96e02d1586
Setting the task name is done within setup_new_exec() by accessing bprm->filename. However this happens after flush_old_exec(). This may result in a use after free bug, flush_old_exec() may "complete" vfork_done, which will wake up the parent which in turn may free the passed in filename. To fix this add a new tcomm field in struct linux_binprm which contains the now early generated task name until it is used. Fixes this bug on s390: Unable to handle kernel pointer dereference at virtual kernel address 0000000039768000 Process kworker/u:3 (pid: 245, task: 000000003a3dc840, ksp: 0000000039453818) Krnl PSW : 0704000180000000 0000000000282e94 (setup_new_exec+0xa0/0x374) Call Trace: ([<0000000000282e2c>] setup_new_exec+0x38/0x374) [<00000000002dd12e>] load_elf_binary+0x402/0x1bf4 [<0000000000280a42>] search_binary_handler+0x38e/0x5bc [<0000000000282b6c>] do_execve_common+0x410/0x514 [<0000000000282cb6>] do_execve+0x46/0x58 [<00000000005bce58>] kernel_execve+0x28/0x70 [<000000000014ba2e>] ____call_usermodehelper+0x102/0x140 [<00000000005bc8da>] kernel_thread_starter+0x6/0xc [<00000000005bc8d4>] kernel_thread_starter+0x0/0xc Last Breaking-Event-Address: [<00000000002830f0>] setup_new_exec+0x2fc/0x374 Kernel panic - not syncing: Fatal exception: panic_on_oops Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
140 lines
4.4 KiB
C
140 lines
4.4 KiB
C
#ifndef _LINUX_BINFMTS_H
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#define _LINUX_BINFMTS_H
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#include <linux/capability.h>
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struct pt_regs;
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/*
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* These are the maximum length and maximum number of strings passed to the
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* execve() system call. MAX_ARG_STRLEN is essentially random but serves to
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* prevent the kernel from being unduly impacted by misaddressed pointers.
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* MAX_ARG_STRINGS is chosen to fit in a signed 32-bit integer.
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*/
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#define MAX_ARG_STRLEN (PAGE_SIZE * 32)
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#define MAX_ARG_STRINGS 0x7FFFFFFF
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/* sizeof(linux_binprm->buf) */
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#define BINPRM_BUF_SIZE 128
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#ifdef __KERNEL__
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#include <linux/sched.h>
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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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cred_prepared:1,/* true if creds already prepared (multiple
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* preps happen for interpreters) */
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cap_effective:1;/* true if has elevated effective capabilities,
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* false if not; except for init which inherits
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* its parent's caps anyway */
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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;
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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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char tcomm[TASK_COMM_LEN];
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};
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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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#define BINPRM_MAX_RECURSION 4
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/* Function parameter for binfmt->coredump */
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struct coredump_params {
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long signr;
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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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};
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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 *, struct pt_regs * regs);
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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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};
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extern int __register_binfmt(struct linux_binfmt *fmt, int insert);
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/* Registration of default binfmt handlers */
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static inline int register_binfmt(struct linux_binfmt *fmt)
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{
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return __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 int insert_binfmt(struct linux_binfmt *fmt)
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{
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return __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 *, struct pt_regs *);
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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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#define SUID_DUMP_DISABLE 0 /* No setuid dumping */
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#define SUID_DUMP_USER 1 /* Dump as user of process */
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#define SUID_DUMP_ROOT 2 /* Dump as root */
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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 bprm_mm_init(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 do_coredump(long signr, int exit_code, struct pt_regs *regs);
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extern void set_binfmt(struct linux_binfmt *new);
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extern void free_bprm(struct linux_binprm *);
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#endif /* __KERNEL__ */
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#endif /* _LINUX_BINFMTS_H */
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