cregit-Linux how code gets into the kernel

Release 4.15 fs/binfmt_aout.c

Directory: fs
/*
 *  linux/fs/binfmt_aout.c
 *
 *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
 */

#include <linux/module.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/coredump.h>
#include <linux/slab.h>
#include <linux/sched/task_stack.h>

#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/a.out-core.h>

static int load_aout_binary(struct linux_binprm *);
static int load_aout_library(struct file*);

#ifdef CONFIG_COREDUMP
/*
 * Routine writes a core dump image in the current directory.
 * Currently only a stub-function.
 *
 * Note that setuid/setgid files won't make a core-dump if the uid/gid
 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
 * field, which also makes sure the core-dumps won't be recursive if the
 * dumping of the process results in another error..
 */

static int aout_core_dump(struct coredump_params *cprm) { mm_segment_t fs; int has_dumped = 0; void __user *dump_start; int dump_size; struct user dump; #ifdef __alpha__ # define START_DATA(u) ((void __user *)u.start_data) #else # define START_DATA(u) ((void __user *)((u.u_tsize << PAGE_SHIFT) + \ u.start_code)) #endif # define START_STACK(u) ((void __user *)u.start_stack) fs = get_fs(); set_fs(KERNEL_DS); has_dumped = 1; strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm)); dump.u_ar0 = offsetof(struct user, regs); dump.signal = cprm->siginfo->si_signo; aout_dump_thread(cprm->regs, &dump); /* If the size of the dump file exceeds the rlimit, then see what would happen if we wrote the stack, but not the data area. */ if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit) dump.u_dsize = 0; /* Make sure we have enough room to write the stack and data areas. */ if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit) dump.u_ssize = 0; /* make sure we actually have a data and stack area to dump */ set_fs(USER_DS); if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT)) dump.u_dsize = 0; if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT)) dump.u_ssize = 0; set_fs(KERNEL_DS); /* struct user */ if (!dump_emit(cprm, &dump, sizeof(dump))) goto end_coredump; /* Now dump all of the user data. Include malloced stuff as well */ if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump))) goto end_coredump; /* now we start writing out the user space info */ set_fs(USER_DS); /* Dump the data area */ if (dump.u_dsize != 0) { dump_start = START_DATA(dump); dump_size = dump.u_dsize << PAGE_SHIFT; if (!dump_emit(cprm, dump_start, dump_size)) goto end_coredump; } /* Now prepare to dump the stack area */ if (dump.u_ssize != 0) { dump_start = START_STACK(dump); dump_size = dump.u_ssize << PAGE_SHIFT; if (!dump_emit(cprm, dump_start, dump_size)) goto end_coredump; } end_coredump: set_fs(fs); return has_dumped; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)28576.82%527.78%
Daisuke Hatayama3810.24%211.11%
Masami Hiramatsu123.23%15.56%
Al Viro112.96%316.67%
Borislav Petkov82.16%15.56%
H. Peter Anvin41.08%15.56%
Jesper Juhl41.08%15.56%
Denys Vlasenko30.81%15.56%
Prasanna Meda30.81%15.56%
Neil Horman20.54%15.56%
David Howells10.27%15.56%
Total371100.00%18100.00%

#else #define aout_core_dump NULL #endif static struct linux_binfmt aout_format = { .module = THIS_MODULE, .load_binary = load_aout_binary, .load_shlib = load_aout_library, .core_dump = aout_core_dump, .min_coredump = PAGE_SIZE }; #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
static int set_brk(unsigned long start, unsigned long end) { start = PAGE_ALIGN(start); end = PAGE_ALIGN(end); if (end > start) return vm_brk(start, end - start); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Alex Kelly4595.74%133.33%
Guenter Roeck12.13%133.33%
Linus Torvalds12.13%133.33%
Total47100.00%3100.00%

/* * create_aout_tables() parses the env- and arg-strings in new user * memory and creates the pointer tables from them, and puts their * addresses on the "stack", returning the new stack pointer value. */
static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm) { char __user * __user *argv; char __user * __user *envp; unsigned long __user *sp; int argc = bprm->argc; int envc = bprm->envc; sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p); #ifdef __alpha__ /* whee.. test-programs are so much fun. */ put_user(0, --sp); put_user(0, --sp); if (bprm->loader) { put_user(0, --sp); put_user(1003, --sp); put_user(bprm->loader, --sp); put_user(1002, --sp); } put_user(bprm->exec, --sp); put_user(1001, --sp); #endif sp -= envc+1; envp = (char __user * __user *) sp; sp -= argc+1; argv = (char __user * __user *) sp; #ifndef __alpha__ put_user((unsigned long) envp,--sp); put_user((unsigned long) argv,--sp); #endif put_user(argc,--sp); current->mm->arg_start = (unsigned long) p; while (argc-->0) { char c; put_user(p,argv++); do { get_user(c,p++); } while (c); } put_user(NULL,argv); current->mm->arg_end = current->mm->env_start = (unsigned long) p; while (envc-->0) { char c; put_user(p,envp++); do { get_user(c,p++); } while (c); } put_user(NULL,envp); current->mm->env_end = (unsigned long) p; return sp; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)34393.97%350.00%
Al Viro215.75%233.33%
Guenter Roeck10.27%116.67%
Total365100.00%6100.00%

/* * These are the functions used to load a.out style executables and shared * libraries. There is no binary dependent code anywhere else. */
static int load_aout_binary(struct linux_binprm * bprm) { struct pt_regs *regs = current_pt_regs(); struct exec ex; unsigned long error; unsigned long fd_offset; unsigned long rlim; int retval; ex = *((struct exec *) bprm->buf); /* exec-header */ if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC && N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) || N_TRSIZE(ex) || N_DRSIZE(ex) || i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) { return -ENOEXEC; } /* * Requires a mmap handler. This prevents people from using a.out * as part of an exploit attack against /proc-related vulnerabilities. */ if (!bprm->file->f_op->mmap) return -ENOEXEC; fd_offset = N_TXTOFF(ex); /* Check initial limits. This avoids letting people circumvent * size limits imposed on them by creating programs with large * arrays in the data or bss. */ rlim = rlimit(RLIMIT_DATA); if (rlim >= RLIM_INFINITY) rlim = ~0; if (ex.a_data + ex.a_bss > rlim) return -ENOMEM; /* Flush all traces of the currently running executable */ retval = flush_old_exec(bprm); if (retval) return retval; /* OK, This is the point of no return */ #ifdef __alpha__ SET_AOUT_PERSONALITY(bprm, ex); #else set_personality(PER_LINUX); #endif setup_new_exec(bprm); current->mm->end_code = ex.a_text + (current->mm->start_code = N_TXTADDR(ex)); current->mm->end_data = ex.a_data + (current->mm->start_data = N_DATADDR(ex)); current->mm->brk = ex.a_bss + (current->mm->start_brk = N_BSSADDR(ex)); retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT); if (retval < 0) return retval; install_exec_creds(bprm); if (N_MAGIC(ex) == OMAGIC) { unsigned long text_addr, map_size; loff_t pos; text_addr = N_TXTADDR(ex); #ifdef __alpha__ pos = fd_offset; map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1; #else pos = 32; map_size = ex.a_text+ex.a_data; #endif error = vm_brk(text_addr & PAGE_MASK, map_size); if (error) return error; error = read_code(bprm->file, text_addr, pos, ex.a_text+ex.a_data); if ((signed long)error < 0) return error; } else { if ((ex.a_text & 0xfff || ex.a_data & 0xfff) && (N_MAGIC(ex) != NMAGIC) && printk_ratelimit()) { printk(KERN_NOTICE "executable not page aligned\n"); } if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit()) { printk(KERN_WARNING "fd_offset is not page aligned. Please convert program: %pD\n", bprm->file); } if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) { error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data); if (error) return error; read_code(bprm->file, N_TXTADDR(ex), fd_offset, ex.a_text + ex.a_data); goto beyond_if; } error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text, PROT_READ | PROT_EXEC, MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE, fd_offset); if (error != N_TXTADDR(ex)) return error; error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE, fd_offset + ex.a_text); if (error != N_DATADDR(ex)) return error; } beyond_if: set_binfmt(&aout_format); retval = set_brk(current->mm->start_brk, current->mm->brk); if (retval < 0) return retval; current->mm->start_stack = (unsigned long) create_aout_tables((char __user *) bprm->p, bprm); #ifdef __alpha__ regs->gp = ex.a_gpvalue; #endif start_thread(regs, ex.a_entry, current->mm->start_stack); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)65285.68%1542.86%
Al Viro405.26%822.86%
Linus Torvalds253.29%514.29%
Eugene Teo162.10%12.86%
Michal Hocko91.18%12.86%
Chris Wright81.05%12.86%
S.Çağlar Onur40.53%12.86%
Andrew Morton30.39%12.86%
Jiri Slaby30.39%12.86%
David Howells10.13%12.86%
Total761100.00%35100.00%


static int load_aout_library(struct file *file) { struct inode * inode; unsigned long bss, start_addr, len; unsigned long error; int retval; struct exec ex; loff_t pos = 0; inode = file_inode(file); retval = -ENOEXEC; error = kernel_read(file, &ex, sizeof(ex), &pos); if (error != sizeof(ex)) goto out; /* We come in here for the regular a.out style of shared libraries */ if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) || N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) || i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) { goto out; } /* * Requires a mmap handler. This prevents people from using a.out * as part of an exploit attack against /proc-related vulnerabilities. */ if (!file->f_op->mmap) goto out; if (N_FLAGS(ex)) goto out; /* For QMAGIC, the starting address is 0x20 into the page. We mask this off to get the starting address for the page */ start_addr = ex.a_entry & 0xfffff000; if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) { if (printk_ratelimit()) { printk(KERN_WARNING "N_TXTOFF is not page aligned. Please convert library: %pD\n", file); } retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss); if (retval) goto out; read_code(file, start_addr, N_TXTOFF(ex), ex.a_text + ex.a_data); retval = 0; goto out; } /* Now use mmap to map the library into memory. */ error = vm_mmap(file, start_addr, ex.a_text + ex.a_data, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE, N_TXTOFF(ex)); retval = error; if (error != start_addr) goto out; len = PAGE_ALIGN(ex.a_text + ex.a_data); bss = ex.a_text + ex.a_data + ex.a_bss; if (bss > len) { retval = vm_brk(start_addr + len, bss - len); if (retval) goto out; } retval = 0; out: return retval; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)33787.76%945.00%
Eugene Teo133.39%15.00%
Michal Hocko92.34%15.00%
Christoph Hellwig82.08%15.00%
Al Viro71.82%315.00%
Linus Torvalds51.30%315.00%
Andrew Morton30.78%15.00%
S.Çağlar Onur20.52%15.00%
Total384100.00%20100.00%


static int __init init_aout_binfmt(void) { register_binfmt(&aout_format); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)1583.33%375.00%
Al Viro316.67%125.00%
Total18100.00%4100.00%


static void __exit exit_aout_binfmt(void) { unregister_binfmt(&aout_format); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)15100.00%2100.00%
Total15100.00%2100.00%

core_initcall(init_aout_binfmt); module_exit(exit_aout_binfmt); MODULE_LICENSE("GPL");

Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)173381.75%2939.19%
Alex Kelly954.48%11.35%
Al Viro823.87%1114.86%
Daisuke Hatayama401.89%22.70%
Linus Torvalds381.79%912.16%
Eugene Teo291.37%11.35%
Michal Hocko180.85%11.35%
Masami Hiramatsu120.57%11.35%
Christoph Hellwig80.38%11.35%
Chris Wright80.38%11.35%
Borislav Petkov80.38%11.35%
Andrew Morton70.33%22.70%
S.Çağlar Onur60.28%11.35%
David Howells50.24%22.70%
Tejun Heo50.24%11.35%
H. Peter Anvin40.19%11.35%
Jesper Juhl40.19%11.35%
Ingo Molnar30.14%11.35%
Prasanna Meda30.14%11.35%
Jiri Slaby30.14%11.35%
Denys Vlasenko30.14%11.35%
Guenter Roeck20.09%11.35%
Neil Horman20.09%11.35%
Dave Jones10.05%11.35%
Richard Henderson10.05%11.35%
Total2120100.00%74100.00%
Directory: fs
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