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authorJarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com>2010-12-07 13:34:01 +0200
committerCasey Schaufler <casey@schaufler-ca.com>2010-12-07 14:04:02 -0800
commit5c6d1125f8dbd1bfef39e38fbc2837003be78a59 (patch)
tree368d34e800bc5478442679323270d776b79501e8 /security/smack/smackfs.c
parentfe27d4b012273640e033be80f143bdc54daa8e16 (diff)
Smack: Transmute labels on specified directories
In a situation where Smack access rules allow processes with multiple labels to write to a directory it is easy to get into a situation where the directory gets cluttered with files that the owner can't deal with because while they could be written to the directory a process at the label of the directory can't write them. This is generally the desired behavior, but when it isn't it is a real issue. This patch introduces a new attribute SMACK64TRANSMUTE that instructs Smack to create the file with the label of the directory under certain circumstances. A new access mode, "t" for transmute, is made available to Smack access rules, which are expanded from "rwxa" to "rwxat". If a file is created in a directory marked as transmutable and if access was granted to perform the operation by a rule that included the transmute mode, then the file gets the Smack label of the directory instead of the Smack label of the creating process. Note that this is equivalent to creating an empty file at the label of the directory and then having the other process write to it. The transmute scheme requires that both the access rule allows transmutation and that the directory be explicitly marked. Signed-off-by: Jarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Diffstat (limited to 'security/smack/smackfs.c')
-rw-r--r--security/smack/smackfs.c37
1 files changed, 32 insertions, 5 deletions
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 01a0be93d8d0..362d5eda948b 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -109,9 +109,12 @@ const char *smack_cipso_option = SMACK_CIPSO_OPTION;
* SMK_ACCESSLEN: Maximum length for a rule access field
* SMK_LOADLEN: Smack rule length
*/
-#define SMK_ACCESS "rwxa"
-#define SMK_ACCESSLEN (sizeof(SMK_ACCESS) - 1)
-#define SMK_LOADLEN (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSLEN)
+#define SMK_OACCESS "rwxa"
+#define SMK_ACCESS "rwxat"
+#define SMK_OACCESSLEN (sizeof(SMK_OACCESS) - 1)
+#define SMK_ACCESSLEN (sizeof(SMK_ACCESS) - 1)
+#define SMK_OLOADLEN (SMK_LABELLEN + SMK_LABELLEN + SMK_OACCESSLEN)
+#define SMK_LOADLEN (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSLEN)
/**
* smk_netlabel_audit_set - fill a netlbl_audit struct
@@ -175,6 +178,8 @@ static int load_seq_show(struct seq_file *s, void *v)
seq_putc(s, 'x');
if (srp->smk_access & MAY_APPEND)
seq_putc(s, 'a');
+ if (srp->smk_access & MAY_TRANSMUTE)
+ seq_putc(s, 't');
if (srp->smk_access == 0)
seq_putc(s, '-');
@@ -273,10 +278,15 @@ static ssize_t smk_write_load(struct file *file, const char __user *buf,
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
- if (*ppos != 0 || count != SMK_LOADLEN)
+ if (*ppos != 0)
+ return -EINVAL;
+ /*
+ * Minor hack for backward compatability
+ */
+ if (count < (SMK_OLOADLEN) || count > SMK_LOADLEN)
return -EINVAL;
- data = kzalloc(count, GFP_KERNEL);
+ data = kzalloc(SMK_LOADLEN, GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
@@ -285,6 +295,12 @@ static ssize_t smk_write_load(struct file *file, const char __user *buf,
goto out;
}
+ /*
+ * More on the minor hack for backward compatability
+ */
+ if (count == (SMK_OLOADLEN))
+ data[SMK_OLOADLEN] = '-';
+
rule = kzalloc(sizeof(*rule), GFP_KERNEL);
if (rule == NULL) {
rc = -ENOMEM;
@@ -345,6 +361,17 @@ static ssize_t smk_write_load(struct file *file, const char __user *buf,
goto out_free_rule;
}
+ switch (data[SMK_LABELLEN + SMK_LABELLEN + 4]) {
+ case '-':
+ break;
+ case 't':
+ case 'T':
+ rule->smk_access |= MAY_TRANSMUTE;
+ break;
+ default:
+ goto out_free_rule;
+ }
+
rc = smk_set_access(rule);
if (!rc)

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