diff options
author | Casey Schaufler <casey@schaufler-ca.com> | 2013-10-11 18:06:39 -0700 |
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committer | Casey Schaufler <casey@schaufler-ca.com> | 2013-10-18 09:39:33 -0700 |
commit | c0ab6e56dcb7ca9903d460247cb464e769ae6e77 (patch) | |
tree | 52da39cb2798c0a4276d0d23fa3b4f1dbcd732f2 /security/smack/smackfs.c | |
parent | 5a5f2acfd04269e2e0958067216b68ff461c285c (diff) |
Smack: Implement lock security mode
Linux file locking does not follow the same rules
as other mechanisms. Even though it is a write operation
a process can set a read lock on files which it has open
only for read access. Two programs with read access to
a file can use read locks to communicate.
This is not acceptable in a Mandatory Access Control
environment. Smack treats setting a read lock as the
write operation that it is. Unfortunately, many programs
assume that setting a read lock is a read operation.
These programs are unhappy in the Smack environment.
This patch introduces a new access mode (lock) to address
this problem. A process with lock access to a file can
set a read lock. A process with write access to a file can
set a read lock or a write lock. This prevents a situation
where processes are granted write access just so they can
set read locks.
Targeted for git://git.gitorious.org/smack-next/kernel.git
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Diffstat (limited to 'security/smack/smackfs.c')
-rw-r--r-- | security/smack/smackfs.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 80f4b4a45725..160aa08e3cd5 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -139,7 +139,7 @@ const char *smack_cipso_option = SMACK_CIPSO_OPTION; * SMK_LOADLEN: Smack rule length */ #define SMK_OACCESS "rwxa" -#define SMK_ACCESS "rwxat" +#define SMK_ACCESS "rwxatl" #define SMK_OACCESSLEN (sizeof(SMK_OACCESS) - 1) #define SMK_ACCESSLEN (sizeof(SMK_ACCESS) - 1) #define SMK_OLOADLEN (SMK_LABELLEN + SMK_LABELLEN + SMK_OACCESSLEN) @@ -282,6 +282,10 @@ static int smk_perm_from_str(const char *string) case 'T': perm |= MAY_TRANSMUTE; break; + case 'l': + case 'L': + perm |= MAY_LOCK; + break; default: return perm; } @@ -452,7 +456,7 @@ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf, /* * Minor hack for backward compatibility */ - if (count != SMK_OLOADLEN && count != SMK_LOADLEN) + if (count < SMK_OLOADLEN || count > SMK_LOADLEN) return -EINVAL; } else { if (count >= PAGE_SIZE) { @@ -592,6 +596,8 @@ static void smk_rule_show(struct seq_file *s, struct smack_rule *srp, int max) seq_putc(s, 'a'); if (srp->smk_access & MAY_TRANSMUTE) seq_putc(s, 't'); + if (srp->smk_access & MAY_LOCK) + seq_putc(s, 'l'); seq_putc(s, '\n'); } |