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Date: Mon, 26 Sep 2011 12:26:49 -0700
From: Casey Schaufler <casey@...aufler-ca.com>
To: Casey Schaufler <casey@...aufler-ca.com>
CC: LKLM <linux-kernel@...r.kernel.org>,
LSM <linux-security-module@...r.kernel.org>,
Al Viro <viro@...IV.linux.org.uk>
Subject: Re: [PATCH] Smack: Repair processing of fcntl
On 9/19/2011 12:41 PM, Casey Schaufler wrote:
>
> Al Viro pointed out that the processing of fcntl done
> by Smack appeared poorly designed. He was right. There
> are three things that required change. Most obviously,
> the list of commands that really imply writing is limited
> to those involving file locking and signal handling.
> The initialization if the file security blob was
> incomplete, requiring use of a heretofore unused LSM hook.
> Finally, the audit information coming from a helper
> masked the identity of the LSM hook. This patch corrects
> all three of these defects.
>
> This is targeted for the smack-next tree pending comments.
>
> Signed-off-by: Casey Schaufler <casey@...aufler-ca.com>
Applied to gitorious.org/smack-next/kernel.git
>
> ---
> security/smack/smack_lsm.c | 67 +++++++++++++++++++++++++++----------------
> 1 files changed, 42 insertions(+), 25 deletions(-)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index b9c5e14..a0d3eaa 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -1088,36 +1088,31 @@ static int smack_file_lock(struct file *file, unsigned int cmd)
> * @cmd: what action to check
> * @arg: unused
> *
> + * Generally these operations are harmless.
> + * File locking operations present an obvious mechanism
> + * for passing information, so they require write access.
> + *
> * Returns 0 if current has access, error code otherwise
> */
> static int smack_file_fcntl(struct file *file, unsigned int cmd,
> unsigned long arg)
> {
> struct smk_audit_info ad;
> - int rc;
> + int rc = 0;
>
> - smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
> - smk_ad_setfield_u_fs_path(&ad, file->f_path);
>
> switch (cmd) {
> - case F_DUPFD:
> - case F_GETFD:
> - case F_GETFL:
> case F_GETLK:
> - case F_GETOWN:
> - case F_GETSIG:
> - rc = smk_curacc(file->f_security, MAY_READ, &ad);
> - break;
> - case F_SETFD:
> - case F_SETFL:
> case F_SETLK:
> case F_SETLKW:
> case F_SETOWN:
> case F_SETSIG:
> + smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
> + smk_ad_setfield_u_fs_path(&ad, file->f_path);
> rc = smk_curacc(file->f_security, MAY_WRITE, &ad);
> break;
> default:
> - rc = smk_curacc(file->f_security, MAY_READWRITE, &ad);
> + break;
> }
>
> return rc;
> @@ -1315,6 +1310,24 @@ static int smack_file_receive(struct file *file)
> return smk_curacc(file->f_security, may, &ad);
> }
>
> +/**
> + * smack_dentry_open - Smack dentry open processing
> + * @file: the object
> + * @cred: unused
> + *
> + * Set the security blob in the file structure.
> + *
> + * Returns 0
> + */
> +static int smack_dentry_open(struct file *file, const struct cred *cred)
> +{
> + struct inode_smack *isp = file->f_path.dentry->d_inode->i_security;
> +
> + file->f_security = isp->smk_inode;
> +
> + return 0;
> +}
> +
> /*
> * Task hooks
> */
> @@ -1455,15 +1468,17 @@ static int smack_kernel_create_files_as(struct cred *new,
> /**
> * smk_curacc_on_task - helper to log task related access
> * @p: the task object
> - * @access : the access requested
> + * @access: the access requested
> + * @caller: name of the calling function for audit
> *
> * Return 0 if access is permitted
> */
> -static int smk_curacc_on_task(struct task_struct *p, int access)
> +static int smk_curacc_on_task(struct task_struct *p, int access,
> + const char *caller)
> {
> struct smk_audit_info ad;
>
> - smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
> + smk_ad_init(&ad, caller, LSM_AUDIT_DATA_TASK);
> smk_ad_setfield_u_tsk(&ad, p);
> return smk_curacc(smk_of_task(task_security(p)), access, &ad);
> }
> @@ -1477,7 +1492,7 @@ static int smk_curacc_on_task(struct task_struct *p, int access)
> */
> static int smack_task_setpgid(struct task_struct *p, pid_t pgid)
> {
> - return smk_curacc_on_task(p, MAY_WRITE);
> + return smk_curacc_on_task(p, MAY_WRITE, __func__);
> }
>
> /**
> @@ -1488,7 +1503,7 @@ static int smack_task_setpgid(struct task_struct *p, pid_t pgid)
> */
> static int smack_task_getpgid(struct task_struct *p)
> {
> - return smk_curacc_on_task(p, MAY_READ);
> + return smk_curacc_on_task(p, MAY_READ, __func__);
> }
>
> /**
> @@ -1499,7 +1514,7 @@ static int smack_task_getpgid(struct task_struct *p)
> */
> static int smack_task_getsid(struct task_struct *p)
> {
> - return smk_curacc_on_task(p, MAY_READ);
> + return smk_curacc_on_task(p, MAY_READ, __func__);
> }
>
> /**
> @@ -1527,7 +1542,7 @@ static int smack_task_setnice(struct task_struct *p, int nice)
>
> rc = cap_task_setnice(p, nice);
> if (rc == 0)
> - rc = smk_curacc_on_task(p, MAY_WRITE);
> + rc = smk_curacc_on_task(p, MAY_WRITE, __func__);
> return rc;
> }
>
> @@ -1544,7 +1559,7 @@ static int smack_task_setioprio(struct task_struct *p, int ioprio)
>
> rc = cap_task_setioprio(p, ioprio);
> if (rc == 0)
> - rc = smk_curacc_on_task(p, MAY_WRITE);
> + rc = smk_curacc_on_task(p, MAY_WRITE, __func__);
> return rc;
> }
>
> @@ -1556,7 +1571,7 @@ static int smack_task_setioprio(struct task_struct *p, int ioprio)
> */
> static int smack_task_getioprio(struct task_struct *p)
> {
> - return smk_curacc_on_task(p, MAY_READ);
> + return smk_curacc_on_task(p, MAY_READ, __func__);
> }
>
> /**
> @@ -1573,7 +1588,7 @@ static int smack_task_setscheduler(struct task_struct *p)
>
> rc = cap_task_setscheduler(p);
> if (rc == 0)
> - rc = smk_curacc_on_task(p, MAY_WRITE);
> + rc = smk_curacc_on_task(p, MAY_WRITE, __func__);
> return rc;
> }
>
> @@ -1585,7 +1600,7 @@ static int smack_task_setscheduler(struct task_struct *p)
> */
> static int smack_task_getscheduler(struct task_struct *p)
> {
> - return smk_curacc_on_task(p, MAY_READ);
> + return smk_curacc_on_task(p, MAY_READ, __func__);
> }
>
> /**
> @@ -1596,7 +1611,7 @@ static int smack_task_getscheduler(struct task_struct *p)
> */
> static int smack_task_movememory(struct task_struct *p)
> {
> - return smk_curacc_on_task(p, MAY_WRITE);
> + return smk_curacc_on_task(p, MAY_WRITE, __func__);
> }
>
> /**
> @@ -3440,6 +3455,8 @@ struct security_operations smack_ops = {
> .file_send_sigiotask = smack_file_send_sigiotask,
> .file_receive = smack_file_receive,
>
> + .dentry_open = smack_dentry_open,
> +
> .cred_alloc_blank = smack_cred_alloc_blank,
> .cred_free = smack_cred_free,
> .cred_prepare = smack_cred_prepare,
>
>
>
> --
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