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authorMimi Zohar <zohar@linux.vnet.ibm.com>2018-02-21 11:33:37 -0500
committerMimi Zohar <zohar@linux.vnet.ibm.com>2018-03-23 06:31:37 -0400
commit57b56ac6fecb05c3192586e4892572dd13d972de (patch)
tree125efeee62e9ec9a3fc99a761151569cdba7e26c /security
parentd906c10d8a31654cb9167c9a2ebc7d3e43820bad (diff)
downloadlinux-stericsson-57b56ac6fecb05c3192586e4892572dd13d972de.tar.gz
ima: fail file signature verification on non-init mounted filesystems
FUSE can be mounted by unprivileged users either today with fusermount installed with setuid, or soon with the upcoming patches to allow FUSE mounts in a non-init user namespace. This patch addresses the new unprivileged non-init mounted filesystems, which are untrusted, by failing the signature verification. This patch defines two new flags SB_I_IMA_UNVERIFIABLE_SIGNATURE and SB_I_UNTRUSTED_MOUNTER. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Seth Forshee <seth.forshee@canonical.com> Cc: Dongsu Park <dongsu@kinvolk.io> Cc: Alban Crequy <alban@kinvolk.io> Acked-by: Serge Hallyn <serge@hallyn.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima_appraise.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 1b177461f20e..4bafb397ee91 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -302,7 +302,19 @@ int ima_appraise_measurement(enum ima_hooks func,
}
out:
- if (status != INTEGRITY_PASS) {
+ /*
+ * File signatures on some filesystems can not be properly verified.
+ * On these filesytems, that are mounted by an untrusted mounter,
+ * fail the file signature verification.
+ */
+ if ((inode->i_sb->s_iflags &
+ (SB_I_IMA_UNVERIFIABLE_SIGNATURE | SB_I_UNTRUSTED_MOUNTER)) ==
+ (SB_I_IMA_UNVERIFIABLE_SIGNATURE | SB_I_UNTRUSTED_MOUNTER)) {
+ status = INTEGRITY_FAIL;
+ cause = "unverifiable-signature";
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
+ op, cause, rc, 0);
+ } else if (status != INTEGRITY_PASS) {
if ((ima_appraise & IMA_APPRAISE_FIX) &&
(!xattr_value ||
xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
@@ -319,6 +331,7 @@ out:
} else {
ima_cache_flags(iint, func);
}
+
ima_set_cache_status(iint, func, status);
return status;
}