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Adds flag to exec events indicating a memfd target #161

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Adds flag to exec events indicating a memfd target #161

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3 changes: 3 additions & 0 deletions GPL/Events/EbpfEventProto.h
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,9 @@ struct ebpf_process_exec_event {
struct ebpf_pid_info pids;
struct ebpf_cred_info creds;
struct ebpf_tty_dev ctty;
bool is_memfd;
bool is_setuid;
bool is_setgid;

// Variable length fields: cwd, argv, filename, pids_ss_cgroup_path
struct ebpf_varlen_fields_start vl_fields;
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12 changes: 12 additions & 0 deletions GPL/Events/Process/Probe.bpf.c
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Expand Up @@ -17,6 +17,9 @@
#include "PathResolver.h"
#include "Varlen.h"

#define S_ISUID 0004000
#define S_ISGID 0002000

// Limits on large things we send up as variable length parameters.
//
// These should be kept _well_ under half the size of the event_buffer_map or
Expand Down Expand Up @@ -115,6 +118,15 @@ int BPF_PROG(sched_process_exec,
size = read_kernel_str_or_empty_str(field->data, PATH_MAX, binprm->filename);
ebpf_vl_field__set_size(&event->vl_fields, field, size);

// memfd exec
char buf [7];
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nit: needs code format, CI won't pass without it.

bpf_probe_read_kernel_str(buf, 7, binprm->file->f_path.dentry->d_iname);
if (buf[0] == 'm' && buf[1] == 'e' && buf[2] == 'm' && buf[3] == 'f' && buf[4] == 'd' && buf[5] == ':' )
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For readability, I'd recommend just writing a 4 line implementation of strncmp in Helpers.h and using that here. You can put the string memfd: on the stack.

event->is_memfd = 1;

event->is_setuid = (binprm->file->f_inode->i_mode & S_ISUID) ? true : false;
event->is_setgid = (binprm->file->f_inode->i_mode & S_ISGID) ? true : false;

bpf_ringbuf_output(&ringbuf, event, EVENT_SIZE(event), 0);

out:
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19 changes: 19 additions & 0 deletions non-GPL/Events/EventsTrace/EventsTrace.c
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Expand Up @@ -174,6 +174,16 @@ static void out_newline()
printf("\n");
}

static void out_bool_flag(const char *name, bool value)
{
printf("\"%s\":%s", name, value ? "true" : "false");
}

static void out_named_object_start(const char *name)
{
printf("\"%s\":{", name);
}

static void out_object_start()
{
printf("{");
Expand Down Expand Up @@ -446,6 +456,15 @@ static void out_process_exec(struct ebpf_process_exec_event *evt)
out_cred_info("creds", &evt->creds);
out_comma();

out_named_object_start("red_flags");
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IMO the nesting here is unnecessary, I say just keep them at the top level.

out_bool_flag("is_memfd", evt->is_memfd);
out_comma();
out_bool_flag("is_setuid", evt->is_setuid);
out_comma();
out_bool_flag("is_setgid", evt->is_setgid);
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IMO out_bool_flag should just be out_bool for simplicity and consistency with the other out_ functions.

out_object_end();
out_comma();

out_tty_dev("ctty", &evt->ctty);

struct ebpf_varlen_field *field;
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