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Smack: Make the syslog control configurable

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The syslog control requires that the calling proccess
have the floor ("_") Smack label. Tizen does not run any
processes except for kernel helpers with the floor label.
This changes allows the admin to configure a specific
label for syslog. The default value is the star ("*")
label, effectively removing the restriction. The value
can be set using smackfs/syslog for anyone who wants
a more restrictive behavior.

Targeted for git://git.gitorious.org/smack-next/kernel.git

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
This commit is contained in:
Casey Schaufler 2013-12-23 11:07:10 -08:00
parent 19760ad03c
commit 00f84f3f2e
3 changed files with 99 additions and 13 deletions
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5
security/smack/smack.h
View file

@ -241,7 +241,8 @@ u32 smack_to_secid(const char *);
extern int smack_cipso_direct;
extern int smack_cipso_mapped;
extern struct smack_known *smack_net_ambient;
extern char *smack_onlycap;
extern struct smack_known *smack_onlycap;
extern struct smack_known *smack_syslog_label;
extern const char *smack_cipso_option;
extern struct smack_known smack_known_floor;
@ -312,7 +313,7 @@ static inline int smack_privileged(int cap)
if (!capable(cap))
return 0;
if (smack_onlycap == NULL || smack_onlycap == skp->smk_known)
if (smack_onlycap == NULL || smack_onlycap == skp)
return 1;
return 0;
}

4
security/smack/smack_lsm.c
View file

@ -219,8 +219,6 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
* smack_syslog - Smack approval on syslog
* @type: message type
*
* Require that the task has the floor label
*
* Returns 0 on success, error code otherwise.
*/
static int smack_syslog(int typefrom_file)
@ -231,7 +229,7 @@ static int smack_syslog(int typefrom_file)
if (smack_privileged(CAP_MAC_OVERRIDE))
return 0;
if (skp != &smack_known_floor)
if (smack_syslog_label != NULL && smack_syslog_label != skp)
rc = -EACCES;
return rc;

103
security/smack/smackfs.c
View file

@ -52,6 +52,7 @@ enum smk_inos {
SMK_CIPSO2 = 17, /* load long label -> CIPSO mapping */
SMK_REVOKE_SUBJ = 18, /* set rules with subject label to '-' */
SMK_CHANGE_RULE = 19, /* change or add rules (long labels) */
SMK_SYSLOG = 20, /* change syslog label) */
};
/*
@ -59,6 +60,7 @@ enum smk_inos {
*/
static DEFINE_MUTEX(smack_cipso_lock);
static DEFINE_MUTEX(smack_ambient_lock);
static DEFINE_MUTEX(smack_syslog_lock);
static DEFINE_MUTEX(smk_netlbladdr_lock);
/*
@ -90,7 +92,13 @@ int smack_cipso_mapped = SMACK_CIPSO_MAPPED_DEFAULT;
* everyone. It is expected that the hat (^) label
* will be used if any label is used.
*/
char *smack_onlycap;
struct smack_known *smack_onlycap;
/*
* If this value is set restrict syslog use to the label specified.
* It can be reset via smackfs/syslog
*/
struct smack_known *smack_syslog_label;
/*
* Certain IP addresses may be designated as single label hosts.
@ -1603,7 +1611,7 @@ static const struct file_operations smk_ambient_ops = {
};
/**
* smk_read_onlycap - read() for /smack/onlycap
* smk_read_onlycap - read() for smackfs/onlycap
* @filp: file pointer, not actually used
* @buf: where to put the result
* @cn: maximum to send along
@ -1622,7 +1630,7 @@ static ssize_t smk_read_onlycap(struct file *filp, char __user *buf,
return 0;
if (smack_onlycap != NULL)
smack = smack_onlycap;
smack = smack_onlycap->smk_known;
asize = strlen(smack) + 1;
@ -1633,7 +1641,7 @@ static ssize_t smk_read_onlycap(struct file *filp, char __user *buf,
}
/**
* smk_write_onlycap - write() for /smack/onlycap
* smk_write_onlycap - write() for smackfs/onlycap
* @file: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
@ -1656,7 +1664,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
* explicitly for clarity. The smk_access() implementation
* would use smk_access(smack_onlycap, MAY_WRITE)
*/
if (smack_onlycap != NULL && smack_onlycap != skp->smk_known)
if (smack_onlycap != NULL && smack_onlycap != skp)
return -EPERM;
data = kzalloc(count, GFP_KERNEL);
@ -1676,7 +1684,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
if (copy_from_user(data, buf, count) != 0)
rc = -EFAULT;
else
smack_onlycap = smk_import(data, count);
smack_onlycap = smk_import_entry(data, count);
kfree(data);
return rc;
@ -2159,12 +2167,89 @@ static const struct file_operations smk_change_rule_ops = {
};
/**
* smk_fill_super - fill the /smackfs superblock
* smk_read_syslog - read() for smackfs/syslog
* @filp: file pointer, not actually used
* @buf: where to put the result
* @cn: maximum to send along
* @ppos: where to start
*
* Returns number of bytes read or error code, as appropriate
*/
static ssize_t smk_read_syslog(struct file *filp, char __user *buf,
size_t cn, loff_t *ppos)
{
struct smack_known *skp;
ssize_t rc = -EINVAL;
int asize;
if (*ppos != 0)
return 0;
if (smack_syslog_label == NULL)
skp = &smack_known_star;
else
skp = smack_syslog_label;
asize = strlen(skp->smk_known) + 1;
if (cn >= asize)
rc = simple_read_from_buffer(buf, cn, ppos, skp->smk_known,
asize);
return rc;
}
/**
* smk_write_syslog - write() for smackfs/syslog
* @file: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start
*
* Returns number of bytes written or error code, as appropriate
*/
static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char *data;
struct smack_known *skp;
int rc = count;
if (!smack_privileged(CAP_MAC_ADMIN))
return -EPERM;
data = kzalloc(count, GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
if (copy_from_user(data, buf, count) != 0)
rc = -EFAULT;
else {
skp = smk_import_entry(data, count);
if (skp == NULL)
rc = -EINVAL;
else
smack_syslog_label = smk_import_entry(data, count);
}
kfree(data);
return rc;
}
static const struct file_operations smk_syslog_ops = {
.read = smk_read_syslog,
.write = smk_write_syslog,
.llseek = default_llseek,
};
/**
* smk_fill_super - fill the smackfs superblock
* @sb: the empty superblock
* @data: unused
* @silent: unused
*
* Fill in the well known entries for /smack
* Fill in the well known entries for the smack filesystem
*
* Returns 0 on success, an error code on failure
*/
@ -2209,6 +2294,8 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent)
S_IRUGO|S_IWUSR},
[SMK_CHANGE_RULE] = {
"change-rule", &smk_change_rule_ops, S_IRUGO|S_IWUSR},
[SMK_SYSLOG] = {
"syslog", &smk_syslog_ops, S_IRUGO|S_IWUSR},
/* last one */
{""}
};