b45605fac3
[ Upstream commit 543841d1806029889c2f69f040e88b247aba8e22 ] Zbigniew mentioned at Linux Plumber's that systemd is interested in switching to execveat() for service execution, but can't, because the contents of /proc/pid/comm are the file descriptor which was used, instead of the path to the binary[1]. This makes the output of tools like top and ps useless, especially in a world where most fds are opened CLOEXEC so the number is truly meaningless. When the filename passed in is empty (e.g. with AT_EMPTY_PATH), use the dentry's filename for "comm" instead of using the useless numeral from the synthetic fdpath construction. This way the actual exec machinery is unchanged, but cosmetically the comm looks reasonable to admins investigating things. Instead of adding TASK_COMM_LEN more bytes to bprm, use one of the unused flag bits to indicate that we need to set "comm" from the dentry. Suggested-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> Suggested-by: Tycho Andersen <tandersen@netflix.com> Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://github.com/uapi-group/kernel-features#set-comm-field-before-exec [1] Reviewed-by: Aleksa Sarai <cyphar@cyphar.com> Tested-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
137 lines
4.3 KiB
C
137 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#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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struct coredump_params;
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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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#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 long argmin; /* rlimit marker for copy_strings() */
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unsigned int
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/* Should an execfd be passed to userspace? */
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have_execfd:1,
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/* Use the creds of a script (see binfmt_misc) */
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execfd_creds:1,
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/*
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* Set by bprm_creds_for_exec hook to indicate a
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* privilege-gaining exec has happened. Used to set
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* AT_SECURE auxv for glibc.
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*/
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secureexec:1,
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/*
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* Set when errors can no longer be returned to the
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* original userspace.
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*/
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point_of_no_return:1,
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/* Set when "comm" must come from the dentry. */
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comm_from_dentry:1;
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struct file *executable; /* Executable to pass to the interpreter */
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struct file *interpreter;
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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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const char *fdpath; /* generated filename for execveat */
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unsigned interp_flags;
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int execfd; /* File descriptor of the executable */
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unsigned long loader, exec;
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struct rlimit rlim_stack; /* Saved RLIMIT_STACK used during exec. */
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char buf[BINPRM_BUF_SIZE];
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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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/* 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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/* preserve argv0 for the interpreter */
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#define BINPRM_FLAGS_PRESERVE_ARGV0_BIT 3
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#define BINPRM_FLAGS_PRESERVE_ARGV0 (1 << BINPRM_FLAGS_PRESERVE_ARGV0_BIT)
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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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#ifdef CONFIG_COREDUMP
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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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#endif
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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 __must_check remove_arg_zero(struct linux_binprm *);
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extern int begin_new_exec(struct linux_binprm * bprm);
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extern void setup_new_exec(struct linux_binprm * bprm);
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extern void finalize_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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int copy_string_kernel(const char *arg, 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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int kernel_execve(const char *filename,
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const char *const *argv, const char *const *envp);
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#endif /* _LINUX_BINFMTS_H */
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