From e89b8081327ac9efbf273e790b8677e64fd0361a Mon Sep 17 00:00:00 2001 From: Vegard Nossum <vegard.nossum@oracle.com> Date: Thu, 7 Jul 2016 13:41:11 -0700 Subject: [PATCH] apparmor: fix oops, validate buffer size in apparmor_setprocattr() When proc_pid_attr_write() was changed to use memdup_user apparmor's (interface violating) assumption that the setprocattr buffer was always a single page was violated. The size test is not strictly speaking needed as proc_pid_attr_write() will reject anything larger, but for the sake of robustness we can keep it in. SMACK and SELinux look safe to me, but somebody else should probably have a look just in case. Based on original patch from Vegard Nossum <vegard.nossum@oracle.com> modified for the case that apparmor provides null termination. Fixes: bb646cdb12e75d82258c2f2e7746d5952d3e321a Reported-by: Vegard Nossum <vegard.nossum@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: John Johansen <john.johansen@canonical.com> Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Eric Paris <eparis@parisplace.org> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: stable@kernel.org Signed-off-by: John Johansen <john.johansen@canonical.com> Reviewed-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: James Morris <james.l.morris@oracle.com> --- security/apparmor/lsm.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-) diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 300f8336fb8e..c6921a0145ed 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -500,34 +500,34 @@ static int apparmor_setprocattr(struct task_struct *task, char *name, { struct common_audit_data sa; struct apparmor_audit_data aad = {0,}; - char *command, *args = value; + char *command, *largs = NULL, *args = value; size_t arg_size; int error; if (size == 0) return -EINVAL; - /* args points to a PAGE_SIZE buffer, AppArmor requires that - * the buffer must be null terminated or have size <= PAGE_SIZE -1 - * so that AppArmor can null terminate them - */ - if (args[size - 1] != '\0') { - if (size == PAGE_SIZE) - return -EINVAL; - args[size] = '\0'; - } - /* task can only write its own attributes */ if (current != task) return -EACCES; - args = value; + /* AppArmor requires that the buffer must be null terminated atm */ + if (args[size - 1] != '\0') { + /* null terminate */ + largs = args = kmalloc(size + 1, GFP_KERNEL); + if (!args) + return -ENOMEM; + memcpy(args, value, size); + args[size] = '\0'; + } + + error = -EINVAL; args = strim(args); command = strsep(&args, " "); if (!args) - return -EINVAL; + goto out; args = skip_spaces(args); if (!*args) - return -EINVAL; + goto out; arg_size = size - (args - (char *) value); if (strcmp(name, "current") == 0) { @@ -553,10 +553,12 @@ static int apparmor_setprocattr(struct task_struct *task, char *name, goto fail; } else /* only support the "current" and "exec" process attributes */ - return -EINVAL; + goto fail; if (!error) error = size; +out: + kfree(largs); return error; fail: @@ -565,9 +567,9 @@ fail: aad.profile = aa_current_profile(); aad.op = OP_SETPROCATTR; aad.info = name; - aad.error = -EINVAL; + aad.error = error = -EINVAL; aa_audit_msg(AUDIT_APPARMOR_DENIED, &sa, NULL); - return -EINVAL; + goto out; } static int apparmor_task_setrlimit(struct task_struct *task,