to a file.
@@ -388,7 +591,10 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
__u32 magic_etc;
unsigned tocopy, i;
int size;
- struct vfs_cap_data caps;
+ struct vfs_ns_cap_data data, *nscaps = &data;
+ struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
+ kuid_t rootkuid;
+ struct user_namespace *fs_ns = inode->i_sb->s_user_ns;
memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
@@ -396,18 +602,20 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
return -ENODATA;
size = __vfs_getxattr((struct dentry *)dentry, inode,
- XATTR_NAME_CAPS, &caps, XATTR_CAPS_SZ);
+ XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
if (size == -ENODATA || size == -EOPNOTSUPP)
/* no data, that's ok */
return -ENODATA;
+
if (size < 0)
return size;
if (size < sizeof(magic_etc))
return -EINVAL;
- cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
+ cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc);
+ rootkuid = make_kuid(fs_ns, 0);
switch (magic_etc & VFS_CAP_REVISION_MASK) {
case VFS_CAP_REVISION_1:
if (size != XATTR_CAPS_SZ_1)
@@ -419,15 +627,27 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
return -EINVAL;
tocopy = VFS_CAP_U32_2;
break;
+ case VFS_CAP_REVISION_3:
+ if (size != XATTR_CAPS_SZ_3)
+ return -EINVAL;
+ tocopy = VFS_CAP_U32_3;
+ rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid));
+ break;
+
default:
return -EINVAL;
}
+ /* Limit the caps to the mounter of the filesystem
+ * or the more limited uid specified in the xattr.
+ */
+ if (!rootid_owns_currentns(rootkuid))
+ return -ENODATA;
CAP_FOR_EACH_U32(i) {
if (i >= tocopy)
break;
- cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
- cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
+ cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted);
+ cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable);
}
cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
@@ -465,8 +685,8 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_c
rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
if (rc < 0) {
if (rc == -EINVAL)
- printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
- __func__, rc, bprm->filename);
+ printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
+ bprm->filename);
else if (rc == -ENODATA)
rc = 0;
goto out;
@@ -663,15 +883,19 @@ int cap_bprm_secureexec(struct linux_binprm *bprm)
int cap_inode_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
- if (!strcmp(name, XATTR_NAME_CAPS)) {
- if (!capable(CAP_SETFCAP))
- return -EPERM;
+ /* Ignore non-security xattrs */
+ if (strncmp(name, XATTR_SECURITY_PREFIX,
+ sizeof(XATTR_SECURITY_PREFIX) - 1) != 0)
+ return 0;
+
+ /*
+ * For XATTR_NAME_CAPS the check will be done in
+ * cap_convert_nscap(), called by setxattr()
+ */
+ if (strcmp(name, XATTR_NAME_CAPS) == 0)
return 0;
- }
- if (!strncmp(name, XATTR_SECURITY_PREFIX,
- sizeof(XATTR_SECURITY_PREFIX) - 1) &&
- !capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
@@ -689,15 +913,22 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name,
*/
int cap_inode_removexattr(struct dentry *dentry, const char *name)
{
- if (!strcmp(name, XATTR_NAME_CAPS)) {
- if (!capable(CAP_SETFCAP))
+ /* Ignore non-security xattrs */
+ if (strncmp(name, XATTR_SECURITY_PREFIX,
+ sizeof(XATTR_SECURITY_PREFIX) - 1) != 0)
+ return 0;
+
+ if (strcmp(name, XATTR_NAME_CAPS) == 0) {
+ /* security.capability gets namespaced */
+ struct inode *inode = d_backing_inode(dentry);
+ if (!inode)
+ return -EINVAL;
+ if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
return -EPERM;
return 0;
}
- if (!strncmp(name, XATTR_SECURITY_PREFIX,
- sizeof(XATTR_SECURITY_PREFIX) - 1) &&
- !capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
@@ -1085,6 +1316,7 @@ struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(bprm_secureexec, cap_bprm_secureexec),
LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
+ LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
LSM_HOOK_INIT(mmap_file, cap_mmap_file),
LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-01 01:51:27 +0000