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Commit 19760ad0 authored by Casey Schaufler's avatar Casey Schaufler
Browse files

Smack: Prevent the * and @ labels from being used in SMACK64EXEC 

Smack prohibits processes from using the star ("*") and web ("@") labels
because we don't want files with those labels getting created implicitly.
All setting of those labels should be done explicitly. The trouble is that
there is no check for these labels in the processing of SMACK64EXEC. That
is repaired.

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



Signed-off-by: default avatarCasey Schaufler <casey@schaufler-ca.com>
parent 398ce073

security/smack/smack_lsm.c

+37 −16
Original line number Diff line number Diff line
@@ -837,31 +837,43 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name, 
				const void *value, size_t size, int flags)

{

	struct smk_audit_info ad;

	struct smack_known *skp;

	int check_priv = 0;

	int check_import = 0;

	int check_star = 0;

	int rc = 0;



	/*

	 * Check label validity here so import won't fail in post_setxattr

	 */

	if (strcmp(name, XATTR_NAME_SMACK) == 0 ||

	    strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||

	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||

	    strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||

	    strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {

		check_priv = 1;

		check_import = 1;

	} else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||

		   strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {

		if (!smack_privileged(CAP_MAC_ADMIN))

			rc = -EPERM;

		/*

		 * check label validity here so import wont fail on

		 * post_setxattr

		 */

		if (size == 0 || size >= SMK_LONGLABEL ||

		    smk_import(value, size) == NULL)

			rc = -EINVAL;

		check_priv = 1;

		check_import = 1;

		check_star = 1;

	} else if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {

		if (!smack_privileged(CAP_MAC_ADMIN))

			rc = -EPERM;

		check_priv = 1;

		if (size != TRANS_TRUE_SIZE ||

		    strncmp(value, TRANS_TRUE, TRANS_TRUE_SIZE) != 0)

			rc = -EINVAL;

	} else

		rc = cap_inode_setxattr(dentry, name, value, size, flags);



	if (check_priv && !smack_privileged(CAP_MAC_ADMIN))

		rc = -EPERM;



	if (rc == 0 && check_import) {

		skp = smk_import_entry(value, size);

		if (skp == NULL || (check_star &&

		    (skp == &smack_known_star || skp == &smack_known_web)))

			rc = -EINVAL;

	}



	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);

	smk_ad_setfield_u_fs_path_dentry(&ad, dentry);
@@ -2847,8 +2859,17 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode) 
			if (rc >= 0)

				transflag = SMK_INODE_TRANSMUTE;

		}

		isp->smk_task = smk_fetch(XATTR_NAME_SMACKEXEC, inode, dp);

		isp->smk_mmap = smk_fetch(XATTR_NAME_SMACKMMAP, inode, dp);

		/*

		 * Don't let the exec or mmap label be "*" or "@".

		 */

		skp = smk_fetch(XATTR_NAME_SMACKEXEC, inode, dp);

		if (skp == &smack_known_star || skp == &smack_known_web)

			skp = NULL;

		isp->smk_task = skp;

		skp = smk_fetch(XATTR_NAME_SMACKMMAP, inode, dp);

		if (skp == &smack_known_star || skp == &smack_known_web)

			skp = NULL;

		isp->smk_mmap = skp;



		dput(dp);

		break;