5.10-stable review patch. If anyone has any objections, please let me know.
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From: Laurent Vivier laurent@vivier.eu
commit 2347961b11d4079deace3c81dceed460c08a8fc1 upstream.
It can be useful to the interpreter to know which flags are in use.
For instance, knowing if the preserve-argv[0] is in use would allow to skip the pathname argument.
This patch uses an unused auxiliary vector, AT_FLAGS, to add a flag to inform interpreter if the preserve-argv[0] is enabled.
Note by Helge Deller: The real-world user of this patch is qemu-user, which needs to know if it has to preserve the argv[0]. See Debian bug #970460.
Signed-off-by: Laurent Vivier laurent@vivier.eu Reviewed-by: YunQiang Su ysu@wavecomp.com URL: http://bugs.debian.org/970460 Signed-off-by: Helge Deller deller@gmx.de Cc: Thorsten Glaser tg@debian.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/binfmt_elf.c | 5 ++++- fs/binfmt_elf_fdpic.c | 5 ++++- fs/binfmt_misc.c | 4 +++- include/linux/binfmts.h | 4 ++++ include/uapi/linux/binfmts.h | 4 ++++ 5 files changed, 19 insertions(+), 3 deletions(-)
--- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -186,6 +186,7 @@ create_elf_tables(struct linux_binprm *b unsigned char k_rand_bytes[16]; int items; elf_addr_t *elf_info; + elf_addr_t flags = 0; int ei_index; const struct cred *cred = current_cred(); struct vm_area_struct *vma; @@ -260,7 +261,9 @@ create_elf_tables(struct linux_binprm *b NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr)); NEW_AUX_ENT(AT_PHNUM, exec->e_phnum); NEW_AUX_ENT(AT_BASE, interp_load_addr); - NEW_AUX_ENT(AT_FLAGS, 0); + if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0) + flags |= AT_FLAGS_PRESERVE_ARGV0; + NEW_AUX_ENT(AT_FLAGS, flags); NEW_AUX_ENT(AT_ENTRY, e_entry); NEW_AUX_ENT(AT_UID, from_kuid_munged(cred->user_ns, cred->uid)); NEW_AUX_ENT(AT_EUID, from_kuid_munged(cred->user_ns, cred->euid)); --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -506,6 +506,7 @@ static int create_elf_fdpic_tables(struc char __user *u_platform, *u_base_platform, *p; int loop; int nr; /* reset for each csp adjustment */ + unsigned long flags = 0;
#ifdef CONFIG_MMU /* In some cases (e.g. Hyper-Threading), we want to avoid L1 evictions @@ -648,7 +649,9 @@ static int create_elf_fdpic_tables(struc NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr)); NEW_AUX_ENT(AT_PHNUM, exec_params->hdr.e_phnum); NEW_AUX_ENT(AT_BASE, interp_params->elfhdr_addr); - NEW_AUX_ENT(AT_FLAGS, 0); + if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0) + flags |= AT_FLAGS_PRESERVE_ARGV0; + NEW_AUX_ENT(AT_FLAGS, flags); NEW_AUX_ENT(AT_ENTRY, exec_params->entry_addr); NEW_AUX_ENT(AT_UID, (elf_addr_t) from_kuid_munged(cred->user_ns, cred->uid)); NEW_AUX_ENT(AT_EUID, (elf_addr_t) from_kuid_munged(cred->user_ns, cred->euid)); --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -191,7 +191,9 @@ static int load_misc_binary(struct linux if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) goto ret;
- if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) { + if (fmt->flags & MISC_FMT_PRESERVE_ARGV0) { + bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0; + } else { retval = remove_arg_zero(bprm); if (retval) goto ret; --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -73,6 +73,10 @@ struct linux_binprm { #define BINPRM_FLAGS_PATH_INACCESSIBLE_BIT 2 #define BINPRM_FLAGS_PATH_INACCESSIBLE (1 << BINPRM_FLAGS_PATH_INACCESSIBLE_BIT)
+/* preserve argv0 for the interpreter */ +#define BINPRM_FLAGS_PRESERVE_ARGV0_BIT 3 +#define BINPRM_FLAGS_PRESERVE_ARGV0 (1 << BINPRM_FLAGS_PRESERVE_ARGV0_BIT) + /* Function parameter for binfmt->coredump */ struct coredump_params { const kernel_siginfo_t *siginfo; --- a/include/uapi/linux/binfmts.h +++ b/include/uapi/linux/binfmts.h @@ -18,4 +18,8 @@ struct pt_regs; /* sizeof(linux_binprm->buf) */ #define BINPRM_BUF_SIZE 256
+/* preserve argv0 for the interpreter */ +#define AT_FLAGS_PRESERVE_ARGV0_BIT 0 +#define AT_FLAGS_PRESERVE_ARGV0 (1 << AT_FLAGS_PRESERVE_ARGV0_BIT) + #endif /* _UAPI_LINUX_BINFMTS_H */