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Subject[PATCH 10/15] binfmt_flat: make support for old format binaries optional
Date
No need to carry the extra code around, given that systems using flat
binaries are generally very resource constrained.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/Kconfig.binfmt | 7 +++++++
fs/binfmt_flat.c | 29 +++++++++++++++++++++--------
2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 286b425b30b9..62dc4f577ba1 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -106,6 +106,13 @@ config BINFMT_FLAT_ARGVP_ENVP_ON_STACK
config BINFMT_FLAT_OLD_ALWAYS_RAM
bool

+config BINFMT_FLAT_OLD
+ bool "Enable support for very old legacy flat binaries"
+ depends on BINFMT_FLAT
+ help
+ Support decade old uClinux FLAT format binaries. Unless you know
+ you have some of those say N here.
+
config BINFMT_ZFLAT
bool "Enable ZFLAT support"
depends on BINFMT_FLAT
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 6c1848dee724..ed7d969593d2 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -374,6 +374,7 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)

/****************************************************************************/

+#ifdef CONFIG_BINFMT_FLAT_OLD
static void old_reloc(unsigned long rl)
{
static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
@@ -411,6 +412,7 @@ static void old_reloc(unsigned long rl)

pr_debug("Relocation became %lx\n", val);
}
+#endif /* CONFIG_BINFMT_FLAT_OLD */

/****************************************************************************/

@@ -461,6 +463,7 @@ static int load_flat_file(struct linux_binprm *bprm,
if (flags & FLAT_FLAG_KTRACE)
pr_info("Loading file: %s\n", bprm->filename);

+#ifdef CONFIG_BINFMT_FLAT_OLD
if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
pr_err("bad flat file version 0x%x (supported 0x%lx and 0x%lx)\n",
rev, FLAT_VERSION, OLD_FLAT_VERSION);
@@ -476,6 +479,22 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}

+ /*
+ * fix up the flags for the older format, there were all kinds
+ * of endian hacks, this only works for the simple cases
+ */
+ if (IS_ENABLED(CONFIG_BINFMT_FLAT_OLD_ALWAYS_RAM) &&
+ rev == OLD_FLAT_VERSION)
+ flags = FLAT_FLAG_RAM;
+#else /* CONFIG_BINFMT_FLAT_OLD */
+ if (rev != FLAT_VERSION) {
+ pr_err("bad flat file version 0x%x (supported 0x%lx)\n",
+ rev, FLAT_VERSION);
+ ret = -ENOEXEC;
+ goto err;
+ }
+#endif /* !CONFIG_BINFMT_FLAT_OLD */
+
/*
* Make sure the header params are sane.
* 28 bits (256 MB) is way more than reasonable in this case.
@@ -487,14 +506,6 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}

- /*
- * fix up the flags for the older format, there were all kinds
- * of endian hacks, this only works for the simple cases
- */
- if (IS_ENABLED(CONFIG_BINFMT_FLAT_OLD_ALWAYS_RAM) &&
- rev == OLD_FLAT_VERSION)
- flags = FLAT_FLAG_RAM;
-
#ifndef CONFIG_BINFMT_ZFLAT
if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
pr_err("Support for ZFLAT executables is not enabled.\n");
@@ -833,6 +844,7 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}
}
+#ifdef CONFIG_BINFMT_FLAT_OLD
} else {
for (i = 0; i < relocs; i++) {
__be32 relval;
@@ -840,6 +852,7 @@ static int load_flat_file(struct linux_binprm *bprm,
return -EFAULT;
old_reloc(ntohl(relval));
}
+#endif /* CONFIG_BINFMT_FLAT_OLD */
}

flush_icache_range(start_code, end_code);
--
2.20.1
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