scanelf

1 &project;

scanelf

user-space utility to scan ELF files

      scanelf

       options

       ELFs
       or
       directories

### DESCRIPTION

`scanelf` is a user-space utility to quickly scan given ELFs, directories, or common system paths for different information. This may include ELF types, their PaX markings, TEXTRELs, etc...

### OPTIONS

`-A`, `--archives`

- Scan archives (.a files)

`-a`, `--all`

- Print all useful/simple info

`-B`, `--nobanner`

- Don't display the header

`-b`, `--bind`

- Print symbol binding information (lazy or now)

`-D`, `--endian`

- Print ELF endianness (big/little/...)

`-E`, `--etype` `ETYPE`

- Print only ELF files matching specified etype (like ET_DYN, ET_EXEC, etc...)

`-e`, `--header`

- Print GNU_STACK markings

`-F`, `--format` `FORMAT`

- Use specified format for output; see the FORMAT section for more information

`-f`, `--from` `FILE`

- Read input stream from specified filename

`-g`, `--gmatch`

- Use strncmp to match libraries (use with `-N`). Or regexp with symbol matching

`-h`, `--help`

- Show condensed usage and exit

`-I`, `--osabi`

- Print OSABI

`-i`, `--interp`

- Print the interpreter information (.interp/PT_INTERP)

`-k`, `--section` `SECTION`

- Find ELFs with the specified section. May be specified multiple times to match multiple sections simultaneously. See SECTION MATCHING for more info.

`-L`, `--ldcache`

- Utilize `ld.so.cache` information (use with `-r`/`-n`)

`-l`, `--ldpath`

- Scan all directories in `/etc/ld.so.conf`

`-M`, `--bits` `BITS`

- Print only ELF files matching specified numeric bits (like 32/64)

`-m`, `--mount`

- Don't recursively cross mount points

`-N`, `--lib` `SONAME`

- Find ELFs that need the specified SONAME. May be specified multiple times to match multiple SONAMEs simultaneously. See SONAME MATCHING for more info.

`-n`, `--needed`

- Print libraries the ELF is linked against (DT_NEEDED)

`-O`, `--perms` `PERMS`

- Print only ELF files with matching specified octal bits (like 755)

`-o`, `--file` `FILE`

- Write output stream to specified filename

`-p`, `--path`

- Scan all directories in PATH environment

`-q`, `--quiet`

- Only output 'bad' things

`-R`, `--recursive`

- Scan directories recursively

`-r`, `--rpath`

- Print runpaths encoded in the ELF (DT_RPATH/DT_RUNPATH)

`-S`, `--soname`

- Print the ELF's shared library name (DT_SONAME)

`-s`, `--symbol` `SYMBOL`

- Find the specified symbol; see SYMBOL MATCHING for more info

`-T`, `--textrels`

- Locate cause of TEXTRELs via objdump

`-t`, `--textrel`

- Print TEXTREL information

`-V`, `--version`

- Print version and exit

`-v`, `--verbose`

- Be verbose (can be used more than once)

`-X`, `--fix`

- Try and 'fix' bad things (use with `-r`/`-e`)

`-x`, `--pax`

- Print PaX markings

`-Y`, `--eabi`

- Print EABI (only matters for a few architectures)

`-y`, `--symlink`

- Don't scan symlinks

`-Z`, `--size` `SIZE`

- Print ELF file size

`-z`, `--setpax` `FLAGS`

- Sets EI_PAX/PT_PAX_FLAGS to specified flags (use with `-Xx`)

`--use-ldpath`

- Use the ld.so.conf paths to find the full path to libraries (use in conjunction with --needed).

`--root` `PATH`

- Search the specified root tree instead of /. Generally paired with options like -l or -p. This implicitly treats all paths specified on the command line as relative to the root, so be sure to omit it if you are explicitly listing ELFs.

`--ldcache` `PATH`

- Use specified path instead of /etc/ld.so.cache. Generally paired with options like -L or -n.

### FORMAT

The format string is much like a printf string in that it is a literal string with flags requesting different information. For example, you could use a format string and expect the following results.

      # scanelf -BF "file %f needs %n; funky time" /bin/bash
      file bash needs libncurses.so.5,libdl.so.2,libc.so.6; funky time

Note that when you use a format string, generally information related flags should be omitted. In other words, you do not want to try and request NEEDED output (`-n`) and try to specify a format output at the same time as these operations are mutually exclusive. Each information related flag has an equivalent conversion specifier, so use those instead. You can of course continue to use non-information related flags (such as `--verbose`).

There are three characters that introduce conversion specifiers.

- % - replace with info

- # - silent boolean match

- + - verbose match

And there are a number of conversion specifiers. We try to match up the specifier with corresponding option.

- a - machine (EM) type

- b - bind flags

- e - program headers

- D - endian

- I - osabi

- Y - eabi

- F - long filename

- f - short filename

- i - interp

- k - section

- M - EI class

- N - specified needed

- n - needed libraries

- p - filename (minus search)

- o - etype

- O - perms

- r - runpaths

- S - SONAME

- s - symbol

- T - all textrels

- t - textrel status

- x - pax flags

### Symbol Matching

The string specified takes the form [%[modifiers]%][[+-]<symbol name>][,[.....]].

If the `symbol name` is empty, then all symbols are matched.

If the `symbol name` is a glob ("*"), then all symbols are dumped in a debug format. Do not rely on the structure of this output as it changes whenever we feel like it.

If the first char of the symbol name is a plus ("+"), then only match defined symbols. If it's a minus ("-"), only match undefined symbols. When we say "defined", we mean the symbol is defined in the ELF vs having an external reference.

Putting modifiers in between the percent signs ("%") allows for more in depth filters. There are groups of modifiers. If you don't specify a member of a group, then all types in that group are matched.

- STT group (symbol type)

- n - STT_NOTYPE

- o - STT_OBJECT

- f - STT_FUNC

- F - STT_FILE

- STB group (symbol binding)

- l - STB_LOCAL

- g - STB_GLOBAL

- w - STB_WEAK

- STV group (symbol visibility)

- p - STV_DEFAULT

- i - STV_INTERNAL

- h - STV_HIDDEN

- P - STV_PROTECTED

- SHN group (section header)

- d - defined

- u - SHN_UNDEF

- a - SHN_ABS

- c - SHN_COMMON

You can search for multiple symbols simultaneously by using a comma (",") to separate different searches. Every symbol that matches will be displayed while unmatched symbols will not.

### ELF ETYPES

You can narrow your search by specifying the ELF object file type (ETYPE). The commandline option takes the numeric value and or symbolic type. Multiple values can be passed comma separated. Example -E ET_EXEC,ET_DYN,1

Here is the normal list available for your pleasure. You of course are free to specify any numeric value you want.

- 0 - ET_NONE - unknown type

- 1 - ET_REL - relocatable file

- 2 - ET_EXEC - executable file

- 3 - ET_DYN - shared object

- 4 - ET_CORE - core file

### ELF BITS

You can also narrow your search by specifying the ELF bitsize. Again, specify the numeric value or the symbolic define.

- 32 - ELFCLASS32 - 32bit ELFs

- 64 - ELFCLASS64 - 64bit ELFs

### Section Matching

A ! prefix will only show ELF's that do not have the specified section.

### Needed SONAME Matching

A ! prefix will only show ELF's that do not depend on the specified library.

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