From: Mimi Zohar <zohar@linux.vnet.ibm.com> To: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, Mimi Zohar <zohar@linux.vnet.ibm.com>, Miklos Szeredi <miklos@szeredi.hu>, Seth Forshee <seth.forshee@canonical.com>, "Eric W . Biederman" <ebiederm@xmission.com>, Dongsu Park <dongsu@kinvolk.io>, Alban Crequy <alban@kinvolk.io>, "Serge E. Hallyn" <serge@hallyn.com> Subject: [PATCH v2 4/4] fuse: define the filesystem as untrusted Date: Thu, 22 Feb 2018 16:33:04 -0500 [thread overview] Message-ID: <1519335184-17808-5-git-send-email-zohar@linux.vnet.ibm.com> (raw) In-Reply-To: <1519335184-17808-1-git-send-email-zohar@linux.vnet.ibm.com> Files on FUSE can change at any point in time without IMA being able to detect it. The file data read for the file signature verification could be totally different from what is subsequently read, making the signature verification useless. 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 sets the SB_I_IMA_UNVERIFIABLE_SIGNATURE flag and when appropriate sets the SB_I_UNTRUSTED_MOUNTER flag. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Seth Forshee <seth.forshee@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Dongsu Park <dongsu@kinvolk.io> Cc: Alban Crequy <alban@kinvolk.io> Cc: "Serge E. Hallyn" <serge@hallyn.com> --- fs/fuse/inode.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 624f18bbfd2b..ef309958e060 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1080,6 +1080,9 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_time_gran = 1; sb->s_export_op = &fuse_export_operations; + sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE; + if (sb->s_user_ns != &init_user_ns) + sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER; file = fget(d.fd); err = -EINVAL; -- 2.7.5
WARNING: multiple messages have this Message-ID (diff)
From: zohar@linux.vnet.ibm.com (Mimi Zohar) To: linux-security-module@vger.kernel.org Subject: [PATCH v2 4/4] fuse: define the filesystem as untrusted Date: Thu, 22 Feb 2018 16:33:04 -0500 [thread overview] Message-ID: <1519335184-17808-5-git-send-email-zohar@linux.vnet.ibm.com> (raw) In-Reply-To: <1519335184-17808-1-git-send-email-zohar@linux.vnet.ibm.com> Files on FUSE can change at any point in time without IMA being able to detect it. The file data read for the file signature verification could be totally different from what is subsequently read, making the signature verification useless. 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 sets the SB_I_IMA_UNVERIFIABLE_SIGNATURE flag and when appropriate sets the SB_I_UNTRUSTED_MOUNTER flag. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Seth Forshee <seth.forshee@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Dongsu Park <dongsu@kinvolk.io> Cc: Alban Crequy <alban@kinvolk.io> Cc: "Serge E. Hallyn" <serge@hallyn.com> --- fs/fuse/inode.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 624f18bbfd2b..ef309958e060 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1080,6 +1080,9 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_time_gran = 1; sb->s_export_op = &fuse_export_operations; + sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE; + if (sb->s_user_ns != &init_user_ns) + sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER; file = fget(d.fd); err = -EINVAL; -- 2.7.5 -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2018-02-22 21:33 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-02-22 21:33 [PATCH v2 0/4] ima: unverifiable file signatures Mimi Zohar 2018-02-22 21:33 ` Mimi Zohar 2018-02-22 21:33 ` [PATCH v2 1/4] ima: fail file signature verification on non-init mounted filesystems Mimi Zohar 2018-02-22 21:33 ` Mimi Zohar 2018-02-27 1:47 ` Eric W. Biederman 2018-02-27 1:47 ` Eric W. Biederman 2018-02-27 15:33 ` Mimi Zohar 2018-02-27 15:33 ` Mimi Zohar 2018-02-27 15:33 ` Mimi Zohar 2018-02-22 21:33 ` [PATCH v2 2/4] ima: re-evaluate files on privileged " Mimi Zohar 2018-02-22 21:33 ` Mimi Zohar 2018-02-22 21:33 ` [PATCH v2 3/4] ima: fail signature verification based on policy Mimi Zohar 2018-02-22 21:33 ` Mimi Zohar 2018-02-27 22:35 ` Serge E. Hallyn 2018-02-27 22:35 ` Serge E. Hallyn 2018-02-28 11:38 ` Mimi Zohar 2018-02-28 11:38 ` Mimi Zohar 2018-02-28 11:38 ` Mimi Zohar 2018-02-28 15:30 ` Serge E. Hallyn 2018-02-28 15:30 ` Serge E. Hallyn 2018-02-28 15:30 ` Serge E. Hallyn 2018-03-02 21:10 ` Mimi Zohar 2018-03-02 21:10 ` Mimi Zohar 2018-03-02 21:10 ` Mimi Zohar 2018-02-22 21:33 ` Mimi Zohar [this message] 2018-02-22 21:33 ` [PATCH v2 4/4] fuse: define the filesystem as untrusted Mimi Zohar 2018-02-23 4:00 ` [PATCH v2 0/4] ima: unverifiable file signatures James Morris 2018-02-23 4:00 ` James Morris 2018-02-27 2:08 ` Eric W. Biederman 2018-02-27 2:08 ` Eric W. Biederman 2018-02-27 16:17 ` Mimi Zohar 2018-02-27 16:17 ` Mimi Zohar 2018-02-27 16:17 ` Mimi Zohar
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