utils: add bounds checking for Unix domain socket paths

[jnovy]

Replace unsafe strcpy() with proper length validation and strncpy() to prevent buffer overflow when copying socket paths to sockaddr_un.sun_path.

This prevents potential buffer overflow vulnerabilities when handling long socket paths.

Summary by Sourcery

Add bounds checking and safe copying for Unix domain socket paths in open_unix_domain_client_socket and open_unix_domain_socket to eliminate buffer overflow vulnerabilities.

Bug Fixes:

• Prevent potential buffer overflows when copying Unix domain socket paths by validating path length before copying

Enhancements:

• Replace unsafe strcpy() calls with bounded strncpy() and explicit null-termination
• Return ENAMETOOLONG error if socket path exceeds sockaddr_un.sun_path size

[sourcery-ai]

Reviewer's Guide

Replaces unsafe strcpy calls when assigning to sockaddr_un.sun_path with explicit length validation, strncpy, and manual null-termination to prevent buffer overflows.

Class diagram for updated Unix domain socket path handling

classDiagram
    class sockaddr_un {
        char sun_path[108]
    }
    class libcrun_error_t
    class open_unix_domain_client_socket {
        +int open_unix_domain_client_socket(const char *path, int dgram, libcrun_error_t *err)
        +// Now checks path length before copying
    }
    class open_unix_domain_socket {
        +int open_unix_domain_socket(const char *path, int dgram, libcrun_error_t *err)
        +// Now checks path length before copying
    }
    sockaddr_un <.. open_unix_domain_client_socket : uses
    sockaddr_un <.. open_unix_domain_socket : uses
    libcrun_error_t <.. open_unix_domain_client_socket : error reporting
    libcrun_error_t <.. open_unix_domain_socket : error reporting

Loading

File-Level Changes

Change	Details	Files
Introduced bounds checking and safe copy for Unix domain socket paths	Validate path length against sun_path buffer size, returning ENAMETOOLONG error on overflow Replace strcpy() with strncpy() limiting copy to sizeof(sun_path)-1 Add explicit null-termination of sun_path buffer	src/libcrun/utils.c

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[sourcery-ai]

Hey @jnovy - I've reviewed your changes and they look great!

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[giuseppe]

LGTM

[giuseppe]

since you are already computing the strlen(). Could we just store it in a variable and then use memcpy instead? That would be faster (and we don't have to drop the check for strncpy in make syntax-check)

[jnovy]

Replaced the strncpy() with memcpy() @giuseppe PTAL

[giuseppe]

LGTM