From 99b817c173cd213671daecd25ca27f56b0c7c4ec Mon Sep 17 00:00:00 2001 From: Ondrej Mosnacek Date: Fri, 26 Jan 2024 11:44:03 +0100 Subject: lsm: fix the logic in security_inode_getsecctx() The inode_getsecctx LSM hook has previously been corrected to have -EOPNOTSUPP instead of 0 as the default return value to fix BPF LSM behavior. However, the call_int_hook()-generated loop in security_inode_getsecctx() was left treating 0 as the neutral value, so after an LSM returns 0, the loop continues to try other LSMs, and if one of them returns a non-zero value, the function immediately returns with said value. So in a situation where SELinux and the BPF LSMs registered this hook, -EOPNOTSUPP would be incorrectly returned whenever SELinux returned 0. Fix this by open-coding the call_int_hook() loop and making it use the correct LSM_RET_DEFAULT() value as the neutral one, similar to what other hooks do. Cc: stable@vger.kernel.org Reported-by: Stephen Smalley Link: https://lore.kernel.org/selinux/CAEjxPJ4ev-pasUwGx48fDhnmjBnq_Wh90jYPwRQRAqXxmOKD4Q@mail.gmail.com/ Link: https://bugzilla.redhat.com/show_bug.cgi?id=2257983 Fixes: b36995b8609a ("lsm: fix default return value for inode_getsecctx") Signed-off-by: Ondrej Mosnacek Reviewed-by: Casey Schaufler [PM: subject line tweak] Signed-off-by: Paul Moore --- security/security.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'security/security.c') diff --git a/security/security.c b/security/security.c index 0144a98d3712..6196ccaba433 100644 --- a/security/security.c +++ b/security/security.c @@ -4255,7 +4255,19 @@ EXPORT_SYMBOL(security_inode_setsecctx); */ int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen) { - return call_int_hook(inode_getsecctx, -EOPNOTSUPP, inode, ctx, ctxlen); + struct security_hook_list *hp; + int rc; + + /* + * Only one module will provide a security context. + */ + hlist_for_each_entry(hp, &security_hook_heads.inode_getsecctx, list) { + rc = hp->hook.inode_getsecctx(inode, ctx, ctxlen); + if (rc != LSM_RET_DEFAULT(inode_getsecctx)) + return rc; + } + + return LSM_RET_DEFAULT(inode_getsecctx); } EXPORT_SYMBOL(security_inode_getsecctx); -- cgit v1.2.3 From 5a287d3d2b9de2b3e747132c615599907ba5c3c1 Mon Sep 17 00:00:00 2001 From: Ondrej Mosnacek Date: Fri, 26 Jan 2024 19:45:31 +0100 Subject: lsm: fix default return value of the socket_getpeersec_*() hooks For these hooks the true "neutral" value is -EOPNOTSUPP, which is currently what is returned when no LSM provides this hook and what LSMs return when there is no security context set on the socket. Correct the value in and adjust the dispatch functions in security/security.c to avoid issues when the BPF LSM is enabled. Cc: stable@vger.kernel.org Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") Signed-off-by: Ondrej Mosnacek [PM: subject line tweak] Signed-off-by: Paul Moore --- include/linux/lsm_hook_defs.h | 4 ++-- security/security.c | 31 +++++++++++++++++++++++++++---- 2 files changed, 29 insertions(+), 6 deletions(-) (limited to 'security/security.c') diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 185924c56378..76458b6d53da 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -315,9 +315,9 @@ LSM_HOOK(int, 0, socket_getsockopt, struct socket *sock, int level, int optname) LSM_HOOK(int, 0, socket_setsockopt, struct socket *sock, int level, int optname) LSM_HOOK(int, 0, socket_shutdown, struct socket *sock, int how) LSM_HOOK(int, 0, socket_sock_rcv_skb, struct sock *sk, struct sk_buff *skb) -LSM_HOOK(int, 0, socket_getpeersec_stream, struct socket *sock, +LSM_HOOK(int, -ENOPROTOOPT, socket_getpeersec_stream, struct socket *sock, sockptr_t optval, sockptr_t optlen, unsigned int len) -LSM_HOOK(int, 0, socket_getpeersec_dgram, struct socket *sock, +LSM_HOOK(int, -ENOPROTOOPT, socket_getpeersec_dgram, struct socket *sock, struct sk_buff *skb, u32 *secid) LSM_HOOK(int, 0, sk_alloc_security, struct sock *sk, int family, gfp_t priority) LSM_HOOK(void, LSM_RET_VOID, sk_free_security, struct sock *sk) diff --git a/security/security.c b/security/security.c index 6196ccaba433..3aaad75c9ce8 100644 --- a/security/security.c +++ b/security/security.c @@ -4624,8 +4624,20 @@ EXPORT_SYMBOL(security_sock_rcv_skb); int security_socket_getpeersec_stream(struct socket *sock, sockptr_t optval, sockptr_t optlen, unsigned int len) { - return call_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock, - optval, optlen, len); + struct security_hook_list *hp; + int rc; + + /* + * Only one module will provide a security context. + */ + hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_stream, + list) { + rc = hp->hook.socket_getpeersec_stream(sock, optval, optlen, + len); + if (rc != LSM_RET_DEFAULT(socket_getpeersec_stream)) + return rc; + } + return LSM_RET_DEFAULT(socket_getpeersec_stream); } /** @@ -4645,8 +4657,19 @@ int security_socket_getpeersec_stream(struct socket *sock, sockptr_t optval, int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid) { - return call_int_hook(socket_getpeersec_dgram, -ENOPROTOOPT, sock, - skb, secid); + struct security_hook_list *hp; + int rc; + + /* + * Only one module will provide a security context. + */ + hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_dgram, + list) { + rc = hp->hook.socket_getpeersec_dgram(sock, skb, secid); + if (rc != LSM_RET_DEFAULT(socket_getpeersec_dgram)) + return rc; + } + return LSM_RET_DEFAULT(socket_getpeersec_dgram); } EXPORT_SYMBOL(security_socket_getpeersec_dgram); -- cgit v1.2.3 From d8bdd795d383a23e38ac48a40d3d223caf47b290 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Wed, 14 Feb 2024 17:05:38 +0100 Subject: lsm: fix integer overflow in lsm_set_self_attr() syscall security_setselfattr() has an integer overflow bug that leads to out-of-bounds access when userspace provides bogus input: `lctx->ctx_len + sizeof(*lctx)` is checked against `lctx->len` (and, redundantly, also against `size`), but there are no checks on `lctx->ctx_len`. Therefore, userspace can provide an `lsm_ctx` with `->ctx_len` set to a value between `-sizeof(struct lsm_ctx)` and -1, and this bogus `->ctx_len` will then be passed to an LSM module as a buffer length, causing LSM modules to perform out-of-bounds accesses. The following reproducer will demonstrate this under ASAN (if AppArmor is loaded as an LSM): ``` struct lsm_ctx { uint64_t id; uint64_t flags; uint64_t len; uint64_t ctx_len; char ctx[]; }; int main(void) { size_t size = sizeof(struct lsm_ctx); struct lsm_ctx *ctx = malloc(size); ctx->id = 104/*LSM_ID_APPARMOR*/; ctx->flags = 0; ctx->len = size; ctx->ctx_len = -sizeof(struct lsm_ctx); syscall( 460/*__NR_lsm_set_self_attr*/, /*attr=*/ 100/*LSM_ATTR_CURRENT*/, /*ctx=*/ ctx, /*size=*/ size, /*flags=*/ 0 ); } ``` Fixes: a04a1198088a ("LSM: syscalls for current process attributes") Signed-off-by: Jann Horn Acked-by: Casey Schaufler [PM: subj tweak, removed ref to ASAN splat that isn't included] Signed-off-by: Paul Moore --- security/security.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'security/security.c') diff --git a/security/security.c b/security/security.c index 3aaad75c9ce8..7035ee35a393 100644 --- a/security/security.c +++ b/security/security.c @@ -29,6 +29,7 @@ #include #include #include +#include #include /* How many LSMs were built into the kernel? */ @@ -4015,6 +4016,7 @@ int security_setselfattr(unsigned int attr, struct lsm_ctx __user *uctx, struct security_hook_list *hp; struct lsm_ctx *lctx; int rc = LSM_RET_DEFAULT(setselfattr); + u64 required_len; if (flags) return -EINVAL; @@ -4027,8 +4029,9 @@ int security_setselfattr(unsigned int attr, struct lsm_ctx __user *uctx, if (IS_ERR(lctx)) return PTR_ERR(lctx); - if (size < lctx->len || size < lctx->ctx_len + sizeof(*lctx) || - lctx->len < lctx->ctx_len + sizeof(*lctx)) { + if (size < lctx->len || + check_add_overflow(sizeof(*lctx), lctx->ctx_len, &required_len) || + lctx->len < required_len) { rc = -EINVAL; goto free_out; } -- cgit v1.2.3