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![Oleg Nesterov](/assets/img/avatar_default.png)
Patch series "exec: binfmt_misc: fix use-after-free, kill
iname[BINPRM_BUF_SIZE]".
It looks like this code was always wrong, then commit 948b701a60
("binfmt_misc: add persistent opened binary handler for containers")
added more problems.
This patch (of 6):
load_script() can simply use i_name instead, it points into bprm->buf[]
and nobody can change this memory until we call prepare_binprm().
The only complication is that we need to also change the signature of
bprm_change_interp() but this change looks good too.
While at it, do whitespace/style cleanups.
NOTE: the real motivation for this change is that people want to
increase BINPRM_BUF_SIZE, we need to change load_misc_binary() too but
this looks more complicated because afaics it is very buggy.
Link: http://lkml.kernel.org/r/20170918163446.GA26793@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Travis Gummels <tgummels@redhat.com>
Cc: Ben Woodard <woodard@redhat.com>
Cc: Jim Foraker <foraker1@llnl.gov>
Cc: <tdhooge@llnl.gov>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
150 lines
4.7 KiB
C
150 lines
4.7 KiB
C
#ifndef _LINUX_BINFMTS_H
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#define _LINUX_BINFMTS_H
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#include <linux/sched.h>
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#include <linux/unistd.h>
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#include <asm/exec.h>
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#include <uapi/linux/binfmts.h>
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struct filename;
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#define CORENAME_MAX_SIZE 128
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/*
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* This structure is used to hold the arguments that are used when loading binaries.
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*/
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struct linux_binprm {
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char buf[BINPRM_BUF_SIZE];
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#ifdef CONFIG_MMU
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struct vm_area_struct *vma;
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unsigned long vma_pages;
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#else
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# define MAX_ARG_PAGES 32
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struct page *page[MAX_ARG_PAGES];
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#endif
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struct mm_struct *mm;
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unsigned long p; /* current top of mem */
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unsigned int
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/*
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* True after the bprm_set_creds hook has been called once
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* (multiple calls can be made via prepare_binprm() for
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* binfmt_script/misc).
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*/
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called_set_creds:1,
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/*
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* True if most recent call to the commoncaps bprm_set_creds
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* hook (due to multiple prepare_binprm() calls from the
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* binfmt_script/misc handlers) resulted in elevated
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* privileges.
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*/
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cap_elevated:1,
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/*
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* Set by bprm_set_creds hook to indicate a privilege-gaining
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* exec has happened. Used to sanitize execution environment
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* and to set AT_SECURE auxv for glibc.
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*/
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secureexec:1;
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#ifdef __alpha__
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unsigned int taso:1;
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#endif
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unsigned int recursion_depth; /* only for search_binary_handler() */
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struct file * file;
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struct cred *cred; /* new credentials */
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int unsafe; /* how unsafe this exec is (mask of LSM_UNSAFE_*) */
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unsigned int per_clear; /* bits to clear in current->personality */
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int argc, envc;
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const char * filename; /* Name of binary as seen by procps */
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const char * interp; /* Name of the binary really executed. Most
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of the time same as filename, but could be
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different for binfmt_{misc,script} */
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unsigned interp_flags;
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unsigned interp_data;
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unsigned long loader, exec;
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} __randomize_layout;
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#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0
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#define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT)
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/* fd of the binary should be passed to the interpreter */
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#define BINPRM_FLAGS_EXECFD_BIT 1
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#define BINPRM_FLAGS_EXECFD (1 << BINPRM_FLAGS_EXECFD_BIT)
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/* filename of the binary will be inaccessible after exec */
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#define BINPRM_FLAGS_PATH_INACCESSIBLE_BIT 2
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#define BINPRM_FLAGS_PATH_INACCESSIBLE (1 << BINPRM_FLAGS_PATH_INACCESSIBLE_BIT)
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/* Function parameter for binfmt->coredump */
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struct coredump_params {
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const siginfo_t *siginfo;
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struct pt_regs *regs;
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struct file *file;
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unsigned long limit;
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unsigned long mm_flags;
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loff_t written;
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loff_t pos;
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};
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/*
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* This structure defines the functions that are used to load the binary formats that
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* linux accepts.
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*/
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struct linux_binfmt {
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struct list_head lh;
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struct module *module;
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int (*load_binary)(struct linux_binprm *);
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int (*load_shlib)(struct file *);
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int (*core_dump)(struct coredump_params *cprm);
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unsigned long min_coredump; /* minimal dump size */
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} __randomize_layout;
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extern void __register_binfmt(struct linux_binfmt *fmt, int insert);
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/* Registration of default binfmt handlers */
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static inline void register_binfmt(struct linux_binfmt *fmt)
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{
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__register_binfmt(fmt, 0);
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}
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/* Same as above, but adds a new binfmt at the top of the list */
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static inline void insert_binfmt(struct linux_binfmt *fmt)
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{
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__register_binfmt(fmt, 1);
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}
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extern void unregister_binfmt(struct linux_binfmt *);
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extern int prepare_binprm(struct linux_binprm *);
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extern int __must_check remove_arg_zero(struct linux_binprm *);
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extern int search_binary_handler(struct linux_binprm *);
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extern int flush_old_exec(struct linux_binprm * bprm);
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extern void setup_new_exec(struct linux_binprm * bprm);
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extern void would_dump(struct linux_binprm *, struct file *);
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extern int suid_dumpable;
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/* Stack area protections */
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#define EXSTACK_DEFAULT 0 /* Whatever the arch defaults to */
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#define EXSTACK_DISABLE_X 1 /* Disable executable stacks */
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#define EXSTACK_ENABLE_X 2 /* Enable executable stacks */
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extern int setup_arg_pages(struct linux_binprm * bprm,
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unsigned long stack_top,
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int executable_stack);
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extern int transfer_args_to_stack(struct linux_binprm *bprm,
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unsigned long *sp_location);
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extern int bprm_change_interp(const char *interp, struct linux_binprm *bprm);
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extern int copy_strings_kernel(int argc, const char *const *argv,
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struct linux_binprm *bprm);
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extern int prepare_bprm_creds(struct linux_binprm *bprm);
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extern void install_exec_creds(struct linux_binprm *bprm);
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extern void set_binfmt(struct linux_binfmt *new);
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extern ssize_t read_code(struct file *, unsigned long, loff_t, size_t);
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extern int do_execve(struct filename *,
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const char __user * const __user *,
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const char __user * const __user *);
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extern int do_execveat(int, struct filename *,
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const char __user * const __user *,
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const char __user * const __user *,
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int);
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#endif /* _LINUX_BINFMTS_H */
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