From 6fba89813ccf333d2bc4d5caea04cd5f3c39eb50 Mon Sep 17 00:00:00 2001 From: Casey Schaufler Date: Wed, 23 Oct 2024 14:21:54 -0700 Subject: lsm: ensure the correct LSM context releaser Add a new lsm_context data structure to hold all the information about a "security context", including the string, its size and which LSM allocated the string. The allocation information is necessary because LSMs have different policies regarding the lifecycle of these strings. SELinux allocates and destroys them on each use, whereas Smack provides a pointer to an entry in a list that never goes away. Update security_release_secctx() to use the lsm_context instead of a (char *, len) pair. Change its callers to do likewise. The LSMs supporting this hook have had comments added to remind the developer that there is more work to be done. The BPF security module provides all LSM hooks. While there has yet to be a known instance of a BPF configuration that uses security contexts, the possibility is real. In the existing implementation there is potential for multiple frees in that case. Cc: linux-integrity@vger.kernel.org Cc: netdev@vger.kernel.org Cc: audit@vger.kernel.org Cc: netfilter-devel@vger.kernel.org To: Pablo Neira Ayuso Cc: linux-nfs@vger.kernel.org Cc: Todd Kjos Signed-off-by: Casey Schaufler [PM: subject tweak] Signed-off-by: Paul Moore --- kernel/auditsc.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) (limited to 'kernel/auditsc.c') diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 279ba5c420a4..de8fac6c5bd3 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1098,8 +1098,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid, char *comm) { struct audit_buffer *ab; - char *ctx = NULL; - u32 len; + struct lsm_context ctx; int rc = 0; ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID); @@ -1110,12 +1109,12 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid, from_kuid(&init_user_ns, auid), from_kuid(&init_user_ns, uid), sessionid); if (lsmprop_is_set(prop)) { - if (security_lsmprop_to_secctx(prop, &ctx, &len)) { + if (security_lsmprop_to_secctx(prop, &ctx.context, &ctx.len)) { audit_log_format(ab, " obj=(none)"); rc = 1; } else { - audit_log_format(ab, " obj=%s", ctx); - security_release_secctx(ctx, len); + audit_log_format(ab, " obj=%s", ctx.context); + security_release_secctx(&ctx); } } audit_log_format(ab, " ocomm="); @@ -1371,6 +1370,7 @@ static void audit_log_time(struct audit_context *context, struct audit_buffer ** static void show_special(struct audit_context *context, int *call_panic) { + struct lsm_context lsmcxt; struct audit_buffer *ab; int i; @@ -1401,7 +1401,8 @@ static void show_special(struct audit_context *context, int *call_panic) *call_panic = 1; } else { audit_log_format(ab, " obj=%s", ctx); - security_release_secctx(ctx, len); + lsmcontext_init(&lsmcxt, ctx, len, 0); + security_release_secctx(&lsmcxt); } } if (context->ipc.has_perm) { @@ -1560,15 +1561,15 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n, MAJOR(n->rdev), MINOR(n->rdev)); if (lsmprop_is_set(&n->oprop)) { - char *ctx = NULL; - u32 len; + struct lsm_context ctx; - if (security_lsmprop_to_secctx(&n->oprop, &ctx, &len)) { + if (security_lsmprop_to_secctx(&n->oprop, &ctx.context, + &ctx.len)) { if (call_panic) *call_panic = 2; } else { - audit_log_format(ab, " obj=%s", ctx); - security_release_secctx(ctx, len); + audit_log_format(ab, " obj=%s", ctx.context); + security_release_secctx(&ctx); } } -- cgit v1.2.3 From 2d470c778120d3cdb8d8ab250329ca85f49f12b1 Mon Sep 17 00:00:00 2001 From: Casey Schaufler Date: Wed, 23 Oct 2024 14:21:55 -0700 Subject: lsm: replace context+len with lsm_context Replace the (secctx,seclen) pointer pair with a single lsm_context pointer to allow return of the LSM identifier along with the context and context length. This allows security_release_secctx() to know how to release the context. Callers have been modified to use or save the returned data from the new structure. security_secid_to_secctx() and security_lsmproc_to_secctx() will now return the length value on success instead of 0. Cc: netdev@vger.kernel.org Cc: audit@vger.kernel.org Cc: netfilter-devel@vger.kernel.org Cc: Todd Kjos Signed-off-by: Casey Schaufler [PM: subject tweak, kdoc fix, signedness fix from Dan Carpenter] Signed-off-by: Paul Moore --- kernel/auditsc.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) (limited to 'kernel/auditsc.c') diff --git a/kernel/auditsc.c b/kernel/auditsc.c index de8fac6c5bd3..bb0e7346d916 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1109,7 +1109,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid, from_kuid(&init_user_ns, auid), from_kuid(&init_user_ns, uid), sessionid); if (lsmprop_is_set(prop)) { - if (security_lsmprop_to_secctx(prop, &ctx.context, &ctx.len)) { + if (security_lsmprop_to_secctx(prop, &ctx) < 0) { audit_log_format(ab, " obj=(none)"); rc = 1; } else { @@ -1370,7 +1370,6 @@ static void audit_log_time(struct audit_context *context, struct audit_buffer ** static void show_special(struct audit_context *context, int *call_panic) { - struct lsm_context lsmcxt; struct audit_buffer *ab; int i; @@ -1393,16 +1392,14 @@ static void show_special(struct audit_context *context, int *call_panic) from_kgid(&init_user_ns, context->ipc.gid), context->ipc.mode); if (lsmprop_is_set(&context->ipc.oprop)) { - char *ctx = NULL; - u32 len; + struct lsm_context lsmctx; if (security_lsmprop_to_secctx(&context->ipc.oprop, - &ctx, &len)) { + &lsmctx) < 0) { *call_panic = 1; } else { - audit_log_format(ab, " obj=%s", ctx); - lsmcontext_init(&lsmcxt, ctx, len, 0); - security_release_secctx(&lsmcxt); + audit_log_format(ab, " obj=%s", lsmctx.context); + security_release_secctx(&lsmctx); } } if (context->ipc.has_perm) { @@ -1563,8 +1560,7 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n, if (lsmprop_is_set(&n->oprop)) { struct lsm_context ctx; - if (security_lsmprop_to_secctx(&n->oprop, &ctx.context, - &ctx.len)) { + if (security_lsmprop_to_secctx(&n->oprop, &ctx) < 0) { if (call_panic) *call_panic = 2; } else { -- cgit v1.2.3