ovl: filter trusted xattr for non-admin
[ Upstream commit a082c6f680
]
Filesystems filter out extended attributes in the "trusted." domain for
unprivlieged callers.
Overlay calls underlying filesystem's method with elevated privs, so need
to do the filtering in overlayfs too.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -227,6 +227,16 @@ int ovl_xattr_get(struct dentry *dentry, const char *name,
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return res;
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}
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static bool ovl_can_list(const char *s)
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{
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/* List all non-trusted xatts */
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if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
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return true;
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/* Never list trusted.overlay, list other trusted for superuser only */
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return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
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}
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ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
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{
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struct dentry *realdentry = ovl_dentry_real(dentry);
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@ -250,7 +260,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
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return -EIO;
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len -= slen;
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if (ovl_is_private_xattr(s)) {
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if (!ovl_can_list(s)) {
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res -= slen;
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memmove(s, s + slen, len);
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} else {
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