From dc49c1f94e3469d94b952e8f5160dd4ccd791d79 Mon Sep 17 00:00:00 2001 From: Catherine Zhang Date: Wed, 2 Aug 2006 14:12:06 -0700 Subject: [PATCH] [AF_UNIX]: Kernel memory leak fix for af_unix datagram getpeersec patch From: Catherine Zhang This patch implements a cleaner fix for the memory leak problem of the original unix datagram getpeersec patch. Instead of creating a security context each time a unix datagram is sent, we only create the security context when the receiver requests it. This new design requires modification of the current unix_getsecpeer_dgram LSM hook and addition of two new hooks, namely, secid_to_secctx and release_secctx. The former retrieves the security context and the latter releases it. A hook is required for releasing the security context because it is up to the security module to decide how that's done. In the case of Selinux, it's a simple kfree operation. Acked-by: Stephen Smalley Signed-off-by: David S. Miller --- include/linux/security.h | 41 ++++++++++++++++++++++++++++++++++------ include/net/af_unix.h | 6 ++---- include/net/scm.h | 29 ++++++++++++++++++++++++---- net/ipv4/ip_sockglue.c | 9 +++++++-- net/unix/af_unix.c | 17 +++++------------ security/dummy.c | 14 ++++++++++++-- security/selinux/hooks.c | 38 +++++++++++++++++++++++-------------- 7 files changed, 110 insertions(+), 44 deletions(-) diff --git a/include/linux/security.h b/include/linux/security.h index f75303831d0..aa5b8043dc3 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1109,6 +1109,16 @@ struct swap_info_struct; * @name contains the name of the security module being unstacked. * @ops contains a pointer to the struct security_operations of the module to unstack. * + * @secid_to_secctx: + * Convert secid to security context. + * @secid contains the security ID. + * @secdata contains the pointer that stores the converted security context. + * + * @release_secctx: + * Release the security context. + * @secdata contains the security context. + * @seclen contains the length of the security context. + * * This is the main security structure. */ struct security_operations { @@ -1289,6 +1299,8 @@ struct security_operations { int (*getprocattr)(struct task_struct *p, char *name, void *value, size_t size); int (*setprocattr)(struct task_struct *p, char *name, void *value, size_t size); + int (*secid_to_secctx)(u32 secid, char **secdata, u32 *seclen); + void (*release_secctx)(char *secdata, u32 seclen); #ifdef CONFIG_SECURITY_NETWORK int (*unix_stream_connect) (struct socket * sock, @@ -1317,7 +1329,7 @@ struct security_operations { int (*socket_shutdown) (struct socket * sock, int how); int (*socket_sock_rcv_skb) (struct sock * sk, struct sk_buff * skb); int (*socket_getpeersec_stream) (struct socket *sock, char __user *optval, int __user *optlen, unsigned len); - int (*socket_getpeersec_dgram) (struct sk_buff *skb, char **secdata, u32 *seclen); + int (*socket_getpeersec_dgram) (struct socket *sock, struct sk_buff *skb, u32 *secid); int (*sk_alloc_security) (struct sock *sk, int family, gfp_t priority); void (*sk_free_security) (struct sock *sk); unsigned int (*sk_getsid) (struct sock *sk, struct flowi *fl, u8 dir); @@ -2059,6 +2071,16 @@ static inline int security_netlink_recv(struct sk_buff * skb, int cap) return security_ops->netlink_recv(skb, cap); } +static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen) +{ + return security_ops->secid_to_secctx(secid, secdata, seclen); +} + +static inline void security_release_secctx(char *secdata, u32 seclen) +{ + return security_ops->release_secctx(secdata, seclen); +} + /* prototypes */ extern int security_init (void); extern int register_security (struct security_operations *ops); @@ -2725,6 +2747,15 @@ static inline void securityfs_remove(struct dentry *dentry) { } +static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen) +{ + return -EOPNOTSUPP; +} + +static inline void security_release_secctx(char *secdata, u32 seclen) +{ + return -EOPNOTSUPP; +} #endif /* CONFIG_SECURITY */ #ifdef CONFIG_SECURITY_NETWORK @@ -2840,10 +2871,9 @@ static inline int security_socket_getpeersec_stream(struct socket *sock, char __ return security_ops->socket_getpeersec_stream(sock, optval, optlen, len); } -static inline int security_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata, - u32 *seclen) +static inline int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid) { - return security_ops->socket_getpeersec_dgram(skb, secdata, seclen); + return security_ops->socket_getpeersec_dgram(sock, skb, secid); } static inline int security_sk_alloc(struct sock *sk, int family, gfp_t priority) @@ -2968,8 +2998,7 @@ static inline int security_socket_getpeersec_stream(struct socket *sock, char __ return -ENOPROTOOPT; } -static inline int security_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata, - u32 *seclen) +static inline int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid) { return -ENOPROTOOPT; } diff --git a/include/net/af_unix.h b/include/net/af_unix.h index 2fec827c880..c0398f5a8cb 100644 --- a/include/net/af_unix.h +++ b/include/net/af_unix.h @@ -54,15 +54,13 @@ struct unix_skb_parms { struct ucred creds; /* Skb credentials */ struct scm_fp_list *fp; /* Passed files */ #ifdef CONFIG_SECURITY_NETWORK - char *secdata; /* Security context */ - u32 seclen; /* Security length */ + u32 secid; /* Security ID */ #endif }; #define UNIXCB(skb) (*(struct unix_skb_parms*)&((skb)->cb)) #define UNIXCREDS(skb) (&UNIXCB((skb)).creds) -#define UNIXSECDATA(skb) (&UNIXCB((skb)).secdata) -#define UNIXSECLEN(skb) (&UNIXCB((skb)).seclen) +#define UNIXSID(skb) (&UNIXCB((skb)).secid) #define unix_state_rlock(s) spin_lock(&unix_sk(s)->lock) #define unix_state_runlock(s) spin_unlock(&unix_sk(s)->lock) diff --git a/include/net/scm.h b/include/net/scm.h index 02daa097cdc..5637d5e22d5 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -3,6 +3,7 @@ #include #include +#include /* Well, we should have at least one descriptor open * to accept passed FDs 8) @@ -20,8 +21,7 @@ struct scm_cookie struct ucred creds; /* Skb credentials */ struct scm_fp_list *fp; /* Passed files */ #ifdef CONFIG_SECURITY_NETWORK - char *secdata; /* Security context */ - u32 seclen; /* Security length */ + u32 secid; /* Passed security ID */ #endif unsigned long seq; /* Connection seqno */ }; @@ -32,6 +32,16 @@ extern int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie extern void __scm_destroy(struct scm_cookie *scm); extern struct scm_fp_list * scm_fp_dup(struct scm_fp_list *fpl); +#ifdef CONFIG_SECURITY_NETWORK +static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) +{ + security_socket_getpeersec_dgram(sock, NULL, &scm->secid); +} +#else +static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) +{ } +#endif /* CONFIG_SECURITY_NETWORK */ + static __inline__ void scm_destroy(struct scm_cookie *scm) { if (scm && scm->fp) @@ -47,6 +57,7 @@ static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, scm->creds.pid = p->tgid; scm->fp = NULL; scm->seq = 0; + unix_get_peersec_dgram(sock, scm); if (msg->msg_controllen <= 0) return 0; return __scm_send(sock, msg, scm); @@ -55,8 +66,18 @@ static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, #ifdef CONFIG_SECURITY_NETWORK static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) { - if (test_bit(SOCK_PASSSEC, &sock->flags) && scm->secdata != NULL) - put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, scm->seclen, scm->secdata); + char *secdata; + u32 seclen; + int err; + + if (test_bit(SOCK_PASSSEC, &sock->flags)) { + err = security_secid_to_secctx(scm->secid, &secdata, &seclen); + + if (!err) { + put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata); + security_release_secctx(secdata, seclen); + } + } } #else static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 84f43a3c909..2d05c4133d3 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -112,14 +112,19 @@ static void ip_cmsg_recv_retopts(struct msghdr *msg, struct sk_buff *skb) static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb) { char *secdata; - u32 seclen; + u32 seclen, secid; int err; - err = security_socket_getpeersec_dgram(skb, &secdata, &seclen); + err = security_socket_getpeersec_dgram(NULL, skb, &secid); + if (err) + return; + + err = security_secid_to_secctx(secid, &secdata, &seclen); if (err) return; put_cmsg(msg, SOL_IP, SCM_SECURITY, seclen, secdata); + security_release_secctx(secdata, seclen); } diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 6f290927926..de6ec519272 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -128,23 +128,17 @@ static atomic_t unix_nr_socks = ATOMIC_INIT(0); #define UNIX_ABSTRACT(sk) (unix_sk(sk)->addr->hash != UNIX_HASH_SIZE) #ifdef CONFIG_SECURITY_NETWORK -static void unix_get_peersec_dgram(struct sk_buff *skb) +static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb) { - int err; - - err = security_socket_getpeersec_dgram(skb, UNIXSECDATA(skb), - UNIXSECLEN(skb)); - if (err) - *(UNIXSECDATA(skb)) = NULL; + memcpy(UNIXSID(skb), &scm->secid, sizeof(u32)); } static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb) { - scm->secdata = *UNIXSECDATA(skb); - scm->seclen = *UNIXSECLEN(skb); + scm->secid = *UNIXSID(skb); } #else -static inline void unix_get_peersec_dgram(struct sk_buff *skb) +static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb) { } static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb) @@ -1322,8 +1316,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock, memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred)); if (siocb->scm->fp) unix_attach_fds(siocb->scm, skb); - - unix_get_peersec_dgram(skb); + unix_get_secdata(siocb->scm, skb); skb->h.raw = skb->data; err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len); diff --git a/security/dummy.c b/security/dummy.c index bbbfda70e13..58c6d399c84 100644 --- a/security/dummy.c +++ b/security/dummy.c @@ -791,8 +791,7 @@ static int dummy_socket_getpeersec_stream(struct socket *sock, char __user *optv return -ENOPROTOOPT; } -static int dummy_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata, - u32 *seclen) +static int dummy_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid) { return -ENOPROTOOPT; } @@ -876,6 +875,15 @@ static int dummy_setprocattr(struct task_struct *p, char *name, void *value, siz return -EINVAL; } +static int dummy_secid_to_secctx(u32 secid, char **secdata, u32 *seclen) +{ + return -EOPNOTSUPP; +} + +static void dummy_release_secctx(char *secdata, u32 seclen) +{ +} + #ifdef CONFIG_KEYS static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx, unsigned long flags) @@ -1028,6 +1036,8 @@ void security_fixup_ops (struct security_operations *ops) set_to_dummy_if_null(ops, d_instantiate); set_to_dummy_if_null(ops, getprocattr); set_to_dummy_if_null(ops, setprocattr); + set_to_dummy_if_null(ops, secid_to_secctx); + set_to_dummy_if_null(ops, release_secctx); #ifdef CONFIG_SECURITY_NETWORK set_to_dummy_if_null(ops, unix_stream_connect); set_to_dummy_if_null(ops, unix_may_send); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index a91c961ba38..5d1b8c73319 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3524,25 +3524,21 @@ out: return err; } -static int selinux_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata, u32 *seclen) +static int selinux_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid) { + u32 peer_secid = SECSID_NULL; int err = 0; - u32 peer_sid; - if (skb->sk->sk_family == PF_UNIX) - selinux_get_inode_sid(SOCK_INODE(skb->sk->sk_socket), - &peer_sid); - else - peer_sid = selinux_socket_getpeer_dgram(skb); + if (sock && (sock->sk->sk_family == PF_UNIX)) + selinux_get_inode_sid(SOCK_INODE(sock), &peer_secid); + else if (skb) + peer_secid = selinux_socket_getpeer_dgram(skb); - if (peer_sid == SECSID_NULL) - return -EINVAL; + if (peer_secid == SECSID_NULL) + err = -EINVAL; + *secid = peer_secid; - err = security_sid_to_context(peer_sid, secdata, seclen); - if (err) - return err; - - return 0; + return err; } static int selinux_sk_alloc_security(struct sock *sk, int family, gfp_t priority) @@ -4407,6 +4403,17 @@ static int selinux_setprocattr(struct task_struct *p, return size; } +static int selinux_secid_to_secctx(u32 secid, char **secdata, u32 *seclen) +{ + return security_sid_to_context(secid, secdata, seclen); +} + +static void selinux_release_secctx(char *secdata, u32 seclen) +{ + if (secdata) + kfree(secdata); +} + #ifdef CONFIG_KEYS static int selinux_key_alloc(struct key *k, struct task_struct *tsk, @@ -4587,6 +4594,9 @@ static struct security_operations selinux_ops = { .getprocattr = selinux_getprocattr, .setprocattr = selinux_setprocattr, + .secid_to_secctx = selinux_secid_to_secctx, + .release_secctx = selinux_release_secctx, + .unix_stream_connect = selinux_socket_unix_stream_connect, .unix_may_send = selinux_socket_unix_may_send,