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 BB8E123C4F2; Tue, 11 Nov 2025 01:39:01 +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=1762825142; cv=none; b=YyVRJ0R74RTj73U6tOIzwMB3hRPOjjMZHRgOKeh4YfJyf67MwMJpxq6XQWNT6xp0KipDJrKF6OyF38+nE3ADJNv7Y72IvjpE4dXWFaMT3H6xGzt/A5Quo69pTX8ZWbJXWiHAjDVa8IeJKRrVvNzdI+Nl9fobijxT7OAQozscaqQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762825142; c=relaxed/simple; bh=fHUc5ALrsZODuvM46xkMQard+alvuVKZOIzITnh/DcA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VB3S2dGLATtQ6d3bye07VYyAJcMpBLFCfVrS/JUh5Jv3bhBV7G73P5oyUuIEgYC0ambLI4+iSYsNv2J0Wnl3ztQEgRP+Oub+DR5BEkKH10cN6ehNq5tnVtuFQqGO2JjS1VYL7Khb1xL1IPsmzLLWQF15pVS5WFkrcml6vs1oQ+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XTBgtUkL; 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="XTBgtUkL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EF2CC116B1; Tue, 11 Nov 2025 01:39:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1762825141; bh=fHUc5ALrsZODuvM46xkMQard+alvuVKZOIzITnh/DcA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XTBgtUkLyr1/QhS5oaYQ3jlQLHQ8sbmrxIk2TyWZo6GRQijlce6K7L6D+Ak0EFiJu FZl7X/YuwkjRRDIOdrgBpvaKN4pifCnTfGu0EH+iOKm0xb5dY9c+lDMMRoRD4LX5re mFwPUh2VhlSUqUxxl92s06NIhsEtRnrXTvDoM+SY= 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 6.17 679/849] ima: dont clear IMA_DIGSIG flag when setting or removing non-IMA xattr Date: Tue, 11 Nov 2025 09:44:09 +0900 Message-ID: <20251111004552.839901169@linuxfoundation.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251111004536.460310036@linuxfoundation.org> References: <20251111004536.460310036@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 6.17-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 f435eff4667f8..5149ff4fd50d2 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -694,6 +694,15 @@ 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 ima_iint_cache *iint; @@ -706,9 +715,9 @@ 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); } @@ -794,6 +803,8 @@ static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, 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); @@ -807,7 +818,7 @@ static 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; } @@ -815,11 +826,13 @@ static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, static int ima_inode_removexattr(struct mnt_idmap *idmap, 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