1 *
2  * sys_execve() executes a new program.
3  */
4 int do_execve(char * filename,
5     char __user *__user *argv,
6     char __user *__user *envp,
7     struct pt_regs * regs)

 1 /* 
 2  * Fill the binprm structure from the inode. 
 3  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 4  */
 5 int prepare_binprm(struct linux_binprm *bprm)
 6 {
 7     int mode;
 8     struct inode * inode = bprm->file->f_path.dentry->d_inode;
 9     int retval;
10 
11     mode = inode->i_mode;
12     if (bprm->file->f_op == NULL)
13         return -EACCES;
14 
15     bprm->e_uid = current->euid;
16     bprm->e_gid = current->egid;
17 
18     if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
19         /* Set-uid? */
20         if (mode & S_ISUID) {
21             current->personality &= ~PER_CLEAR_ON_SETID;
22             bprm->e_uid = inode->i_uid;
23         }
24 
25         /* Set-gid? */
26         /*
27          * If setgid is set but no group execute bit then this
28          * is a candidate for mandatory locking, not a setgid
29          * executable.
30          */
31         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
32             current->personality &= ~PER_CLEAR_ON_SETID;
33             bprm->e_gid = inode->i_gid;
34         }
35     }
36 
37     /* fill in binprm security blob */
38     retval = security_bprm_set(bprm);
39     if (retval)
40         return retval;
41 
42     memset(bprm->buf,0,BINPRM_BUF_SIZE);
43     return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
44 }

 1 /*
 2  * This structure defines the functions that are used to load the binary formats that
 3  * linux accepts.
 4  */
 5 struct linux_binfmt {
 6     struct list_head lh;
 7     struct module *module;
 8     int (*load_binary)(struct linux_binprm *, struct  pt_regs * regs);
 9     int (*load_shlib)(struct file *);
10     int (*core_dump)(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
11     unsigned long min_coredump;    /* minimal dump size */
12     int hasvdso;
13 };