From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C8F7347BC6; Fri, 21 Nov 2025 13:49:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763732944; cv=none; b=hvR91Zp+Om9KI01inL2OvQ4GsdE1fZp6QEquuQR3ii6ianeBJXE0s7LyLAJfOO2HOALnnGjvaQO22r2c+EJssQkrsI3/K0gLmtM0CiizvHhdGt0uBK2cJOtj3v47K7s3j3InZHMxY4fc5OdbUrrsIb0c+BeYf3RzLk3c704CGJ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763732944; c=relaxed/simple; bh=gwd7rz7o/jL9vQ0gLxxKi9LJBNzg2l3x2y2lOAtjz8U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EU6D2ECZLDGg1xfIMXJsVmzd/aagwTSxdPAdH1YtsALzwMJpgp2yxSc2UcrXI8UNqwiRkD75mp/Fcj+u/PTyqRqWoIhQ29K+KbF3PYjO24E9O60KAmwmQc5jysYslyPuBNaDvJMiBEwGlby7Hm2UThyg4HEOdMBoTyaF76d2qjw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FzXuWxtD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FzXuWxtD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 831DEC4CEFB; Fri, 21 Nov 2025 13:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1763732943; bh=gwd7rz7o/jL9vQ0gLxxKi9LJBNzg2l3x2y2lOAtjz8U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FzXuWxtDI8MR6j/YYEH1up7Tt68+7A6wnfOj/rff8QYIxAQFKwCm9E5Jip9evyjEb n9uIRrDS1zzT97qH4SEnEx7gihy5KM8I3JP7JNs6RvC+EJkvo0jwT99vR9nAuSeLU0 MgWM5T2m/qYv/aGg2saX4jwVidsmrT79nrsHLJNw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Coiby Xu , Mimi Zohar , Sasha Levin Subject: [PATCH 6.6 297/529] ima: dont clear IMA_DIGSIG flag when setting or removing non-IMA xattr Date: Fri, 21 Nov 2025 14:09:56 +0100 Message-ID: <20251121130241.594435986@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251121130230.985163914@linuxfoundation.org> References: <20251121130230.985163914@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Coiby Xu [ Upstream commit 88b4cbcf6b041ae0f2fc8a34554a5b6a83a2b7cd ] Currently when both IMA and EVM are in fix mode, the IMA signature will be reset to IMA hash if a program first stores IMA signature in security.ima and then writes/removes some other security xattr for the file. For example, on Fedora, after booting the kernel with "ima_appraise=fix evm=fix ima_policy=appraise_tcb" and installing rpm-plugin-ima, installing/reinstalling a package will not make good reference IMA signature generated. Instead IMA hash is generated, # getfattr -m - -d -e hex /usr/bin/bash # file: usr/bin/bash security.ima=0x0404... This happens because when setting security.selinux, the IMA_DIGSIG flag that had been set early was cleared. As a result, IMA hash is generated when the file is closed. Similarly, IMA signature can be cleared on file close after removing security xattr like security.evm or setting/removing ACL. Prevent replacing the IMA file signature with a file hash, by preventing the IMA_DIGSIG flag from being reset. Here's a minimal C reproducer which sets security.selinux as the last step which can also replaced by removing security.evm or setting ACL, #include #include #include #include #include #include int main() { const char* file_path = "/usr/sbin/test_binary"; const char* hex_string = "030204d33204490066306402304"; int length = strlen(hex_string); char* ima_attr_value; int fd; fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644); if (fd == -1) { perror("Error opening file"); return 1; } ima_attr_value = (char*)malloc(length / 2 ); for (int i = 0, j = 0; i < length; i += 2, j++) { sscanf(hex_string + i, "%2hhx", &ima_attr_value[j]); } if (fsetxattr(fd, "security.ima", ima_attr_value, length/2, 0) == -1) { perror("Error setting extended attribute"); close(fd); return 1; } const char* selinux_value= "system_u:object_r:bin_t:s0"; if (fsetxattr(fd, "security.selinux", selinux_value, strlen(selinux_value), 0) == -1) { perror("Error setting extended attribute"); close(fd); return 1; } close(fd); return 0; } Signed-off-by: Coiby Xu Signed-off-by: Mimi Zohar Signed-off-by: Sasha Levin --- security/integrity/ima/ima_appraise.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 870dde67707b1..0acf7d6baa37f 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -671,6 +671,15 @@ static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, return 0; } +/* + * ima_reset_appraise_flags - reset ima_iint_cache flags + * + * @digsig: whether to clear/set IMA_DIGSIG flag, tristate values + * 0: clear IMA_DIGSIG + * 1: set IMA_DIGSIG + * -1: don't change IMA_DIGSIG + * + */ static void ima_reset_appraise_flags(struct inode *inode, int digsig) { struct integrity_iint_cache *iint; @@ -683,9 +692,9 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig) return; iint->measured_pcrs = 0; set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); - if (digsig) + if (digsig == 1) set_bit(IMA_DIGSIG, &iint->atomic_flags); - else + else if (digsig == 0) clear_bit(IMA_DIGSIG, &iint->atomic_flags); } @@ -770,6 +779,8 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) { digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); + } else { + digsig = -1; } if (result == 1 || evm_revalidate_status(xattr_name)) { ima_reset_appraise_flags(d_backing_inode(dentry), digsig); @@ -783,18 +794,20 @@ int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) { if (evm_revalidate_status(acl_name)) - ima_reset_appraise_flags(d_backing_inode(dentry), 0); + ima_reset_appraise_flags(d_backing_inode(dentry), -1); return 0; } int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name) { - int result; + int result, digsig = -1; result = ima_protect_xattr(dentry, xattr_name, NULL, 0); if (result == 1 || evm_revalidate_status(xattr_name)) { - ima_reset_appraise_flags(d_backing_inode(dentry), 0); + if (!strcmp(xattr_name, XATTR_NAME_IMA)) + digsig = 0; + ima_reset_appraise_flags(d_backing_inode(dentry), digsig); if (result == 1) result = 0; } -- 2.51.0