From: Miklos Szeredi mszeredi@redhat.com

commit 7c03e2cda4a584cadc398e8f6641ca9988a39d52 upstream.

cap_convert_nscap() does permission checking as well as conversion of the xattr value conditionally based on fs's user-ns.

This is needed by overlayfs and probably other layered fs (ecryptfs) and is what vfs_foo() is supposed to do anyway.

Signed-off-by: Miklos Szeredi mszeredi@redhat.com Acked-by: James Morris jamorris@linux.microsoft.com Signed-off-by: Hugo SIMELIERE hsimeliere.opensource@witekio.com --- fs/xattr.c | 17 +++++++++++------ include/linux/capability.h | 2 +- security/commoncap.c | 3 +-- 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/fs/xattr.c b/fs/xattr.c index 5c3407e18e15..aa66b4efef6b 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -248,8 +248,16 @@ vfs_setxattr(struct dentry *dentry, const char *name, const void *value, { struct inode *inode = dentry->d_inode; struct inode *delegated_inode = NULL; + const void *orig_value = value; int error;

+ if (size && strcmp(name, XATTR_NAME_CAPS) == 0) { + error = cap_convert_nscap(dentry, &value, size); + if (error < 0) + return error; + size = error; + } + retry_deleg: inode_lock(inode); error = __vfs_setxattr_locked(dentry, name, value, size, flags, @@ -261,6 +269,9 @@ vfs_setxattr(struct dentry *dentry, const char *name, const void *value, if (!error) goto retry_deleg; } + if (value != orig_value) + kfree(value); + return error; } EXPORT_SYMBOL_GPL(vfs_setxattr); @@ -509,12 +520,6 @@ 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 f640dcbc880c..9fee9a86505c 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h @@ -249,6 +249,6 @@ 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); +extern int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size);

#endif /* !_LINUX_CAPABILITY_H */ diff --git a/security/commoncap.c b/security/commoncap.c index 28b204eacc7a..0e9f543d05f5 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -500,7 +500,7 @@ static bool validheader(size_t size, const struct vfs_cap_data *cap) * * 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) +int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size) { struct vfs_ns_cap_data *nscap; uid_t nsrootid; @@ -543,7 +543,6 @@ int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size) nscap->magic_etc = cpu_to_le32(nsmagic); memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);

- kvfree(*ivalue); *ivalue = nscap; return newsize; }