From d77ccdc644a59b412d8e101576134c90a0aa6797 Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Wed, 21 Feb 2018 11:35:20 -0500 Subject: [PATCH] ima: re-evaluate files on privileged mounted filesystems This patch addresses the fuse privileged mounted filesystems in a "secure" environment, with a correctly enforced security policy, which is willing to assume the inherent risk of specific fuse filesystems that are well defined and properly implemented. As there is no way for the kernel to detect file changes, the kernel ignores the cached file integrity results and re-measures, re-appraises, and re-audits the file. Signed-off-by: Mimi Zohar Cc: Miklos Szeredi Cc: Seth Forshee Cc: Dongsu Park Cc: Alban Crequy Acked-by: Serge Hallyn Acked-by: "Eric W. Biederman" --- security/integrity/ima/ima_main.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index a5d225ffc388..f550f25294a3 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -25,6 +25,7 @@ #include #include #include +#include #include "ima.h" @@ -230,9 +231,17 @@ static int process_measurement(struct file *file, const struct cred *cred, IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK | IMA_ACTION_FLAGS); - if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags)) - /* reset all flags if ima_inode_setxattr was called */ + /* + * Re-evaulate the file if either the xattr has changed or the + * kernel has no way of detecting file change on the filesystem. + * (Limited to privileged mounted filesystems.) + */ + if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) || + ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) && + !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER))) { iint->flags &= ~IMA_DONE_MASK; + iint->measured_pcrs = 0; + } /* Determine if already appraised/measured based on bitmask * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,