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Date: Wed, 06 Jun 2012 19:31:06 -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>
Subject: Re: [PATCH] Smack: onlycap limits on CAP_MAC_ADMIN
On 6/5/2012 3:28 PM, Casey Schaufler wrote:
> From: Casey Schaufler <casey@...aufler-ca.com>
> Subject: [PATCH] Smack: onlycap limits on CAP_MAC_ADMIN
>
> Smack is integrated with the POSIX capabilities scheme,
> using the capabilities CAP_MAC_OVERRIDE and CAP_MAC_ADMIN to
> determine if a process is allowed to ignore Smack checks or
> change Smack related data respectively. Smack provides an
> additional restriction that if an onlycap value is set
> by writing to /smack/onlycap only tasks with that Smack
> label are allowed to use CAP_MAC_OVERRIDE.
>
> This change adds CAP_MAC_ADMIN as a capability that is affected
> by the onlycap mechanism.
>
> Targeted for git://git.gitorious.org/smack-next/kernel.git
>
> Signed-off-by: Casey Schaufler <casey@...aufler-ca.com>
Applied to git://git.gitorious.org/smack-next/kernel.git
>
> ---
> security/smack/smack.h | 13 +++++++++++++
> security/smack/smack_access.c | 9 ++-------
> security/smack/smack_lsm.c | 17 +++++++++--------
> security/smack/smackfs.c | 21 ++++++++++-----------
> 4 files changed, 34 insertions(+), 26 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index 76feb31..99b3612 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -283,6 +283,19 @@ static inline char *smk_of_current(void)
> }
>
> /*
> + * Is the task privileged and allowed to be privileged
> + * by the onlycap rule.
> + */
> +static inline int smack_privileged(int cap)
> +{
> + if (!capable(cap))
> + return 0;
> + if (smack_onlycap == NULL || smack_onlycap == smk_of_current())
> + return 1;
> + return 0;
> +}
> +
> +/*
> * logging functions
> */
> #define SMACK_AUDIT_DENIED 0x1
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 9f3705e..db14689 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -220,14 +220,9 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
> }
>
> /*
> - * Return if a specific label has been designated as the
> - * only one that gets privilege and current does not
> - * have that label.
> + * Allow for priviliged to override policy.
> */
> - if (smack_onlycap != NULL && smack_onlycap != sp)
> - goto out_audit;
> -
> - if (capable(CAP_MAC_OVERRIDE))
> + if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
> rc = 0;
>
> out_audit:
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 5a4d52c..99a457a 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -217,7 +217,7 @@ static int smack_syslog(int typefrom_file)
> int rc = 0;
> char *sp = smk_of_current();
>
> - if (capable(CAP_MAC_OVERRIDE))
> + if (smack_privileged(CAP_MAC_OVERRIDE))
> return 0;
>
> if (sp != smack_known_floor.smk_known)
> @@ -821,7 +821,7 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
> strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||
> strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||
> strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> rc = -EPERM;
> /*
> * check label validity here so import wont fail on
> @@ -831,7 +831,7 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
> smk_import(value, size) == NULL)
> rc = -EINVAL;
> } else if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> rc = -EPERM;
> if (size != TRANS_TRUE_SIZE ||
> strncmp(value, TRANS_TRUE, TRANS_TRUE_SIZE) != 0)
> @@ -927,7 +927,7 @@ static int smack_inode_removexattr(struct dentry *dentry, const char *name)
> strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||
> strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0 ||
> strcmp(name, XATTR_NAME_SMACKMMAP)) {
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> rc = -EPERM;
> } else
> rc = cap_inode_removexattr(dentry, name);
> @@ -1722,7 +1722,8 @@ static int smack_task_wait(struct task_struct *p)
> * state into account in the decision as well as
> * the smack value.
> */
> - if (capable(CAP_MAC_OVERRIDE) || has_capability(p, CAP_MAC_OVERRIDE))
> + if (smack_privileged(CAP_MAC_OVERRIDE) ||
> + has_capability(p, CAP_MAC_OVERRIDE))
> rc = 0;
> /* we log only if we didn't get overriden */
> out_log:
> @@ -2723,7 +2724,7 @@ static int smack_setprocattr(struct task_struct *p, char *name,
> if (p != current)
> return -EPERM;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
> @@ -2786,7 +2787,7 @@ static int smack_unix_stream_connect(struct sock *sock,
> smk_ad_setfield_u_net_sk(&ad, other);
> #endif
>
> - if (!capable(CAP_MAC_OVERRIDE))
> + if (!smack_privileged(CAP_MAC_OVERRIDE))
> rc = smk_access(ssp->smk_out, osp->smk_in, MAY_WRITE, &ad);
>
> /*
> @@ -2822,7 +2823,7 @@ static int smack_unix_may_send(struct socket *sock, struct socket *other)
> smk_ad_setfield_u_net_sk(&ad, other->sk);
> #endif
>
> - if (!capable(CAP_MAC_OVERRIDE))
> + if (!smack_privileged(CAP_MAC_OVERRIDE))
> rc = smk_access(ssp->smk_out, osp->smk_in, MAY_WRITE, &ad);
>
> return rc;
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index 3686db7..2152965 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -595,13 +595,12 @@ static int smk_open_load(struct inode *inode, struct file *file)
> static ssize_t smk_write_load(struct file *file, const char __user *buf,
> size_t count, loff_t *ppos)
> {
> -
> /*
> * Must have privilege.
> * No partial writes.
> * Enough data must be present.
> */
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> return smk_write_rules_list(file, buf, count, ppos, NULL, NULL,
> @@ -787,7 +786,7 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
> * No partial writes.
> * Enough data must be present.
> */
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
> if (*ppos != 0)
> return -EINVAL;
> @@ -1090,7 +1089,7 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
> * "<addr/mask, as a.b.c.d/e><space><label>"
> * "<addr, as a.b.c.d><space><label>"
> */
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
> if (*ppos != 0)
> return -EINVAL;
> @@ -1267,7 +1266,7 @@ static ssize_t smk_write_doi(struct file *file, const char __user *buf,
> char temp[80];
> int i;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> if (count >= sizeof(temp) || count == 0)
> @@ -1334,7 +1333,7 @@ static ssize_t smk_write_direct(struct file *file, const char __user *buf,
> char temp[80];
> int i;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> if (count >= sizeof(temp) || count == 0)
> @@ -1412,7 +1411,7 @@ static ssize_t smk_write_mapped(struct file *file, const char __user *buf,
> char temp[80];
> int i;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> if (count >= sizeof(temp) || count == 0)
> @@ -1503,7 +1502,7 @@ static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
> char *data;
> int rc = count;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> data = kzalloc(count + 1, GFP_KERNEL);
> @@ -1586,7 +1585,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
> char *sp = smk_of_task(current->cred->security);
> int rc = count;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> /*
> @@ -1664,7 +1663,7 @@ static ssize_t smk_write_logging(struct file *file, const char __user *buf,
> char temp[32];
> int i;
>
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> if (count >= sizeof(temp) || count == 0)
> @@ -1885,7 +1884,7 @@ static ssize_t smk_write_load2(struct file *file, const char __user *buf,
> /*
> * Must have privilege.
> */
> - if (!capable(CAP_MAC_ADMIN))
> + if (!smack_privileged(CAP_MAC_ADMIN))
> return -EPERM;
>
> return smk_write_rules_list(file, buf, count, ppos, NULL, NULL,
>
>
>
> --
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