From: Casey Schaufler <casey@schaufler-ca.com>
To: Roberto Sassu <roberto.sassu@huaweicloud.com>,
zohar@linux.ibm.com, dmitry.kasatkin@gmail.com,
paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com,
stephen.smalley.work@gmail.com, eparis@parisplace.org
Cc: reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
bpf@vger.kernel.org, kpsingh@kernel.org, keescook@chromium.org,
nicolas.bouchinet@clip-os.org,
Roberto Sassu <roberto.sassu@huawei.com>,
Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: [PATCH] Smack modifications for: security: Allow all LSMs to provide xattrs for inode_init_security hook
Date: Tue, 11 Apr 2023 10:54:30 -0700 [thread overview]
Message-ID: <2dc6486f-ce9b-f171-14fe-48a90386e1b7@schaufler-ca.com> (raw)
In-Reply-To: <20230411172337.340518-1-roberto.sassu@huaweicloud.com>
On 4/11/2023 10:23 AM, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Very very quick modification. Not tested.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
> security/smack/smack.h | 2 +-
> security/smack/smack_lsm.c | 42 ++++++++++++++++++++------------------
> 2 files changed, 23 insertions(+), 21 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index e2239be7bd6..f00c8498c60 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -127,7 +127,7 @@ struct task_smack {
>
> #define SMK_INODE_INSTANT 0x01 /* inode is instantiated */
> #define SMK_INODE_TRANSMUTE 0x02 /* directory is transmuting */
> -#define SMK_INODE_CHANGED 0x04 /* smack was transmuted */
> +#define SMK_INODE_CHANGED 0x04 /* smack was transmuted (unused) */
See below ...
> #define SMK_INODE_IMPURE 0x08 /* involved in an impure transaction */
>
> /*
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 8392983334b..b43820bdbd0 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -54,12 +54,12 @@
>
> /*
> * Smack uses multiple xattrs.
> - * SMACK64 - for access control, SMACK64EXEC - label for the program,
> - * SMACK64MMAP - controls library loading,
> + * SMACK64 - for access control,
> * SMACK64TRANSMUTE - label initialization,
> - * Not saved on files - SMACK64IPIN and SMACK64IPOUT
> + * Not saved on files - SMACK64IPIN and SMACK64IPOUT,
> + * Must be set explicitly - SMACK64EXEC and SMACK64MMAP
> */
> -#define SMACK_INODE_INIT_XATTRS 4
> +#define SMACK_INODE_INIT_XATTRS 2
>
> #ifdef SMACK_IPV6_PORT_LABELING
> static DEFINE_MUTEX(smack_ipv6_lock);
> @@ -957,11 +957,11 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
> const struct qstr *qstr,
> struct xattr *xattrs, int *xattr_count)
> {
> - struct inode_smack *issp = smack_inode(inode);
> struct smack_known *skp = smk_of_current();
> struct smack_known *isp = smk_of_inode(inode);
> struct smack_known *dsp = smk_of_inode(dir);
> struct xattr *xattr = lsm_get_xattr_slot(xattrs, xattr_count);
> + struct xattr *xattr2;
I'm going to channel Paul and suggest this be xattr_transmute instead of xattr2.
It also looks like it could move to be declared in the if clause.
> int may;
>
> if (xattr) {
> @@ -979,7 +979,17 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
> if (may > 0 && ((may & MAY_TRANSMUTE) != 0) &&
> smk_inode_transmutable(dir)) {
> isp = dsp;
> - issp->smk_flags |= SMK_INODE_CHANGED;
I think you need to keep this. More below.
> + xattr2 = lsm_get_xattr_slot(xattrs, xattr_count);
> + if (xattr2) {
> + xattr2->value = kmemdup(TRANS_TRUE,
> + TRANS_TRUE_SIZE,
> + GFP_NOFS);
> + if (xattr2->value == NULL)
> + return -ENOMEM;
> +
> + xattr2->value_len = TRANS_TRUE_SIZE;
> + xattr2->name = XATTR_NAME_SMACKTRANSMUTE;
> + }
> }
>
> xattr->value = kstrdup(isp->smk_known, GFP_NOFS);
> @@ -3512,20 +3522,12 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
> * If there is a transmute attribute on the
> * directory mark the inode.
> */
> - if (isp->smk_flags & SMK_INODE_CHANGED) {
> - isp->smk_flags &= ~SMK_INODE_CHANGED;
> - rc = __vfs_setxattr(&nop_mnt_idmap, dp, inode,
> - XATTR_NAME_SMACKTRANSMUTE,
> - TRANS_TRUE, TRANS_TRUE_SIZE,
> - 0);
> - } else {
> - rc = __vfs_getxattr(dp, inode,
> - XATTR_NAME_SMACKTRANSMUTE, trattr,
> - TRANS_TRUE_SIZE);
> - if (rc >= 0 && strncmp(trattr, TRANS_TRUE,
> - TRANS_TRUE_SIZE) != 0)
> - rc = -EINVAL;
> - }
> + rc = __vfs_getxattr(dp, inode,
> + XATTR_NAME_SMACKTRANSMUTE, trattr,
> + TRANS_TRUE_SIZE);
> + if (rc >= 0 && strncmp(trattr, TRANS_TRUE,
> + TRANS_TRUE_SIZE) != 0)
> + rc = -EINVAL;
Where is the SMACK64_TRANSMUTE attribute going to get set on the file?
It's not going to get set in smack_init_inode_security(). The inode will
know it's transmuting, but it won't get to disk without the __vfs_setxattr()
here in smack_d_instantiate(). Now, it's been a long time since that code
was written, so I could be wrong, but I'm pretty sure about that.
I think that you should be fine with the changes in smack_init_inode_security(),
and leaving smack_d_instantiate() untouched.
> if (rc >= 0)
> transflag = SMK_INODE_TRANSMUTE;
> }
next prev parent reply other threads:[~2023-04-11 17:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-31 12:32 [PATCH v10 0/4] evm: Do HMAC of multiple per LSM xattrs for new inodes Roberto Sassu
2023-03-31 12:32 ` [PATCH v10 1/4] reiserfs: Add security prefix to xattr name in reiserfs_security_write() Roberto Sassu
2023-04-04 18:25 ` Paul Moore
2023-03-31 12:32 ` [PATCH v10 2/4] security: Allow all LSMs to provide xattrs for inode_init_security hook Roberto Sassu
2023-04-04 18:54 ` Paul Moore
2023-04-05 2:08 ` Casey Schaufler
2023-04-05 9:43 ` Roberto Sassu
2023-04-05 19:59 ` Paul Moore
2023-04-05 20:43 ` Casey Schaufler
2023-04-05 20:49 ` Paul Moore
2023-04-05 21:07 ` Casey Schaufler
2023-04-06 9:14 ` Roberto Sassu
2023-04-06 16:17 ` Casey Schaufler
2023-04-06 9:08 ` Roberto Sassu
2023-04-11 7:22 ` Mimi Zohar
2023-04-11 7:53 ` Roberto Sassu
2023-04-11 16:42 ` Casey Schaufler
2023-04-11 17:23 ` [PATCH] Smack modifications for: " Roberto Sassu
2023-04-11 17:54 ` Casey Schaufler [this message]
2023-04-12 7:22 ` Roberto Sassu
2023-04-12 20:29 ` Casey Schaufler
2023-04-13 7:11 ` Roberto Sassu
2023-04-17 16:41 ` Casey Schaufler
2023-04-18 7:05 ` Roberto Sassu
2023-04-18 16:02 ` Casey Schaufler
2023-04-19 13:46 ` Roberto Sassu
2023-04-19 19:25 ` Mengchi Cheng
2023-04-20 8:48 ` Roberto Sassu
2023-05-08 12:29 ` Roberto Sassu
2023-05-09 23:44 ` Mengchi Cheng
2023-05-09 23:56 ` Casey Schaufler
2023-04-19 21:00 ` Casey Schaufler
2023-04-20 8:50 ` Roberto Sassu
2023-04-20 10:44 ` Mimi Zohar
2023-04-20 14:10 ` Roberto Sassu
2023-04-11 17:25 ` [PATCH v10 2/4] " Roberto Sassu
2023-04-11 17:40 ` Casey Schaufler
2023-03-31 12:32 ` [PATCH v10 3/4] evm: Align evm_inode_init_security() definition with LSM infrastructure Roberto Sassu
2023-04-04 18:56 ` Paul Moore
2023-04-11 7:22 ` Mimi Zohar
2023-04-11 7:58 ` Roberto Sassu
2023-03-31 12:32 ` [PATCH v10 4/4] evm: Support multiple LSMs providing an xattr Roberto Sassu
2023-04-11 7:22 ` Mimi Zohar
2023-04-03 10:36 ` [PATCH v10 0/4] evm: Do HMAC of multiple per LSM xattrs for new inodes Mimi Zohar
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